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991.
A stable La2NiO4 catalyst active in CH4/CO2 reforming has been prepared by a sol–gel method. The catalyst was characterized by techniques such as XRD, BET, TPR and TG/DTG. The results show that the conversions of CH4 and CO2 in CH4/CO2 reforming over this catalyst are significantly higher than those over a Ni/La2O3 catalyst prepared by wet impregnation and those over a La2NiO4/-Al2O3 catalyst. The TG/DTG outcome confirmed that the amount of carbon deposition observed in the former case was less than that observed in the latter two cases, a phenomenon attributable to the uniform dispersion of nanoscale Ni particles in the sol–gel-generated La2NiO4 catalyst. 相似文献
992.
The aim of this work is to study from an experimental point of view the oxidative steam reforming of methanol by investigating the behaviour of a dense Pd/Ag membrane reactor (MR) in terms of methanol conversion as well as hydrogen production. The main parameters considered are the operating temperature and the O2/CH3OH feed ratio. This is a pioneer work in the application of MR to this kind of reaction, whose goal should be to produce a CO-free hydrogen stream suitable for hydrogen fuel cell applications. The experimental results show that the MR gives methanol conversions higher than traditional reactors (TRs) at each temperature investigated, confirming the good potential of the membrane reactor device for this interesting reaction system. 相似文献
993.
PS-Ⅵ连续重整催化剂的工业应用 总被引:2,自引:0,他引:2
PS-Ⅵ连续重整催化剂在中国石化洛阳分公司炼油厂700 kt/a连续重整装置上进行了工业应用。开工运转和两次标定结果表明,PS-Ⅵ催化剂的活性、选择性、水热稳定性及抗干扰能力较好,反应性能优于原来使用的3861连续重整催化剂。在质量空速提高20%,反应条件基本相同的情况下,重整生成油的收率、纯氢产率和芳烃产率分别可提高1.3%、0.5%和2.2%。 相似文献
994.
采用CO2吸附剂吸附强化的甲烷水蒸汽反应制药厂氢过程特点 总被引:1,自引:0,他引:1
The objective of the present study is to characterize the production of hydrogen with a sorptionenhanced steam-methane reaction process using Ca(OH)2 as the CO2 adsorbent. Theoretical equilibrium compositions at different operation conditions were calculated using an iterative method. It was found that with Ca(OH)2 as the CO2 sorbent, the concentration of CO2 adsorption was reduced in the product stream, that gave rise to higher methane conversion and higher H2 concentration. An experimental setup was built to test the theoretical calculation. The effects of sorbents and the particle size of Ca(OH)2 on the concentration of CO2 and H2 were investigated in detail. Results showed that the reactor packed with catalyst and Ca(OH)2 particles produced H2 concentration of 94%. It was nearly 96% of the theoretical equilibrium limit, much higher than H2 equilibrium concentration of 67.5% without CO2 sorption under the same conditions of 500℃, 0.2 MPa pressure and a steam-to-methane ratio 6. In addition, the residual mole fraction of CO2 was less than 0.001. 相似文献
995.
Ting Dong Zhaoxiang Wang Lixia Yuan Youshifumi Torimoto Masayoshi Sadakata Quanxin Li 《Catalysis Letters》2007,119(1-2):29-39
The performance of hydrogen production from steam reforming of ethanol were investigated by using the K-doped 12CaO · 7Al2 O3 catalyst (defined as C12A7–O−/x%K). The conversion of ethanol and hydrogen yield over C12A7–O−/x%K catalyst mainly depended on the temperature, K-doping amount, steam-to-carbon ratios (S/C) and contact time (W/F). In order
to identify the catalyst’s characteristic and active species on the catalyst’s surface, Brunauer-Emmett-Teller (BET) surface
area, CO2 temperature programmed desorption (CO2TPD), X-ray diffraction (XRD), Fourier transform infrared (FT–IR) and X-ray photoelectron spectroscopy (XPS) were carried
out. Based on the characterization, it was found that active oxygen species and doped potassium play important roles in steam
reforming of ethanol over C12A7–O−/27.3%K catalyst. 相似文献
996.
