The Synthesis Of Dimethyl Ether From The Hydrolysis Of Methyl Bromide

Dimethyl ether (DME) is an important feed stock and intermediate of chemical industry. It is widely used in our daily life. It was called potential clean fuel of the 21th centuries. Currently, DME is synthesized from syngas process, in which, methanol is synthesized from the syngas, and then from the catalytic dehydration of methanol, DME is synthesized. There is process to prepare DME in one step reaction from syngas. However, the one step reaction process is still in developing. No commercial process exists yet. The syngas process is a high energy consuming process, which need to produce syngas either from the steam reformation of coal or natural gas and also, the syngas process forms stoichiometric amount of CO2. Our laboratory developed a process to synthesize CH3Br from the oxidative bromination of methane (OBM). The reaction is an exotheric reaction. No extra energy is needed for the CH3Br synthesis reaction. Dimethyl ether is synthesized from the hydrolysis of CH3Br over catalyst. The priority of the process is that it is an energy saving process and also, no stoichiometric CO2 formation. In the dimethyl ether synthesis reaction, nitrogen was used as standard for analysis of product. By reacting CH3Br with water over a catalyst, DME is formed. Catalysts with varies of compositions was tested to find high active catalyst for the hydrolysis of CH3Br. The reaction conditions including reaction temperature, the flow of nitrogen, the ratio of bromomethane to water were optimized for the dimethyl ether synthesis reaction. XRD and BET characterizations were used to investigate the relationship of catalytic properties and catalyst structure. The investigations show that ZnCl2/SiO2 is the most active catalyst. 95.0% of CH3Br conversion with 100% dimethyl ether selectivity was obtained over 12mol%ZnCl2/SiO2 at conditions of 160°C, CH3Br flow of 10.0 ml/min, water flow of 0.5 ml/h, and nitrogen flow of 10.0 ml/min. The serial reaction, which includes the oxidative bromination of methane and the hydrolysis reaction of CH3Br revealed that the products or reactants of the oxidative bromination of methane did not influence the dimethyl ether synthesis reaction of CH3Br. The serial reaction also produced dimethyl ether directly from methane.