共查询到19条相似文献,搜索用时 484 毫秒
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过氧化氢(H2O2)是一种高效的绿色氧化剂,广泛应用于化学品合成、印染纺织、污水处理等领域。近年来,氢氧直接合成过氧化氢作为一种简单、环保、原子效率高的合成方法,成为一大研究热点。本文系统性地介绍了近年来氢氧直接合成过氧化氢催化剂的催化反应机理,负载金属的不同结构和性质对直接合成过氧化氢的催化性能与作用机理,重点讨论了与催化剂载体相关的载体结构、载体酸性、载体添加物、载体与金属相互作用等方面对反应活性和选择性的影响。最后对比了近年来直接合成过氧化氢用催化剂的催化性能,认为合成高选择性、高产率的催化剂仍是未来直接合成过氧化氢工业化应用的发展方向。 相似文献
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介绍了Pd催化剂催化加氢反应的机理,以及Pd催化剂在工业加氢反应中的应用现状和研究进展。重点讨论了负载型Pd催化剂的制备方式、载体、助催化剂等因素对其催化加氢性能的影响,以期为新型负载型加氢Pd催化剂的研究和开发提供参考。 相似文献
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胡长诚 《化学推进剂与高分子材料》2008,6(1):7-14
介绍了氢、氧直接合成过氧化氢过程中催化剂、反应介质、反应器(微反应器、膜反应器等)、操作方式等方面近2~3年来的研发新进展。重点介绍了Au-Pd负载催化剂研究应用情况,涉及不同载体、不同Au与Pd质量比等对过氧化氢生成速率、选择性及浓度的影响。还较详细地介绍了无机酸和卤离子在不同条件下对合成反应结果(包括氢转化率、生成过氧化氢选择率及浓度等)的提高所起到的促进作用及其机理。 相似文献
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Sunyoung Park Tae Jin Kim Young-Min Chung Seung-Hoon Oh In Kyu Song 《Catalysis Letters》2009,130(3-4):296-300
Palladium catalyst supported on SO3H-functionalized SBA-15 (denoted as Pd/SO3H-SBA-15) was applied to the direct synthesis of hydrogen peroxide from hydrogen and oxygen. For comparison, palladium catalyst supported on SBA-15 (denoted as Pd/SBA-15) was also employed for the direct synthesis of hydrogen peroxide. Selectivity for hydrogen peroxide, yield for hydrogen peroxide, and final concentration of hydrogen peroxide over Pd/SO3H-SBA-15 catalyst were much higher than those over Pd/SBA-15 catalyst. The high catalytic performance of Pd/SO3H-SBA-15 catalyst was attributed to the enhanced acid amount of SO3H-SBA-15 support, which served as an alternate acid source in the direct synthesis of hydrogen peroxide from hydrogen and oxygen. 相似文献
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Jennifer K. Edwards Adrian Thomas Benjamin E. Solsona Philip Landon Albert F. Carley Graham J. Hutchings 《Catalysis Today》2007,122(3-4):397-402
The direct synthesis of hydrogen peroxide from H2 and O2 using a range of supported Au–Pd alloy catalysts is compared for different supports using conditions previously identified as being optimal for hydrogen peroxide synthesis, i.e. low temperature (2 °C) using a water–methanol solvent mixture and short reaction time. Five supports are compared and contrasted, namely Al2O3, -Fe2O3, TiO2, SiO2 and carbon. For all catalysts the addition of Pd to the Au only catalyst increases the rate of hydrogen peroxide synthesis as well as the concentration of hydrogen peroxide formed. Of the materials evaluated, the carbon-supported Au–Pd alloy catalysts give the highest reactivity. The results show that the support can have an important influence on the synthesis of hydrogen peroxide from the direct reaction. The effect of the methanol–water solvent is studied in detail for the 2.5 wt% Au–2.5 wt% Pd/TiO2 catalyst and the ratio of methanol to water is found to have a major effect on the rate of hydrogen peroxide synthesis. The optimum mixture for this solvent system is 80 vol.% methanol with 20 vol.% water. However, the use of water alone is still effective albeit at a decreased rate. The effect of catalyst mass was therefore also investigated for the water and water–methanol solvents and the observed effect on the hydrogen peroxide productivity using water as a solvent is not considered to be due to mass transfer limitations. These results are of importance with respect to the industrial application of these Au–Pd catalysts. 相似文献
