乙苯脱氢制苯乙烯氧化铁系催化剂的研究——晶格氧的作用  

Mechanistic Studies on Catalytic Dehydrogenation of Ethylbenzene Over Iron-Oxide-Based Catalyst Systems --Role of Lattice Oxygen

作　　者：陈慧贞 何淡云[1] 肖漳龄[1] 蔡启瑞 Chen Huizhen;He Danyuen;Xiao Zhangling;K.R.Tsai(Department of Chemistry and Inst itute of Physical Chemistry,Xiamen University,Xiamten)

机构地区：[1]厦门大学化学系 [2]国家海洋局第三海洋研究所

出　　处：《高等学校化学学报》1985年第5期433-440,共8页Chemical Journal of Chinese Universities

摘　　要：本文探讨了乙苯催化脱氢制苯乙烯工业氧化铁系催化剂晶格氧与水蒸汽氧的交换以及晶格氧参与反应的微观机理.实验结果表明:催化剂晶格氧参与反应,与水蒸汽氧有交换,反应途径以直接脱氢为主,并发生氧转移脱氢.讨论了两种脱氢反应途径中,晶格氧参与反应的微观过程.强调指出,晶格电子传递和邻近活性位氧化还原周期协同进行是氧转移脱氢机理的必要条件.The role of lattice oxygen in catalytic dehydrogcnation of ethylbenzene over industrial iron-oxide-based catalysts, 11^(#) (Cr-consaining) and 210^(#) (Cr-free), has been investigated by means of the following experiments: (1) Determination of amounts of H_(2)O produced due to removal of lattice oxygen by reaction with ethyl-benzene used as the feed without addition of steam, and observation of gradual decay of catalytic activities, and changes in the X-ray powder-diffraction patterns of the used catalysts;(2) with elhylbcnzcne plus D_(2)O as the feed, determination of the change in D_(2)/H_(2) ratio in the exit gas for very high and very low space velocities;and (3) vvith ethylbenzene plus D_(2)^(18)O as the feed, observation of isotopic exchange of lattice ^(16)O with steam ^(18)O from the red shifts in the IR spectra of the used catalyst. The results indicate that direct heterolytic dehydrogenalion of ethylbenzene appcared to be the major rcction pathway, but a minor reaction pathway of cthyl-benzcne dehydiogenation by oxygen-transfer mechanism also appeared to make an appreciable contribution (about 20%) to the overall conversion. Mechanisms of these two reaction pathways are discussed. For the oxygen-transfer dehydrogenation mechanism, the importance of electron transport between neighboring active-sites operating cooperatively in opposite phases of their redox cycles is pointed out.

关 键 词：乙苯脱氢 催化脱氢 脱氢反应 晶格氧 氧化铁系催化剂 微观过程 反应途径 氧化还原 

分 类 号：TQ2[化学工程—有机化工]