| 摘要： |
Ethane aromatization is a promising process to achieve the efficient utilization of abundant ethane into high value-added chemicals. However, rapid coking deactivation has hindered the application of this technique. In this work, to improve catalyst stability, mesopores are introduced into the conventional Zn modified HZSM-5 catalysts. ICP, XRD, N-2 adsorption-desorption, HRTEM, NH3-TPD, TG, and XPS are used to study the structure property, acidity, and coke formation of conventional and mesoporous catalysts. For ethane aromatization, upon reacting for 262 min, the yield of main products including benzene, toluene, and ethylene decreased by 48.7% for conv-Zn/HZSM-5 while only 16.6% for meso-Zn/HZSM-5. The significantly enhanced catalytic activity and stability of meso-Zn/HZSM-5 is primarily ascribed to the generation of mesopores after alkali treatment. As suggested by TG and N-2 adsorption-desorption, conv-Zn/HZSM-5 exhibited not only faster coke deposition than meso-Zn/HZSM-5, but also major coke formation within the micropores, thus accelerating the catalyst deactivation. In contrast, the introduction of mesopores seems to availably facilitate the diffusion and escape of products from zeolite channels and subsequently suppress the internal coke formation, resulting in improved catalyst stability. In addition, a reaction-regeneration protocol was operated on meso-Zn/HZSM-5, which can effectively remove the deposited coke and extend the life of catalyst. [GRAPHICS] . |
