Study On The Interaction Of Zn And Cl On The Reaction Of Ethylene - Based ZnCl2 / Hβ Catalyst

Propylene, one of the most fundamental chemical engineering raw materials in industrial scale, is in great demand across the world in recent years, due to the significant increase need of the propylene derivates products. Because of the world wide shortage of oil resources, in coordination with the limitation of oil processing techniques, the traditional techniques of industrial production is unable to meet the growing demand of propylene, therefore, new methods should be developed. Recently, with the breakthroughs of fermentation of biomass, the synthesis of propylene from ethanol received great attention. Moreover, this technique can link the bio-chemical engineering and organic chemical engineering together and balance the carbon emission, known as carbon neutral.In the scope of promoting the industrial synthesis of propylene from ethanol, research are concentrating on the development of highly efficient catalysts and the optimization of reaction condition. Our previous work has investigated Zn//Hβ catalysts prepared from different zinc salts and applied in the synthesis of propylene from ethanol, indicating that the zinc can improve the catalytic performance of Hβ, among which the Hβ modified by ZnCl₂ obtained the best catalytic behavior among all prepared materials.The yield of propylene could reach 43.4% using 16% Zn/Hβ-a catalyst under following condition:0.1MPa, 773 K, P Ethanol=23 kPa, WHSV=2.8 h-1. The results showed several factors could influence the performance of catalysts,including surface acid sites, reaction condition structural properties and chloride. In this work, the synergic effect of zinc ions and chloride ions on the synthesis of propylene from ethanol, providing insights for the future improvement of catalysts.The Zn/Hβ catalysts were prepared by impregnation of ZnCl₂ or Z n（AC）2 solution on purchased Hβ catalysts and applied in the reaction. First, synergic effect of zinc ions and chloride ions on the synthesis of propylene from ethanol was investigated, followed by the estimation of contribution of Zn²⁺ in the reaction. Further, the purchased Hβ catalysts were modified by HCl to find out the influence of Cl- on the catalytic behavior. Several characterization techniques were applied to study the properties of prepared samples, including XRD, NH₃-TPD, TPR, N₂ adsorption-desorption analysis. he synergic effect of zinc ions and chloride ions on the synthesis of propylene from ethanol was discussed:（1）Zn/Hβ-a prepared by ZnCl₂ obtained better catalytic performance in the synthesis of propylene from ethanol reaction, showing the evidence for the synergic effect of zinc ions and chloride ions, which could change the acid properties and oxidation-reduction behavior of the catalyst.（2）Under reaction condition:0.1MPa,773 K, P Ethanol=23 kPa, WHSV=2.8 h-1, and applied ZnCl₂ modified 16% Zn/Hβ-a as catalyst, the yield of propylene could reach 43.3%.（3）Zn²⁺ participated in the dehydrogenation process, and optimized yield of propylene may result from the balance of the dehydrogenation effect of Zn²⁺ and the upper-middle acid sites formed by the presence of Cl- on the catalyst surface.