Abstract:

ZSM-5 zeolite, one of the important shape selective catalysts with high molar ratio of silica to alumina, possesses strong acidity and excellent thermal and hydrothermal stability. The acidity and pore structure of ZSM-5 zeolite were adjusted by combinatorially modifying ZSM-5 molecular sieves with phosphorus and aluminum. Results showed lamellar-structured phosphorus and aluminum deposits on the surface of ZSM-5 zeolite at greater than 10% (mass) load of phosphorus and aluminum, which increased its acidity and formed new mesopores about 10 nm in diameter. Such highly acidic porous structures significantly increased the conversion of n-octane and the propylene yield by more than 20%. When used in catalytic cracking of heavy oil, the yield of oil residual and coke was decreased but the yield of propylene was increased by 1%.

Key words: ZSM-5 zeolite, hydrothermal, phosphorus and aluminum combined modification, composites, catalysis, acidity

摘要：

ZSM-5分子筛是一种重要的高硅铝比择形催化剂，具有较强的酸性和较好的热、水热稳定性，通过对该分子筛进行磷与铝的复合改性，对其酸性质和孔结构进行了调变。研究结果表明，当磷铝负载量（质量分数）大于10%时，磷铝物种以片状形式沉积在ZSM-5分子筛表面，不仅提高了分子筛的酸量，还形成了孔径在10 nm左右的介孔。这种高酸性的多级孔结构使其正辛烷裂化转化率明显提高，丙烯收率增加20%以上；在重油催化裂化评价反应中降低了渣油和焦炭收率，丙烯的收率提高了1%。

关键词: ZSM-5分子筛, 水热, 磷铝复合改性, 复合材料, 催化, 酸性质