Cu-Ni-Al尖晶石催化甲醇水蒸气重整制氢性能的研究

以氢氧化铜、醋酸镍和拟薄水铝石为原料,通过固相法合成了Cu-Ni-Al尖晶石催化剂。采用N2物理吸附、XRD、H2-TPR和XPS等表征方法,研究Cu/Ni/Al的物质的量比和焙烧温度对催化剂的比表面积、物相、还原性能以及表面性质的影响,并以甲醇水蒸气重整制氢为探针反应,考察催化剂的缓释催化性能。结果表明,随着焙烧温度的升高,Cu-Ni-Al催化剂的尖晶石含量增加,但尖晶石晶粒增大,且比表面积下降。不同的焙烧温度和Cu/Ni/Al物质的量比,所得催化剂的比表面积、还原性能和表面性质不同,从而表现出不同的缓释催化性能。与计量比Cu/Al=1∶2的合成比较,Cu/Al=1∶3形成了非计量比的富Al尖晶石固溶体,生成的晶体粒子小、比表面积和孔容大、难还原的尖晶石部分增多,呈现出更好的缓释催化性能。甲醇制氢反应性能评价结果显示,Cu-Ni-Al尖晶石在反应条件下逐渐释放活性铜而催化反应的进行,其中,CNA3-1000催化剂表现中最高的催化活性和稳定性。

Catalytic performance of Cu-Ni-Al spinel for methanol steam reforming to hydrogen

Using copper hydroxide, nickel acetate and pseudoboehmite as materials, the Cu-Ni-Al spinel catalysts were synthesized by the solid-phase method. The effects of Cu/Ni/Al molar ratio and calcination temperature on specific surface area, phase composition, reduction performance and surface property of Cu-Ni-Al spinel catalysts were characterized by BET, XRD, H₂-TPR and XPS. Moreover, the sustained release catalytic performances of Cu-Ni-Al spinel samples for methanol steam reforming were tested. The obtained results indicated that with increasing the calcination temperature, the content of Cu-Ni-Al spinel increased, but the size of spinel particles increased and the specific surface area decreased. Change of the calcination temperature and Cu/Ni/Al molar ratio led to different specific surface area, reduction performance and surface property of Cu-Ni-Al spinel catalysts, thus showing different sustained release catalytic performance. Comparing with those of stoichiometric ratio of Cu/Al=1:2, spinel solid solutions with smaller particle size, higher specific surface area and pore volume, more hardly-reducible spinel and better sustained release catalytic performance were obtained with the nonstoichiometric ratio of Cu/Al=1:3. The results of catalyst evaluation indicated that active copper species were released from Cu-Ni-Al spinel lattice and thus took part in the catalytic action. Among the prepared catalysts, CNA3-1000 catalyst showed the highest catalytic activity and stability.