正丁烷和异丁烷在改性纳米HZSM-5上的芳构化反应

用脉冲微反装置评价了正丁烷和异丁烷在氢型和锌改性的纳米ZSM-5催化剂上的反应活性和芳构化选择性.结果表明,在550℃下,异丁烷在氢型和不同锌负载量的纳米ZSM-5催化剂上的转化率都远高于正丁烷,但其芳构化选择性低于正丁烷.脱甲基活化是异丁烷和正丁烷的重要活化方式,也是影响其芳构化选择性的主要因素.锌改性在提高异丁烷和正丁烷转化率的同时,也促进了正丁烷和异丁烷的脱甲基活化.在混合丁烷进料反应的情况下,正丁烷和异丁烷的转化率与其单独进料时十分接近,这说明正丁烷和异丁烷共存时不会发生明显的竞争吸附和反应.纳米ZSM-5因晶粒度小,孔道短和微孔扩散阻力低而有利于异丁烷转化.

Aromatization of n-butane and i-butane over modified nano-HZSM-5 catalyst

The conversion of n-butane and i-butane over HZSM-5 and Zn/HZSM-5 catalysts were evaluated with mini-scale pulse reactor in terms of reactivity and aromatization selectivity.Results show that,i-butane has higher conversion than n-butane at 550 ℃ on both HZSM-5 and Zn/HZSM-5 catalysts,however,the aromatics selectivity of i-butane is lower than that of n-butane.Demethylation is the main path of n-butane and i-butane activation,and which is also an important factor to affect aromatization selectivity.Zinc modificatioin remarkably increases the conversion of i-butane and n-butane and,at the same time,promotes their demethylation activation.When the mixture of n-butane and i-butane were used as feedstock,no difference is seen in terms of n-butane and i-butane conversions compared with the pure butane feedstocks,which implies that there is no obvious competition between n-butane and i-butane during adsorption activation and subsequent reactions.Nano-ZSM-5 zeolite is beneficial to the conversion of i-butane due to its small grain size,short channel and lower diffusion resistence.