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A numerical simulation study of the 80 kW Chemical Looping Gasification (CLG) pilot plant fuel reactor was conducted using the Computational Particle Fluid Dynamics (CPFD) method to investigate the influence of superficial gas velocity, coal particle size and static bed height on the gas-solid fluidization characteristics in the bed. The results showed that the suitable operating ranges were superficial gas velocity in 0.36~0.48 m/s, coal particle size in 0.3~0.4 mm, and static bed height in 0.6~0.8 m, and the CLG process released gas in the whole bed compared with the cold condition, which could effectively alleviate the uneven pressure gradient distribution. In addition, the working conditions with superficial gas velocity higher than 0.36 m/s, coal particle size higher than 0.35 mm and static bed height higher than 0.6 m are more favorable to the full contact between coal particles, oxygen carrier bed particles and gas phase, thus obtaining a higher carbon conversion rate.

The detailed reaction mechanism of CO conversion over the LaFeO3 oxygen carrier was systematically explored.

Dioxins are a kind of persistent organic pollutants (POPs) with extremely toxic. Municipal solid waste incineration (MSWI) process has become one of the most dominant discharge sources of dioxins. A comprehensive discussion about dioxin formation mechanisms was reviewed in this paper, and the mechanisms of high-temperature gas-phase reaction and "de novo" synthesis were systematically illustrated in the form of diagrams. What's more, the effects of various influencing factors on the formation of PCDD/Fs were briefly analyzed in the form of a table. We believed that temperature, catalyst, chlorine source, carbon source, oxygen concentration and moisture were necessary factors for PCDD/Fs formation. Control technologies of dioxins in MSWI process were summarized subsequently from three stages: pre-combustion, in-combustion and post-combustion, and a device for synergistic removal of dioxins based on multi-field force coupling and technical routes for controlling dioxin emissions were proposed, so as to provide mechanisms and methods for effectively reducing the emission concentration of dioxins. An introduction was also conducted of dioxin control technologies in municipal solid waste incineration fly ash (MSWI-FA) in this paper, and their mechanisms, advantages, disadvantages and technical maturity were illustrated in the form of diagrams, which can provide theory and reference for in-depth research of follow-up scholars and industrial application of dioxin control technologies. Finally, current research hotspots, challenges and future research directions were proposed.

The accumulation and incineration of crop waste pollutes the environment and releases a large amount of CO2.

HCl exhibits a preferred interaction with the O atom of CaO (100) surface, with the adsorption energy of −1.85 eV. HCl and CO2 are in competition with one another at the O site. The presence of HCl inhibits CO2 adsorption and promotes CO2 desorption.

The selective oxidation of amines into imines is a priority research topic in organic synthesis and has attracted much attention over the past few decades. However, the oxidation of amines generally suffers from the drawback of transition-metal, even noble-metal catalysts. Thus, the strategy of metal- and oxidant-free selective synthesis of imines is highly desirable yet largely unmet. This paper unravels a metal-free and external oxidant-free electrochemical strategy for the oxidative coupling methodology of amines. This general transformation is compatible with various functional amines and led to functionalized imines in moderate to satisfactory yields.

Membrane-based separation is an appealing solution to mitigate CO2 emission sustainably due to its energy efficiency and environmental friendliness. Attributed to its excellent separation endowed by nanomaterial incorporation, nanocomposite membrane is rigorously developed. This study explored the feasibility of boron nitride (BN) embedment and changes to formation mechanism of ultrathin selective layer of thin film nanocomposite (TFN) are investigated. The effects of amine-functionalization on nanosheet-polymer interaction and CO2 separation performance are also identified. Participation of nanosheets during interfacial polymerization reduced the crosslinking of selective layer, hence, improved TFN permeance while the formation of contorted diffusion paths by the nanosheets favors transport of small gases. Amine-functionalization enhanced the nanosheet-polymer interaction and elevated the membrane affinity towards CO2 which led to enhanced CO2 selectivity. The best TFN prepared in this study exhibited 37% and 20% increment in permeability and selectivity, respectively with respect to neat thin film composite (TFC). It is found that the CO2 separation performance of BN incorporated TFN is on par with many non-porous nanosheet-incorporated TFNs reported in literatures. The transport and barrier effects of BN and functionalized BN are discussed in detail to provide further insights into the development of commercially attractive CO2 selective TFN membranes.

