锌和钾改性HZSM-5临氢芳构化催化剂研究

以等体积浸渍法制备了Zn/HZSM-5和不同含量K改性的K-Zn/HZSM-5催化剂，采用XRD、NH3-TPD、py-IR和N2吸附-脱附等方法对所制备催化剂进行了表征，在HZSM-5催化剂中加入5%质量分数的ZnO，催化剂的总酸量略有增加，L/B酸比值增加；同时又加入不同含量的K2O，随着K2O含量的增加，催化剂的L酸量和L/B酸比值均降低,少量K2O的引入对催化剂酸性质影响较小。以正庚烷为原料考察HZSM-5催化剂以及Zn和K改性后的催化剂的临氢芳构化性能，结果表明，ZnO质量分数为5%、K2O质量分数不超过0.5%时，随着钾含量的升高，改性催化剂的芳构化率和苯、甲苯、二甲苯(BTX)的选择性大幅提高，C9+芳烃的选择性降低，Zn和K改性催化剂的活性和稳定性较好。

Study on HZSM-5 Catalyst Modified by Zn and K for Hydroaromatization

HZSM-5 zeolite was modified by Zn and K using equal volume impregnation method. These catalysts were characterized by XRD, NH3-TPD, Py-IR and N2 adsorption-desorption methods. When adding 5% (mass fraction) ZnO to HZSM-5 catalyst, the total acid amount and the ratio of L acid amount to B acid amount become slightly increased. When adding different content of K2O and 5% mass fraction ZnO to HZSM-5 catalyst, the amount of L acid and the ratio of L acid amount to B acid amount are decreasing with the increase of K2O content. The catalytic properties of HZSM-5，Zn/HZSM-5 and K-Zn/HZSM-5 in hydroaromatization were investigated with n-heptane as probe reactant. Results show that the aromatization rate and the selectivities of benzene, toluene and xylene(BTX) increase greatly with the increasing of K when the mass fraction of ZnO is 5% and the mass fraction of K2O is not more than 0.5%， while the selectivity of C9+ aromatics decreases greatly, and the activity and stability of the K-Zn/HZSM-5 catalyst are good.