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[Display omitted] • Gravity separation was used to mass-produce GC. • GC preparation would promote efficient and high-value utilization of coal gasification slag. • Valuable metals in oceanic manganese nodules were efficiently reduced by GC. • The reaction mechanism was explored based on thermodynamics and phase conversions. In line with the concept of coal gasification slag treatment and marine mineral exploitation, this research proposed a residual carbon roasting-acid leaching process to extract various valuable metals from oceanic manganese nodules. The residual carbon obtained from coal gasification coarse slag was enriched via gravity separation without chemical treatment, and this carbon-high product served as an inexpensive reducing agent. The feasibility of carbon-high reduction of oceanic manganese nodules was explored using a thermogravimetric-mass spectrometric coupling system and thermodynamic analysis. The influence of mass ratio, roasting time, and roasting temperature on the reduction effect of oceanic manganese nodules was examined, and optimal conditions were determined through orthogonal tests. The results demonstrated that under the optimized conditions, the leaching rate of Mn exceeded 98%, and that of Cu, Co, and Ni exceeded 96%. The reduction and leaching processes were elucidated at the crystal scale through various ways. Finally, a comprehensive process flow diagram was summarized for the extraction of various valuable metals from oceanic manganese nodules using the residual carbon roasting-acid leaching process. This research will pave the way for the design of cost-effective and sustainable roasting reductants and reduction roasting processes for manganese oxide ores, contributing to economic and environmental benefits. [ABSTRACT FROM AUTHOR]

The application of porous carbon in electrochemical energy storage devices (e.g., symmetrical capacitors, SCs, zinc ion capacitors, ZICs) is of great value, while pitch is one of the excellent precursors of porous carbon. Herein, the pitch-based 3D tremella-like porous carbons with heteroatoms (N and O) and cavitary structures have been synthesized via one-step oxidation activation. This strategy can introduce oxygen atoms to effectively inhibit the conjugation effect of the pitch and improve the convenience of preparation. The melting and crystallizing effect of NaCl can help the creation of cavitary structures and hierarchical pores. Gases released from the pyrolysis of pitches and decomposition of K2C2O4contribute to the distortion of the carbon structure, resulting in the tremella-like morphology. The best sample, PC-825, has a specific capacitance of 338.5 F g−1in a three-electrode system and an energy density of 12.2 Wh kg−1in SCs. More importantly, PC-825 as cathodes in ZICs has a specific capacitance of up to 193.1 mAh g−1and an energy density of up to 154.5 Wh kg−1, realizing an outstanding zinc storage capacity. This work realizes the conversion of cheap pitch to high-value-added electrochemical materials.

A high organic-sulfur coking coal and two high-volatile gas coals were selected to partially replace a low-sulfur coking coal in an industrial coal blend. The effects of various coal properties on directional regulation of sulfur during coal blend pyrolysis were investigated by a lab-scale fixed-bed reactor, and the coke quality indices were evaluated by a 10 kg-scale coke oven. After adding gas coals in the coal blend, the experimental sulfur content in coke and sulfur removal were determined to be lower and higher, respectively, than the calculated values, as a result of the directional regulation effect of gas coals on sulfur transformation. Interactions between hydrogen radicals and nascent coke played a more dominant role in sulfur regulation with the addition of the lower ratio of gas coal. The effect of sulfur fixation by minerals deteriorated the sulfur regulation with the further increase of gas coal in the coal blend. These effects were also reflected from the changes of sulfur distribution in coke. The 10 kg-scale coke oven test results showed that adding 7% high-sulfur coking coal and 3% low-ash gas coal into the coal blend could obtain a coke with the quality close to the basic coke, which proved the feasibility of sulfur regulation and indicated that the coking cost would be reduced based on the lower price of the alternative coals than the premium coking coal.

In this work, a series of hierarchical Y-type zeolites were rapidly synthesized using organosilane as templates through a microwave hydrothermal method. The effects of hierarchical Y-type zeolites on the product composition and the yield of light aromatics in gaseous tar from coal pyrolysis were studied. The results showed that the hierarchical Y-type zeolites showed better catalytic properties than the traditional microporous zeolite in the catalytic conversion of gaseous tar and can greatly increase the yield of light aromatics in the pyrolysis products. The hierarchical Y-type zeolite has abundant mesopores, which contribute to the access of bulky molecules into the porous channel and the contact of active sites. Meanwhile, the mesopores reduce the diffusion length of the reaction products, thus promoting the conversion of heavy components in gaseous tar to light aromatics.

