溶胶-凝胶法制备Cr-基催化剂及其CO_2氧化乙烷制乙烯  

Oxidative dehydrogenation of ethane with carbon dioxide over the Cr-based catalysts prepared by sol-gel method

作　　者：李宁[1] 季生福[1] 史雪君[1] 李成岳[1] 

机构地区：[1]北京化工大学化工资源有效利用国家重点实验室,北京100029

出　　处：《燃料化学学报》2009年第3期339-345,共7页Journal of Fuel Chemistry and Technology

基　　金：国家重点基础研究发展规划(973计划;2005CB221405)

摘　　要：以硝酸铬为Cr源,正硅酸乙酯为Si源,采用溶胶-凝胶法制备了Cr质量分数为2.5%～10%的Cr-基催化剂;采用XRD、BET、SEM、H2-TPR等分析测试技术对催化剂的结构进行了表征;在微型固定床反应器中对催化剂乙烷二氧化碳氧化脱氢制乙烯的催化性能进行了评价,并考察了反应条件对催化性能的影响。结果表明,催化剂中Cr的质量分数大于5%时,Cr的物相为Cr2O3,但Cr质量分数较低时,检测不到Cr的物相;Cr质量分数为5%的催化剂具有较大的比表面积,Cr质量分数变大或变小,催化剂的比表面积都会减小;催化剂的孔径在2nm左右,并与Cr的质量分数关系不大;Cr质量分数为5%的催化剂具有最好的催化活性,在750℃的反应条件下,乙烷和二氧化碳的转化率可达79.29%和23.74%,乙烯的收率可达67.91%;Cr质量分数为5%的催化剂具有适宜的氧化还原性能,这有利于乙烷和二氧化碳的转化。A series of Cr/SiO2-G catalysts with different chromium contents were prepared by sol-gel method using chromium nitrate as the chromium source and tetraethyl orthosilieate （TEOS） as the silica source. The catalysts were characterized by XRD, BET, SEM and TPR. The catalytic performances of Cr/SiO2-G for the oxidative dehydrogenation of ethane to ethylene with CO2 were evaluated in a fixed-bed micro-reactor. XRD results indicated that Cr species were presented in Cr2O3 phase when the Cr content exceeded 5% , while the Cr species was not observed in the XRD patterns of the catalyst with a lower Cr content. The pore diameter of the catalyst was 2 nm, irrelevant to the Cr content. The Cr/SiO2-G with 5% Cr exhibited largest surface area and highest catalytic activity; at 750℃, the conversions of ethane and CO2 are 79.29% and 23.74% , respectively, with the yield of ethylene being 67.91%. The catalyst containing 5% Cr exhibits appropriate redox properties, which may be relevant to its high catalytic activity for the ethane dehydrogenation with CO2.

关 键 词：溶胶-凝胶法 Cr-基催化剂 乙烷 氧化脱氢 CO2 乙烯 

分 类 号：O643.3[理学—物理化学]