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Abstract: The gasification activities of three kinds of Binxian chars with carbon dioxide were studied at 1000–1300°C and under atmospheric pressure in self-made thermal balance. The specific surface area of coal or chars was determined with BET methods during gasification. The results showed that the reaction rate of two rapid pyrolysis chars increases at the beginning and decreases subsequently with increasing carbon conversion at relatively high temperatures. The heating rate of coal has a significant effect on the gasification process. The activation energy of slow pyrolysis char varies between 160kJ/mol and 180kJ/mol during gasification. The activation energy of the two rapid pyrolysis chars displays a linear trend when the carbon conversion is less than 40% and decreases slowly afterwards. [Copyright &y& Elsevier]

[Display omitted] • Hydrothermal and sol-gel method were combined to prepare carbon microspheres. • Carbon microspheres with multi-layer dendritic hollow structure, high specific surface area and abundant micropores were successfully prepared. • Excellent cycle stability and great specific capacitance were obtained by the supercapacitor prepared from the carbon microspheres. The electrochemical properties of corn starch (CS)-based hydrothermal carbon microsphere (CMS) electrode materials for supercapacitor are closely related to their structures. Herein, cetyltrimethyl ammonium bromide (CTAB) was used as a soft template to form the corn starch (CS)-based carbon microspheres with radial hollow structure in the inner and middle layers by hydrothermal and sol-gel method. Due to the introduction of multi-layer hollow structure of carbon microsphere, more micropores were produced during CO 2 activation, which increased the specific surface area and improved the capacitance performance. Compared to commercial activated carbon, the four different morphologies of corn starch CMS had better electrochemical performances. Consequently, the proposed CO 2 –(CTAB)-CS-CS exhibits a high discharge specific capacitance of 242.5F/g at 1 A/g in three-electrode system with 6 M KOH electrolyte, better than commercial activated carbon with 208.5F/g. Moreover, excellent stability is achieved for CO 2 –(CTAB)-CS-CS with approximately 97.14 % retention of the initial specific capacitance value after 10,000 cycles at a current density of 2 A/g, while the commercial activated carbon has 86.96 % retention. This implies that the corn starch-based multilayer hollow CMS could be a promising electrode material for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect of hydrothermal acid treatment on the formation of lignin-based porous carbon (LPC) has been revealed. • The CO 2 adsorption mechanism of LPCs with hydrothermal pretreatment of different pH values was explored. • A feasible method to make highly efficient LPCs for CO 2 capture was developed. The study reports the economic and sustainable syntheses of a lignin-based porous carbon (LPC) for CO 2 capture application. The pH values of hydrothermal solution affected the polymerization and aromatization of spheroidization, with morphological changes from blocky to microsphere. In addition, the reliable mechanisms of CO 2 adsorption were proposed by combining experiments with Gaussian16 simulations based on DFT. The electrostatic attraction of oxygen-containing functional groups and the diffusivity resistance of CO 2 in the pores are the key factors for the CO 2 adsorption. ​The carboxyl groups have the strongest electrostatic attraction to CO 2. LPC-pH 1 has the highest carboxyl group content, possessing a CO 2 adsorption capacity of up to 5.10 mmol/g at 0℃, 1 bar. Furthermore, CO 2 diffusion resistance became a main factor as the adsorption temperature increases. The innovative combination of quantum chemical calculations and microscopic properties provides a viable pathway for an insight into the future control of lignin-based carbon formation. [ABSTRACT FROM AUTHOR]

Abstract: The selective oxidation of hydrogen sulfide (H2S) to sulfur on activated carbon-supported metal oxide sorbents (M/AC) was investigated for hot fuel gas desulfurization. Various M/AC sorbents loaded with 1wt.% metal oxide were separately prepared by pore volume impregnation and their breakthrough capacity was examined. The results showed that the breakthrough capacity of different sorbents can be placed in the following order: Mn/AC>Cu/AC>Fe/AC>Ce/AC>Co/AC>V/AC. The metal oxides loaded on the M/AC surface catalyze the reaction between hydrogen sulfide and oxygen to form element sulfur; the activated carbon, as an adsorbent, can adsorb and store the element sulfur in its pore passage. The DTG analysis and determination of forms of sulfur confirmed that the main product of the catalytic oxidation of hydrogen sulfide was elemental sulfur. The regeneration of exhausted sorbents was carried out using hot gas N2 and H2O desorption methods at temperature 500°C. The breakthrough capacity of the sorbent was mostly recovered after regeneration. The mechanism of the catalytic oxidation of H2S on M/AC sorbent was also discussed. [Copyright &y& Elsevier]

Abstract: Experiments have been conducted with Huolinhe (HLH), Xiaolongtan (XLT), and Ethiopian (ET) lignites to investigate the effects of washing with water, acid-leaching, and floatation on their ash fusion temperatures (AFTs). The results show that the AFTs of XLT and ET are elevated by washing with water and floatation, but the AFT of HLH is decreased. The AFTs of all three lignites are increased markedly by acid leaching. A decrease in the total basic composition in ash increases its AFT, and vice versa. Changes in the mineral contents of the coals after treatment contribute to the variations in their AFTs. After washing with water, the lower AFT of HLH is brought about by the increases in the amounts of cordierite and anhydrite, whereas the higher AFT of XLT is caused by the decreases in the amounts of anhydrite and calcite. For the floatation treatment, the decrease of AFT for HLH is due to the reduction in the amount of kaolinite, but the elevation of AFT for XLT or ET is caused by the decrease in the amount of pyrite and the reductions in the amounts of gypsum and xanthoxenite, respectively. For the acid-leaching treatment, a decrease in the amount of pyrite and an increase in the amount of kaolinite result in increases in AFTs for HLH and XLT. Increases in the amounts of kaolinite and cristobalite in FET (ET after floatation), WET (ET after washing with water), and AET (ET after acid-leaching) lead to corresponding increases in the AFTs. [Copyright &y& Elsevier]

