Abstract:

Using ultra-fine silicon oxide as carrier, ZSM-5 molecular sieves with high n(SiO₂)/n(Al₂O₃) ratio were extruded yielding catalyst for catalytic cracking of C₄ alkenes to propylene and ethylene. Precursors of calcium oxide and boron oxide were used to adjust the acidic property of the catalyst. The catalyst was pretreated with water vapor for 24 h at 580 ℃ under atmospheric pressure and water WHSV of 1 h^－1. The catalyst was evaluated at 500℃ under 0.1MPa with w(H₂O):w(C₄^＝)=0.2 and WHSV of 3 h^－1, the continuous operation of 25 days proved the stability of catalyst；the conversion of C₄ alkenes was higher than 68%, the yield of propylene and ethylene were higher than 30% and 6%, respectively, and the amount of carbon deposition on catalyst was 6.2%. The catalysts were characterized by BET, NH₃-TPD and Py-IR, which illustrated that the catalytic activity is corelated with B acid in the catalyst.

摘要：

用超细氧化硅为载体、高硅铝比的ZSM-5分子筛为活性组分，挤条成型制成催化剂。用氧化钙和氧化硼的前体化合物改性，在580 ℃、常压、水质量空速为1 h^－1的条件下进行预处理24 h，在500 ℃、0.1 MPa、水/C₄质量比为0.2、C₄质量空速为3 h^－1的条件下，C₄烯烃制丙烯和乙烯的反应产物组成稳定，在连续25天的反应过程中，C₄烯烃转化率大于68%，丙烯收率大于30%，乙烯收率大于6%，催化剂的积炭量为6.2%。对成型、改性、水蒸气预处理和再生后的催化剂用BET、NH₃-TPD 和 Py-IR进行表征，分析催化剂活性与酸性的关系，认为催化剂表面质子酸（B酸）与催化剂的活性有关。