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The texture of Fe2O3 support and Ru/Fe2O3 catalysts supported on iron oxides obtained from β-FeOOH (B) or δ-FeOOH (D) and their catalytic activity in WGSR were studied. Also their susceptibilities to reduction and reoxidation, were studied by TPR, using H2 or CO and TPO methods. In the case of TPRCO the composition of the reducing mixture containing traces of H2O enabled investigation of water gas shift reaction (WGSR).
The catalysts from series D were found more readily reducible and oxidised than those from series B. The supported ruthenium enhanced the redox effects and caused the appearance of additional effects related directly to its presence. Depending on the kind of support and on ruthenium presence considerable differences in temperatures of WGSR onset were found. It is suggested that the susceptibility of the catalysts to reduction and oxidation is responsible for their activity in the WGSR. 相似文献
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Previous results on different catalysts revealed that methylcyclohexane underwent selective dehydrogenation to form toluene and hydrogen. This reaction system is a useful prototype model for similar systems in the chemical process and petroleum refining industries, such as hydrotreating for aromatics reduction, desulfurization, denitrogenation, reforming for aromatics reduction, dehydrocyclization, and fuel processing of liquid hydrocarbons in the generation of hydrogen feed for fuel cells. Dehydrogenation of methylcyclohexane to toluene is a method for hydrogen storage in the form of liquid organic hydrides. The efficiency of the dehydrogenation reactions and the quantity of products depend on the catalyst used. In the case of the dehydrogenation of methylcyclohexane to toluene, a metallic function, usually platinum is required as the catalyst. Although, there were some different catalysts used by former researchers, there was almost no investigation about the use of the nickel catalysts for this reaction. From the economical point of view, more efficient catalysts and reaction engineering methods should be developed for these reactions.In this work dehydrogenation of methylcyclohexane was performed in a fixed-bed catalytic reactor in the temperature range of 653–713 K on prepared Ni/Al2O3 catalysts having 5, 10, 15 and 20 wt.% Ni content. The inlet flowrates of methylcyclohexane and hydrogen to the reactor were changed by keeping one of them constant in order to investigate their effects on this reaction. 相似文献
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以碱共沉淀法制备Mg-Al水滑石,然后采用浸渍法负载活性组分Pt,经焙烧、氢气还原得到Pt/Al_2O_3与Pt/Mg O-Al_2O_3催化剂,采用XRD、N2吸附-脱附、FT-IR、H2-TPR和Py-IR等分析Mg O的加入对Pt/Al_2O_3催化剂结构性能的影响,并在甲基环己烷连续脱氢反应中对比两种催化剂活性。结果表明,Pt/Mg O-Al_2O_3催化剂比表面积小于Pt/Al_2O_3催化剂,且表面基本无酸性活性中心,但表现出与Pt/Al_2O_3催化剂相同的脱氢活性。在Pt负载质量分数2%、催化剂用量0.5 g、甲基环己烷0.1 m L·min-1纯样进料和325℃反应10 h后,原料平均转化率79.9%,脱氢产物只有甲苯,对应的产氢速率192.8 mmol·(g-metal·min)-1,表现出优良的脱氢活性。 相似文献
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Fe2O3 catalysts supported on Al2O3 were used to remove nitrous oxide from the nitric acid plant simulated process stream (containing O2, NO and H2O). Catalysts were prepared by the coprecipitation method and were characterized for their physico-chemical properties by BET, XRD, AFM and TPR analysis. A strong influence of the post-preparation heating conditions on the structural and catalytic properties of the catalysts has been evidenced. Laboratory tests revealed 95% conversion of N2O at temperature 750 °C and a slight decrease in activity in the presence of H2O and NO. The catalysts were inert towards decomposition of NO. The pilot-plant reactor and real plant studies (up to 3300 h time-on-stream) confirmed high activity and very good mechanical stability of the catalysts as well as no decomposition of nitric oxide. 相似文献
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Ken-ichi Shimizu Atsushi Satsuma Tadashi Hattori 《Applied catalysis. B, Environmental》1998,16(4):1338-326