The Bunsen reaction is the center reaction for both the sulfur–iodine water splitting cycle for hydrogen production and the novel hydrogen sulfide splitting cycle for hydrogen and sulfuric acid production from the sulfur-containing gases. This paper reviews the research progress of the Bunsen reaction in recent 10–15 years. Researches were initially focused on the optimization of the operating conditions of the conventional Bunsen reaction requiring excessive water and iodine to improve the products separation efficiency and to avoid the side reactions and iodine vapor deposition. Alternative methods including electrochemical methods, precipitation methods, and non-aqueous solvent methods had their respective advantages, but still faced challenges. In development of the technology of H2S splitting cycle, dissolving iodine in toluene solvent could render the Bunsen reaction to occur with the flowable I2stream at ambient temperature such that the side reactions and iodine vaporization can be avoided and the corrosion hazard lessened. It also prevented the Bunsen reaction from using excessive iodine and water. The products from the Bunsen reaction including HI, H2SO4, H2O, and toluene could be directly electrolyzed.

Cu-SSZ-13 catalyst has excellent performance for removing NOx. In this study, the in-situinterzeolite transformation (IZT) method was proposed to prepare Cu-SSZ-13 catalyst. The coal fly ash-derived zeolite acted as a raw material rather than the chemical silicon and aluminum source. A series of catalysts were prepared using the in-situIZT method with different ratios of the two template agents. The NO conversion of Cu-SSZ-13 catalysts was above 90% within the temperature range of 200-700 °C, whereas the N2selectivity was maintained at about 100%. The as-synthesized catalysts had higher conversion rates for Si and Al, higher copper loading and more isolated Cu2+. The selective catalytic reduction (SCR) reaction mechanisms of Cu-SSZ-13 catalyst prepared using the in-situIZT method followed both the Eley-Rideal (E-R) mechanism and the Langmuir-Hinshelwood (L-H) mechanism, though it was mainly based on the E-R reaction. In this study, the Cu-SSZ-13 catalysts were synthesized using coal fly ash based zeolite in one step. This study further improved the synthesis process route from coal based solid waste to SCR catalyst, shortened the preparation cycle, and improved catalyst performance.

Pd–Fe bimetallic sorbents were shown to be a great potential sorbent for Hg0removal from coal-derived fuel gas. In this work, activated carbon (AC), Al2O3, and Beta molecular sieve were chosen as supports to disperse Pd–Fe bimetallic components. The effects of the supports on Hg0removal of Pd–Fe bimetallic sorbents were evaluated using a fixed-bed reactor at 200 °C. The regeneration performance of sorbents was also investigated. The results showed that Hg0removal activity and regeneration performance over Pd–Fe/AC was the best, followed by Pd–Fe/Beta, and Pd–Fe/Al2O3. The Hg0removal efficiency of Pd–Fe/AC bimetallic sorbents remained above 80% within 400 min after regeneration 4 times. The Pd–Fe bimetallic sorbents were characterized by N2adsorption–desorption, Fourier transform infrared spectroscopy, X-ray diffraction, CO pulse adsorption, Hg temperature-programmed thermal desorption, and X-ray photoelectron spectroscopy. The analysis results revealed that three sorbents had a similar Hg0removal mechanism. Hg0transformed to Pd–Hg amalgam and HgS after reacting with the sorbents. Pd0and Fe2O3were the active species for the removal of Hg0. The removal performance of Hg0by Pd–Fe/Al2O3sorbents was the lowest. It is because Pd–Fe/Al2O3sorbents have the lowest specific surface area, surface content, and dispersion degree of the Pd component. Furthermore, Pd0over Pd–Fe/Al2O3sorbents was severely poisoned and transformed to PdS during the regeneration process.

