乙二醇水相重整制氢催化剂制备及反应特性研究

发布时间：2018-05-29 11:03

  本文选题：乙二醇 + 水相重整制氢　； 参考：《天津大学》2016年博士论文

【摘要】：化石能源的短缺和高污染使氢气成为理想的替代能源,以生物质为原料制取氢气极具发展潜力。传统制氢方法H_2产量低、设备复杂,水相重整制氢反应过程简单,可一步制取H_2,相比其他方法更具优越性。Pt系贵金属催化剂转化率高,H_2产率较低,高昂的成本也限制了该系催化剂的应用,Ni系催化剂C-C键断裂能力较强,但使用中易失活。针对上述问题,本论文采用等体积浸渍法、共沉淀法、沉积沉淀法和柠檬酸溶胶-凝胶法制备了Pd、NiFeCo和NiFe/CeO_2系列催化剂,考察催化剂的结构特性和乙二醇水相重整制氢反应的催化活性,取得的主要成果如下:1.采用等体积浸渍法制备了Pd/γ-Al_2O_3、PdNi/γ-Al_2O_3和Ni/γ-Al_2O_3催化剂研究Ni掺杂的影响。实验结果表明,Pd/γ-Al_2O_3催化剂上H_2选择性和乙二醇转化率分别为38.9%和13.7%,烷烃选择性仅为11.3%。PdNi/γ-Al_2O_3催化剂上形成了PdNi合金,二者之间存在较强的相互作用,促进CO的脱附,提高金属分散性,H_2选择性和乙二醇转化率分别提高至49.5%和21.9%。2.采用柠檬酸溶胶-凝胶法制备了NiFeCo催化剂,考察Fe/Co摩尔比和还原温度对反应结果的影响。Ni对C-C键断裂能力较强,但甲烷化程度较高;Fe促进水汽水汽变换反应(WGS)反应进行,但本身催化活性较低;Co对FeNi合金的形成有促进作用,WGS反应活性较高。660℃还原后的NiFeCo催化剂上H_2选择性和乙二醇转化率分别为99.8%和95.1%,而烷烃选择性降至1.3%,FeNi合金中Fe/Ni摩尔比对催化活性有较大影响,但该系列催化剂容易失活。3.考察制备方法对NiFe/CeO_2催化剂水相重整制氢反应的影响。cal-NiFe/CeO_2催化剂上H_2选择性为75.5%,乙二醇转化率为76.3%,烷烃选择性为12.5%。孔结构良好和大比表面积利于反应物和产物的进出;FeNi合金与CeO_2存在较强的相互作用,促进了催化活性的提高。4.采用沉积沉淀法制备NiFe/CeO_2催化剂,考察Ni/Fe摩尔比对水相重整制氢反应的影响。Fe与Ni之间存在相互作用,提高了FeNi合金在CeO_2表面的分散度,增加了H_2选择性和乙二醇转化率。CeO_2消除了活性位表面的积碳,抑制了颗粒烧结,提高了催化剂稳定性。四种多元醇上H_2选择性和多元醇转化率按如下顺序递减:甲醇乙二醇丙三醇山梨醇。
[Abstract]:Because of the shortage of fossil energy and high pollution, hydrogen is an ideal alternative energy, and it has great potential to produce hydrogen from biomass. The traditional hydrogen production method H _ 2 has low yield, complex equipment, simple process of hydrogen production by water phase reforming, and can be used to produce H _ 2 in one step. Compared with other methods, the conversion rate of noble metal catalyst based on Pt system is higher than that of other methods, and the yield of H _ S _ 2 is lower than that of other methods. The high cost also limits the application of the catalyst. The C-C bond fracture ability of Ni catalyst is strong, but it is easy to be deactivated. In order to solve the above problems, PdN NiFeCo and NiFe/CeO_2 series catalysts were prepared by equal volume impregnation method, co-precipitation method, deposition precipitation method and citric acid sol-gel method. The structure characteristics of the catalyst and the catalytic activity of ethylene glycol reforming in aqueous phase for hydrogen production were investigated. The main results obtained are as follows: 1. The effects of Ni doping on Pd/ 纬 -Al _ 2O _ 3 / 纬 -Al _ 2O _ 3 and Ni/ 纬 -Al _ 2O _ 3 catalysts were prepared by the same volume impregnation method. The experimental results show that the selectivity of H _ 2 and conversion of ethylene glycol on Pd / 纬 -Al _ 2O _ 3 catalyst are 38.9% and 13.7%, respectively, and the selectivity of alkane is only formed on 11.3%.PdNi/ 纬 -Al _ 2O _ 3 catalyst. There is a strong interaction between the two catalysts to promote the desorption of CO. The selectivity of H2 and the conversion of ethylene glycol were increased to 49.5% and 21.9% respectively. NiFeCo catalyst was prepared by citric acid sol-gel method. The effects of Fe/Co molar ratio and reduction temperature on the results of the reaction were investigated. However, the lower catalytic activity of Co could promote the formation of FeNi alloy. The H-2 selectivity and ethylene glycol conversion on NiFeCo catalyst reduced at 0.660 鈩，

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