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[Display omitted] • Relationship between CaO intrinsic properties and bio-oil components was explored. • Adsorption energy of RS pyrolysis products on CaO was calculated by DFT simulation. • Modification with acid enhanced the length of Ca-O bond and strong basic sites. • Longer Ca-O bond promoted the conversion of cellulose/hemicellulose into ketones. CaO modified with acetic acid solution or sodium hydroxide (H-CaO/OH-CaO) was used to explore the relationship between the physical and chemical properties of CaO and the components of bio-oil during the pyrolysis of rice straw (RS) and model compounds via experiment and density functional theory(DFT) simulation. The results showed that the modification changed the properties of CaO, and thus the catalytic performance on production of bio-oil components. H-CaO with the larger number of strong basic sites (1.10 ∼ 2 times than commercial CaO) and the longer Ca-O bond length showed the better selectivity and performance on formation of ketones (the maximum relative content in bio-oil reached 43 %). The conversion pathway of cellulose/hemicellulose was changed by H-CaO, which promoted the formation of ketones. The easier combining of H-CaO with the pyrolysis primary products due to the longer Ca-O bond was the key to its better performance. [ABSTRACT FROM AUTHOR]

N-doped carbon catalysts were prepared using corn straw (CS) and cow manure (CD) as carbon and N resources, and used for the CS catalytic fast pyrolysis in Py-GCMS to improve the quality of bio-oil products. Through the methods combining hydrothermal treatment and carbonization, the N from CD was efficiently fixed into the straw biochar, showing the better catalytic effect. The moderate carbonization temperature (600 °C) and the lower HTC temperature benefited the improvement of N-doped biochars on the relative content of phenols in bio-oil, with the maximum increment of 8.32%. The pyridinic-N and pyrrolic-N in N-doped biochars mainly enhanced the relative content rather than the yields of phenols and ketones, respectively. Compared with the surface area and the degree of disorder, the types and content of N species in N-doped biochar had the greater promoting effect on the relative content of phenols in bio-oil. [Display omitted] • N from cow dung was fixed into straw biochar, showing the better catalytic effect. • NC3-180-200-600 increased the proportion of phenols in bio-oil by 8.32%. • Pyrrolic-N enhanced the selectivity of N-doped biochar catalyst for ketones. • Pyridinic-N enhanced the selectivity of N-doped biochar catalyst for phenols/ketones. [ABSTRACT FROM AUTHOR]

• A VFB-LIBS online system was applied for the in-situ detection of released AMs. • The concentration of released AMs in gaseous phase was quantitatively measured. • The temporal release of AMs can be limited in the whole pyrolysis. • The higher content of C = O in coal, the stronger limitation on the release of AMs. • The inhibition of OCFG was not selective for the release of K and Na. Co-pyrolysis of coal and biomass is a promising technology for clean and efficient utilization of these two carbon resources. In this study, a visual fixed bed (VFB) combined with laser-induced breakdown spectroscopy (LIBS) was applied to investigate the effect of O-containing functional groups (OCFG) in coal on the release of alkali metals (AMs) during the co-pyrolysis of coal and biomass. The results showed that low temperature pre-oxidation increased the content of OCFG in coal, especially C=O and O–C=O groups, and limited the release of AMs during the co-pyrolysis. The higher pre-oxidation degree, the stronger limitation on the release of AMs. The increase of OCFG declined the maximum release concentrations of AMs and the temporal release of AMs in the whole pyrolysis process rather than some period. The release ratio of AMs can be maximally reduced about 39% by the OCFG. The relationship between release of AMs and structure of chars during the pyrolysis was also investigated. It was obtained that the layering placement of biomass and coal showed the less volatilization of AMs than the mixing placement of them. This study provided the theoretical basis for mitigating equipment corrosion problems caused by AMs in industrial applications. [ABSTRACT FROM AUTHOR]

Biomass catalytic pyrolysis is a promising way for the clean and even "Carbon-Negative" utilization of biomass via the in-situ upgrading bio-oil and reducing the emissions of CO 2. In this work, CaO microspheres (CaO-H) prepared via hydrothermal method were used to adsorb CO 2 and catalyze the reforming of bio-oil in the pyrolysis process of rice straw (RS) simultaneously. The results showed that CaO-H had the more strong basic sites compared with commercial CaO and thus the better adsorption capacity of CO 2 (∼0.5 g/g CaO) at 700 °C and the stronger effect on the generation of bio-oil components and CO 2. And strong relationships presented between the formation of CO 2 and the composition of bio-oil. The yield of phenols and ketones can be enhanced by 37.17% and 56.76% respectively via the addition of CaO-H at the pyrolysis temperature of 650 °C, companying with the decrease of CO 2 yield by 35.13%. It is also inferred that the CO 2 reforming of bio-oil and the insertion of C O in CO 2 into bio-oil components was strengthened during the biomass pyrolysis over CaO-H especially at the temperature of 650 °C. The possible mechanism of biomass pyrolysis over CaO-H was also proposed. • Using CaO microsphere to adsorb CO 2 and catalyze bio-oil reforming simultaneously. • CaO microsphere had more strong-basic sites and better adsorption capacity of CO 2. • Temperature and strong basic sites affected the dynamically catalytic roles of CaO. • Relationship between the production of CO 2 and bio-oil components was explored. [ABSTRACT FROM AUTHOR]

The effect of H 2 addition on CH 4 decomposition over activated carbon (AC) catalyst was investigated. The results show that the addition of H 2 to CH 4 changes both methane conversion over AC and the properties of carbon deposits produced from methane decomposition. The initial methane conversion declines from 6.6% to 3.3% with the increasing H 2 flowrate from 0 to 25 mL/min, while the methane conversion in steady stage increases first and then decreases with the flowrate of H 2 , and when the H 2 flowrate is 10 mL/min, i.e. quarter flowrate of methane, the methane conversion over AC in steady stage is four times more than that without hydrogen addition. It seems that the activity and stability of catalyst are improved by the introduction of H 2 to CH 4 and the catalyst deactivation is restrained. Filamentous carbon is obtained when H 2 is introduced into CH 4 reaction gas compared with the agglomerate carbon without H 2 addition. The formation of filamentous carbon on the surface of AC and slower decrease rate of surface area and pores volume may cause the stable activity of AC during methane decomposition. [ABSTRACT FROM AUTHOR]

Activated carbon (AC) was prepared from a subbituminous coal with addition of Ca(NO 3 ) 2 by KOH activation, and used for catalytic methane decomposition to produce hydrogen. The effects of calcium addition amount on the structure and catalytic performance of the resultant ACs were investigated. As the addition of Ca(NO 3 ) 2 , the surface area and pore volume of ACs increase significantly compared with that of AC without addition, especially the mesoporous surface area improved from 480 m 2 /g to 1119 m 2 /g. Almost hyaline structure of carbons are obtained when a high amount of calcium is added into the coal. The addition of calcium in coal leads to the significant increase of methane conversion over the resultant carbon catalysts, and when the calcium addition amount is 15 wt%, the prepared AC has the highest mesoporous surface area and the best stability. No direct relationship was found between specific surface area and the activity of carbons, but the mesopores benefit the stability of ACs in methane decomposition. Carbon fiber was produced on AC from the coal with addition of calcium compared with the aggregated carbon on that from coal without addition of calcium. [ABSTRACT FROM AUTHOR]

[Display omitted] • Visual fixed bed combined with LIBS was applied for the detection of released alkali metals. • The concentration of released alkali metals was quantitatively measured. • Synergy effect between RS and YCW suppressed significantly the release of alkali metals. • Relation between disorder degree of char and release concentration of alkali metals was obtained. In this article, a visual fixed bed (VFB) combined with laser-induced breakdown spectroscopy (LIBS) was innovatively applied to investigate the in-situ release characteristics of alkali metals during fast co-pyrolysis of coal and biomass. The concentration of released alkali metals in gas phase was measured and used to reflect their temporal release behavior. The results showed that the release of alkali metals first increased and then decreased over time. The pyrolysis temperature, mass ratio of biomass to coal, and minerals in coal had little effect on the temporal release trends but seriously affected the release concentration extremity of alkali metals. Moreover, the interaction between coal and biomass caused the less release of alkali metals during the co-pyrolysis than biomass pyrolysis. This study benefited the better understanding on the release of alkali metals and the further industrial application of coal and biomass co-pyrolysis. [ABSTRACT FROM AUTHOR]

