How many molecules can fit in a zeolite pore? Implications for the hydrocarbon pool mechanism of the methanol-to-hydrocarbons process

Abstract

The methanol-to-hydrocarbons (MTH) process is a very advantageous way to upgrade Abstract: The methanol-to-hydrocarbons (MTH) process is a very advantageous way to upgrade methanol to more valuable commodity chemicals such as light alkenes and gasoline. There is general agreement that, at steady state, the process operates via a dual cycle “hydrocarbon pool” mech-methanol to more valuable commodity chemicals such as light alkenes and gasoline. There is general agreement that, at steady state, the process operates via a dual cycle “hydrocarbon pool” mechanism. anism. This mechanism defines a minimum number of reactants, intermediates, and products that This mechanism defines a minimum number of reactants, intermediates, and products that must must be present for the reaction to occur. In this paper, we calculate (by three independent methods) be present for the reaction to occur. In this paper, we calculate (by three independent methods) the the volume required for a range of compounds that must be present in a working catalyst. These are volume required for a range of compounds that must be present in a working catalyst. These are compared to the available volume in a range of zeolites that have been used, or tested, for MTH. We compared to the available volume in a range of zeolites that have been used, or tested, for MTH. We show that this straightforward comparison provides a means to rationalize the product slate and show that this straightforward comparison provides means to rationalize the product slate and the the deactivation pathways in zeotype materials used for the MTH reaction. deactivation pathways in zeotype materials used for the MTH reaction.