Ishihara Atsushi, Takai Kentarou, Hashimoto Tadanori, Nasu Hiroyuki
Division of Chemistry for Materials, Graduate School of Engineering, Mie University, Tsu 514-8507 Japan.
ACS Omega. 2020 May 11;5(19):11160-11166. doi: 10.1021/acsomega.0c01147. eCollection 2020 May 19.
In this study, the effects of the combination of a mesoporous material and Zn-exchanged ZSM-5 on the activity and selectivity of aromatic compounds in dehydrocyclization of -pentane were investigated. A total of 65-85 wt % of ZnZSM-5 was mixed with 0-20 wt % of AlO and 15 wt % of the alumina-sol binder using a conventional kneading method. Dehydrocyclization of -pentane was performed using a fixed-bed reactor under the conditions of a H atmosphere and the temperature range of 450-550 °C. Conversions of -pentane tended to increase upon increasing the amounts of zeolite content and ZnZSM/0A (85 wt % ZnZSM-5, 0 wt % AlO, and 15 wt % binder) exhibited the highest value. The selectivity for toluene and benzene increased with increasing temperature, while it decreased in the order ZnZSM/10A > ZnZSM/0A > ZnZSM/20A in comparison at the same temperature. Upon changing the carrier gas, the conversion decreased in the order CH > H > H + N > N. Although the selectivity for aromatics was higher under CH and N atmospheres, the conversions decreased at 550 °C with time, suggesting that the deactivation would proceed by coke formation. Furthermore, the selectivity for aromatics of ZnZSM/10A was higher than that of ZnZSM/0A, indicating that the use of mesoporous AlO as a matrix would be very effective for this reaction and draw the maximum catalytic functions. When the reaction route was estimated from the amounts of methane and C2 and C3 fractions formed, it was proposed that active Zn species would catalyze the aromatization of olefins where benzene is formed from ethene and butene, toluene from propene and butene, and xylene from 2 molecules of butene.
在本研究中，研究了介孔材料与锌交换ZSM-5的组合对戊烷脱氢环化中芳烃化合物活性和选择性的影响。使用传统捏合方法将总共65-85 wt%的ZnZSM-5与0-20 wt%的AlO和15 wt%的氧化铝溶胶粘合剂混合。在H气氛和450-550°C的温度范围内，使用固定床反应器进行戊烷的脱氢环化。随着沸石含量的增加，戊烷的转化率趋于增加，并且ZnZSM/0A（85 wt% ZnZSM-5、0 wt% AlO和15 wt%粘合剂）表现出最高值。甲苯和苯的选择性随温度升高而增加，而在相同温度下比较时，其选择性按ZnZSM/10A>ZnZSM/0A>ZnZSM/20A的顺序降低。改变载气时，转化率按CH>H>H + N>N的顺序降低。尽管在CH和N气氛下芳烃的选择性较高，但在550°C下转化率随时间下降，这表明失活将通过焦炭形成而进行。此外，ZnZSM/10A的芳烃选择性高于ZnZSM/0A，这表明使用介孔AlO作为基质对该反应非常有效，并能发挥最大的催化功能。当根据形成的甲烷以及C2和C3馏分的量估算反应路线时，有人提出活性锌物种将催化烯烃的芳构化反应，其中乙烯和丁烯生成苯，丙烯和丁烯生成甲苯，2分子丁烯生成二甲苯。