Nowadays, the efficient and cleaner utilization of coal have attracted wide attention due to the rich coal and rare oil/gas resources structure in China. Coal chemical looping gasification (CCLG) is a promising coal utilization technology to achieve energy conservation and emission reduction targets for highly pure synthesis gas. As a downstream product of synthesis gas, methyl methacrylate (MMA), is widely used as raw material for synthesizing polymethyl methacrylate and resin products with excellent properties. So this paper proposes a novel system integrating MMA production and CCLG (CCLG-MMA) processes aiming at “energy saving and low emission”, in which the synthesis gas produced by CCLG and purified by dry methane reforming (DMR) reaction and Rectisol process reacts with ethylene for synthesizing MMA. Firstly, the reaction mechanism of CCLG is investigated by using Reactive force field (ReaxFF) MD simulation based on atomic models of char and oxygen carrier (Fe2O3) for obtaining optimum reaction temperature of fuel reactor (FR). Secondly, the steady-state simulation of CCLG-MMA system is carried out to verify the feasibility of MMA production. The amount of CO2 emitted by CCLG process and DMR reaction is 0.0028 (kg CO2)−1·(kg MMA)−1. The total energy consumption of the CCLG-MMA system is 45521 kJ·(kg MMA)−1, among which the consumption of MMA production part is 25293 kJ·(kg MMA)−1. The results show that the CCLG-MMA system meets CO2 emission standard and has lower energy consumption compared to conventional MMA production process. Finally, one control scheme is designed to verify the stability of CCLG-MMA system. The CCLG-MMA integration strategy aims to obtain highly pure MMA from multi-scale simulation perspectives, so this is an optimal design regarding all factors influencing cleaner MMA production.

Fe-based oxygen carriers (OCs) are currently the crucial material basis for chemical looping technology to realize industrial applications. However, the relatively low reactivity of pure Fe-based OCs limits their extensive applications. One strategy to enhance reactivity in the chemical looping process is the introduction of another metallic element by doping. This study prepared a series of Fe-based OCs (Cu2xFe2(1-x)O3) with low concentration doping of Cu. The reaction mechanism and reactivity modulation of Cu2xFe2(1-x)O3 OCs in the chemical looping process were systematically investigated by means of experiments and density function theory (DFT) calculations. Activation energies for Cu2xFe2(1-x)O3 ranging between 72 and 37 kJ/mol were detected using H2 and the thermogravimetric analyzer (TGA) test, indicating enhanced reactivity in the chemical looping process as compared with that of pure Fe-based OCs of 84 kJ/mol. Thus, the low concentration doping of Cu can effectively improve the reactivity of Fe-based OCs. Furthermore, comprehensive DFT calculations upon the transition state indicated the reaction energy barrier for Cu2xFe2(1-x)O3 with different doping concentration and configurations to be in the range of 1.68–1.02 eV, lower than that of pure Fe2O3 of 2.30 eV. The Cu doping and the modulation of the reaction pathways are important reasons for the enhanced reactivity of Cu2xFe2(1-x)O3 OCs. Additionally, this study proposed a lattice oxygen release mechanism of Cu2xFe2(1-x)O3 OCs during chemical looping combustion.