The Inner Mongolia lignite was selected as the feedstock and dewatered by hydrothermal, fixed-bed, and microwave upgrading techniques. The physicochemical structures of the raw coal and dewatered coal samples were determined by N2adsorption, Fourier transform infrared, and chemical titration methods. The combustion behavior of coals was investigated by thermogravimetric analyzer, and the results demonstrated that the combustion reactivity of the dewatered coals was enhanced. The apparent activation energies of the coal samples were obtained from nonisothermal single heating rate method, and the results illuminated that the combustion process of these coals could be divided into three stages according to the variations of their apparent activation energies. Those variations were used as the medium to investigate the correlations between combustion reactivity parameters and physicochemical structures. It was found that at stage I of the combustion process, the ignition temperature of the coal was mainly affected by intrinsic chemical reactivity; at stage II, the maximum combustion reaction rate of the coal was affected by intrinsic chemical reactivity and specific area diffusion, and the temperature corresponding to the maximum combustion reaction rate was mainly affected by intrinsic chemical reactivity; and at stage III, the burnout temperature was affected by intrinsic chemical reactivity, and the overall reaction rate was controlled by gas diffusion rate.

Series of HY sorbents with different amounts and strength of Brønsted and Lewis acidic sites were prepared. Their adsorption performance in thiophene–benzene solution, pure benzene, and pure thiophene were evaluated, and the desulfurization mechanisms were studied. The results show that both thiophene and benzene could be effectively adsorbed through the interaction between Lewis acid sites and the conjugated π bond in these two molecules, and thus thiophene adsorption could be obviously competed by benzene on Lewis acidic sites. By contrast, on Brønsted acidic sites, thiophene can be efficiently adsorbed via H–S bond, which is stronger than the former interaction. Moreover, the middle strong Brønsted acid could cause thiophene oligomerization. Hence, for the desulfurization purpose by NaY zeolite in aromatic free system, its weak and middle strong Lewis acid should be increased, and for that in aromatic existing system, the Brønsted acid site with relative low strength should be promoted.

Coal gasification fine slag (CGFS) is a solid waste byproduct generated during the coal gasification process. However, the high content of residual carbon hinders its potential for resource utilization. The urgent need for an efficient carbon extraction and ash reduction technology is evident. Hydrophobic–hydrophilic separation (HHS) is a technology that enriches hydrophobic particles in the oil phase while hydrophilic particles are in the water phase by stirring, and the different hydrophobic particles are separated by the separation of the oil and water phases. The molecular dynamics simulations revealed that the adsorption of n-heptane onto the residual carbon surface occurred spontaneously and was primarily driven by van der Waals forces. Ultrasonic pre-treatment pulp could enhance the effect of HHS. The fluctuation in tailings ash did not exceed 2% while the concentrate ash was reduced from 31.81% to 18.93% with a continual increase in ultrasonic power. The application of ultrasonic treatment on CGFS facilitated the separation of Carbon-ash molten state, as well as the elimination of ash materials particles residing within the pores of the residual carbon matrix and on its surface. Notably, many residual carbon particles are concentrated in the particle size range of 0.045–0 mm. The heightened hydrophobicity exhibited by particles within this size range enhanced the capture of oil droplets, thereby promoting the efficiency of HHS. This research aims to provide technical support and theoretical foundation for utilizing ultrasonic pretreatment as a means to enhance the HHS efficiency of CGFS.

Hierarchical porous carbon nanospheres (HPCNs) with uniform morphology are highly significant for the application of supercapacitors. In this paper, carbon nanospheres (CNs) are synthesized via Stöber method with small molecular phenols fractionated from low-medium temperature coal tar. The factors behind the morphology of CNs have been investigated during the synthesizing process. It is found that the CNs prepared with a phenol content of 50 wt% and a hydrothermal temperature of 160 °C display the characteristics of an average particle size of 667 nm and a uniform morphology with narrow particle size distribution. Besides, the processing time of CO2-activation are then optimized based on the pore structure and electrochemical properties of CNs. The optimized CNs offer the features of ultra large specific surface area (2812 m2g−1), hierarchical porous structure and numerous nitrogen and oxygen functional groups. The as-prepared electrode is thus featured by a high specific capacitance of 258 F g−1at 0.5 A g−1, good rate characteristic and remarkable electrochemical stability (only 0.7% loss after 8000 cycles). The present strategy provides a promising candidate for the high-value utilization of coal tar and the low-cost preparation of electrode materials.