Highlights • Sodium recovery with water leaching was low due to the formation of NaAlSiO 4. • The synchronous recovery of sodium and alumina from NCGA is feasible. • The formation of Na 2 CaSiO 4 accounts for the low sodium recovery with Ca-calcination. • The combination of water leaching and alumina extraction can improve sodium recovery. Abstract The catalyst recovery from Na 2 CO 3 -catalyzed steam gasification ash of Sunjiahao (SJH) high-aluminium coal char was investigated using water leaching method combined with extracting alumina by means of Ca(OH) 2 thermal activation. The recovery efficiency of sodium catalyst from Na 2 CO 3 -catalyzed gasification ash (NCGA) with single water leaching method was as low as 39.5 wt%, which resulted from the formation of water insoluble sodium aluminosilicate during Na 2 CO 3 -catalyzed gasification. In order to improve sodium recovery, the water-washed NCGA was activated by means of Ca(OH) 2 thermal activation for simultaneous recovery of sodium and alumina. The recovery efficiency of sodium from the water insoluble sodium aluminosilicate is 63.6 wt%, thus the total sodium recovery can be remarkably improved and reach 72 wt%. Meanwhile, the extraction efficiency of alumina from NCGA can reach 88.46 wt%. The low sodium recovery with Ca(OH) 2 thermal activation is attributed to the formation of Na 2 CaSiO 4 during Ca(OH) 2 calcination. Extracting alumina process from NCGA of SJH high-aluminium coal can effectively promote the recovery of sodium catalyst and the process economy. [ABSTRACT FROM AUTHOR]

To produce a qualified gasification-coke by blending a larger proportion of low-rank coal, the effects of blending ratio, particle size distribution, and maceral components on the coke strength were studied, and a new coking mechanism was put forward in terms of the physical texture. The results show that the influence of coal particle size varies with the different cohesiveness of coals. Fat coal (FC) with a smaller size gets a better performance on the coke strength, while a larger size is needed for gas coal (GC), and the optimum size of long flame coal (Shenfu coal, SFC) varied with its blending ratio. SFC and GC should be crushed coarsely (2–3 mm surpasses 40%) to act as the framework with the less external surface in the viscous embedded state. FC should be crushed finely (<0.2 mm) to form flowing metaplast that being filled uniformly in the gap between these coarse particles, thus reinforcing the embedded state and leading to a high coke strength with a less blend of FC (25 wt%). Moreover, liptinite enriched in the coarse particles of GC and SFC improves the cohesiveness of blended coal moderately. A qualified gasification-coke ( M 25  > 90%, CRI  > 50%, CSR  > 35%) can be obtained by blending >40 wt% SFC with this new coking mechanism. [ABSTRACT FROM AUTHOR]

KOH activation of high sulfur petroleum coke (HSPC) is one of the main methods to get advanced carbon materials, so it is essential to have a deep understanding of sulfur transformation during KOH activation of HSPC. In this study, the activation of two kinds of HSPCs (Zibo petroleum coke (ZPC) and American petroleum coke (APC)) was studied in a fixed-bed reactor with temperature programming under N 2 atmosphere in different alkali/PC mass ratios (from 0.5 to 5), and the products were analyzed by XRD, XPS, ICP and gas analyzer. During KOH activation, the release of sulfur increased sharply at the beginning and then flattened out. When carbon conversion approximates to 50%, the sulfur in HSPC is released by near 90%. The sulfur product of sulfate and SO 2 was more than that of sulfide and H 2 S, which can be explained by the thermodynamic calculation. Thiophene (the main form of sulfur species in HSPCs) reaction with alkali tends to generate equal amount of sulfate and sulfide but more SO 2 than H 2 S, while sulfoxide reaction with alkali tends to generate much more sulfate than sulfide. [ABSTRACT FROM AUTHOR]

The ash adhesion and deposition (AD)characteristics of three low-rank coal (LRC) were investigated by self-made AD analyzer, X-ray fluorescence spectrometry, scanning electron microscopy equipped with energy dispersive X-ray detector, and X-ray diffraction. Under a given condition, the deposition mass ratios of different LRC ashes are different, which mainly due to the difference in iron content. The mass ratios of ash deposition under oxidizing atmospheres are higher than those under reducing atmospheres because of the effects of different valence of iron. The mass ratio of AD increases with the increase of temperature, while it decreases with gas velocity increases. The possible formation mechanism of AD is proposed by adhesive amorphous matter formation, iron enrichment and the generation of ferro-aluminate and ferro-alumino silicate, substitution of Fe 2 + by Ca 2 + , and mullite adhesion. [ABSTRACT FROM AUTHOR]