Maximizing Chlorine Gas Conversion in Methyl Chloride Production by the Integration of Methane Chlorination and Methanol Hydrochlorination

In this study, the development of kinetic rate equations for catalytic methane chlorination over pellet-type catalysts was addressed. Experimental data at various temperatures, feed compositions, space velocities, and pressures were used to estimate the kinetic parameters. The average errors for methane conversion and methyl chloride (MCM) selectivity were 15.9 and 4.4%, respectively, validating the effectiveness of the developed kinetics. A process model was developed by considering a commercial-scale methane chlorination reactor and separation train. HCl, which was responsible for half of the chlorine gas in the feed, might reduce the economics of the process. The MeOH hydrochlorination reaction was combined with methane chlorination, and three variations of the combined process were suggested, depending on the configuration of the separation sequence. The MeOH hydrochlorination reduced the energy requirement by more than 80% compared to methane chlorination. Techno-economic analysis showed that the feeding of pure HCl had the lowest purchase and annual production costs, resulting in the lowest minimum selling price (MSP) of 0.90 $/kg-MCM. The sensitivity analysis of the MSP concerning the MeOH and HCl price showed that the proposed process is the most economical up to 1.8 $/kg-MeOH and 160 $/ton-HCl, respectively.