Oxidization is considered to be an indispensable step for coals with thermoplastic properties to act as the precursor of activated carbon (AC). In this work, the effect of oxidization conditions of coal on the texture and surface properties of resultant ACs and their catalytic performances in decomposition of methane to hydrogen were investigated. The results show that the surface oxygen containing groups of the resultant ACs changed, the surface area of ACs increases from 1892 m 2 /g to 2407 m 2 /g, and the mesoporosity significantly increases after the precursor coal is pre-oxidized. The ACs from oxidized coals show higher catalytic activities in methane decomposition reaction than that from raw coal. The ACs prepared from oxidized coal at 373 K show the best stability while the AC from the oxidized coal at 573 K for 4 h exhibits the highest initial activity among the ACs. Additionally, the oxidization time has a negative effect on initial activities but little positive influence on stability of ACs when the precursor is oxidized at 373 K. It is thought that the increased mesoporosity is beneficial to the catalytic activity and stability of AC in methane decomposition to hydrogen. [ABSTRACT FROM AUTHOR]

In this study, the volatile–char interaction in coal and cow manure co-pyrolysis process was decoupled by adding internals in a two-stage fixed bed reactor, and the effect of vapor-residence time on coal char reactivity at 850 °C was investigated. The results indicated that the volatile–char interaction inhibited coal char reactivity, but the inhibition showed an opposite rule with the vapor-residence time in different co-pyrolysis modes. The reformed gas-phase volatiles entered the macromolecular framework of coal and generated PAHs, increasing the aromatization degree and large aromatic rings numbers of char, resulting in the reduction of the O-containing functional groups and the behavioral effects of C–O and C O being particularly pronounced. The interaction promoted the release of Na/K, and the release behavior changed when only volatile−volatile interaction existed in the co-pyrolysis samples. The reduction of O-containing functional groups resulted in the loss of active sites number after the interaction, AAEM showed limited catalytic behavior. The O-containing functional groups and cross-linking structure act as active sites in the interaction process. This work is beneficial to enrich and develop the synergistic transformation theoretical system of carbon-containing energy materials, and provides theoretical support for promoting the industrial application of related technologies. • The interaction behaviour in the biomass and coal co-pyrolysis process was decoupled. • Multifaceted characterization of the in-situ interacting char carbon chemical structure. • The increase of vapor-residence time promoted the precipitation of Na and K. • The interaction process was not conducive to the cracking of alkyl aryl ether. • C–O, C O content and cross-linking structure act as active sites in the interaction. [ABSTRACT FROM AUTHOR]

• The application of IWC as a cheap catalyst for PC CO 2 gasification was evaluated • IWC can significantly improve the reactivity of PC at different temperatures • The catalytic effect of IWC is weakened when the temperature exceeds 1100 °C • Possible catalytic mechanism of IWC catalytic PC CO 2 gasification was proposed In this study, the influence of iron-based waste catalyst (IWC) from F-T synthesis as a cheap additive on the gasification reaction characteristics of petroleum coke (PC) with CO 2 at 1000–1300°C was investigated by thermogravimetric analyzer. The gasification kinetics of PC was analyzed by free model method. The surface complexes of PC were determined through temperature-programmed desorption (TPD) methods to reveal the mechanism of IWC catalytic PC gasification. The results show that IWC is an efficient PC gasification catalyst and can reduce the activation energy of PC CO 2 gasification. The induction of iron in IWC makes the surface of PC have more activated carbon sites, thereby forming more oxygen-containing intermediates, and the cyclic redox reaction of iron can act as an oxygen carrier to accelerate the reaction of CO 2 and carbon, both of these may be the essential reasons for the CO 2 gasification of PC catalyzed by IWC. [Display omitted] [ABSTRACT FROM AUTHOR]

• The pyrolysis activation energy of iron based waste catalysts containing wax is in 126–331 kJ/mol. • Olefins of C 5 -C 20 are the main products at the wax pyrolysis of 900 °C. • The used iron based catalyst can be converted to active Fe metal during the pyrolysis. • Possible multi-step pyrolysis mechanism of iron based waste catalysts is proposed. The pyrolysis process was a promising technology for the clean, efficient and resource utilization of iron-based waste catalysts containing wax (IWC) produced from Fisher-Tropsch synthesis. In this study, TG and Py-GCMS were used to investigate the pyrolysis characteristics of IWC. The results showed that the main pyrolysis temperature range of IWC was 200–500 °C, attributed to the decomposition of wax. Iron species in IWC were converted to Fe metal at >500 °C and slightly promoted the pyrolysis of wax. The tar components produced at low temperature were mainly alkanes of C 21+ and C 11 C 20 , but linear alpha olefins of C 5 C 20 and few dienes at higher temperature. It was also concluded that some aromatics were also produced from IWC especially at above 700 °C. TG and kinetic analyses demonstrated that pyrolysis of IWC occurred in a three-stage reaction with activation energy in the range of 126–331 kJ/mol. A possible pyrolysis mechanism of IWC was also proposed. [ABSTRACT FROM AUTHOR]

The iron-based waste catalysts (IWC) from Fisher-Tropsch synthesis, as a kind of waste containing abundant hydrocarbons and iron species, can be treated by the co-pyrolysis technology to realize the clean, efficient utilization of waste and coal. In this study, the synergistic effect and co-pyrolysis characteristics of IWCs and a bituminous coal were investigated by TG-MS and Py-GCMS. The results show that the co-pyrolysis of IWCs and coal occurs primarily in the range of 200–500 °C. The tar composition from the co-pyrolysis of coal and IWC 1 composed of paraffins is mainly aliphatic acids and olefins, while the co-pyrolysis of coal and IWC 2 with higher content of mineral matters principally yields aromatics and phenols. The strength of synergistic effect between coal and IWCs is enhanced by the increasing mass ratio of IWCs to coal and affected by the co-pyrolysis temperature, but the effects of temperature in the range of 200–400 °C and 400–500 °C are almost opposite. These changes of strength are related to the content of paraffins and iron species in IWCs, promoting or limiting the release of volatiles and changing the content of tar components, especially the content of aliphatic acids. The gas composition is also affected by the interaction. This study provides a basis for the further clean co-utilization of iron based waste catalysts from FT synthesis process and coal. • Co-pyrolysis of iron based waste catalysts and coal improves the yield of volatiles from coal. • The variation of weight difference with temperature was used to judge the interaction. • Co-pyrolysis temperature has different effects on the synergies in different stages. • The strength of synergies is attributed to the content of iron species and paraffins in waste. [ABSTRACT FROM AUTHOR]

The Cu/CeO2-nanopolyhedrals and pure Cu/CeO2-nanorods with different sizes were synthesized for CO2 hydrogenation to methanol. With increasing the percentage composition of CeO2 nanorods, the surface concentrations of Cu+, Ce3+ and oxygen vacancies were gradually enhanced. However, the amount of surface Cu+ species and oxygen vacancies would be decreased instead if the size of pure CeO2 nanorods was too large. The variation tendency of catalytic performance for CO2 hydrogenation to methanol was well consistent with that of Cu+ species and oxygen vacancies. Cu/CeO2 nanorods with small size exhibited the strongest interaction in Cu-CeO2 interface and the highest methanol production activity among all Cu/CeO2 nano-catalysts. The small size of CeO2-nanorods obtained at NaOH concentration of 10 mol/L, hydrothermal temperature of 80 °C and hydrothermal time of 24 h showed the best catalytic performance (XCO2 = 5.8%, SCH3OH = 92.0%, YCH3OH = 5.3%) at 280 °C and 3 MPa. The stronger interaction accelerated the charge transfer between CuOx species and CeO2 nanorods, which produced the larger amount of surface Cu+ species and oxygen vacancies. The synergistic effect between reduced Cu species and oxygen vacancies improved methanol selectivity and was responsible for CO2 hydrogenation to methanol. [ABSTRACT FROM AUTHOR]

