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The mesopores Hβ-Tx (x = 1, 2, 3, 4, 5) zeolites were synthesized in different crystallization time (48 h, 72 h, 120 h, 168 h, 240 h), and then the NiMoC/Hβ-Tx catalysts were synthesized by equal volume impregnation and programmed temperature carbonization. The effects of crystallization time on the catalytic activity were investigated by hydrogenation of naphthalene, quinoline and aromatics from low temperature coal tar in a fixed bed. The NiMoC/Hβ-T4 catalysts with β zeolite crystallization time of 168 h, exhibited the highest catalytic activity in hydrogenation of aromatics. It can be concluded that higher density of B acid sites of supports, and higher active metal dispersion will enhance the tolerance of catalysts to heteroatoms, while larger grain size of support is unfavorable to resist heteroatoms. Additionally, hydrogenation of aromatics can occur over the prepared NiMoC/Hβ catalysts under mild conditions (275 °C, 3 MPa). The NiMoC/Hβ-T4 catalysts is better than traditional catalysts including NiMoC/Al2O3, NiMoS/Al2O3 and NiMoS/Hβ catalysts in hydrogenation of aromatics. [ABSTRACT FROM AUTHOR]

Purpose: Synthetic ammonia is not only the basis of the fertilizer industry in China but also has the highest energy consumption and pollution emissions in the chemical industry. The objective of this study was to conduct a cradle-to-gate life cycle assessment (LCA) of ammonia production based on different raw materials to identify the crucial processes and parameters and to provide suggestions for clean and sustainable development of the ammonia industry in China. Methods: Based on actual industrial data, this study comprehensively evaluated the resource consumption and pollution emissions caused by different raw material routes and coal-to-ammonia technologies from a life cycle perspective according to the LCA standards ISO 14040 series and using the CML 2001 method and identified the key environmental impact categories and stage contributions. In addition, the effects of various input parameters on the environmental burden were specified through sensitivity analysis. Accordingly, suggestions for improving the environmental performance of ammonia production are proposed. Results: The environmental burdens of the coal-based and coke oven gas-based routes were 1.43 and 1.7 times higher than that of the natural gas-based route, respectively. The significant differences were mainly reflected in the greenhouse effect, acidification, and fossil energy depletion. Advanced coal-to-ammonia technology, represented by coal water slurry gasification, showed a lower environmental burden than the traditional intermittent gasification technology, especially in terms of greenhouse gas (GHG) emissions and energy consumption. The GHG emissions involved in producing ammonia decreased from 3.88 to 2.18 kg per 1 kg of ammonia, and energy consumption decreased by approximately 17%, from 5.69 to 4.71 MJ. Conclusions: Coal is the main raw material used for ammonia production in China, and the results showed that the application of advanced coal gasification with energy-saving technologies can effectively improve the environmental performance of synthetic ammonia production in China. [ABSTRACT FROM AUTHOR]

A series of Ni-Al2O3 catalysts with attractive catalytic activity and thermal stability have been developed via a facile hydrolysis-precipitation technique (xNiAl-HP, x representing the weight percentage of NiO). Based on the high nickel active surface area, good dispersion of NiO and high content of α- and β1-type NiO, outstanding CO conversion (99%) and CH4 yield (96%) can be achieved over 40NiAl-HP under mild conditions [T = 220 °C, P = 1.0 MPa, and WHSV = 20,000 mL/(g·h)]. The reaction-sintering at high temperature (800 °C) evolves through: (a) the migration of nickel crystals, (b) the phase transformation from γ- to θ- and then to α-Al2O3, and (c) the agglomeration of catalyst particles. The 40NiAl-HP catalyst could still maintain CO conversion over 99% at 300 °C after being used at 800 °C for 100 h. Herein, the high catalytic activity, good sintering resistance and noble-metal-/promoter-free nature might make 40NiAl-HP a competitive candidate for industrial methanation. [ABSTRACT FROM AUTHOR]

This paper aims to discuss an environmental, social, and economic analysis of energy utilization of crop residues from life cycle perspectives in China. The methodologies employed to achieve this objective are environmental life cycle assessment (E-LCA), life cycle cost (LCC), and social life cycle assessment (S-LCA). Five scenarios are developed based on the conversion technologies and final bioenergy products. The system boundaries include crop residue collection, transportation, pre-treatment, and conversion process. The replaced amounts of energy are also taken into account in the E-LCA analysis. The functional unit is defined as 1 MJ of energy produced. Eight impact categories are considered besides climate change in E-LCA. The investment capital cost and salary cost are collected and compared in the life cycle of the scenarios. Three stakeholders and several subcategories are considered in the S-LCA analysis defined by UNEP/ SETAS guidelines. The results show that the energy utilization of crop residue has carbon emission factors of 0.09–0.18 kg (CO2 eq per 1 MJ), and presents a net carbon emissions reduction of 0.03–0.15 kg (CO2 eq per 1 MJ) compared with the convectional electricity or petrol, but the other impacts should be paid attention to in the biomass energy scenarios. The energy utilization of crop residues can bring economic benefit to local communities and the society, but the working conditions of local workers need to be improved in future biomass energy development. [ABSTRACT FROM AUTHOR]

