Investigation on the mechanism of diffusion in mesopore structured ZSM-5 and improved heavy oil conversion
Investigation on the mechanism of diffusion in mesopore structured ZSM-5 and improved heavy oil conversion
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DOI：
10.1016/j.jcat.2008.06.015
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发表时间：
2008-08
影响因子：
7.3
通讯作者：
Liang Zhao;B. Shen;Jinsen Gao;Chunming Xu
中科院分区：
文献类型：
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作者：
Liang Zhao;B. Shen;Jinsen Gao;Chunming Xu
以异丙苯为探针分子，采用高精度智能重量分析仪研究了异丙苯在介孔ZSM-5分子筛上的扩散和吸附行为。与ZSM-5相比，异丙苯在中孔ZSM-5上的扩散系数提高了2-3个数量级。增加的吸附速率和增加的吸附热与增加的枯烯覆盖，支持的扩散，相变，和重排的枯烯分子在吸附过程中的中孔结构的ZSM-5的机制。引入的中孔也降低了扩散-吸附活化能的4.6倍。结果表明，以大庆重油为原料，虽然强布朗斯特酸中心减少，但异丙苯在中孔ZSM-5催化剂上的转化率比ZSM-5催化剂提高了一倍，低碳烯烃总收率提高了2.47wt%。
A large probe molecule, cumene, was chosen to study diffusion and adsorption on mesopore structured ZSM-5, using a high precision intelligent gravimetric analyzer. Compared with ZSM-5, a 2–3 order of magnitude increase in the diffusion coefficient of cumene was observed on the mesopore structured ZSM-5. The increased adsorption rate and the increased adsorption heat with increased cumene coverage, supported a mechanism of diffusion, phase transition, and re-arrangement of cumene molecules during the adsorption process on the mesopore structured ZSM-5. The introduced mesopores also decreased the diffusion–adsorption activation energy by a factor of 4.6. Consequently, although the amount of strong Brønsted acid sites decreased, the conversion of cumene on the mesopore structured ZSM-5 catalyst doubled compared to ZSM-5 catalyst, and the total light olefins yield increased by 2.47 wt% with Daqing heavy oil as a feedstock.