• Volatile–char interactions inhibited the gasification reactivity of coal char. • Five volatile–char interaction modes were designed and studied in detail. • The aromatic C-O was particularly important in char reactivity. • Volatile-char interaction and secondary cracking reduced the amorphous carbon structure. • Volatile–char interaction inhibits the cracking of alkyl aryl ethers. Cow manure is a special biological waste with potential for energy utilization and heat recovery. Various aspects of biomass utilization process is affected by volatile – char interaction. In order to reveal the changes of chemical structure and reactivity of coal char induced by cow manure biomass volatile–coal char interactions, five types of volatile–char contact modes were designed to obtain coal chars through fixed bed reactor. Fourier infrared transform spectroscopy (FT – IR), X-ray photoelectron spectroscopy (XPS), temperature programmed oxidation (TPO), and laser Raman spectroscopy (Raman) were used to analyze the change of char chemical structure. The results indicate that the type and content of O-containing functional groups have important influence on char reactivity, and the aromatic C – O is particularly obvious. Volatile–char interactions lead to the decrease of the gasification reactivity which is attribute to the decreased aromatic C – O, C = O and increased graphite carbon structures in coal char. By the deconvolution of the TPO curves, it found that the volatile–char interaction inhibits the cracking of alkyl aryl ethers structures. This work is helpful to understand the mechanism of volatile–char interaction on the structure evolution of coal char. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization (HTC) followed by gasification technology is a promising process to realize the high efficient and clean utilization of municipal solid waste (MSW). However, the complex components of MSW made it difficult to understand the gasification mechanism. In this paper, the individual and co-HTC coupled with gasification of three typical components of MSW (disposable bamboo chopsticks (DBC), waste paper (WP) and peanut shells (PS)) were investigated to reveal their interactions and the combining effect of interactions and HTC on the gasification reactivity. The results showed that the antagonistic effect existed between WP and PS during the co-HTC process, reducing the yield of co-hydrochar. For WP and DBC, the synergistic effect between them was present during the co-HTC at the WP proportion of 25 %, but changed into an antagonistic effect at the higher proportion. The gasification reactivity of DBC and PS was dramatically decreased by HTC treatment because of the remove of active minerals or the increase of aromatization degree, but significantly improved via the addition of WP due to the significant synergistic effect between their hydrochars. Retention of Ca element and the higher content of volatiles in WP were two possible factors causing the synergistic effect during the co-gasification. • Investigated individual and co-HTC/gasification of typical components in MSW. • Interaction between DBC/WP with PS during the co-HTC/gasification were revealed. • The addition of WP improved the gasification reaction activity of DBC/PS. • Alkali metals was main factor affecting the gasification reactivity of MSW. [ABSTRACT FROM AUTHOR]

• The effect of CDA on ash fusion behavior of high-silicon-aluminum coal was discussed. • Mullite with a skeleton structure was the main reason for high AFTs of SHA. • By adding CDA, low-melting-temperature minerals, anorthite and chlorapatite formed. • The melting flow behavior of ash was studied by in-situ visualization technique. The influence of cow dung ash (CDA) additive on the ash fusion characteristics of high-silicon-aluminum coal ash (SHA) was investigated using ash fusion temperature analyzer (AFTA), X-ray diffraction (XRD), thermogravimetric analyzer (TG-DSC) and FactSage thermodynamics software. In order to clarify the shrinkage/expansion and flow behavior of ash, high-temperature heating stage coupled with optical microscope (HSOM) was used to record the morphological change of ash in the heating process. The results show that the ash fusion temperatures (AFTs) decreased firstly and then increased with the addition of CDA. There was a minimum value of AFTs when the addition amount of CDA was 60%. Due to the high content of silicon and aluminum in SHA, the mullite with skeleton structure became the main crystalline phase in molten ash, which led to the high AFTs of SHA. The addition of CDA resulted in the increase of calcium and phosphorus in coal ash. Consequently, low-melting-temperature minerals such as anorthite and chlorapatite, which were responsible for the decrease in AFTs of blended ash, would be formed. With the continuous addition of CDA, the decrease of amorphous content led to the increase of AFTs. According to the results of ash fusion characteristics, SHA melting process only underwent the sintering stage due to the high AFTs, and its ash fusion behavior followed "softening-melting" mechanism. For CDA and blended ash (60% CDA), the melting process went through the sintering and melting stages, and the ash fusion behavior followed the "melting-dissolution" mechanism. [ABSTRACT FROM AUTHOR]

Co-pyrolysis of coal and biomass has an important function on high efficient and clean utilization of coal and biomass. Effect of CaO additive on the co-pyrolysis behavior of Meihuajing (MHJ) bituminous coal and cow dung (CD) and the synergistic effect between them were investigated by using TG and Py-GC/MS. The results show that both the heating rate and the addition of CaO have an important influence on the co-pyrolysis of coal and cow dung. As the heating rate increases from 5 to 25 °C/min, the negative synergistic effect for the yield of char weakens during the co-pyrolysis when no CaO is added to the MHJ and CD. CaO partly delays the pyrolysis of CD and declines the pyrolysis temperature of MHJ, providing an overlapping pyrolysis range for the two fuels at around 370 °C. The synergies between CD and MHJ are enhanced by the addition of CaO during their co-pyrolysis at the range of 350 to 450 °C. The positive role of CaO increases with the increasing heating rate, and reaches its maximum at the heating rate of 15 °C/min. It is also worth noting that the addition of CaO raises the content of high-valued tar products such as benzenes and nephthalenes. [ABSTRACT FROM AUTHOR]

A novel in-situ pyrolysis-electron impact ionization time of flight mass spectrometry (Py-EI-TOFMS) combining with isotope tracing was first used to investigate the mechanism of methane decomposition with hydrogen addition over activated carbon (AC). The results show that free radicals produced from decomposition of methane labelled by four deuterium atoms (CD 4) are directly detected by in-situ Py-EI-TOFMS. The breakage of first C-D bond is the control step of CD 4 decomposition. During CD 4 decomposition with hydrogen addition, the added hydrogen takes part in the free radical reaction process, promotes the decomposition and improves catalytic stability of AC. Two reactions happen during the CD 4 decomposition with hydrogen addition, including CD 4 cracking to free radicals and hydrogen reacting with the free radicals. The former produces D 2 molecules by combining of two D free radicals, while the latter generates more HD molecules than D 2. It is inferred that the addition of H 2 declines the collision between CD 4 molecules or CD x free radicals, and stabilizes the produced CD x free radicals from CD 4 decomposition over AC, leading to the enhancement of CH 4 conversion and catalytic stability. This work provides a deep insight of H 2 promotion on CH 4 decomposition over AC. [ABSTRACT FROM AUTHOR]

The kinetics and thermal behaviors of cow manure (CM) and Meihuajing bituminous coal (MHJ) blending from room temperature to 950°C were investigated by thermal gravimetric analyzer (TGA) coupled with differential scanning calorimetry (DSC) and mass spectrometer (MS). TG curves show that the high heating rate accelerates thermal decomposition rate, and the position of differential thermal gravity (DTG) peaks shifts to a higher temperature. Owing to the heat transfer limitation phenomenon, the residual weight of CM is only 40.38% with the heating rate of 1°C/min in comparison with other heating rate. DSC takes more time to reach a steady state than TGA. Gaseous evolution curves of HCN and NH3 were obtained during the pyrolysis of blends based on TG–MS experiments. With the increased heating rate, the emissions increased a lot due to the secondary reaction of volatiles. The Eα of 1C1M obtained using Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO), Friedman, and Kissinger methods is within 124.58–317.18, 121.97–321.11, 150.28–331.64, and 209.26 kJ/mol, respectively. The kinetic parameters calculated based on four model‐free kinetic modeling methods shows good agreement. And the thermodynamic parameters were obtained and discussed under different conversion rates. This work is greatly important to understand the co‐prolysis mechanism of CM and coal and to design the pyrolysis reactors. [ABSTRACT FROM AUTHOR]

Understanding the methane-hydrogen lifted flame behavior is significant for improving the stability and safety of practical combustion systems. In this study, the effects of the hydrogen addition ratios and oxygen-fuel ratio on the lifted flame stability, OH* chemiluminescence distribution, and lift-off height are investigated using spectral diagnostic techniques. The results show that the addition of hydrogen can enhance the stability of lifted flame. The flame exists in a single main reaction zone and the peak intensity decreases as the hydrogen addition ratio increases. The flame lift-off height decreases as the hydrogen addition ratio increases at low oxygen-fuel ratios, but there is an opposite trend at high oxygen-fuel ratios. In addition, a fitting line is obtained by considering the effect of co-flow to summarize the effect of jet velocity variation on flame lift-off height after hydrogen addition and the fitting correlation is well established. [Display omitted] • The OH* chemiluminescence characterize of lifted flame is investigated. • The stability of methane/oxygen lifted flame is greatly improved by adding hydrogen. • The lift-off height is related to the oxygen-fuel ratio and hydrogen addition ratio. • The dimensionless correlation between jet velocity and lift-off height is obtained. [ABSTRACT FROM AUTHOR]

Cu/ZnO/C–P were prepared via the deposition-precipitation for CO 2 hydrogenation to methanol. At 280 °C, Cu/ZnO/C–P reached the maximum methanol space-time yield (STY) of 0.66 g CH3OH ·g cat −1·h−1, significantly higher than Cu/ZnO (0.48 g CH3OH ·g cat −1·h−1). The addition of C–P escalated the reduction of Cu2+ and made Cu/ZnO interface much tighter. Phosphorus-doped Carbon (C–P) was not only favorable for the formation of Cu/ZnO contact interfaces and boosted Cu0 amount at the Cu/ZnO interfaces, but also further strengthened the interaction between Cu0 and ZnO. Cu0/ZnO interfaces also improved the adsorption and activation of CO 2 and H 2 , eventually advanced methanol formation. The variation trend between methanol STY and Cu0 species content at the Cu/ZnO interface was in good agreement with each other. Cu0 species strongly interacted with ZnO at the Cu/ZnO contact interfaces may be indispensable for methanol generation on Cu/ZnO/C–P. The Cu0/ZnO interface serves as the active center to efficiently escalate CO 2 hydrogenation to methanol. [Display omitted] • Phosphorus-doped carbon materials were synthesized using a simple hydrothermal method. • C–P promoted the generation of Cu/ZnO interfaces and enhanced the interaction between Cu0 and ZnO. • Cu0/ZnO interfaces were the active sites of Cu/ZnO/C–P for CO 2 hydrogenation to methanol. • Cu/ZnO modified by appropriate amount of C–P promoted the methanol formation. [ABSTRACT FROM AUTHOR]