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《Journal of Catalysis》2006,237(2):213-219
Tubular catalytic membranes (TMCs) active in the direct synthesis of hydrogen peroxide were prepared, characterized, and tested using methanol as the reaction medium. Low hydrogen peroxide selectivity was found when only palladium was used as a catalyst, whereas palladium/platinum bimetallic samples gave higher productivity and selectivity, with an optimum molar ratio of 18. The H2O2 decomposition rate is influenced by the feed gases. O2 improves H2O2 stability, whereas H2 causes hydrogen peroxide to decompose at a higher rate. The most likely decomposition pathway should be the reduction of H2O2 to water by H2. Bromide ion was used as a promoter and when used in excess (60 ppm) causes a decrease in overall catalytic activity. 相似文献
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国外用过氧化氢环氧化丙烯制环氧丙烷研发近况 总被引:3,自引:3,他引:0
胡长诚 《化学推进剂与高分子材料》2006,4(2):1-5,10
介绍了国外用过氧化氢环氧化丙烯制备环氧丙烷(PO)工艺技术近期研发概况,内容包括所用过氧化氢来源(来自蒽醌法或氢、氧直接化合法)、丙烯环氧化反应以及反应产物精制和原料回收循环利用过程,工艺涉及催化剂、溶剂、流程、反应器、操作方法和试验结果等。不少工艺是将过氧化氢合成与丙烯环氧化加以耦合,形成完整体系,提高运转效率和经济效益。此外,简略介绍了用过氧化氢制PO工艺在产业化方面的最新进展。 相似文献
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考察了Ni—Pd/C双金属催化剂上催化乙醇气相羰基化合成丙酸的反应。实验结果表明,负载活性炭Ni—Pd双金属催化剂相比普通非贵金属催化剂具有很高的活性及选择性,最佳反应工艺条件为,在少量碘代乙烷存在下,压力0.15MPa,温度220℃,n(CO):n(C2H5OH)=2.0:1,乙醇液体空速1.5h^-1此时乙醇羰基化反应产物中丙酸及丙酸酯的选择性可高达96.7%,通过GC—MS对反应产物分析,分析了反应过程的机理。 相似文献
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Sunyoung Park Tae Jin Kim Young-Min Chung Seung-Hoon Oh In Kyu Song 《Korean Journal of Chemical Engineering》2011,28(6):1359-1363
Palladium catalysts supported on SO3H-functionalized MCF silica (Pd/SO3H-MCF-T (T=450, 550, 650, 750, 850, and 950)) were prepared with a variation of calcination temperature (T, °C) of MCF silica.
They were then applied to the direct synthesis of hydrogen peroxide from hydrogen and oxygen. Conversion of hydrogen, selectivity
for hydrogen peroxide, and yield for hydrogen peroxide showed volcano-shaped curves with respect to calcination temperature
of MCF silica. Yield for hydrogen peroxide increased with increasing acid density of Pd/SO3H-MCF-T catalysts. Thus, acid density of Pd/SO3H-MCF-T catalysts played an important role in determining the catalytic performance in the direct synthesis of hydrogen peroxide.
Pd/SO3H-MCF-T catalysts efficiently served as an acid source and as an active metal catalyst in the direct synthesis of hydrogen
peroxide. 相似文献
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Shuqi Ma Gang Li Xiangsheng Wang 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2010,156(3):532-539
Direct synthesis of hydrogen peroxide from H2 and O2 was performed over supported gold catalysts. The catalysts were characterized by means of UV–vis, H2-TPR, TEM and XPS. Based on the results we conclude that metallic Au is the active species in the direct synthesis of hydrogen peroxide from H2 and O2. During preparation process of catalyst by deposition–precipitation with urea, the pH value increased and the gold particle size decreased with increasing the urea concentration. The catalyst prepared with higher urea concentration showed a higher activity and its stability also was efficiently improved. Gold nanoparticles, supported on TiO2 or Ti contained supports, gave a higher catalytic activity. Thiophene can be efficiently oxidized by hydrogen peroxide synthesized in situ from H2 and O2 over Au/TS-1. 相似文献