(40c) Alcohol Synthesis in a High-Pressure Membrane Contactor Reactor (MCR) Employing a Liquid Sweep

Methanol (MeOH) finds use as a transportation fuel and as a raw material in the production of other fuels and chemicals. There are several commercial methanol synthesis (MeS) processes, but they are challenged by low per-pass conversion that necessitates recycling of the unreacted syngas. This is especially problematic for MeOH production from biomass, where the use of oxygen-blown gasifiers is not economic, and the available syngas has a large nitrogen content. One way to overcome the thermodynamic limitations of MeS, and thus increase the per-pass conversion is to utilize a membrane contactor reactor (MCR). In this study, a novel high-pressure MCR is used, in which a mesoporous inorganic membrane with the desired characteristics serves as an interface contactor between the MeS environment in the shell-side and a sweep liquid flow in the permeate-side. Two different types of sweep liquids have been employed in the study: High boiling point (BP) petroleum-derived solvents and ionic liquids (IL), chosen because MeOH has high solubility in both of them, while the syngas components have negligible solubility. The MCR studies are coupled with parallel investigations of the solubility properties of the liquids sweep fluids and their chemical stability under conditions relevant to MeS.

The MR conversions significantly exceed those of the packed bed reactors. In addition, for the pressures and flow rates investigated, the IL studied attain higher conversions than the petroleum solvents, likely relating to their higher methanol solubility. Companion modeling studies indicate that the proposed process is capable to operate on biomass-derived syngas in an one-pass configuration without recycle needed. Current emphasis in the study is on the use of CO₂ waste streams relevant to CO₂ capture and storage operations. The process modifications needed to beneficially utilize such mixtures will be discussed during the talk. Preliminary TEA findings will be also presented.