摘要
考察了水蒸气处理温度和时间对ZSM 5分子筛酸性及其催化丁烯裂解性能的影响 .结果表明 ,通过水蒸气处理可降低ZSM 5分子筛的酸量和酸强度 ,明显提高产物中丙烯与乙烯的选择性和收率 ,抑制副产物芳烃和低碳烷烃的生成 .用柠檬酸脱除水蒸气处理过程中产生的非骨架铝 ,可提高ZSM 5分子筛孔道的容碳能力 ,从而提高催化剂的稳定性 .考察了反应条件对催化剂性能的影响 ,结果表明较佳的反应条件为WHSV =3 5～ 8 8h-1 ,p =0 0 6～ 0 1MPa ,θ =6 0 0～ 6 2 0℃ .
Propylene is one of the fastest growing petrochemicals, driven primarily by the high growth rate of polypropylene. The traditional methods to produce propylene cannot satisfy its demand. To increase the production of propylene, the catalytic cracking of low value C 4+ hydrocarbons, by products of petrochemical industry, to propylene and ethylene was investigated. The ZSM 5 zeolite was modified by steam treatment at different temperatures and for different time, and its acidity was measured by NH 3 TPD technique. With increasing treatment temperature and time, the acid density and the acid strength of ZSM 5 decreased. When used as a catalyst for butene cracking, the ZSM 5 with low acid density and weak acid strength was favorable to enhance the yield of propylene plus ethylene, besides decreased the production of aromatics and low carbon paraffins. By leaching out the non skeletal Al produced by the steam treatment with citric acid, the pore volume of ZSM 5 was enlarged and had a better capacity of accommodating the carbon deposit so that the catalyst life was prolonged. The yield of propylene plus ethylene could be enhanced if the reaction conditions were properly selected, as well as the yield of aromatics and paraffins could be decreased. The optimum conditions were as follows: WHSV=3 5～8 8 h -1 , p =0 06～0 1 MPa and θ =600～620 ℃.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2004年第7期571-576,共6页
基金
国家自然科学基金资助项目 ( 2 0 3 0 3 0 19)
国家 973计划项目 ( 2 0 0 3CB615 80 2 )
