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Torrefaction has been one of the most significant steps to improve the biomass-based fuel quality. Rice husk has been widely used as typical agricultural biomass, due to a large annual yield in China. It is of great significance to explore the effect of dry/wet torrefaction on biomass pyrolysis and combustion reaction characteristics. In this study, the dry/wet torrefaction pretreatment of rice husk was carried out at various temperatures (200, 250, and 300 ; 180, 200, and 220 ) in ℃ ℃ the fixed bed and high-pressure reactor, where the starting temperature was room temperature, and the heating rate was 10 /min. The proximate and ultimate analysis of samples was then conducted by the infrared fast coal quality analyzer ℃ (5E-MAG6700) and element analyzer (Vario MACRO), respectively. The Thermogravimetric Analyzer (TGA) was selected for the non-isothermal (room temperature to 800, 20 /min) combustion of rice husk, rice husk torrefied char, and rice ℃ ℃ husk hydrochar. Moreover, the kinetics analysis of pyrolysis and combustion of samples were also conducted with the Coats−Redfern method and three common gas-solid reaction mechanism models (first-order model O1, phase boundary controlled reaction model R2 and R3). An evaluation was made on the effects of dry/wet torrefaction on the pyrolysis and combustion characteristics of rice husk. The results show that the dry/wet torrefaction increased the ash, fixed carbon, and carbon content of raw materials, while decreasing the volatile, hydrogen, and oxygen content. van Krevelen diagram displayed that the dry/wet torrefaction pretreatment behaved essentially like the process of dehydration and decarboxylation of raw materials, where the rice husk torrefied char at 300 (RT ℃ -300) was the most significant. Both pretreatments dominated the pyrolysis and combustion reaction parameters of rice husk, leading to the reduction in the pyrolysis reactivity. Dry torrefaction improved the combustion reactivity of rice husk, particularly with the temperature (200-300 ) rising. But the wet torrefaction ℃ slightly reduced the combustion reactivity of rice husk. The rice husk torrefied char presented a higher temperature of initial weight loss, a lower maximum rate of weight loss, the corresponding temperature and reactivity than the rice husk hydrochar during pyrolysis at 200 . More ℃ over, the rice husk torrefied char behaved with the lower final temperature of combustion and the maximum rate of weight loss corresponding to temperature, while the higher maximum rate of weight loss and reactivity, compared with the rice husk hydrochar. Interestingly, the linear regression index of model O1 was higher than that of the other two models for the pyrolysis and combustion reactivity of rice husk, rice husk torrefied char and rice husk hydrochar (the regression indexes were all above 0.95). The dry/wet torrefaction increased the pyrolysis activation energy of rice husk, whereas, the wet torrefaction decreased the combustion activation energy. Moreover, the pre-exponential factor of the samples in the two stages increased with an outstanding linear relationship, as the activation energy increased, indicating the kinetic compensation effect between pre-exponential factor and activation energy during combustion. The rice husk torrefied char had a lower pyrolysis activation energy and a higher pre-exponential factor than the rice husk hydrochar at the pretreatment temperature of 200 . In addition, the higher activation energy of combustion and the lower pre ℃ -exponential factor were achieved in the rice husk torrefied char, compared with the rice husk hydrochar. [ABSTRACT FROM AUTHOR]

Oil shale samples from Longkou City, Shandong Province, China, were pyrolyzed in a fixed bed reactor at retorting temperature varied from 400 to 550°C under nitrogen atmosphere with heating rate of 15°C/min. The influence of retorting temperature on the yield and characteristics of shale oil and retorting gases were determined. It was observed that the oil yield increased to the maximum value, 15.68 wt%, as the retorting temperature increased from 440 to 550°C. And increasing retorting temperature improved also gas yields, but reduced the char yield. The contents of H2, CO2, and CH4 in the retorting gas increased with the rising of retorting temperature. The ratio of alkane/alkene hydrocarbon (C1-C5) decreased because of the secondary cracking reactions of gas phase in the high temperature. The carbon and nitrogen contents of shale oil increased with increasing retorting temperature, while those of hydrogen and oxygen decreased. The sulfur content was not significantly affected by the retorting temperature. In addition, the shale oil obtained from 550°C had the lowest aromatic content, 25.12 wt%, and the highest saturate content, 50.03 wt%, compared to the other retorting temperatures due to the cracking of aliphatic compounds. The alkanes with 8-34 carbons and alkenes with 8-27 carbons were detected in the shale oil. The concentration more than 20 mg/goil was C23-C30 in the range of 400-550°C. The total content of n-alkanes decreased to 369.25 mg g-1oil, and that of n-alkene reached the maximum value at 550°C, 181.62 mg/goil, with the rise of retorting temperature. It was demonstrated that the higher temperature was beneficial to promoting the reaction of aromatization, dehydrogenation, fraction, and other reactions in the pyrolysis process. [ABSTRACT FROM AUTHOR]

BACKGROUND: Methyl tert‐butyl ether (referred to as MTBE) is harmful to the environment and hence its use is limited in China. To avoid the waste of isobutylene as MTBE raw material and improve the utilization rate of isobutylene in mixed C4 fraction, supported Fe(NO3)3/β molecular sieve catalysts with different active components were prepared by the equal volume impregnation method. The catalysts were analyzed by X‐ray diffraction (XRD), Thermogravimetric analysis (TG), Temperature programmed desorption of NH3, Brunauer–Emmett–Teller analysis and scanning electron microscopy, and the catalytic performance of catalysts with mixed C4 fractions as raw materials and different active component loadings for selective oligomerization of isobutylene was investigated in a fixed bed reactor. RESULTS: The results show that the catalyst has the best catalytic performance when the active component loading was 6%, the reaction temperature was 60 °C, the reaction pressure was 1 MPa and the reaction space velocity was 1.5 h−1. CONCLUSION: The conversion rate of isobutylene was >90%, the selectivity of C8 olefin was ≈80% and there was almost no loss of n‐butene. © 2021 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