China's fossil energy is characterized by an abundance of coal and a relative lack of oil and natural gas. Developing a strategy in which coal can replace oil and natural gas is, therefore, a necessary and practical approach to easing the excessive external dependence on oil and natural gas. Based on the perspective of energy security, this paper proposes a technical framework for defining the substitution of oil and natural gas with coal in China. In this framework, three substitution classifications and 11 industrialized technical routes are reviewed. Then, three scenarios (namely, the cautious scenario, baseline scenario, and positive scenario) are developed to estimate the potential of this strategy for 2020 and 2030. The results indicate that oil and natural gas replaced by coal will reach 67 to 81 Mt and 8.7 to 14.3 Gm3 in 2020 and reach 93 to 138 Mt and 32.3 to 47.3 Gm3 in 2030, respectively. By implementing this strategy, China's external dependence on oil, natural gas, and primary energy is expected to be curbed at approximately 70%, 40%, and 20% by 2030, respectively. This paper also demonstrates how coal, as a substitute for oil and natural gas, can contribute to carbon and pollution reduction and economic cost savings. It suggests a new direction for the development of the global coal industry and provides a crucial reference for energy transformation in China and other countries with similar energy situations. [ABSTRACT FROM AUTHOR]

In this work, we investigated the effect of Cu doping on the energetic, structural, and electronic properties of (ZnCu)(OH)(CO) (0 ≤ x ≤ 0.5) by density functional theory (DFT). Our calculation results demonstrate that (ZnCu)(OH)(CO) is the most stable structure in thermodynamics. Cu atoms prefer to occupy Zn + Zn + 2Zn sites in the case of x = 0.4. The calculated equilibrium lattice constants and average bond lengths agree well with the available experimental results. With increasing the amounts of Cu dopant (0.1 ≤ x ≤ 0.4), the covalent features of Cu-doped Zn(OH)(CO) systems are gradually weakened, while the Cu site exhibits the strongest Jahn-Teller distortion. Besides, the calculated population analysis illuminates the variation of -OH infrared stretching vibration frequency and the thermal decomposition order of CO. The TDOS curve of (ZnCu)(OH)(CO) shifts to the lower energy region than other systems, confirming its thermodynamic stability. Moreover, hydrogen locations are determined by performing structural optimization using DFT. These derived computational findings of (ZnCu)(OH)(CO) are expected to help improve our fundamental understanding of improving the Cu/ZnO catalysts. [ABSTRACT FROM AUTHOR]

In poly-generation and integrated gasification-combined cycle (IGCC) systems for clean energy conversion, it is essential to remove impurities such as sulfur species from hot coal gases prior to entering the subsequent units. This paper provides a comprehensive review on previous studies on high temperature removal of hydrogen sulfide from high temperature coal gases using iron-based sorbents. A two-step desulphurization process for hot coal gas cleanup is highlighted, which is integrated with direct production of elemental sulfur during regeneration of iron-based sorbents in the primary desulphurization step. Different kinetic modeling approaches for sulfidation and regeneration were compared. Limited research on activated carbon supported sorbents was also briefly summarized. [ABSTRACT FROM AUTHOR]

series of iron-manganese-based sorbents were prepared by co-precipitation and physical mixing method, and used for HS removal from hot coal gas. The sulfidation tests were carried out in a fixed-bed reactor with space velocity of 2000 h(STP). The results show that the suitable addition of manganese oxide in iron-based sorbent can decrease HS and COS concentration in exit before breakthrough due to its simultaneous reaction capability with HS and COS. FeO and MnO are the initial active components in iron-manganese-based sorbent, and FeO and Fe are active components formed by reduction during sulfidation. The crystal phases of iron affect obviously their desulfurization capacity. The reducibility of sorbent changes with the content of MnO in sorbent. S7F3M and S3F7M have bigger sulfur capacities (32.68 and 32.30 gS/100 g total active component), while S5F5M has smaller sulfur capacity (21.92 gS/100 g total active component). S7F3M sorbent has stable sulfidation performance in three sulfidation-regeneration cycles and no apparent structure degradation. The sulfidation performance of iron-manganese-based sorbent is also related with its specific surface area and pore volume. [ABSTRACT FROM AUTHOR]

Four CuZnAl slurry catalysts with different contents of Al were directly prepared from the solution of these metal salts to catalyst slurry by a complete liquid-phase method. The structure properties of the catalysts were characterized by XRD, BET, XPS, FTIR, and their catalytic performances for the single-step synthesis of Dimethyl ether (DME) from syngas were evaluated in a slurry reactor of 250 mL with a mechanical magnetic agitator. The results indicate the main phase existed in the catalysts are Cu, Cu2O, ZnO and boehmite (AlOOH) and the structures of pore and surface are comparable with those of the commercial methanol synthesis catalysts. Activity tests show that the slurry catalysts are quite effective for the single-step synthesis of DME from syngas. Among them, the catalyst with 2.09 mol% Al is best, whose DME selectivity reaches 93.08%. All of the catalysts prepared by the novel method exhibit good stability during the reaction time investigated for 18 days. [ABSTRACT FROM AUTHOR]

Reports research on uniform shape platinum nanocrystals with narrow size distribution and controlled average dimension, which are embedded in a polymeric matrix and supported on zeolite Β. Investigation into the surface structure and reactivity of nanometalclusters; Use of TEM, EXAFS, CO adsorption and methane activation; Finding that the surface activity and reactivity of nanometalparticles in PVP-Pt/Β materials is high enough to activate methane even at a temperature of 373K.