级孔HZSM-5分子筛上超临界正十二烷催化裂解

以四丙基氢氧化铵(TPAOH)和四丁基氢氧化铵为碱源,在十六烷基三甲基溴化铵存在下,通过脱硅和再晶化合成了级孔HZSM-5分子筛。采用XRD、TEM、N2吸附-脱附、原位Py-IR和NH3-TPD等方法表征了分子筛的结构和酸性,在500℃、4 MPa下考察了级孔HZSM-5分子筛涂层上超临界正十二烷催化裂解的性能。实验结果表明,用TPAOH脱硅得到的级孔HZSM-5分子筛具有较大的外比表面积、微孔体积及酸量,其活性较未处理的HZSM-5原粉提高了76%,失活速率下降了61%。再晶化后,试样表面被MCM-41和HZSM-5碎片包裹,活性反而下降。表明TPAOH可缓和脱硅过程,保护分子筛的微孔结构;开放的介孔结构和中等的强酸量,有利于改善级孔HZSM-5分子筛的催化裂解性能。

探索合适的正十二烷催化裂解用ZSM-5/MCM-41:初始晶粒尺寸和Si/Al的影响（英文）

In this study,various ZSM-5/MCM-41 micro/mesoporous zeolite composites have been prepared by alkalidesilication and surfactant-directed recrystallization of ZSM-5.The effects of particle size and Si/Al ratio of initial ZSM-5 zeolites on the structure and catalytic performance of ZSM-5/MCM-41 composites are studied.The results of XRD,TEM N_2-adsorption-desorption,NH_3-TPD and in situ FT-IR revealed that ordered hexagonal MCM-41 mesopores with 3-4 nm pore size were formed around ZSM-5 crystals,and the specific surface area and mesopore volume of composites increased with increasing the Si/Al ratio of initial ZSM-5.Catalytic cracking of n-dodecane(550℃,4 MPa) showed that the ZSM-5/MCM-41 composites obtained from the high Si/Al ratio and nano-sized initial ZSM-5 zeolites exhibited superior catalytic performance,with the improvement higher than 87%in the catalytic activities and 21%in the deactivation rate compared with untreated zeolites.This could be ascribed to their suitable pore structure,which enhanced the diffusion of reactant molecules in pores of catalysts.

b轴取向MFI型沸石分子筛膜的构筑与应用进展

综述了b轴取向MFI型沸石分子筛膜在构筑、应用方面的最新研究成果,从原位水热晶化法、二次水热晶化法和干胶转化法等方面总结了b轴取向MFI型沸石分子筛膜构筑方法,对比了构筑方法的优缺点;介绍了b轴取向MFI型沸石分子筛膜在分离与催化领域的应用进展;讨论了b轴取向分子筛膜目前面临的挑战和未来的发展方向。