In this work, a model of hydrogen production by double chemical looping is introduced. The efficiency benefit obtained was investigated. The chemical looping hydrogen generation unit is connected in series to the downstream of a chemical looping gasification unit as an additional system for 100 MW·h coal gasification, with the function of supplementary combustion to produce hydrogen. Using Aspen Plus software for process simulation, the production of H2 and N2 in the series system is higher than that in the independent Chemical looping gasification and Chemical looping hydrogen generation systems, and the production of hydrogen is approximately 25.63% and 12.90% higher, respectively; The study found that when the gasification temperature is 900 °C, steam-carbon ratio is 0.84 and oxygen-carbon ratio is 1.5, the hydrogen production rate of the system was the maximum. At the same time, through heat exchange between logistics, high-pressure steam at 8.010 × 104 kg·h−1 and medium-pressure steam at 1.101 × 104 kg·h−1 are generated, and utility consumption is reduced by 61.58%, with utility costs decreasing by 48.69%. An economic estimation study found that the production cost of ammonia is 108.66 USD·(t NH3)−1. Finally, cost of equipment is the main factors influencing ammonia production cost were proposed by sensitivity analysis.

LaBO3 (B = Fe, Mn, and FeMn) perovskite-type oxides were prepared by sol–gel method and then used as catalysts in CO hydrogenation for light olefins. The catalysts were characterized using XRD, H2-TPR, SEM, CO (CO2)-TPD, and XPS. The results showed that the lattice oxygen migration and oxygen vacancies promoted oxygen mobility by doping Mn2+ at the B site, Moreover, the presence of manganese as a promoter in the catalyst increased olefin selectivity compared with the olefin selectivity of the catalyst containing iron at the B-site and exhibited resistance to carbon deposition; while reducing the metal elements. In CO hydrogenation, potassium-promoted LaFeMnO3 catalysts afforded high catalytic activity and C2=–C4= selectivity. An O/P value of 5.0 and a C2=–C4= fraction of 54% were achieved for all hydrocarbons with low methane selectivity.

In order to produce high-quality bio-oils and syngas from biomass, a novel pyrolysis approach based on the chemical looping concept, namely chemical looping pyrolysis (CLPy), was proposed. In the current work, thermodynamic feasibility study and experimental investigations of the proposed CLPy with calcium-ferrite oxygen carriers and Nannochloropsis sp. microalgal biomass were conducted. The results suggested that the reduced calcium-ferrite oxygen carrier facilitated the denitrification, ketonization, and hydrodeoxygenation (HDO) of bio-oils during the pyrolysis stage. Since large amounts of oxygen in bio-oils were transferred to the reduced oxygen carrier, the heating value of bio-oils was remarkably increased up to 34.2 MJ/kg and 36.0 MJ/kg by employing the reduced CaFe2O4 and Ca2Fe2O5 oxygen carrier, respectively. In addition, a high H2 content of 50% in the pyrolysis gas was observed at the optimal pyrolysis temperature. In the gasification stage, the production of high-quality syngas was achieved. The content of H2 accounted for up to 70% of the gasification products when taking steam as gasifying agent, while that of CO was composed of 66% without the use of a gasifying agent. Moreover, the oxygen carrier was reduced to its reduction state, available for the next loop. In summary, CLPy proposed in this work involves the continuous transference of the oxygen from bio-oils to syngas by an oxygen carrier and provides a brand-new approach for the comprehensive utilization of biomass.

The hydrogenation catalyst plays an important role in removing trace olefins from aromatics. In this work, a Cu/ZnO/montmorillonite catalyst was developed. The Cu/ZnO/montmorillonite catalyst is not only comparable in performance to the noble metal Pt/montmorillonite catalyst, but also has greater potential because the activity of the catalyst at low hydrogen flow is almost the same as that at high hydrogen flow. Moreover, aromatic cracking will not occur under the action of the Cu/ZnO/montmorillonite catalyst. The activity of the modified catalyst used to remove olefins is stable at about 92% at low weight hourly space velocity (WHSV). The three functions of ZnO are summarized as follows: (i) Zinc oxide is beneficial to restore the BET surface area of the Cu-based catalyst. (ii) Zinc oxide can improve the amount of Cu that can be reduced by hydrogen. (iii) ZnO increases the grain size of Cu2(NO3)(OH)3, resulting in a higher reduction temperature for Cu-based catalysts.

