水热沉淀法制备NiO-CaO/Al_2O_3复合催化剂及其在ReSER制氢中的应用  

Preparation of a NiO-CaO/Al_2O_3 Sorption Complex Catalyst by Hydrothermal Precipitation Method and its Application in ReSER Process

作　　者：张帆[1] 吴嵘[1] 吴素芳[1] 

机构地区：[1]浙江大学化学工程与生物工程学院,浙江杭州310027

出　　处：《高校化学工程学报》2014年第5期985-991,共7页Journal of Chemical Engineering of Chinese Universities

基　　金：国家自然科学基金(20876142)

摘　　要：制备了一组高催化活性的NiO-CaO/Al2O3复合催化剂并将其应用于反应吸附强化甲烷水蒸气重整制氢(ReSER)过程中。采用水热沉淀法制备了具有层状复合金属氢氧化物结构(NiAl-LDHs)的复合催化剂前驱体,高温焙烧后得到NiO-CaO/Al2O3复合催化剂hd-cat。通过传统浸渍法制备了另一组相同组分含量的NiO-CaO/Al2O3复合催化剂ci-cat作为对比。BET测得催化剂hd-cat比表面积为134.4 m2·g-1,H2-TPD测得其Ni金属分散度为9.25%,分别为催化剂ci-cat的3.8倍和1.3倍。CO2反应吸附性能(TGA)测试结果表明hd-cat吸附容量和吸附速率分别是ci-cat的1.8倍和2.7倍。在固定床反应器上,反应压力0.1 MPa、温度600℃、H2O/CH4摩尔比4:1条件下,评价了不同体积空速下复合催化剂ReSER制氢效果。hd-cat能达到的最大体积空速为2376 h-1,在此条件下能得到94.4%浓度的H2和98.4%的CH4转化率,十次反应-再生循环中,H2浓度和CH4转化率均保持在90%以上。相同反应条件下,复合催化剂ci-cat在体积空速1188 h-1时便失去制氢活性。实验结果证明水热沉淀法制备的高活性的复合催化剂hd-cat能适于高空速下的ReSER循环制氢要求。A NiO-CaO/Al2O3 sorption complex catalyst with highly catalytic activity was prepared and applied in reactive sorption enhanced reforming （ReSER） process. A layer-structured double hydroxide precursor （NiAl-LDHs） was prepared by hydrothermal precipitation method. The precursor was then calcined to NiO-CaO/Al2O3 composite catalyst hd-cat. Another NiO-CaO/Al2O3 composite catalyst ci-cat was prepared by impregnation method for comparison. The catalyst hd-cat was observed to have a surface area of 134.4 m2？g-1 by BET testing and a Ni dispersion of 9.25%in H2-TPD testing, which were 3.8 times and 1.3 times as much as those of ci-cat, respectively. TGA testing indicated that the sorption capacity and the sorption rate of hd-cat were 1.8 times and 2.7 times as much as those of ci-cat. The catalysts were evaluated in ReSER process in a fixed-bed reactor system at 0.1 MPa and 600℃ with a H2O/CH4 molar ratio of 4：1. The hydrogen production performances under different volumetric space velocities were studied. A H2 concentration of 94.4%and a CH4 conversion of 98.4%were achieved at a space velocity of 2376 h-1 using the hd-cat catalyst. And during 10 times reaction-regeneration cycles, both H2 concentration and CH4 conversion exceeded 90%. However, the ci-cat catalyst lost its activity under a space velocity of 1188 h-1. These results demonstrate that composite catalyst prepared by hydrothermal precipitation method can perform well under high space velocity in ReSER process.

关 键 词：氢气 NI基催化剂 水热沉淀法 氧化钙 

分 类 号：TQ101.3[化学工程]