This study investigates the impact of H 2 addition on soot formation in inverse diffusion flame (IDF) and explores the underlying mechanism of flame structure on soot formation. Experimental measurements and simulation kinetic calculations were performed to explore the influence of free radical (OH*/CH*/C 2 */CO 2 *) chemiluminescence on soot formation mechanism. The investigation ultimately determines the relationship between free radical chemiluminescence and soot formation. The findings reveal that similar to the simulation results, the peak soot volume fraction (SVF) is reduced by approximately 60 % when the hydrogenation increases to 40 %, and the initial soot production position moves downstream of the flame. The free-radical chemiluminescence distribution is mainly concentrated at the burner exit, where the increase in hydrogen concentration leads to a decrease in CH* and C 2 * and an increase in OH* content in the flame. The blue region on the fuel side is consistent with the peak CH* and C 2 * emission region. In the soot formation, the chemiluminescence signal of free radicals is suppressed, indicating that soot formation and free radical chemiluminescence are antithetical. The results of the component yields indicate that soot formation and chemiluminescence are fueled by gas phase components (CH 3 , C 2 H 3 , C 2 H 2 , etc.) and there are generated in opposite pathways, which supports the above statement. Furthermore, the increase of hydrogen content inhibits the production of C 2 H and CH 2 , resulting in the decrease of C 2 *, CH* and CO 2 * radical chemiluminescence by 77.0 %, 75.1 % and 81.2 %, respectively. The decrease of soot concentration is primarily due to the increase of H 2 , which hinders the formation of C 3 H 3 and C 4 H 5 -2. • The different effects of H 2 addition on soot generation and free radical chemiluminescence were determined. • The antiposition relationship between soot generation and free radical chemiluminescence was clarified. • Soot and chemiluminescence reaction pathways were analyzed to gain insight into how H 2 addition affects these pathways. [ABSTRACT FROM AUTHOR]

The co-gasification of biomass and coal is helpful for achieving the clean and efficient utilization of phosphorus-rich biomass. A large number of alkali and alkaline earth metals (AAEMs) present in the ash system of coal (or biomass) cause varying degrees of ash, slagging, and corrosion problems in the entrained flow gasifier. Meanwhile, phosphorus is present in the slag in the form of PO 4 3 − , which has a strong affinity for AAEMs (especially for Ca2+) to produce minerals dominated by calcium phosphates or alkaline Ca-phosphate, effectively mitigating the aforementioned problems. To investigate the changing behavior of the slag flow temperature (FT) under different CaO/P2O5 ratios, 72 synthetic ashes with varying CaO/P2O5 ratios at different Si/Al contents and compositions were prepared, and their ash fusion temperatures were tested. The effects of different CaO/P2O5 ratios on the FT were analyzed using FactSage thermodynamic simulation. A model for predicting slag FT at different CaO/P2O5 ratios was constructed on the basis of the average molar ionic potential (Ia) method and used to predict data reported from 19 mixed ashes in the literature. The results showed that Ia and FT gradually increased with a decreasing CaO/P2O5 ratio, and the main mineral types shifted from anorthite → mullite → berlinite, which reasonably explained the decrease in ash fusion temperatures in the mixed ash. The established model showed good adaptability to the prediction of 19 actual coal ash FTs in the literature; the deviation of the prediction was in the range of 40 °C. The model proposed between FT and Ia based on the different CaO/P2O5 ratios can be used to predict the low-rank coal and phosphorus-rich biomass and their mixed ashes. [ABSTRACT FROM AUTHOR]

• Different zeolite/carbon composites were prepared from coal gasification fine slag. • Catalytic pyrolysis of cow manure over zeolite/carbon composites was evaluated. • Relationship between catalysts structure and product selectivity was clarified. • Mechanism of cow manure pyrolysis vapors to light aromatics was revealed. • Model amino acids used to study the mechanism of nitrogen species transformation. The resource utilization of solid waste not only reduces the environmental pollution, but also reduces the use of fossil energy. In this study, three low-cost zeolite/carbon composites, including Y-type zeolite/carbon, Beta zeolite/carbon and ZSM-5 zeolite/carbon, were prepared from coal gasification fine slag (CGFS), which were used for catalytic upgrading of pyrolysis vapors of cow manure (CM). The composition and distribution of products from the catalytic pyrolysis of CM over different types composites were explored, and the relationship between catalysts structure and product selectivity was clarified. The results show that different types of catalysts have virous effects on the composition and distribution of products due to different physiochemical structures such as pore size and acid site. Among them, ZSM-5 zeolite/carbon is more conducive to the formation of monocyclic aromatics due to its shape selective catalysis, Beta zeolite/carbon has relatively large pore size and has high selectivity for polycyclic aromatics, and Y-type zeolite/carbon is more conducive to the removal of nitrogen and oxygen-containing compounds. Moreover, vanillin, glucose and valine, which are the main components of lignin, cellulose and protein in CM were selected as model compounds to reveal the reaction mechanism of catalytic upgrading. The results of this study can provide reference and theoretical guidance for the comprehensive utilization of solid waste and the development of low-carbon green industry. [ABSTRACT FROM AUTHOR]

Carbon coated In 2 O 3 hollow tube catalysts embedded with ultra-low content ZnO quantum dots (QDs) were synthesized for CO 2 hydrogenation to methanol. [Display omitted] • Carbon coated In 2 O 3 hollow tubes embedded with ultra-low content ZnO QDs were obtained. • The QD heterojunction boosted the CO 2 adsorption and accelerated the electron transfer from In3+ to Zn2+. • The carbon acted as a medium for hydrogen spillover and promoted the electron transfer. • ZnO QDs facilitated the H 2 dissociation and activation. • The highest methanol STY could reach 0.98 g MeOH h−1 g cat −1 on ZnO-In 2 O 3 -II at 350 °C and 3 MPa. CO 2 hydrogenation coupled with renewable energy to produce methanol is of great interest. Carbon coated In 2 O 3 hollow tube catalysts embedded with ultra-low content ZnO quantum dots (QDs) were synthesized for CO 2 hydrogenation to methanol. ZnO-In 2 O 3 -II catalyst had the highest CO 2 and H 2 adsorption capacity, which demonstrated the highest methanol formation rate. When CO 2 conversion was 8.9%, methanol selectivity still exceeded 86% at 3.0 MPa and 320 °C, and STY of methanol reached 0.98 g MeOH h−1g cat −1 at 350 °C. The ZnO/In 2 O 3 QDs heterojunctions were formed at the interface between ZnO and In 2 O 3 (2 2 2). The ZnO/In 2 O 3 heterojunctions, as a key structure to promote the CO 2 hydrogenation to methanol, not only enhanced the interaction between ZnO and In 2 O 3 as well as CO 2 adsorption capacity, but also accelerated the electron transfer from In3+ to Zn2+. ZnO QDs boosted the dissociation and activation of H 2. The carbon layer coated on In 2 O 3 surface played a role of hydrogen spillover medium, and the dissociated H atoms were transferred to the CO 2 adsorption sites on the In 2 O 3 surface through the carbon layer, promoting the reaction of H atoms with CO 2 more effectively. In addition, the conductivity of carbon enhanced the electron transfer from In3+ to Zn2+. The combination of the ZnO/In 2 O 3 QDs heterojunctions and carbon layer greatly improved the methanol generation activity. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization (HTC) of carbonaceous waste is an important way of energy recovery to obtain renewable fuels. Here, cow manure (CM) and industrial sludge (IS), two kinds of wastes with different properties, were pretreated by HTC at different temperatures. The elements migration and the physicochemical structural characteristics of hydrochar during HTC were evaluated. The pyrolysis and gasification performance of hydrochar was also studied. The results show that HTC treatment can significantly increase the carbon content and reduce the oxygen content of feedstocks, so as to obtain clean solid fuels with high energy densification and realize energy recovery from low value wastes. The distribution of pyrolysis products of co-hydrochar is close to that of IS due to the interaction between the components of CM and IS. The co-hydrochar has good gasification reactivity, showing obvious synergistic effect. There is multi-component interaction in the process of co-HTC due to the difference of feedstocks composition and properties between CM and IS. The abundant aliphatic and oxidized aliphatic hydrocarbons in IS may inhibit the polycondensation and aromatization of cellulose and hemicellulose hydrolysates in CM due to hydrogen supply or steric hindrance. Therefore, co-hydrochar has carbon structure and fuel properties close to that of IS hydrochar. [Display omitted] [ABSTRACT FROM AUTHOR]