Chemical looping gasification (CLG) of Ningdong coal by using Fe2O3 as the oxygen carriers (OCs) was studied, and the gasification characteristics were obtained. A computation fluid dynamics (CFD) model based on Eulerian-Lagrangian multiphase framework was established, and a numerical simulation the coal chemical looping gasification processes in fuel reactor (FR) was investigated. In addition, the heterogeneous reactions, homogeneous reactions and Fe2O3 oxygen carriers’ reduction reactions were considered in the gasification process. The characteristics of gas flow and gasification in the FR were analyzed and it was found that the experiment results were consistent with the simulation values. The results show that when the O/C mole rate was 0.5:1, the gasification temperature was 900 °C and the water vapor volume flow rate was 2.2 ml·min-1, the mole fraction of syngas reached a maximum value of the experimental result and simulation value were 71.5 % and 70.2 %, respectively. When the O/C mole rate was 0.5:1, the gasification temperature was 900 °C and the water vapor volume flow was 1.8 ml·min-1, the gasification efficiency reached the maximum value was 62.2 %, and the maximum carbon conversion rate was 84.0 %.

This study numerically investigates the combustion characteristics in a swirl burner for CO-H2 syngas by large eddy simulation. Firstly, experimental data are used to verify the applicability of the Boivin mechanism and the Sandia mechanism. The simulation results show that the Boivin mechanism predicts a more reasonable flame structure. Then, Syngas25, Syngas45, and Syngas100 (composed of 25%, 45%, and 100% H2 by volume, respectively) are set to numerically investigate the effect of hydrogen addition ratio on combustion characteristics by using the dynamic Smagorinsky model and the partially stirred reactor model. The detailed simulation data shows that the addition of hydrogen greatly influences the flame structure and flow field; with an increase in hydrogen addition, the flame length shortens, the temperature rises, and flashback caused by combustion induced vortex breakdown occurs. Furthermore, the precessing vortex core cannot exist stably in Syngas100, though it can be clearly observed in other cases.

In order to explore an efficient and clean conversion way of Ningdong coal, the chemical-looping reaction of Ningdong coal was conducted in a laboratory-scale fluidized-bed reactor using manganese ore as the oxygen carrier (OC), and the reaction characteristics were investigated in combination by thermogravimetric analysis. Experiments included the investigation of the reaction of the manganese ore with 5 vol % H2 and with coal powder at 900 °C, the catalytic and OC effect of manganese ore on coal gasification, the reaction efficiency and reaction products under different mass ratios of OC to coal (O/C), and the effect of multiple cycles on the reaction performance of the manganese ore. At 900 °C, the OC exhibited higher reactivity with coal syngas, significantly reducing the time of coal gasification (∼48% reduction). The manganese ore itself contained alkali metals, exhibiting a certain capacity for sulfur fixation, but the sulfur fixation was gradually weakened during multicycle experiments. The manganese ore did not exhibit any inhibition effect on NO x emission. From the wear rate of the manganese ore during fluidized reaction, its service life could be deduced to be about 150 h. Hence, it is necessary to improve the strength of the manganese ore OC.

In this work, nitrogen-doped porous carbons (NACs) were fabricated as an adsorbent by urea modification and KOH activation. The CO2 adsorption mechanism for the NACs was then explored. The NACs are found to present a large specific surface area (1920.72–3078.99 m2·g−1) and high micropore percentage (61.60%–76.23%). Under a pressure of 1 bar, sample NAC-650-650 shows the highest CO2 adsorption capacity up to 5.96 and 3.92 mmol·g−1 at 0 and 25 °C, respectively. In addition, the CO2/N2 selectivity of NAC-650-650 is 79.93, much higher than the value of 49.77 obtained for the nonnitrogen-doped carbon AC-650-650. The CO2 adsorption capacity of the NAC-650-650 sample maintains over 97% after ten cycles. Analysis of the results show that the CO2 capacity of the NACs has a linear correlation (R2 = 0.9633) with the cumulative pore volume for a pore size less than 1.02 nm. The presence of nitrogen and oxygen enhances the CO2/N2 selectivity, and pyrrole-N and hydroxy groups contribute more to the CO2 adsorption. In situ Fourier transform infrared spectra analysis indicates that CO2 is adsorbed onto the NACs as a gas. Furthermore, the physical adsorption mechanism is confirmed by adsorption kinetic models and the isosteric heat, and it is found to be controlled by CO2 diffusion. The CO2 adsorption kinetics for NACs at room temperature and in pure CO2 is in accordance with the pseudo-first-order model and Avramis fractional-order kinetic model.