•The influences of CO2on coal char structure and the reactivity were studied.•CO2could inhibit the release of volatiles during pyrolysis at low temperatures.•Introducing CO2results in increase of char aromaticity.•The reactivity of chars obtained under CO2atmosphere is lower than that under N2.

MnTiOxcatalysts with different quantities of Ti are synthesized with a hydrothermal method and employed in the catalytic oxidation of benzene. By controlling the relative content of Mn and Ti, the effect of Ti content has been investigated from physicochemical properties and activity points of view. Ti enables the formation of Lewis acid with electrophilic properties and simultaneously leads to the increase of Mn4+and surface lattice oxygen numbers. Additionally, it is established that the addition of Ti4+can lead to the partial substitution of Mn3+in MnTiOxto create the Mn-O-Ti structure, improving the active oxygen transfer capacity, which is crucial for catalytic activity. After optimization, the best catalytic performance sample is MnTiOx-0.33 with the T90= 258 oC at GHSV = 45000 ml·g-1·h-1. It is proposed that the catalytic oxidation of benzene takes place on the surface of MnTiOx-0.33 through the MVK mechanism.

A lignite from Huolinhe mine in China was dewatered in a fixed-bed reactor at different temperature of 80-160°C under nitrogen and argon respectively. Then different drying levels dewatered samples were undergone the moisture re-adsorption in constant temperature and humidity chamber. The physical and chemical structures of all samples were characterised by nitrogen adsorption instrument and diffuse reflectance in-situ FTIR spectrometer. The dehydration rate of lignite under nitrogen is higher and the moisture re-adsorption capacity of dewatered coal is lower than that of sample received from argon. It is also found that the amount of re-adsorbed moisture reduces dramatically when the dewatered coal is held for another 60 min among nitrogen at room temperature. The physical and chemical structure changes of samples before and after drying are the main factors influencing the moisture re-adsorption capacity of dewatered samples. Both specific surface area and pore volume of lignite decrease during drying under two kinds of atmosphere but more obviously under nitrogen. The changes of contents of hydrophilic oxygen-containing functional groups in lignite, especially COO- and COOH, is directly related to the re-adsorbing moisture capacity of de-watered sample. [Received: December 5, 2013; Accepted: October 28, 2014]

The catalytic oxidation over the selective catalytic reduction (SCR) catalysts is efficient and economical for the removal of elemental mercury (Hg0). Herein, we studied the catalytic oxidation of Hg0over the MnCeTiOxcatalysts with different Ce contents synthesized by a polyethylene glycol-assisted (PEG) co-precipitation method. By increasing the contents of Ce loaded, the oxidizability of MnCeTiOxwas reduced, but the NH3-SCR performance and H2O/SO2resistance were improved. The MnCe(0.1)TiOxcatalyst presented high NO conversion rate exceeding 80% at 160–360 °C and gas space hourly velocity (GHSV) of 80, 000 h−1and Hg0oxidation efficiency beyond 95% at 100–300 °C and 400, 000 h−1, respectively. The surface-active oxygen including chemisorbed surface O and unsaturated-coordinated surface lattice O acted as the active sites for Hg0oxidation. The competitive adsorption and oxidation of SO2and NH3could suppress the adsorption of Hg0. NO and SO2could be oxidized into active intermediates, such as NO3-* and SO42-* , which benefited the oxidation of Hg0. However, the NH3was a strong Lewis base and reducing agent, which could be oxidized to NH2* or NH* and then hinder the oxidation of Hg0. These results clarified the interaction among the multi-components during the oxidation of Hg0over the SCR catalysts, which is beneficial to the development of Hg0treatment techniques in low-temperature flue gas.

