Ni基乙烷脱氢催化剂的性能及其改进  

Performance and Improvement of Ni-based Catalysts for Ethane Dehydrogenation

作　　者：罗俊 贾礼超[1] 颜冬[1] 李箭[1] Luo Jun;Jia Lichao;Yan Dong;Li Jian(Center for Fuel Cell Innovation,School of Materials Science and Engineering,Huazhong University of Science and Technology,Wuhan 430074,China)

机构地区：[1]华中科技大学材料科学与工程学院燃料电池研究中心,武汉430074

出　　处：《化学学报》2022年第3期317-326,共10页Acta Chimica Sinica

基　　金：国家自然科学基金(Nos.51972128,U1910209)资助项目。

摘　　要：过渡金属Ni是地球上储量丰富的金属元素,在加氢脱硫、重整制氢等催化领域应用非常广泛,但是关于Ni基催化剂在烷烃脱氢方面的研究较少;因此,本工作采用不同的方法,制备了三种结构的Ni基负载催化剂,即尖晶石分解型、浸渍型和钙钛矿析出型,并在700℃、C_(2)H_(6)-N_(2)气氛中和50 mL·min^(−1)气体流速下,探索了它们的乙烷脱氢性能.结果表明:尖晶石分解型催化剂Ni_(1-x)Cu_(x)Cr_(2)O_(4)还原后在Cr_(2)O_(3)表面形成Ni-Cu合金颗粒,能有效钝化Ni的C—C键断裂活性,提高乙烯的选择性.Ni含量过高时,Ni不能有效地分散而形成大的金属团簇,造成乙烷过度裂解,乙烯选择性较低.浸渍负载型催化剂Ni_(x)M_(y)/Al_(2)O_(3)(M为Cu或Ag)比表面积大,表面活性位点分散,但活性金属与载体结合力弱,在高温下不稳定;Cu或Ag与Ni形成合金,可有效提高乙烯选择性,Ag较Cu的效果更佳.钙钛矿析出型催化剂LaCr_(1-x)Ni_(x)O_(3)(LCNi-100x)在还原气氛中析出均匀细小的Ni颗粒,其与基体结合力强,抗积碳性能和稳定性较高;含15%Ni的LCNi-15还原后(R-LCNi-15)表现出最好的催化性能,乙烯产率最高(24%),同时具有较好的抗积碳性能和稳定性以及氧化再生性.Ethylene is one of the largest chemical products in the world,and its global demand increases significantly every year.At present,ethylene is mainly produced commercially through steam cracking of naphtha or alkane feedstocks.Catalytic dehydrogenation of ethane can effectively reduce energy loss of steam cracking.The transition metal Ni is a metal element with abundant reserves on the earth.It is widely used in the catalytic fields of hydrodesulphurization and reforming hydrogen production.However,there are few studies on Ni-based catalysts in alkanes dehydrogenation;therefore,three kinds of Ni-based supported catalysts,namely spinel decomposition-type,impregnation-type and perovskite precipitation-type,were prepared by different methods and explored for their performance in ethane dehydrogenation at 700℃in C_(2)H_(6)-N_(2)atmos-phere at 50 mL·min^(−1).The results show that the spinel decomposition-type catalyst Ni_(1-x)Cu_(x)Cr_(2)O_(4)prepared by glycine com-bustion method formed Ni-Cu alloy particles on the surface of Cr_(2)O_(3)after reduction,which effectively passivated the C—C bond breaking activity of Ni and improved the selectivity of ethylene.The effect of Cu addition can be explained in geomet-ric effect and electronic effect.When the Ni content was too high,the Ni particles could not be effectively dispersed,forming large metal clusters and resulting in excessive cracking of ethane and low ethylene selectivity.The impregnation-type catalyst NixMy/Al_(2)O_(3)(M=Cu or Ag)had a large specific surface area and dispersed surface active sites,but the active metal particles were weakly interacted with the support and unstable at high temperatures;Cu or Ag forming an alloy with Ni effectively improved the selectivity of ethylene with Ag superior to Cu.The perovskite precipitation-type catalyst LaCr_(1-x)Ni_(x)O_(3)(LCNi-100x)precipitated uniform and fine Ni particles in a reducing atmosphere,which were strongly bonded to the support and demonstrated high carbon deposition resistance and high stability;

关 键 词：NI基催化剂 脱氢 乙烷转化率 乙烯选择性 合金化 

分 类 号：TQ221.211[化学工程—有机化工] TQ426