Coal gasification slag (CGS) is a carbon-containing solid waste used as an adsorbent to remove low concentrations of mercury from wastewater in a series of batch tests to assess its adsorption properties and safe storage. The results showed that the adsorption of mercury on CGS was a very rapid and efficient process, and adsorption equilibrium was reached in only 10–40 min. A pseudo-second-order kinetics model provided a better fit to the equilibrium data. The adsorption capacity on CGS was just slightly below the value of active carbon. CGS showed the highest mercury removal efficiency at a solution pH of 4. Although the presence of other metal cations and anions affected the adsorption, CGS showed good selectivity for mercury ions. The adsorption of mercury was not affected by low concentrations of Cr3+ or Cu2+. The negative interference of anions on the removal efficiency followed the order: Cl−>H2PO4− >CO32− . The adsorption mechanism related to the functional groups included ion exchange, precipitation, coordination complexation, and surface complexation. Mercury adsorbed on CGS leached very slowly in weakly acidic or basic solution. All results of the study indicate that CGS is an economical and safe adsorbent for potential industrial applications.

In this work, Fe6Al4Ca1 composite oxygen carriers were prepared using the impregnation method with Fe2O3 as the active component, Al2O3 as the inert support and CaO as the modifier. The oxygen carr...

Under high-pressure conditions, coal chemical looping gasification (CLG) is a potential technology for industrial applications based on its ability to provide clean and efficient conversion of coal...

It is essential to research the effect of water vapor on CO2 adsorption from flue gas. Tetraethylenepentamine - impregnated hierarchical mesoporous carbon (HMC-TEPA) was fabricated as an adsorbent, and then, the adsorption mechanism and kinetics were investigated through the combination of experiments and density functional theory (DFT) calculations. The results show that both bicarbonate and carbamate are formed in the presence of water vapor, and water vapor has two effects on CO2 adsorption. On one hand, H2O has a higher affinity for TEPA, resulting in the reaction molar ratio of TEPA to CO2 decreasing from 2:1 to 1:1. In addition, increasing water vapor contents facilitates the reaction of TEPA/CO2/H2O, resulting in the CO2 adsorption capacity and TEPA efficiency increasing with the water vapor content within the range of 0 to 15 vol%. On the other hand, adsorption sites are occupied by excessive H2O (> 15 vol%), and the reaction of TEPA/CO2 decreases, resulting in the CO2 adsorption capacity decreasing slightly. Under simulated flue gas conditions ((15 vol% CO2/85 vol% N2) + 15 vol% H2O), HMC-30TEPA shows a higher TEPA efficiency of 256.12 mg g−1 and a CO2 adsorption capacity of 73.48 mg g−1 at 60 °C. Three kinetic models studies indicate that the Avrami model can describe the CO2 adsorption behavior in the presence of water vapor, and the optimized adsorbent shows a higher adsorption rate.

