摘要
乙苯是生产聚苯乙烯的原料,一般都用高浓度乙烯与苯的烃化来制取。以稀乙烯气生产乙苯在国外只有试生产的报导。我国现有催化裂化装置数十套,年产干气近百万吨。其中所含10—25％乙烯尚未得到合理利用,若将它制成乙苯,所得的经济效益将会十分可观。从事这方面研究的主要有U.O.P.,Monsanto/Lummus,Mobil/Badger等,分别使用BF_3,AlCl_3和ZSM-5沸石为催化剂,均要求将原料气中的H_2S,
Highly siliceous zeolite catalysts for ethylbenzene production with dilute ethylenc in FCC dry off-gas have been prepared. As a special feature of the catalyst, purification of the feed gas was unnecessary. By modification and ultra-stable treatment, the catalyst attained a lower carbon depositing rate and higher hydrothermal resistance as well as much less sensitive to impurity poisoning than the conventional alkylation catalybts. The conversion of ethylene could be maintained over 90% Under 345-450℃, 0.7-0.9 MPa, benzene/ethylene mole ratio 5-7 and WHSV 0.8-1.0 h-1 with ethylene of the dry gas containing 5000-8000 ppm of H2S and 500 - 1000 ppm of H2O. The operating cycle length could be maintained more than 50 days with 80-90% selectivity for ethylbenzene. The deactivated catalyst could be regenerated, and could be operated further in a second cycle for 51 days. The catalysts were characterized before and aftct running by TPD, IR, XPS etc. The effects of modifying agent and ultrastable treatment on the nature and the stability of the acid Sites of catalyst were described. The acid sites with medium strength were postulated to be responsible for enhancing the ethylbenzene selectivity.