• Exploring the effect of CaO and MgO on coal ash slag structure at the atomic scale. • At the same content, MgO was more capable of destroying the structure than CaO. • An increase in Mg/Ca ratio significantly reduced the slag complexity and polymerization. • Established the relationship between short/medium-range structure and macroscopic fluidity. The fluidity of slag is a crucial factor to determine the smooth operation of gasifier. However, the different charge compensation capabilities of alkaline components in slag have a significant effect on its structure, which brings a challenge to the accurate prediction of slag fluidity. In this work, a combined molecular dynamics and thermodynamics approach was adopted to evaluate the influence of different charge compensation capacities of CaO and MgO on slag structure and fluidity. It was found that although both CaO and MgO could continuously depolymerize the network structure by providing "free oxygen", thus reducing the slag viscosity. However, since Mg2+ could provide more charge compensation, MgO was more inclined to disrupt the complex network structure at a comparable level, resulting in a reduction in the complexity and polymerization degree in slag structure, ultimately leading to reduced viscosity. Finally, the correlation between slag short/medium-range structural parameters and macroscopic fluidity was also specifically quantified to provide some theoretical support for stable slag discharge in gasifiers. [ABSTRACT FROM AUTHOR]

Alkali metals and alkaline earth metals (AAEM) are important factors to be considered in coal gasification process, and understanding the release behavior of AAEM under the interaction of volatile-char is the key to realize efficient thermal conversion of coal. In this study, four typical O-containing functional groups (—COOH,—OH, C O,—OCH 3) were used to react with coal char in a fixed-bed reactor, the reaction temperature was set up at 750，800，850，900 ℃ to survey the release characteristics of Ca by different oxygen functional groups during the interaction of volatile-char at different temperatures from a quantitative point of view. The result show that the Ca release rate of coal char is not high in the whole reaction temperature range, and the interaction of O-containing compounds-coal char at lower temperature will increase the O content (C—O and C O) of coal char, the content of Ca in interactive coal chars was higher than that of the coal char. At lower temperature, the order of compounds inhibiting Ca release ability is: C 6 H 5 CHO≈C 6 H 5 COOH > C 10 H 8 O 2 > C 6 H 5 OCH 3. In addition, it also seems that O-containing compounds (except C 6 H 5 COOH) can obviously promote the conversion of ammonium acetate-soluble Ca to water-soluble Ca during the interaction with char. As the temperature increases, the change trend of O-containing functional groups on the surface of sample after interaction is completely opposite to that at lower temperature, the O-containing model compounds undergo de-oxidation, cracking and polymerization in the effect of coal char and AAEM, causing the formation of polycyclic aromatic hydrocarbon on the surface of the char, which hinders the diffusion of Ca from the char to the gas phase. This work is good for enriching and developing the study on the release characteristics of alkali earth metals during the interaction of volatile-char, and provides a theoretical basis for the development of related industries. • The effects of O-containing functional groups on Ca release during volatile-char interaction was studied. • O-containing species inhibit Ca release follows the order: C 6 H 5 CHO ≈ C 6 H 5 COOH > C 10 H 8 O 2 > C 6 H 5 OCH 3. • The possible mechanism of O-containing compounds-char interaction induced Ca release was proposed. [ABSTRACT FROM AUTHOR]

For CO 2 hydrogenation over the graphene oxide (GO) modified In 2 O 3 catalysts, GO promoted the transformation from cubic In 2 O 3 (c-In 2 O 3) to hexagonal In 2 O 3 (h-In 2 O 3). The c-In 2 O 3 (4 4 0)/h-In 2 O 3 (1 1 0) homojunction was formed between h-In 2 O 3 (1 1 0) and c-In 2 O 3 (4 4 0). The homojunction strengthened the interaction between the two phases, motivated the reduction of surface In 2 O 3 and facilitated the generation of oxygen vacancies, which was greatly beneficial to the formation of methanol. [Display omitted] • GO promoted the transform of c-In 2 O 3 to h-In 2 O 3 and inhibited the deep reduction of h-In 2 O 3 to In. • The formation energy of oxygen vacancies on homojunction was lower than that of h-In 2 O 3 or c-In 2 O 3. • The highest STY of methanol could reach 0.93 g MeOH h−1g cat −1 on In 2 O 3 -8 wt% GO under 3 MPa and 350 °C. • The homojunction formed by c-In 2 O 3 (4 4 0) and h-In 2 O 3 (1 1 0) was conducive to the methanol formation. The graphene oxide (GO) modified In 2 O 3 composite catalyst was applied for CO 2 hydrogenation to methanol. The GO significantly promoted the formation of hexagonal In 2 O 3 (h-In 2 O 3) and inhibited the deep reduction of h-In 2 O 3 to element In. The homojunction formed by h-In 2 O 3 (1 1 0) and c-In 2 O 3 (4 4 0) strengthened the interaction between the two phases, motivated the reduction of surface In 2 O 3 and facilitated the generation of oxygen vacancies, which was greatly beneficial to the formation of methanol. DFT manifested that the formation energy of oxygen vacancies on c-In 2 O 3 (4 4 0)/h-In 2 O 3 (1 1 0) homojunction was lower than that of single h-In 2 O 3 or c-In 2 O 3 , indicating that more oxygen vacancies were easier to be generated at the two phases interface. For rod In 2 O 3 catalysts modified by different GO content, when the GO content reached 8%, the space–time yield (STY) of methanol could be as high as 0.93 g MeOH h−1g cat −1, and the methanol selectivity could still reach more than 76% with CO 2 conversion of 10.4%. [ABSTRACT FROM AUTHOR]

The study aims to explore the kinetics of coal char during high temperature gasification by thermogravimetric analyzer and in situ heating stage microscope. Yangchangwan coal (YCW) and Shenfu coal (SF) were selected as the feedstock. The kinetics was fitted by using shrinking core, random pore, and homogeneous models, respectively. The in situ heating stage microscope was used to observe the ash morphology change of coal char. The results show that the random pore model was optimal for fitting the kinetics of coals. At 1273–1673 K, the range of apparent activation energy of YCW and SF chars were 82.27–90.74 kJ mol−1 and 89.78–91.42 kJ mol−1, respectively. Most of the YCW and SF chars were observed to participate in gasification by random pore mode and amorphous ash was formed. A few of YCW char particles were observed to undergo gasification by both homogeneous and shrinking core modes. The area shrinkage ratio of YCW char involved in the gasification by shrinking core mode was reduced by 58% after 20 min of reaction. At 1573–1673 K, the char gasification was controlled by ash layer diffusion. Compared with the reactivity at 1273–1473 K, SF char gasification reactivity at higher temperatures was reduced for that SF coal ash could agglomerate into sphere to wrap the residual carbon, while YCW char reactivity was increased since YCW ash was agglomerated into sphere, the sphere were melting and flowing with each other, so the residual carbon was exposed on YCW char surface. [ABSTRACT FROM AUTHOR]

The high-alkali Zhundong coal (ZDC) was considered to be the most promising and ideal feedstock for gasification. However, excessive sodium content could cause serious corrosion problems and restrict the development and utilization of ZDC. In this work, the corrosion behaviors of refractory lining by alkali metal sodium with different presence states were systematically investigated. The results indicated that sodium vapor diffused into refractory and dissociated Cr 2 O 3 aggregate into small pieces, thereby inducing severe volume expansion and structural loosening. Sodium-rich slag has reacted with the refractory to form low-melting-point phases such as Na 2 CrO 4 , NaAlSiO 4 and NaAlSi 3 O 8 , which reduced the penetration corrosion resistance of the refractory. In addition, the formation of dense Fe-Al/Cr spinel layer at slag/refractory interface also exacerbated spalling to some extent. The two actions of liquid-phase slag and alkali vapor corrosion synergized with each other and together led to refractory failure. This work provided theoretical guidance for qualitatively evaluating the corrosion behavior of alkali metal sodium and large-scale utilization of ZDC. • Alkali vapors and slag synergistically led to destruction of refractory structure. • Na(g) caused aggregates to dissociate into small pieces and form lamellar structure. • Molten slag reacted with matrix to form expansion phase and aggravated corrosion. • The depth distribution of Na element was innovatively analyzed by LIBS technique. [ABSTRACT FROM AUTHOR]