In this study, activated clay was used as adsorbent for the removal of methyl orange (MO) from aqueous solution in a batch system. Experiments were carried out as a function of contact time, initial concentrations of solution, adsorbent dosage, solution pH, and temperature, and consequently, optimum condition of adsorption was obtained. The equilibrium adsorption data of MO on activated clay were analyzed by Langmuir, Freundlich and Temkin isotherm models, the results indicate that Langmuir and Temkin models provide better correlation of the experimental data. The pseudo-first-order, pseudo-second-order and Elovich kinetics models were used to analyze the kinetics data obtained at different concentrations. Among the kinetics models studied, the pseudo-second-order model was the best applicable model to describe the adsorption of MO onto activated clay. The values of Gibbs free energy of adsorption (ΔG°) were found to be -7.462 kJ mol-1, the negative value indicated the spontaneity of the adsorption process of MO onto activated clay. The values of ΔH° and ΔS° were found to be -12.289 kJ mol-1and -16.474 J mol-1 K-1, respectively. The negative value of ΔH° reveals the adsorption is exothermic, and the negative value of ΔS° suggests that the confusion degree of adsorption process is decreasing.

AbstractIn this study, activated clay was used as adsorbent for the removal of methyl orange (MO) from aqueous solution in a batch system. Experiments were carried out as a function of contact time, initial concentrations of solution, adsorbent dosage, solution pH, and temperature, and consequently, optimum condition of adsorption was obtained. The equilibrium adsorption data of MO on activated clay were analyzed by Langmuir, Freundlich and Temkin isotherm models, the results indicate that Langmuir and Temkin models provide better correlation of the experimental data. The pseudo-first-order, pseudo-second-order and Elovich kinetics models were used to analyze the kinetics data obtained at different concentrations. Among the kinetics models studied, the pseudo-second-order model was the best applicable model to describe the adsorption of MO onto activated clay. The values of Gibbs free energy of adsorption (ΔG°) were found to be −7.462 kJ mol−1, the negative value indicated the spontaneity of the adsorption process of MO onto activated clay. The values of ΔH° and ΔS° were found to be −12.289 kJ mol−1and −16.474 J mol−1 K−1, respectively. The negative value of ΔH° reveals the adsorption is exothermic, and the negative value of ΔS° suggests that the confusion degree of adsorption process is decreasing.

AbstractA simple process, vacuum distillation, was utilized for purification of methyl orange (MO) as dye effluent. The dye effluent characteristic of high chemical oxygen demand (COD) value and high chromaticity is difficult to treat for the industrial wastewater treatment. In our work, the effect of some factors on the distillation efficiency (DE), including pressure, concentration and the surfactant based on the optimal conditions was evaluated. The results showed that the COD removal for 99.57% was obtained when the concentration of MO is 2000 mg l−1at the pressure of 0.070 MPa. Moreover, the polyacrylamide (cationic) used in initial concentration of 500 mg l−1show satisfactory removal efficiency in the further test.

A simple process, vacuum distillation, was utilized for purification of methyl orange (MO) as dye effluent. The dye effluent characteristic of high chemical oxygen demand (COD) value and high chromaticity is difficult to treat for the industrial wastewater treatment. In our work, the effect of some factors on the distillation efficiency (DE), including pressure, concentration and the surfactant based on the optimal conditions was evaluated. The results showed that the COD removal for 99.57% was obtained when the concentration of MO is 2000 mg l-1at the pressure of 0.070 MPa. Moreover, the polyacrylamide (cationic) used in initial concentration of 500 mg l-1show satisfactory removal efficiency in the further test.

The characteristics of the energy structure of rich coal, less oil and less gas, coupling with a high external dependence on oil and natural gas and the emphasis on the efficient and clean utilisation of coal, have brought opportunities for coal chemical industry. However, with the large-scale popularisation of coal gasification technology, the production and resulting storage of coal gasification slag continue to increase, which not only result in serious environmental pollution and a waste of terrestrial resources, but also seriously affect the sustainable development of coal chemical enterprises. Hence, the treatment of coal gasification slag is extremely important. In this paper, the production, composition, morphology, particle size structure and water holding characteristics of coal gasification slag are introduced, and the methods of carbon ash separation of gasification slag, both domestically and abroad, are summarised. In addition, the paper also summarises the research progress on gasification slag in building materials, ecological restoration, residual carbon utilisation and other high-value utilisation, and ultimately puts forward the idea of the comprehensive utilisation of gasification slag. For large-scale consumption to solve the environmental problems of enterprises and achieve high-value utilisation to increase the economic benefits of enterprises, it is urgent to zealously design a reasonable and comprehensive utilisation technologies with simple operational processes, strong adaptability and economic benefits.