The catalyst in the NH3-SCR process for removing NO from diesel exhaust is prone to poisoning by relatively high sulfur contents in diesel in China. The catalyst should have not only favorable catalytic activity for NO removal, but also high sulfur resistance. The spinel-type Cu1−xNixFe2O4 (x = 0–0.5) catalysts with different Ni contents were prepared by sol–gel method using citric acid as complexing agent. The catalytic activities for NO removal in sulfur-free and sulfur-containing (SO2, 0.035%, volume fraction) air were investigated in a fixed bed reactor. Meanwhile, the sulfur resistance was tested in sulfur-containing air. Moreover, the catalysts before and after the reaction were characterized by XRD, SEM, N2-adsorption, EDS, NH3-TPD, FT-IR and XPS technologies, and the mechanism of sulfur poisoning of the catalyst was also discussed. The results showed that when the Ni content was 0.3, the formed Cu0.7Ni0.3Fe2O4 spinel catalyst had the optimal catalytic performance, of which the NO conversion could be 95.87% in sulfur-free air with 5% oxygen content, and it maintained above 90.12% in the sulfur-containing air within 240 min. Characterization results illustrated that sulfur poisoning of catalyst might be caused by many pathways. The introduction of Ni into catalyst could inhibit destruction of the catalyst structure and make the catalyst become more stable in sulfur-containing air and show high sulfur resistance. [ABSTRACT FROM AUTHOR]

The harmful trace elements will be released during coal utilization, which can cause environment pollution and further endangering human health, especially for heavy metal elements. Compared to combustion, the release of heavy metal elements during coal pyrolysis process, as a critical initial reaction stage of combustion, has not received sufficient attention. In the present paper, a low rank coal, from Xinjiang province in China, was pyrolyzed in a fixed bed reactor from room temperature, at atmospheric pressure, with the heating rate of 10 °C/min, and the final pyrolysis temperature was from 400 to 800 °C with the interval of 100 °C. The volatility of heavy metal elements (including As, Hg, Cd and Pb) during pyrolysis process was investigated. The results showed the volatility of all heavy metal elements increased obviously with increasing temperature, and followed the sequence as Hg > Cd > As > Pb, which was mainly caused by their thermodynamic property and occurrence modes in coal. The occurrence modes of heavy metals were studied by sink-and-float test and sequential chemical extraction procedure, and it can be found that the heavy metal elements were mainly in the organic and residual states (clay minerals) in the raw coal. And most of the organic heavy metals escaped during the pyrolysis process, the remaining elements were mainly in the residual state, and the elements in Fe–Mn state also tended to remain in the char. [ABSTRACT FROM AUTHOR]

[Display omitted] • A Ni-Mo/Al 2 O 3 catalyst was first synthesized with an infrared radiation way. • As-prepared catalysts had high performance for hydrodesulfurization of shale oil. • The sulfur content in the upgraded shale oil was as low as 2600 ppm. • The upgraded shale oil had enhanced heating value, reduced density and viscosity. • The upgraded shale oil met the requirement of national standard Marine fuel oil. Ni-Mo/Al 2 O 3 catalyst calcinated using infrared radiation heating was applied for the first time to hydrodesulfurization (HDS) of shale oil in a fixed bed reactor. Its catalytic performance was measured under varied operating conditions and compared to that obtained by using a catalyst with the same Ni-Mo composition but calcinated in a conventional electric furnace. The operation parameters of HDS were varied among temperature (320–400 °C), pressure (1.0–4.0 Mpa), H 2 /oil (v/v) (200:1–600:1) and LHSV (1–4 h−1). Under all tested conditions, the catalyst using the infrared heating method always yielded a product oil having the lower sulfur content than the catalyst heated by the conventional furnace did. At the optimal condition of T = 380 °C, P = 4 MPa, H 2 /oil (v/v) = 600:1 and LHSV = 4 h−1, the infrared-heating catalyst enabled the oil to decrease its sulfur content to 2600 ppm, which thus met the national Marine fuel oil standard (S < 0.5 wt%, GB1711-2015, China). Characterization of the fresh, sulfided and spent catalysts shown that the catalyst calcinated with the infrared heating had the higher BET surface area, smaller and narrower size distribution of metal particles, higher binding energy between Mo and S, and more oxygen-deficient sites in comparison with the catalyst calcined using conventional electric heating. [ABSTRACT FROM AUTHOR]

Abstract: Nuclear status and expansion in China are overviewed in the present paper. The nuclear electricity capacity was adjusted form 40 GWe–70 GWe by 2020. The target of nuclear electricity capacity will reach 200 GWe by 2030 and 400 GWe by 2050. Based on the nuclear energy expansion, the evolution of spent fuel was anticipated. The accumulation of spent fuel is a serious problem with the expansion of nuclear power. Closed nuclear fuel cycle policy is the only choice for the sustainable development of nuclear energy in China. A roadmap is proposed to develop reprocessing in China by 2050. The first commercial reprocessing plant based on current PUREX technology will be put into operation around 2025. Developing advanced reprocessing technology including actinides partitioning for PWR spent fuel is the most important task during next ten years and the reprocessing technology for FBR spent fuel is needed after 2035. The technology options in back-end of nuclear fuel cycle are analyzed on the basis of the current situation in China. A long-term plan to develop reprocessing technology for FBR spent fuel should be established as soon as possible. [Copyright &y& Elsevier]