• Residual carbon and ash distribution modes of coal gasification fine slag is studied. • Particle size is the main factor determining the distribution modes of carbon and ash. • Revealed the formation mechanism of the fine slag with different distribution modes. Coal gasification fine slag (CGFS) contains an amount of residual carbon, which not only increases the difficulty of utilizing it as a resource but also hinders the efficient and low-carbon operation of gasification processes. In this study, the physicochemical properties, distribution modes and formation mechanisms of different CGFS particle size fractions were investigated. The CGFS particles with size > 180 μm showed the lowest degree of graphitization, the particles in the range of 75 − 180 μm contained the most residual carbon, and the particles < 45 μm exhibited the least roughness. The carbon and ash fractions of CGFS show embedded, crosslink and discrete distribution modes, while the evolutionary process of raw coal particles in the gasifier can be divided into three stages: initial, transitional and late. Due to the different reaction histories experienced by the raw coal particles in the gasifier, the three carbon ash distribution modes do not occur independently. [ABSTRACT FROM AUTHOR]

In this work, the interaction between waste cypress sawdust (WCS) and coal liquefaction residue (CLR), a type of industrial solid waste, during co-pyrolysis was studied by thermogravimetry-mass spectrometry (TG-MS) and pyrolysis-gas chromatography mass spectrometry (Py-GC/MS). The gasification reaction characteristics of co-pyrolysis char were also evaluated. The results showed that both promoting and inhibiting effects existed in the co-pyrolysis process of WCS and CLR. When the pyrolysis temperature was less than 420 °C, the catalysis of minerals was conducive to the pyrolysis reaction. At higher temperatures, the polycondensation and carbonization produced by the interaction between the components inhibited the release of volatiles. The gasification reactivity of co-pyrolysis char was better than that of individual WCS and CLR chars. The synergistic effect was most obvious when the blending ratio of WCS to CLR was 3:1. In the gasification process of co-pyrolysis char, the WCS component with better reactivity preferentially reacted to form an abundant pore structure, which exposed more reactive sites and promoted the diffusion and mass transfer of gasification agent. Moreover, alkali and alkaline earth metal species in WCS and iron bearing minerals in CLR can catalyze the gasification reaction, contributing to the synergistic effect. Therefore, the addition of a suitable solid waste to biomass waste can improve the energy efficiency and simultaneously achieve solid waste utilization. [Display omitted] • Co-thermochemical conversion of biomass and industrial solid waste were conducted. • The formation characteristics of tar and gas during co-pyrolysis were evaluated. • Release of volatiles during co-pyrolysis has both promoting and inhibiting effects. • Co-pyrolysis char has good gasification activity and shows obvious synergistic effect. [ABSTRACT FROM AUTHOR]

[Display omitted] • The structure of ZnO-In 2 O 3 HT-I catalyst promoted the creation of ZnO-In 2 O 3 solid solution. • The high quality oxygen vacancies on the surface of ZnO-In 2 O 3 solid solution favored methanol formation. • The solid solution strengthened electron transfer from Zn2+ to In3+, promoting localized electron imbalance. • The formate was the intermediate species for methanol formation on ZnO-In 2 O 3 solid solution. • The highest STY of methanol could reach 1.12 g MeOH h-1g cat -1 on ZnO-In 2 O 3 HT-I catalyst. Three ZnO-In 2 O 3 solid solution hollow tube catalysts with different microstructure were synthesized for CO 2 hydrogenation to methanol. ZnO could maintain In 2 O 3 hollow tube structure from being destroyed during the reaction, and the ZnO-In 2 O 3 solid solution could be in-situ formed on three catalysts during CO 2 hydrogenation reaction. Especially, the structure of ZnO-In 2 O 3 HT-I was most conducive to the creation of ZnO-In 2 O 3 solid solution. The ZnO-In 2 O 3 solid solution promoted electron transfer from ZnO to In 2 O 3 , resulting in an increase in the electron density of In 2 O 3 surface and local electron imbalance around the oxygen vacancy. ZnO facilitated electron delocalization in surface lattice oxygen. The surface electrons were transferred and concentrated on surface oxygen vacancy, which enhanced the electron density of surface oxygen vacancy especially for ZnO-In 2 O 3 HT-I catalyst. The "quality" of surface oxygen vacancy was raised, which boosted the adsorption and activation of H 2 and CO 2. The density functional theory (DFT) findings suggested that ZnO-In 2 O 3 solid solution caused the energy barrier of formate species to be lowered and those of carboxylate species to be raised, which was more favorable for methanol generation. Combined experimental and DFT data proved that the CO 2 hydrogenation to methanol proceeded via formate reaction route. Among the three ZnO-In 2 O 3 catalysts, ZnO-In 2 O 3 HT-I showed the highest methanol formation activity with 13.9% CO 2 conversion and 68% methanol selectivity at 350 °C, and the methanol space–time yield (STY) reached 1.12 g MeOH h−1 g cat −1. [ABSTRACT FROM AUTHOR]

• Effect of ICLR addition on ash fusibility and viscosity of YCW coal were studied. • "Barbed-shape" needle-like crystal was the main cause of viscosity fluctuation. • ICLR additive inhibited the increase of crystal aspect ratio and volume fraction. • The addition of ICLR alleviated the viscosity fluctuation behavior of YCW coal ash. Co-gasification of coal and indirect coal liquefaction residue (ICLR) is an effective approach to large-scale utilization of ICLR. In this work, the effect of ICLR addition on ash fusion characteristics and viscosity-temperature characteristics of YCW coal were studied by means of ash fusion temperature analyzer (AFTA), XRD, high-temperature-rotary-viscometer, high-temperature heating stage coupled with optical microscope (HTSOM) and FactSage thermodynamics software. The results showed that with the increase of ICLR mass fraction, the low-temperature eutectic anorthite melted into a liquid phase, resulting in a linear decrease of AFTs. Moreover, the causes of viscosity fluctuation were revealed according to the in-situ crystallization morphology variation and viscosity-temperature characteristic curves. It was found that the formation of a large number of "barbed-shape" needle-like crystals during the cooling process was the main reason for the significant viscosity fluctuation. With the addition of ICLR, the length-diameter ratio and volume fraction of the "barbed-shape" needle-like crystals decreased significantly, resulting in the decrease of viscosity fluctuation. When the addition amount of ICLR was 3%, the "barbed-shape" needle-like crystals were not precipitated during the entire crystallization process, and the viscosity no longer fluctuated. As the mass fraction of ICLR increased to 5%, no crystals precipitation was observed in the cooling process. At this time, the slag sample showed the glass slag characteristics. Therefore, for entrained-flow gasification, the addition of ICLR could improve the gasification efficiency by reducing the gasifier operating temperature, and avoid slag-tapping problems by alleviating the viscosity fluctuation. More importantly, it could realize the resource treatment of hazardous waste and transform hazardous waste into solid waste. [ABSTRACT FROM AUTHOR]

Cow manure (CM) is a kind of biowaste with potential for heat recovery and energy. The effects of different leaching solvents on the physicochemical structure of CM and the catalysis role of AAEMs on the thermal behavior were studied. TGA experiments showed that the maximum weight loss rate and the peak temperature of hemicellulose and cellulose increased after leaching, while the TG/DTG curve moved to a high temperature direction. The devolatilization index (Di) value of the raw and leaching samples increased with the increase of the heating rate, indicating that the higher heating rate promoted the release of volatile. The treatment with leaching not only removed AAEMs in CM effectively, but also led to a larger specific surface area and pore volume, and reduced the crystallinity of cellulose and crystal size in CM. Na salt and K salt were mainly in water soluble state, while Ca salt and Mg salt were mainly in acid soluble salt. Compared with the change of physical and chemical structure caused by leaching, the removal of AAEMs played a dominant role in the pyrolysis characteristics of the samples. The removal efficiency of AAEMs increased with the strength of acid. Based on Kissinger model, the Eα of Raw-CM, H 2 O-CM, CH 3 COOH-CM, HCl-CM, HNO 3 -CM and H 2 SO 4 -CM is 171.30 kJ/mol, 187.58 kJ/mol, 190.86 kJ/mol, 292.10 kJ/mol, 287.79 kJ/mol and 280.69 kJ/mol respectively. Both the raw and leaching samples followed the reaction order mechanism and tended to react according to a higher-order reaction model between n = 1.5 and n = 4. In contrast, CH 3 COOH is an ideal solvent for leaching pretreatment. • The devolatilization index of the H 2 O-CM sample reached 11.30 • The crystallinity of cellulose and crystal size were reduced by leaching treatment. • The kinetic parameters of leaching samples at different conversion rates were obtained. • The reaction of leaching samples followed the reaction order mechanism between n = 1.5 and n = 4. [ABSTRACT FROM AUTHOR]

