One Step Methanol-Mediated CO2 Conversion to Gasoline: Comprehensive Review and Critical Outlook

Abstract

Decreasing our demand for fossil feedstock is one of the best ways to support the energy and environmental transitions that are needed for our society. CO₂ utilization and, more specifically, CO₂ conversion to hydrocarbons are an attractive route to reduce CO₂ emissions and to obtain carbon-neutral fuels and chemicals that are conventionally produced from fossil fuels. One way to achieve that is through the conversion of CO₂ to methanol, followed by methanol conversion to hydrocarbons. So far, these processes have mainly been studied as separate steps, and one view is to sequentially operate them. However, it is possible to perform it in one step, in tandem catalysis. Such catalysts are usually an oxide for the first reaction combined with an acidic zeolite that catalyzes the second reaction. Many catalysts have been researched for the two separate steps but only a few have been studied for the tandem when the gasoline range is the target. Among the oxides, ZnZrOx and In₂O₃ dominate the art, while more metallic InCo also has its merits. These lead to interesting selectivities and yields when combined with a zeolite (usually ZSM-5). A clear understanding of the mechanism behind these systems has not been reached; yet, we deliver a summary of the achieved mechanistic results and offer insights for further studies. While parameters such as bed configuration or amount proximity have been studied, more research is needed, especially when looking at the complex kinetics. This “direct CO₂ to gasoline range hydrocarbons” (including aromatics) review aims to connect dots while highlighting the aspects that still need a deeper understanding, and it also pinpoints practical insights and perspectives.