Molecular Physics | 2021
A theoretical study on the feed ratio of dimethyl ether carbonylation on H-MOR zeolites
Abstract
Monte Carlo and molecular dynamics simulations were performed for the adsorption-diffusion properties of dimethyl ether (DME) and carbon monoxide (CO) pure gas and mixture with different feed ratio in H-MOR zeolite to find out the influence of feed ratio on the DME carbonylation activity. For pure gas, DME adsorbs stronger than CO with a competitive adsorption, and all molecules have relatively good diffusion properties. For the mixture, in low feed ratio (P CO/P DME\u2009=\u20091–10), the adsorption capacity of CO in 8-MR cannot meet the reaction requirement caused the low carbonylation activity, while increasing the feed ratio (to P CO/P DME\u2009=\u200920–30) will promote CO adsorption. The optimal feed ratio P CO/P DME\u2009≈\u200927:1 is also discovered. Furthermore, it can also reduce the total molecular per cell and improve the diffusion in each channel which is another factor for the carbonylation activity improvement. Highlights: The adsorption ratio of NCO/NDME in H-MOR was investigated from both adsorption and diffusion sides, which is the key factor affecting the activity of DME carbonylation. A new scheme was proposed to optimise the carbonylation activity by changing the feed ratio, and the mechanism of increase and decrease of feed ratio was analysed from a microscopic point of view. The optimal feed ratio P CO/P DME\u2009≈\u200927:1 for DME carbonylation in H-MOR was discovered. A wide range of experimental feed ratio data (covers P CO/P DME\u2009=\u20091:1 to P CO/P DME\u2009=\u20091:50), so this research work provides a new idea for the next subsequent modification of H-MOR, which is to reduce the optimal feed ratio to an acceptable level. GRAPHICAL ABSTRACT