【摘要】 采用不同链长的有机硅烷作为表面修饰剂,在正庚烷/正丁醇中利用溶剂热合成法制备得到亲油性纳米ZSM-5分子筛.通过有机硅烷与氧化物晶种表面的羟基作用,其长链化学键合到晶种表面,形成保护层,既抑制了氧化物颗粒间的团聚,又控制了纳米ZSM-5的粒径.所制备的纳米ZSM-5平均粒径为20~70nm,且粒径随着有机硅烷碳链长度的降低而逐渐减小.添加一定量的该纳米ZSM-5到碳氢燃料模型化合物正十二烷中,在管式反应器中(550℃,4MPa)考察催化裂解行为,结果表明该亲油性纳米ZSM-5分子筛能有效催化正十二烷裂解,其裂解转化率相对于热裂解明显提高,且转化率的提高随着有机硅烷碳链长度的降低而逐渐增大,其中丙基三甲氧基硅烷修饰的ZSM-5使正十二烷的裂解转化率相对于热裂解提高了115%.更多还原

【Abstract】 Nano ZSM-5 catalysts with hydrophobic surfaces have been prepared by solvent-thermal treatment with an n-heptane/n-butanol mixture as the solvent and different silanes(trimethoxy(propyl)silane,trimethoxy(octyl)silane and hexadecyltrimethoxysilane)as surface modification agents.In order to avoid drastic aggregation,long-chain organic groups are chemically bonded to the surfaces of nano ZSM-5 seeds before the crystallization.The average particle sizes prepared with organosilica are 20~70nm and slightly decrease with the length decrease of the carbon chain.The catalytic cracking behaviors of n-dodecane,as one model of hydrocarbon fuels,dispersed with nano ZSM-5 are studied in a tubular reactor at 550℃ and 4MPa.The results show that the conversions of catalytic cracking are obviously larger than those of thermal cracking,indicating that nano ZSM-5 catalysts have good performance in the catalytic cracking of n-dodecane.The conversion increases with the decrease of the carbon chain length.The conversion of n-dodecane catalyzed by ZSM-5 prepared with propyltrimethoxysilane is 115% larger than that of thermal cracking.更多还原