Bringing down the heat in methanol synthesis

The methanol economy envisioned by Nobel laureate George Olah is growing by leaps and bounds. This growth is spurred by its burgeoning use not only as a major feedstock for a vast range of commodity chemicals and fuels but as a high-capacity and secure hydrogen (H2) storage, transportation, and delivery medium to power the hydrogen economy these days. Methanol is currently produced industrially at more than 100 million metric ton scales from fossil-sourced syngas, CO-H2, and by conventional fossil-powered heterogeneous catalysis, operated under high temperature and pressure conditions. The synthesis process is enabled by a ternary copper-zinc oxide-alumina composite (CZA), the performance metrics of which have remained pre-eminent for the past two decades. There are, however, incentives to lower the energy, economic, and environmental impact of the commercial methanol process, which functions at 250 degrees C and 8 MPa, and to reduce its carbon footprint by switching to a CO2-H2 feedstock rather than continuing the use of CO-H2. Herein, to go beyond CZA, a surface coordination materials chemistry perspective is presented for the thermally enabled adsorption, activation, reaction, and desorption steps of CO2-H2 that ensue on metal oxide catalysts as a function of temperature and pressure. The objective is to identify periodic trends in the chemical and physical properties of the metal oxide that determine its activity and selectivity toward methanol synthesis versus the competitive reverse water gas shift carbon monoxide product. Armed with this materials chemistry perspective of methanol synthesis enabled by CZA, an enquiry is launched into how to rationally envision and design, by human-to-artificial intelligence, low -temperature metal oxide catalysts able to enhance methanol yield and reduce the energy requirement of the reaction. This chimie douce investigation culminates with an exploration of what it will take to power the methanol synthesis reaction directly with light rather than heat to ultimately reduce the dream of solar methanol refineries to practice and realize the solar advantage.