Publications

Process development and techno-economic analysis of a novel process for MeOH production from CO2 using solar-thermal energy

Dedrick, Daniel E.; Stechel-Speicher, Ellen B.

Mitigating and overcoming environmental problems brought about by the current worldwide fossil fuel-based energy infrastructure requires the creation of innovative alternatives. In particular, such alternatives must actively contribute to the reduction of carbon emissions via carbon recycling and a shift to the use of renewable sources of energy. Carbon neutral transformation of biomass to liquid fuels is one of such alternatives, but it is limited by the inherently low energy efficiency of photosynthesis with regard to the net production of biomass. Researchers have thus been looking for alternative, energy-efficient chemical routes inspired in the biological transformation of solar power, CO2 and H2O into useful chemicals; specifically, liquid fuels. Methanol has been the focus of a fair number of publications for its versatility as a fuel, and its use as an intermediate chemical in the synthesis of many compounds. In some of these studies, (e.g. Joo et al., (2004), Mignard and Pritchard (2006), Galindo and Badr (2007)) CO2 and renewable H2 (e.g. electrolytic H2) are considered as the raw materials for the production of methanol and other liquid fuels. Several basic PFD diagrams have been proposed. One of the most promising is the so called CAMERE process (Joo et al., 1999 ). In this process, carbon dioxide and renewable hydrogen are fed to a first reactor and transformed according to: H2 + CO2 <=> H2O + CO Reverse Water Gas Shift (RWGS) After eliminating the produced water the resulting H2/CO2/CO mixture is then feed to a second reactor where it is converted to methanol according to: CO2 + 3.H2 <=> CH3OH + H2O Methanol Synthesis (MS) CO + H2O <=> CO2 + H2 Water Gas Shift (WGS) The approach here is to produce enough CO to eliminate, via WGS, the water produced by MS. This is beneficial since water has been proven to block active sites in the MS catalyst. In this work a different process alternative is presented: One that combines the CO2 recycling of the CAMERE process and the use of solar energy implicit in some of the biomass-based process, but in this case with the potential high energy efficiency of thermo-chemical transformations.