轻汽油在HZSM-5分子筛上催化裂解制丙烯的研究

以催化裂化轻汽油（≤75 ℃）为原料，在小型固定床反应器上，考察了反应温度、反应空速、催化剂不同硅铝物质的量比及载体Al₂O₃含量对轻汽油的催化裂解性能及丙烯选择性的影响。实验结果表明，反应温度和空速对催化裂解的产物分布和丙烯收率有较大的影响，高硅铝比催化剂的丙烯选择性比低硅铝比催化剂好，适量Al₂O₃的添加有助于提高丙烯收率。选择合适的反应条件可以有效提高催化剂的裂化性能并能很好抑制氢转移反应的进行，从而提高丙烯的选择性。在550 ℃、0.2 MPa和空速4 h^－1条件下，高硅铝比n(SiO₂)∶n(Al₂O₃)=200］催化剂的丙烯收率为37.56％，当添加30%的Al₂O₃时，丙烯收率增至38.26%。

Catalytic cracking of FCC light gasoline over HZSM-5 to produce propylene

Catalytic cracking of FCC light gasoline was investigated on a small scale fixed bed reactor over HZSM 5 catalyst, including the influences of reaction temperature, LHSV, Si/Al molar ratio in HZSM-5 and content of Al₂O₃ carrier on the catalytic cracking behaviors and yield of propylene. The results showed that reaction temperature and LHSV had remarkable influence on the product distribution and yield of propylene. The catalysts with higher Si/Al molar ratio exhibited higher selectivity to propylene than those with lower Si/Al molar ratio. Addition of appropriate percentage of Al₂O₃ into HZSM-5 enhanced the yield of propylene. Properly optimized reaction condition can enhance catalytic cracking behavior of the catalyst, inhibit hydrogen transfer reaction and thus greatly improve the selectivity to propylene. Under 500 ℃, 0.2 MPa and LHSV=4 h^－1, the propylene yield of 37.56% was attained over HZSM-5 with n(SiO₂)∶n(Al₂O₃)=20; the yield of propylene increased to 38.26% when adding 30% mass percentage of Al₂O₃.