Aisling M. OConnor Yves Schuurman Julian R.H. Ross Claude Mirodatos 《Catalysis Today》2006,115(1-4):191-198
The mechanism of the CO2 reforming of methane reaction over the Pt/ZrO2 catalyst was investigated using a temporal analysis of products (TAP) reactor system. For comparative purposes, the reaction pathway using a Pt/Al2O3 catalyst was also examined. A reaction sequence is suggested for both catalysts. Over both catalysts, methane decomposition takes place over platinum. The main difference between the two catalysts concerns the carbon dioxide dissociation. Over Pt/Al2O3 this step is assisted by hydrogen. Over Pt/ZrO2 this step takes place over the zirconia support and involves surface vacancies. Moreover, large pools of formate and carbonate species are present on the zirconia. Transient studies conducted to determine the origin of carbon species accumulated during CO2 reforming revealed that more than 99% of the carbon was derived from the methane molecule over both catalysts. Over the Pt/ZrO2 catalyst, only a single very reactive carbon species was detected, while over the Pt/Al2O3 a second less active species was also formed. 相似文献
997.
A new series of Ni-Rh bimetallic catalysts with different Ni and Rh loadings on a high-surface-area CeO2 was developed for the reforming of bio-ethanol at low-temperature (below 450 °C) to produce H2-rich gas for on-site or on-board fuel cell applications. Oxidative steam reforming of ethanol (OSRE) over a Ni-Rh/CeO2 catalyst containing 5 wt% Ni and 1 wt% Rh was found to be more efficient offering about 100% ethanol conversion at 375 °C with high H2 and CO2 selectivity and low CO selectivity compared to the steam reforming of ethanol (SRE) reaction which required a higher temperature of about 450 °C to achieve 100% ethanol conversion. The high temperature SRE reaction favors the formation of large amount of CO, which would make the downsteam CO cleanup more complicated for polymer electrolyte membrane fuel cell (PEMFC). The presence of O2 in the feed gas was found to greatly enhance the conversion of ethanol to produce H2 and CO2 as major products. Increase in Ni content above 5 wt% in the catalyst formulation decreased the H2 selectivity while the selectivity of undesirable CH4 and acetaldehyde increased. The 1 wt% Rh/CeO2 catalyst was twice as active as 10 wt% Ni/CO2 catalyst in terms of ethanol conversion and acetaldehyde selectivity and this indicated that Rh was more effective in C–C bond cleavage than Ni. The reaction was found to proceed through the formation of acetaldehyde intermediate, which subsequently underwent decomposition to produce a mixture of CO and CH4 or reforming with H2O and O2 to produce CO, CO2 and H2. The role of Rh is mainly to cleave the C–C and C–H bonds of ethanol to produce H2 and COx while Ni addition helps converting CO into CO2 and H2 by WGS reaction under the conditions employed. 相似文献
998.
Congwei Wang Na Liu Liwei Pan Sheng Wang Zhongshan Yuan Shudong Wang 《Fuel Processing Technology》2007
Oxidative steam reforming of methanol (OSRM) reaction was investigated over a novel monolithic ZnO–Cr2O3/CeO2–ZrO2 catalyst developed in our laboratory. A novel flat-bed reactor was designed to measure the concentration profiles of the monolithic catalyst beds under different operation conditions: water-to-methanol mole ratio (W/M) between 1 and 1.5; oxygen-to-methanol mole ratio (O/M) in the range of 0.1–0.3; space velocity ranging from 1840 to 2890 h− 1; and reaction temperature in the scale of 400–440 °C. On the basis of these results, reaction pathways for the OSRM were discussed. It is indicated that only three independent reactions dominate in our reaction system, namely, the partial oxidation of methanol, the steam reforming of methanol and the methanol decomposition reaction, whereas the water–gas shift and the reverse water–gas shift reactions should be ignored. In addition, the steam reforming of methanol proceeds along all the catalyst bed, whereas methanol decomposition and oxidation reactions occur mainly at the entrance of the catalyst bed. 相似文献
999.
1000.
根据对堆载预压经验公式的研究及多年设计经验 ,结合疏桩设计理论 ,提出了在没有新的地质资料的情况下 ,如何利用原基础合理确定挖扩桩桩距和桩径。 相似文献