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SiO2改性的Cu-ZnO/HZSM-5催化剂及合成二甲醚性能
引用本文:王继元,曾崇余,吴昌子.SiO2改性的Cu-ZnO/HZSM-5催化剂及合成二甲醚性能[J].燃料化学学报,2006,34(2):195-199.
作者姓名:王继元  曾崇余  吴昌子
作者单位:College of Chemistry and Chemical Engineering, Nanjing University of Technology, Nanjing 210009, China
摘    要:以廉价的硅酸钠为硅源,碳酸钠为沉淀剂,采用共沉淀沉积法制备了SiO2改性的Cu-ZnO/ HZSM-5催化剂,用XRD、SEM、H2-TPR、XPS等手段进行了表征,考察了对CO2加氢合成二甲醚的催化活性。结果表明,SiO2促进了催化剂前驱体的分散,延缓了焙烧后催化剂晶粒的长大和颗粒的团聚。SiO2改性的同时影响了CuO的分布状态及还原过程。1.0%SiO2改性的Cu-ZnO/HZSM-5催化剂,用于CO2加氢合成二甲醚,CO2转化率和二甲醚的收率达28.53%和16.34%,与未经改性的Cu-ZnO/ HZSM-5相比,CO2转化率和二甲醚收率分别提高了20%和34%;继续增大SiO2用量,催化剂的活性反而降低。XPS和AES表征表明,1.0%SiO2改性的Cu-ZnO/HZSM-5催化剂中,Cu0是甲醇合成的活性中心,锌以ZnO的形式存在。

关 键 词:二氧化碳  加氢  二甲醚  SiO2  改性  Cu-ZnO/HZSM-5催化剂  
文章编号:0253-2409(2006)02-0195-05
收稿时间:2005-08-27
修稿时间:2005-11-27

Silica modified Cu-ZnO/HZSM-5 catalyst and its catalytic performance in dimethyl ether synthesis from CO2 hydrogenation
WANG Ji-yuan,ZENG Chong-yu,WU Chang-zi.Silica modified Cu-ZnO/HZSM-5 catalyst and its catalytic performance in dimethyl ether synthesis from CO2 hydrogenation[J].Journal of Fuel Chemistry and Technology,2006,34(2):195-199.
Authors:WANG Ji-yuan  ZENG Chong-yu  WU Chang-zi
Institution:College of Chemistry and Chemical Engineering, Nanjing University of Technology, Nanjing 210009, China
Abstract:The silica modified Cu-ZnO/HZSM-5 catalysts were prepared via the co-precipitation sedimentation method using sodium silicate as silicon source, sodium carbonate as precipitant. These catalysts were characterized by means of XRD, SEM, H2-TPR, XPS techniques, and their catalytic performance in dimethyl ether (DME) synthesis from CO2 hydrogenation were evaluated in a fixed-bed reactor. It was found that the modification of SiO2 had a remarkable effect on the structures of the catalyst precursors, the diffraction peaks of aurichalcite (Zn3Cu2(OH)6(CO3)2) at 2θ=13.2° weakened and broadened with the SiO2 content, interestingly, those peaks disappeared when SiO2 content was beyond 3.5%. The XRD and SEM studies of the calcined catalysts showed that silica retarded the growth of CuO and ZnO crystals and inhibited the agglomeration of the calcined catalysts. The TPR profiles of silica modified Cu-ZnO/HZSM-5 catalysts revealed that the reduction peaks and the peak temperature were different from that of the Cu-ZnO/HZSM-5 catalyst without silica modification. The catalytic performance showed that the activity first increased and then decreases with the increase of the SiO2 content. The CO2 conversion of 28.53% and DME yield of 16.34% was obtained over 1.0% SiO2 modified Cu-ZnO/HZSM-5 catalyst, which was increased by 20% and 34%, respectively, than that of Cu-ZnO/HZSM-5 catalyst without silica modification. XPS and AES measurements of the 1.0% SiO2 modified Cu-ZnO/HZSM-5 catalyst revealed that, during the reduction of the catalyst by H2 at 250℃ or DME synthesis from CO2/H2 at 250℃, the chemical valance of copper and zinc was 0 and 2+, respectively. Cu0 was considered to be the surface active site for the synthesis of methanol from CO2 hydrogenation. The present method may offer opportunities to prepare the ultra-fine mono-component or multi-component catalysts via the coprecipitation method.
Keywords:SiO2
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