Cu/Ni负载型Beta分子筛催化剂的乙醇水蒸气重整制氢催化性能研究

Beta zeolite supported Cu/Ni catalyst for hydrogen production through ethanol steam reforming

采用等体积浸渍的方式,在全硅Beta分子筛载体上担载Cu、Ni活性组分,制备出一系列xCuyNi-ABZ多功能乙醇水蒸气重整制氢催化剂。通过XRD、TEM、SEM-EDX以及XPS等多种表征手段,研究催化剂的结构特性、活性组分含量等因素对催化性能的影响,依据反应产物分布,揭示其作用机理。结果表明,以Beta分子筛为载体可促使活性组分以纳米颗粒的形式高度分散于载体表面,并且存在较强的载体-金属作用力。与传统SiO_2为载体催化剂相比,2.5Cu2.5Ni-ABZ催化剂具备良好的乙醇水蒸气重整催化性能,当反应温度为450℃,实现100%的乙醇转化率和67.23%的H_2选择性,且副产物CO(4.14%)、CH_4(5.65%)含量相对较低。这可归因于Cu和Ni活性组分间的高效协同作用,Cu具有良好的乙醇脱氢性能,生成反应中间体乙醛;在反应过程中,乙醛的重整和分解是两个受温度影响的竞争反应,Ni组分利用其较强的C-C键断裂能力,随温度的升高,乙醛重整反应占主导作用,生成目标产物H_2。通过对反应后样品分析表明,2.5Cu2.5Ni-ABZ催化剂具备良好的抗烧结和抗积炭催化性能。

A group of multi-functional xCujNi-ABZ catalysts supported on all-silicon Beta zeolite were prepared by an incipient wetness impregnation method.The xCujNi-ABZ catalysts were characterized by a variety of techniques to obtain the information of their structures,the effect of different amounts of Cu and Ni active sites and understanding the reaction pathway.Compared with the traditional Si02supported catalyst,the2.5Cu2.5Ni-ABZ catalyst exhibited very good catalytic performance for the ethanol steam reforming,including100%conversion of ethanol,high67.23%H2selectivity(67.23%)and low by-product selectivity(CO=4.14%,CH4=5.65%)at450°C due to the synergistic effects of Ni and Cu.The Cu sites preferentially facilitate the dehydrogenation of ethanol at the initial reaction step,and the Ni metal catalyzes subsequently dissociation of the C-C bond.With increase of reaction temperature,H2and C02selectivity are progressively increased together with the significant decline of CO and CH4selectivity,which indicates that the dominant reaction is steam acetaldehyde reforming.This phenomenon suggests that there is a temperature-related competition between acetaldehyde decomposition and acetaldehyde steam reforming reaction.Moreover,the presence of Cu promoted the water-gas-shift reaction.The2.5Cu2.5Ni-ABZ catalyst possesses good anti-sintering ability and anti-carbon deposition properties.