Inverse diffusion lift-off flame was widely used in industrial fields such as non-catalytic partial oxidation of methane. In order to investigate the stability and chemiluminescence characteristics of the inverse diffusion lift-off flame, the OH∗ and CH∗ radiation characteristics, lift-off height, and transition (attachment, lift-off and blow-out) of flames under different burner structure were discussed. The results showed that burner rim thickness and incidence angles would affect the stability of the inverse diffusion flame. When the thickness of the burner rim exceeded 0.5 mm, the flame would directly change from the attachment state to blow-out state as oxygen velocity increased. Additionally, the values of the blowout limit of the nozzle were inversely proportional to the rim thickness of the burner. Different incident angles would result in various shear angles, which would affect the flame structure. As the incidence angle decreased, the tangential velocity of flame increased and the flame tended to be more stable. When the lift-off flame generated, OH∗ intensity and distribution showed a sudden change, and the OH∗/CH∗ peak intensity ratio of the flame appeared abrupt changes. • Stability of reverse diffusion flame with different structures were investigated. • OH∗ and CH∗chemiluminescence in different inverse diffusion flames was studied. • OH∗ intensity and distribution could reflect change of reaction area for different flames. • OH∗/CH∗ peak intensity ratio of the flame appeared abrupt changes in lift-off flames. [ABSTRACT FROM AUTHOR]

Catalytic methane decomposition (CMD) receives increasing attention for co-production of CO x -free hydrogen and valuable carbon by-product, and the catalyst plays a crucial role on methane conversion and the product features. Unsupported nickel catalysts derived from commercial nickel foam (NF) were prepared for CMD by mild pre-treatment. Effects of the pre-treatment method (acid treatment, thermal treatment, acid-thermal treatment and hydrogen reduction) and reaction temperature were explored on the NF morphology and CMD reactivity in a fixed-bed reactor. It is found that catalytic performance of the NF-based catalyst is highly dependent on the pre-treatment and reaction temperature. The thermal and acid-thermal treatments could greatly promote the catalytic activity (with methane conversion up to 74.6% and 91.8%, respectively) at 850 °C. To fully release potential abilities of the catalyst, the carbon deposited spent catalyst was recycled as a fresh catalyst in the CMD test by several strategies. High and stable methane conversion (up to around 90%–93%) can be achieved by simulating the operation model in a fluidized-bed reactor for a continuous CMD process. Besides, the carbon deposited spent catalyst could serve as a promising candidate of supercapacitor electrode material. • Unsupported nickel catalyst is prepared from nickel foam for CH 4 decomposition. • The catalyst activity highly depends on the pre-treatment and reaction temperature. • The carbon deposited spent catalyst is recycled as a fresh catalyst in the CMD test. • The carbon deposited spent catalyst can serve as a supercapacitor electrode material. [ABSTRACT FROM AUTHOR]

Coal based solid waste has been recognized as a sustainable raw material for the preparation of high added value materials for wastewater treatment. In this paper, a preparation route was designed for the rapid, efficient, and low-cost preparation of MCM-41 zeolite using coal gasification fine slag as raw material. Functionalization modification of MCM-41 was carried out by grafting amino groups on its surface to improve its application performance. Moreover, the prepared functionalized material is used for bidirectional adsorption of anionic and cationic dyes. The experimental results indicate that MCM-41 zeolite with highly ordered pore structure was rapidly prepared using the advantages of fast heating and strong permeability of microwave synthesis method, with a specific surface area of up to 862.03 m2/g. Amine functionalized MCM-41 exhibits strong adsorption capacity for both cationic and anionic dyes, with maximum adsorption capacities for methylene blue and Congo red being 292.40 mg/g and 354.61 mg/g, respectively. The study of adsorption kinetics and adsorption mechanism indicate that the adsorption process is mainly controlled through chemical adsorption, including electrostatic attraction, hydrogen bonding, and π-π interactions. The results of this study will provide useful references for the use of coal based solid waste to prepare functional materials for the treatment of organic wastewater. [Display omitted] • High-quality MCM-41 were rapidly prepared from coal gasification fine slag. • The specific surface area and pore volume reached 862.03 m2/g and 0.75 cm3/g. • The adsorption of anionic and cationic dyes by modified MCM-41 was studied. • The adsorption capacities for MB and CR reached 292.40 mg/g and 354.61 mg/g. • The adsorption kinetics and adsorption mechanism have been detailed studied. [ABSTRACT FROM AUTHOR]

• Residual carbon formation from entrained-flow gasification fine slag was revealed. • Vitrinite is prone to achieve a higher conversion level at entrained-flow conditions. • Vitrinite residual carbon has more active sites, giving a higher gasification activity. The high carbon content and poor combustibility of the fine slag produced by the entrained – flow gasification limits its resource utilization. From coal chemistry, residual carbon formation is highly related to the coal macerals. In this study, Meihuajing coal was selected to be separated and enriched macerals by density gradient centrifugation. Different macerals were gasified at 1300 °C and H 2 O/O 2 conditions in the drop tube furnace to collect residual carbon. The results showed that the area shrinkage of inertinite grew to 0.90 at the early stage, but final conversion required a longer induction period to realize. The residual carbon of vitrinite had richer pore structure and larger specific surface area as well as lower degree of aromatization and graphitization than inertinite, resulting in higher reactivity. The present study is important in understanding the relationship between the formation of residual carbon and the structure of coal macerals. [ABSTRACT FROM AUTHOR]

• The feasibility of catalytic gasification reactivity of IWC was evaluated. • The redox cycle of Fe0, Fe2+ and Fe3+ was the main factors that determine reactivity. • The transformation mechanism of iron species during gasification was proposed. Coal char-CO 2 gasification is a strong endothermic reaction with high energy consumption, and a cheap catalyst use is one of the keys to save process costs. The iron-based waste catalyst (IWC) from indirect coal-liquefaction plant contains active component, but its effect on the gasification reactivity of coal char is seldom reported. Thus, CO 2 gasification of Yangchangwan coal (YCW) was conducted in thermogravimetric analyzer (TGA) with IWC as the catalyst. The change of functional group on coal char surface was measured by a Fourier transform infrared (FT-IR) spectroscopy. The morphology of coal char was characterized by focused ion beam scanning electron microscope (FIB-SEM). X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were employed to analyze phases and valences of iron. The results indicate that IWC was effective for YCW gasification. In the range of 1000–1200 °C, the optimal temperature of catalytic gasification was 1000 °C. The FT-IR spectra of YCW gasified char showed the changes of small molecule active groups, such as –OH, C–O, –CH 2 , –CH 3 , C=C and Fe–O in the process of catalytic gasification. The surface structure of coal char was rough and there were lots of tiny pores. The metallic Fe formed by IWC at 0 min was finally oxidized by gasification agent CO 2 to FeO and Fe 3 O 4. The redox cycle between Fe0, Fe2+ and Fe3+ is the main reason for the catalytic YCW-CO 2 gasification reactivity in the presence of IWC. [ABSTRACT FROM AUTHOR]

Potassium carbonate was employed as an effective catalyst to explore the catalytic pyrolysis characteristics of Shenfu bituminous coal (SF). The online investigation on the effects of catalyst loading amounts (2.2–6.6%) and pyrolysis temperature (650–800°C) on the gas release characteristics of SF pyrolysis were conducted using Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis-mass spectrometry (TG-MS). The results show that the K2CO3 loading could increase the yields of pyrolysis gaseous products and reduce the peak temperature for gaseous product releasing. Peak temperatures for CO2, H2O, and CH4 releasing hardly changed with the pyrolysis temperature, but changed for different K2CO3 loading amounts. Peak temperatures for CH4, CO2, and H2 releasing decreased as catalyst loading increased while the peak temperatures for H2O releasing were almost independent as ~470°C. The increase of the K2CO3 loading amount and pyrolysis temperature could increase the yields of CO2 and H2, but had no significant effect on the CH4 yield. The release mechanism of pyrolysis gaseous products could be well verified by the variation in type and intensity of chemical functional groups from the coal samples versus pyrolysis temperature and K2CO3 loading. [ABSTRACT FROM AUTHOR]