Catalytic properties of supported gallium oxides have been examined for the selective reduction of NO by CH4 in excess oxygen. The activity was greatly affected by the support; Ga2O3/Al2O3 (Al2O3 supported Ga2O3) and Ga2O3–Al2O3 mixed oxide exhibited high activity and selectivity as comparable to Ga-ZSM-5, while unsupported Ga2O3 and the other supported Ga2O3 were ineffective. For Ga2O3/Al2O3, the activity changed with Ga2O3 content, and was highest at about 30 wt% Ga2O3, which corresponds to a theoretical monolayer coverage. Gallium oxide highly dispersed on Al2O3 is considered to be responsible for the high activity and selectivity. The reaction characteristics of Ga2O3/Al2O3 were studied and compared with Ga-ZSM-5 and Co-ZSM-5. Ga2O3/Al2O3 exhibited the highest activity and selectivity at high temperature. In addition, Ga2O3/Al2O3 showed higher tolerance against water than Ga-ZSM-5. C3H8 and C3H6 were also evaluated as reducing agents, and Ga2O3/Al2O3 showed higher activity than Ga-ZSM-5 above 723 K achieving almost complete reduction of NO to N2. 相似文献
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J.D.A. Bellido 《Fuel》2009,88(9):1673-1034
ZrO2, γ-Al2O3 and ZrO2/γ-Al2O3-supported copper catalysts have been prepared, each with three different copper loads (1, 2 and 5 wt%), by the impregnation method. The catalysts were characterized by nitrogen adsorption (BET), X-ray diffraction (XRD), temperature programmed reduction (TPR) with H2, Raman spectroscopy and electronic paramagnetic resonance (EPR). The reduction of NO by CO was studied in a fixed-bed reactor packed with these catalysts and fed with a mixture of 1% CO and 1% NO in helium. The catalyst with 5 wt% copper supported on the ZrO2/γ-Al2O3 matrix achieved 80% reduction of NO. Approximately the same rate of conversion was obtained on the catalyst with 2 wt% copper on ZrO2. Characterization of these catalysts indicated that the active copper species for the reduction of NO are those in direct contact with the oxygen vacancies found in ZrO2. 相似文献
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由丙烷直接催化脱氢制取丙烯已经成为增产丙烯的重要手段之一。以水热法制备Al_2O_3载体,采用等体积浸渍法制备不同PtSn负载量的PtSn/Al_2O_3催化剂。通过XRD、N2-吸附、拉曼光谱和H2-TPR等对其进行表征,并考察不同PtSn负载量对催化剂催化丙烷脱氢性能的影响。结果表明,在制备的催化剂中,Pt1.5Sn3/Al_2O_3具有最高的催化丙烷脱氢活性和稳定性,丙烷初始转化率高达55.6%,丙烯选择性98.1%。反应330 min后,丙烷转化率仅降约10%,选择性保持不变。 相似文献
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Hua Xu 《Powder Technology》2008,185(2):176-180
Nanorods and micro-octahedrons of α-Fe2O3 were selectively synthesized through one-step hydrothermal treatment of iron(III) chloride in aqueous formamide solution for different time. The resulting samples were characterized with XRD, FE-SEM, TEM, and FT-IR. It was found that monodispersed nanorods were 10-25 nm in diameter and 50-100 nm in length, while the octahydrons were 100-400 nm in size. These α-Fe2O3 nanorods and micro-octahedrons exhibited quite different catalytic performances on thermal decomposition of ammonium perchlorate. The nanorods significantly reduced the decomposition temperature of ammonium perchlorate, but the micro-octahedrons did not. This study provides alternative choice of good burning rate catalysts for composite solid propellants in solid fueled rockets. 相似文献
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A three-dimensional (3D) Fe3O4/carbon material functionalized with amino and hydroxyl groups was synthesized by decomposing 2,4,5-trichlorophenol/ferrocene mixture in the presence of ammonia and polyethylene glycol in solvothermal conditions at 250 °C for 30 h by a one-step process. The 3D Fe3O4/carbon materials can be loaded with Pt nanoparticles without adding any reducing agent; Pt-loaded 3D Fe3O4/carbon hybrid materials have superior electrochemical catalytic activity toward methanol oxidation and the oxidation current density on them is nearly triple that on a commercial Pt/C catalyst. 相似文献
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Jian Zhang Hengyong Xu Xianglan Jin Qingjie Ge Wenzhao Li 《Applied Catalysis A: General》2005,290(1-2):87-96
