十氢萘在分子筛催化剂上的开环反应研究

在小型固定流化床(FFB)装置中研究了Y分子筛与ZSM-5分子筛催化剂上的十氢萘裂化开环反应性能,考察了温度和剂油比对Y分子筛开环反应催化性能的影响。结果表明,十氢萘在分子筛催化剂上通过环烷环开环反应生成丙烷、丙烯、丁烷、丁烯、甲基戊烷和环戊烷、环己烷等非芳烃以及苯、C_1~4烷基取代苯等单环芳烃,并通过脱氢缩合反应生成四氢萘、萘、甲基萘和菲、芘等多环芳烃甚至焦炭等。由于扩散和吸附性能的影响,ZSM-5分子筛催化剂的裂化开环反应选择性比Y分子筛催化剂的高,因此,十氢萘环烷环开环与脱氢缩合反应的相对比例(NRO/DHC)在ZSM-5分子筛催化剂上较高。在Y分子筛催化剂上,温度为450~550 ℃、剂油比为3~9,反应温度升高或者剂油比增加,双分子氢转移以及脱氢缩合反应增强,从而导致环烷环开环产物选择性降低。

Opening of naphthenic ring in decalin cracking over zeolite catalysts

Decalin cracking over Y and ZSM-5 zeolites were conducted in a small fixed fluidised bed (FFB) reactor; the effect of temperature and catalyst/oil ratio on the opening of naphthenic ring in decalin cracking over Y zeolite was investigated. The results showed that the products of decalin cracking over zeolite catalysts by naphthenic ring opening involve non-aromatics (propane, propylene, butane, butylenes, methylpenptane, cyclopentane, cyclohexane, etc.) and monocyclic aromatics (benzene, and C_1~4 alkyl benzene); polycyclic aromatics (tetrahydronaphthalene, naphthalene, alkyl naphthalene, phenanthrenes, pyrenes, etc.) and even coke may also be formed through dehydrogenation condensation reactions. The selectivity for naphthenic ring opening over ZSM-5 catalyst is higher than that over Y catalyst, due to difference in the diffusion and adsorption of naphthenic hydrocarbon on two catalysts. The relative ratio of naphthenic ring opening to dehydrogenation condensation reactions (NRO/DHC) is higher over ZSM-5 catalyst than that over Y catalyst. Under the conditions of 450~550 ℃, weight hourly space velocity of 10 h^-1, and catalyst/oil mass ratio of 3~9, with the increase of the reaction temperature or the catalyst/oil ratio, the bimolecular hydrogen transfer and dehydrogenation condensation are enhanced and as a result, the selectivity to the products from naphthenic ring opening is decreased.