Propylene epoxidation by oxygen over Cu-based catalysts is a most ideal and economical process. The unsupported CuOx nanoparticles were synthesized by liquid phase reduction method. The crystalline phase and size of CuOx nanoparticles were characterized by XRD and TEM, respectively. The catalytic performances of CuOx with different pretreatment temperatures and atmospheres were also investigated. The as prepared unsupported CuOx nanoparticles were composed of Cu and Cu2O. With elevating the pretreatment temperatures under N2 atmosphere, the size of CuOx nanoparticles increased gradually from 25 nm to 58 nm. However, the relative content between Cu and Cu2O remained almost unchanged, indicating that the valence state of Cu species in CuOx was kept nearly constant. The C3H6 epoxidation activities showed a first increases and then decreases trend with enhancing the particle size of CuOx. The highest activity of propylene epoxidation was achieved when the particle size of CuOx was 41 nm. The conversion of propylene was 0.14% and the selectivity of propylene oxide was 30% respectively under the reaction temperature of 150 °C. The results indicated that the appropriate CuOx particle size was a key factor for propylene oxide formation on Cu-based catalysts. The C3H6 epoxidation activities showed a first increases and then decreases trend with enhancing the particle size of CuOx. When the CuOx particle size was 41 nm, the formation rate of PO reached maximum. The appropriate particle size of Cu species with low valence state was crucial to the generation of PO for C3H6 epoxidation reaction by O2 on Cu-based catalysts. [ABSTRACT FROM AUTHOR]

Based on the visualization system, the particle tracking method was used to study the influence of slag wall temperature on the deposition characteristics of coal particles under gasification conditions. The results show that particle deposition can be divided into five types: rebound, rebound after blocking for a distance, crushing, rolling, and adhesion. When slag wall temperature is lower than the deformation temperature, the probability of rebound is over 70%. With the increase of slag wall temperature, the global coefficient of restitution remains constant and then decreases with 1100 °C as the dividing line and the tangential coefficient of restitution concentrates around 0.65. It is proved that the fusion characteristics of slag wall are the main cause of the change in particle deposition on the wall. The collision theory is introducted in the study of deposition characteristics of particles. The collision process is classified into "elastic-plastic collision" and "wet collision". [Display omitted] • Particle impact types are divided into "elastic-plastic collision" and "wet collision". • Collision theory is introducted in the study of deposition characteristics of particles. • Particle desposition is due to the change of slag wall viscosity with temperatures. • Slag wall fusion characteristics affects the coefficient of restitution of particle rebound. [ABSTRACT FROM AUTHOR]

Resource utilization of solid waste can aid in gradual substitution of fossil fuels while achieving waste recycling. In this study, residual carbon and ash slag from the coal gasification fine slag were separated by froth flotation, and then was used to prepare Ru/C and ZSM-5 dual catalysts with carbon-rich and ash-rich components as raw materials, respectively. The performance of two catalysts for catalytic upgrading of volatiles from pyrolysis of cow manure (CM) to produce light aromatic hydrocarbons was systematically investigated. The direct pyrolysis products of CM mainly included alcohols, ketones, ethers, and other oxygen-containing compounds. When ZSM-5 was used as the catalyst, the yield of monocyclic aromatic hydrocarbons (MAHs) increased significantly due to the better catalytic cracking and aromatization abilities of ZSM-5 catalyst. However, the yield of phenols in the pyrolysis products improved when Ru/C was used as the catalyst due to the cleavage effect of Ru/C on the C–O bond. When Ru/C and ZSM-5 were used as dual catalysts in relay catalytic pyrolysis of volatiles, the increase in MAHs yield in the pyrolysis product was higher than the total increase obtained under Ru/C and ZSM-5 single catalysis. The possible pathways for the generation of MAHs from CM under Ru/C and ZSM-5 relay catalytic pyrolysis were revealed by the pyrolysis experiment performed on model compounds. [Display omitted] • Ru/C and ZSM-5 catalysts were graded preparation from coal gasification fine slag. • Catalytic pyrolysis of cow manure over Ru/C and ZSM-5 was evaluated. • The relay catalytic pyrolysis of dual catalysts obtained more light aromatics. • Mechanism of cow manure relay catalytic pyrolysis to light aromatics was revealed. • Simultaneously realize the reutilization of two types waste. [ABSTRACT FROM AUTHOR]

• The method for quantification of flame structure and reaction characteristics was defined by LIBS. • The correlation between the breakdown threshold and the flame temperature was determined. • The correlation between atomic composition and soot emission is established. • The optimal angle of burner design was revealed. The structure of a burner is a key issue of boilers and gasifiers in several industries. It significantly influences the flame formation and combustion reaction determining the mixing degree of fuel and oxidant. This study aims to explore the characteristics of flames at different angles and evaluate their advantages in specific applications. The present work explores the correlation between laser-induced breakdown threshold energy and flame temperature based on laser-induced breakdown spectroscopy (LIBS). Subsequently, the local structure and reaction characteristics of the flame at different burner angles (45, 60 and 90°) were investigated with simulation. The local equivalence ratio of the laminar flame was used to determine the distribution of reactants and components in the flame. The results indicated that the breakdown threshold energy was positively correlated with the temperature of the flame, and it was dependent on the gas concentration. With increased laser energy, the O/H ratio could be used as a function of the local equivalence ratio of the flame. In addition, the study of flame images and the spontaneous radiation of soot revealed that the C/H ratio in the flame reached the maximum value when the burner incident angle was 45°. Through simulation and experimental research, we found that the flame at 60° angle is the most stable, produces the least soot, has the highest combustion efficiency, and has better thermal radiation intensity. [ABSTRACT FROM AUTHOR]

Based on previous soot studies, this paper proposes a new method to quantify the evolution of the soot generation mechanism in flames. The soot distribution in inverse diffusion flame at different fuel gas velocities was quantitatively measured by laser-induced incandescent (LII) technique, and the soot structure evolution was analyzed by Raman spectroscopy and field emission transmission electron microscopy (FETEM). Laser-induced breakdown spectroscopy (LIBS) and numerical simulation were used to investigate the association between the intensity ratio of hydrocarbon atoms of at different positions of the flame and soot formation. Meanwhile, a detailed chemical kinetic simulation of the formation process of soot was carried out, and the flame structure was divided in more detail. The flame state in different regions and the key reactions of soot formation were analyzed. The results presented that the volume fraction of soot measured by LII is consistent with the height-dependent graphitization of the flame and is identical to the yellow definition of the flame. The variation of the C/H atomic intensity ratio reflected the soot formation in flame. The C H intensity ratio in the flame axial direction showed a bimodal distribution, corresponding to the blue phase of soot precursor formation and the yellow phase of soot formation, respectively. In addition, the C H atomic intensity ratio and the C H atomic molar ratio showed a parabolic transition from incipient to mature soot in the soot production region. The C H intensity ratios at different heights are linear in the radial direction, and the main core region of soot production can be obtained when the C H intensity ratio is 0.10 ∼ –0.13. With radial distance increases, it is clear results that the most sensitive reaction of (precursor) A1 changes from C 6 H 5 OH + H = A 1 + OH to C 2 H 3 + HCO=C 3 H 3 + OH. It reveals that with the increase of yellow light, the soot structure along the flame center line is gradually graphitized, and the graphitization degree is the highest at the axial height of 18.0De ∼ 22.4De. This is consistent with the distribution of C H atomic intensity ratio. The present results demonstrate that LIBS can quickly achieve the initial measurement of soot and provide a new method for the study of flame soot during its evolution. • A method for characterizing the formation and evolution of soot in flames using LIBS technology was proposed. • The distribution trend of the strength ratio of hydrocarbons is consistent with the distribution trend of the molar ratio. • The atomic intensity ratio of hydrocarbon flames can characterize the formation of initial soot and mature soot. • The transformation of free radicals and key reactions in the formation of soot in different stages of flame were studied. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nanoporous glass microspheres were synthesized from coal gasification fine slag. • Ultra-high content amino functional groups was grafted by multi-step modification. • The adsorption of dyes and heavy metals in single and binary systems was studied. • The synergistic adsorption mechanism of the binary system was revealed. The discharge of large-scale industrial solid waste and wastewater has caused severe damage to environmental health. In this study, the adsorption behaviors of Pb(II) and Congo Red (CR) dye in single and binary aqueous systems were investigated using novel functionalized nanoporous glass microspheres (NGM). The NGM material was fabricated from coal gasification fine slag (CGFS) by a simple treatment and characterized using TG, BET, XRD, TEM, FT-IR, and XPS to analyze its physicochemical properties. The adsorption experiments showed that the adsorption amounts of DMA-NGM for Pb(II) and CR were 302.39 mg/g and 342.74 mg/g for the single systems, and 372.73 mg/g and 412.93 mg/g for the binary systems, respectively. The increased adsorption capacity was attributed to the synergistic effect of electrostatic attraction and chelation. Furthermore, the pseudo-second-order model and Elovich model could reasonably describe the adsorption of Pb(II) and CR on DMA-NGM. Pb(II) adsorption on DMA-NGM was monolayer adsorption and CR adsorption was multilayer adsorption. In summary, the results demonstrate the potential of efficient and environmentally friendly adsorbents for the resource recovery of CGFS and the processing of printing and dyeing wastewater. [ABSTRACT FROM AUTHOR]