The highly efficient removal of tetracycline (TC) from an aqueous solution was accomplished by using the raw shrimp shell waste (SSW) as an environmentally friendly adsorbent. The SSW without any treatment removed TC more efficiently than the SSW after being treated with HCl and NaOH solutions. The SSW was characterized using nitrogen adsorption–desorption isotherms, scanning electron microscopy alongside energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, a thermogravimetric-derivative thermogravimetry analyzer, and a ζ-potential analyzer. The maximum adsorption capacity of 400 mg/L SSW was 229.98 mg/g for 36 h at 55 °C. Both the Langmuir isotherm model and the pseudo-second-order kinetic model well described the experimental data. According to the values of the Gibbs free energy and enthalpy changes, the TC adsorption by SSW proved to be spontaneous and endothermic. The TC adsorption process was controlled by intraparticle diffusion and liquid film diffusion.

Nano-TiO2 photocatalysts doped with La–N(La–N–TiO2) were prepared by solgel method. The La–N–TiO2 was loaded on the cellulose/SiO2 composite aerogel (La–N–TiO2–CSA). La–N–TiO2–CSA had both oil absorption and oil degradation functions under the sun. The static state water contact angle is up to 148° close to superhydrophobic surface. An apparent decomposition rate of oil is 92%, which is much higher than 26% of pure TiO2. Under the visible light irradiation, the photocurrent density has increased by 50%. Characterization results show that LaONO3 was uniformly distributed in TiO2 crystal. Compared with pure TiO2, the UV–Vis DRS data showed the absorption band of La–N–TiO2 had extended to 441 nm. The La increased the valence band position and N lowered the conduction band position, which reduced the band gap of TiO2 from 3.59 to 2.81 eV. The formation of LaONO3 reduced carrier transfer resistance, and the migration rate and electron–hole separation efficiency were improved. The possible oil decomposition pathways were proposed.

The high-temperature sintering of CaO-based materials leads to the serious decay of energy storage performance during the calcination/carbonation cycle. To overcome the loss in porosity problem, an efficient CaO-based material for thermal energy storage was synthesized using bamboo fiber as the biotemplate. The synthesis parameters (bamboo fiber addition, pyrolysis, Al2O3 loading) and the energy storage reaction characteristics of CaO-based energy storage material were optimized on the basis of cyclic calcination/carbonation experiments. The results show that the sacrificed biotemplate enhances the porosity of the synthetic material, denoting improved energy storage density. The cumulative energy storage density of the templated material over 50 cycles is 24,131.44 kJ/kg higher than that of limestone. The carbonation conversion and energy storage density of the templated CaO-based material doped with 5 wt.% Al2O3 and 0.5 g bamboo fiber reach 0.75 mol/mol and 2368.82 kJ/kg after 10 cycles, respectively, which is 2.7 times as high as that of original limestone. The maximum apparent carbonation rate of the templated CaO-based materials in the 1st cycle corresponds to a 240% increment compared to limestone. The maximum calcination rate of the synthetic CaO-based material in the 12th cycle remains 93%, as compared with the initial cycle. The microstructure analysis reveals that the hierarchically-stable structure during the cycle is beneficial for a more effective exposure of surface reactive sites for CaO and inward/outward diffusion for CO2 molecules through CaO. The method using the sacrificed biological template provides an advanced approach to fabricate porous materials, and the composite CaO-based material provides high-return solar energy storage for a potential application in industrial scale.

Nonmetallic materials recycled from waste printed circuit boards (N-WPCBs) were modified by coating KH-550 in a spout-fluid bed. To improve the effect of the modification, PP particles were used to enhance the fluidization quality of the N-WPCB particles in the coating modification. Then, the modified N-WPCBs were used as fillers to fabricate PP/N-WPCB composites. The method of coating in a spout-fluid bed with PP particles enhanced fluidization and showed the best modification effect compared to other coating methods. The FT-IR and SEM results demonstrated that interfacial bonding between N-WPCBs and PP could be enhanced by modified N-WPCBs, which improved the mechanical properties of the composites. When the mass ratio of PP to N-WPCBs is 100:75 and the dose of KH-550 is 4 phr, the flexural strength, tensile strength, and impact strength of the composites increase by 16.60%, 23.22%, and 23.64%, respectively. This would realize the high-value utilization of N-WPCBs with coating modification in the spout-fluid bed.