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本文采用自装的小型固定床常压反应器为反应器,以纳米HZSM-5沸石为催化剂,对混合C8芳烃中的乙苯选择性催化裂解脱烷基反应进行了研究。结果表明,反应温度对于各种碳八芳烃的异构体互相转化有重要影响。通过实验可知乙苯催化裂解后脱烷基反应的最小温度应是450-480℃左右。高的反应温度有利于提高乙苯转化率,但反应温度过高会导致乙苯侧链裂解,并产生二甲苯脱烷基等副反应。根据钠离子改性和NH3-TPD谱图、吡啶红外光谱表征发现,乙苯分子催化裂解脱烷基反应需要强酸中心。但过强的酸中心可能会加重乙苯侧链裂解反应和二甲苯脱甲基、氢转移等副反应。
In this paper, a self-installed small fixed-bed atmospheric reactor was used as a reactor. The selective catalytic cracking dealkylation of ethylbenzene in a mixed C8 aromatics was studied using nano-HZSM-5 zeolite as a catalyst. The results show that the reaction temperature has important influence on the conversion of isomers of various octa-aromatics. The experiment shows that the minimum temperature of dealkylation after ethylbenzene cracking should be about 450-480 ℃. High reaction temperature is conducive to improve the conversion of ethylbenzene, but the reaction temperature is too high will lead to ethylbenzene side chain cracking, and produce xylene dealkylation and other side reactions. According to the results of sodium ion modification and NH3-TPD spectroscopy, IR spectra of pyridine showed that strong acid sites were needed for the de-alkylation of ethylbenzene molecules. However, too strong acid sites may aggravate the side reactions of ethylbenzene cracking and xylene demethylation, hydrogen transfer and other side effects.