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本文就钾助催氧化铁系脱氢催化剂的活性中心原子簇K_2O·Fe_3O_4,对乙苯两步络合活化和脱氢的方式进行EHMO的量子化学处理。计算得到的净电荷、重迭集居数和HOMO的数据表明,乙苯脱氢主要是乙苯受催化剂活性相原子簇中一个铁原子的多位吸附,形成σπ键络合,苯环稍失电子而带少量正电荷,通过超共轭效应和邻近另一个铁原子与氧原子的配位络合作用,两步活化α-H和β-H,最后脱H_2或H_2O并生成苯乙烯。乙苯脱氢反应中,只有在第二步脱β-H生成苯乙烯的过程中,才有付反应产生,其中生成甲苯的趋势较大;钾的加入不仅降低催化剂的电子脱出功,而且降低催化剂的酸强度,抑制了生成苯的付反应。
In this paper, the quantum chemical treatment of EHMO was performed on K_2O · Fe_3O_4, an active center cluster of potassium-promoted iron oxide-based dehydrogenation catalyst, in a two-step complex activation and dehydrogenation of ethylbenzene. Calculated net charge, overlap population and HOMO data show that ethylbenzene dehydrogenation is mainly due to the adsorption of ethylbenzene by a number of iron atoms in an active atomic cluster, resulting in the formation of σπ bond and a slight loss of benzene ring Electrons with a small amount of positive charge, through the superconjugation effect and the coordination of another iron atoms and oxygen atoms complexed with two-step activation of α-H and β-H, and finally H_2 or H_2O and the formation of styrene. Ethylbenzene dehydrogenation reaction, only in the second step β-H to produce styrene in the process, only paid reaction, the trend of generating toluene larger; addition of potassium not only reduces the catalyst prolapse of electrons, but also reduce The acid strength of the catalyst inhibits the benzene-forming reaction.