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摘要: 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。
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关键词:
- Cu-Ni-Al尖晶石 /
- 固相法 /
- 甲醇重整 /
- 氢气
Abstract: 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.-
Key words:
- Cu-Ni-Al spinel /
- solid-phase method /
- methanol steam reforming /
- hydrogen
1) 本文的英文电子版由Elsevier出版社在ScienceDirect上出版(http://www.sciencedirect.com/science/journal/18725813). -
表 1 CNA2-T和CNA3-T催化剂的物理化学性质
Table 1 Physicochemical properties of CNA2-T and CNA3-T catalysts
CNA2-900 CNA2-1000 CNA2-1100 CNA3-900 CNA3-1000 CNA3-1100 A/(m2· g-1) 37.4 19.1 17.0 51.0 30.5 18.2 v/(cm3 · g-1) 0.302 0.176 0.082 0.274 0.223 0.106 Xnon-spinel/% a 35.2 13.4 8.9 35.1 13.8 6.3 Xspinel/% b 64.8 86.6 91.1 64.9 86.2 93.7 XH/% c 25.2 16.2 15.9 42.1 39.9 19.6 xd 0.092 0.033 0.022 0.158 0.114 0.099 dspinel/nme 10.8 25.3 32.8 8.5 15.7 30.8 a/ nmf 0.8064 0.8079 0.8080 0.8046 0.8054 0.8078 dCu/nmg 15.7 15.1 16.2 14.4 10.9 15.2 a: the molar ratio of Cu in non-spinel phase to total Cu as derived from H2-TPR (Figure 3); b: the molar ratio of Cu in spinel phase to total Cu as derived from H2-TPR (Figure 3); c: the molar ratio of hardly-reducible spinel; d: x in Cu1-3x-0.05Ni0.05VxAl2+2xO4; e: the crystallite size of spinels, calculated using the Scherrer equation from the XRD patterns (Figure 2); f: cell parameter of spinel; g: the crystallite size of Cu in tested samples calculated using the Scherrer equation from the XRD patterns (Figure 9) -
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