Synthesis And Modification Of Mordenite And Its Performance Of Dimethyl Ether Carbonylation

The reaction of dimethyl ether(DME)carbonylation to produce methyl acetate(MA)has attracted wide concern because the product of hydrogenation of MA is ethanol,which is a potential fuel substitute and additive.The main challenge of the new DME-to-ethanol process is to develop a mordenite catalyst with high activity and stability.The mordenite catalyst was synthesized by hydrothermal method and modified with different metals.The catalysts were characterized by N2 adsorption/desorption,XRD,ICP-OES,SEM,TEM,UV-Vis,XPS,Raman,NH3-TPD,CO-TPD,27Al MAS NMR,FTIR and Py-IR,and evaluated under the reaction conditions of 473K,1.OMPa and space velocity of 2040ml/(g.h).Co/H-MOR,Zn/H-MOR and Co-Zn/H-MOR catalysts were prepared by ion exchange method.The ion exchange process did not damage the framework structure of mordenite.The incorporation of Co and Zn caused an increase in the amount of acid and acid strength in the catalysts,thereby improving the reaction performance of the catalysts.1Co-2Zn/H-MOR showed the best reaction performance.The maximum DME conversion and MA selectivity reached 58%and 98%respectively,higher than that of H-MOR catalyst.For Co-Zn/H-MOR catalysts,the introduction of Zn maintains the well dispersion of Co while suppresses the deposition of coke on the catalysts during the reaction.Zr-MOR catalysts were prepared by post-treatment method.The introduction of Zr atoms into the mordenite framework by occupying T3 site of 8-MR and existed in a tetrahedral coordination state.Despite the amount of the Brensted acid sites in the 8-MR channels decreased upon the incorporation of zirconium,Zr Lewis acid sites with the ability to adsorb CO molecules were formed during this process.The concentration of zirconium nitrate solution was in the range of 0.02 to 0.08 mol/L,the Zr-MOR obtained by post-treatment with 0.04 mol/L zirconium nitrate solution exhibited the best catalytic performance.The maximum DME conversion and MA selectivity increased to 78%and 96%respectively,much higher than that of H-MOR catalyst.The mordenite catalysts with different Cu content were prepared by hydrothermal synthesis method.Mordenite crystallized well and Cu was well dispersed in the mordenite.The incorporation of Cu caused the increase of acid density and acid strength in the catalysts,and the adsorption capacity of CO also enhanced with the increase of Cu content.The mordenite with Cu content of 2.36%showed the best reaction performance,the maximum DME conversion and MA selectivity reached 58%and 95%respectively,higher than that of H-MOR catalyst.