A series of nano-sized Ni/Al2O3 and Ni/La–Al2O3 catalysts that possess high activities for NH3 decomposition have been successfully synthesized by a coprecipitation method. The catalytic performance was investigated under the atmospheric conditions and a significant enhancement in the activity after the introduction of La was observed. Aiming to study the influence of La promoter on the physicochemical properties, we characterized the catalysts by N2 adsorption/desorption, XRD, H2-TPR, chemisorption and TEM techniques. Physisorption results suggested a high specific surface area and XRD spectra showed that nickel particles are in a highly dispersed state. A combination of XRD, TEM and chemisorption showed that Ni0 particles with the average size lower than 5.0 nm are always obtained even though the Ni loading ranged widely from 4 to 63%. Compared with the Ni/Al2O3 catalysts, the Ni/La–Al2O3 ones with an appropriate amount of promoter enjoy a more open mesoporous structure and higher dispersion of Ni. Reduction kinetic studies of prepared catalysts were investigated by temperature-programmed reduction (TPR) method and the fact that La additive partially destroyed the metastable Ni–Al mixed oxide phase was detailed. 相似文献
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B. Fernández J.M. AlmanzaJ.L. Rodríguez D.A. CortesJ.C. Escobedo E.J. Gutiérrez 《Ceramics International》2011,37(8):2973-2979
The effects of V2O5, NiO, Fe2O3 and vanadium slag on the corrosion of Al2O3 and MgAl2O4 have been investigated. The specimens of Al2O3 and MgAl2O4 with the respective oxides above mentioned were heated at 10 °C/min from room temperature up to three different temperatures: 1400, 1450 and 1500 °C. The corrosion mechanisms of each system were followed by XRD and SEM analyses. The results obtained showed that Al2O3 was less affected by the studied oxides than MgAl2O4. Alumina was only attacked by NiO forming NiAl2O4 spinel, while the MgAl2O4 spinel was attacked by V2O5 forming MgV2O6. It was also observed that Fe2O3 and Mg, Ni, V and Fe present in the vanadium slag diffused into Al2O3. On the other hand, the Fe2O3 and Ca, S, Si, Na, Mg, V and Fe diffused into the MgAl2O4 structure. Finally, the results obtained were compared with those predicted by the FactSage software. 相似文献
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R. S. G. Ferreira P. G. P. de Oliveira F. B. Noronha 《Applied catalysis. B, Environmental》2004,50(4):243-249
The role of vanadium oxide and palladium on the benzene oxidation reaction over Pd/V2O5/Al2O3 catalysts was investigated. The Pd/V2O5/Al2O3 catalysts were more active than V2O5/Al2O3 and Pd/Al2O3 catalysts. The increase of vanadium oxide content decreased the Pd dispersion and increased the benzene conversion. A strong Pd particle size effect on benzene oxidation reaction was observed. Although the catalysts containing high amount of V4+ species were more active, the Pd particle size effect was responsible for the higher activity. 相似文献
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采用共沉淀与复配2种方法制备了Fe2O3-SiO2复合纳米粒子,将其添加到聚氨酯(PU)膜中,研究了粒子复合方式对PU共混膜力学性能和O2、N2分离性能的影响。结果表明,通过共沉淀法制备的Fe2O3-SiO2粒子粒径小且均匀,内部存在硅铁固溶体结构,其PU共混膜的机械强度和氧氮分离性能优于复配法制备的Fe2O3/SiO2粒子;当Fe2O3-SiO2添加量为10%时,PU共混膜的O2渗透系数为13.35 Barrer,O2/N2理论分离因子为7.14。 相似文献
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TiO2-Al2O3 mixed oxides with different compositions ranging from 40wt-% to 95wt-% of TiO2 were prepared by sol-gel method and impregnated with different amounts of VO x . Supports and catalysts were characterized by X-ray diffraction (XRD), physisorption, temperature preprogrammed reduction (H2-TPR), and ammonia temperature programmed desorption (NH3-TPD). TiO2 content in the support had obvious effect on the crystal structure, texture characteristic, acid property, and catalytic activity in dehydrogenation of ethylbenzene (EB) with carbon dioxide. The highest catalytic activity was acquired when the TiO2 content was 50 wt-%. 相似文献