Synthetic Gasoline from Biomass

Clean and renewable liquid fuels from biomass offer reduced net emission of CO2 and less dependence on expensive and unreliable foreign oil. Currently, bioethanol serves in the United States as a blend for gasoline, but eventually it could replace gasoline in passenger cars altogether. Ethanol, however, contains only two-thirds of the energy of gasoline on an equal volume basis, and if used at high concentration, it requires retrofitting of existing cars. It could, therefore, be economically and technologically more attractive to convert biomass to a hydrocarbon-based synthetic gasoline (SG) (i.e., a hydrocarbon mixture performing similarly to petroleum-derived gasoline). The proposed project will develop a novel biomass-derived gasoline fuel. Specifically, we will convert methanol catalytically to C5-C10 isoalkanes. Methanol could be obtained from biomass, either directly by biochemical processes, or indirectly from synthesis gas (CO + H2) produced by biomass gasification. In the proposed catalytic conversion of methanol to SG, the hydrocarbon product is free of any naphthenes and aromatics, and of heteroatom and metal impurities. Co-produced isobutane could be reacted separately to provide isooctane and/or isononane, or ethyl tertiary butyl ether, as additional fuel liquid with very high octane. The overall SG product may be superior to conventional gasoline in having higher ignition and combustion efficiencies, less toxicity, and reduced emission of pollutants such as CO and total hydrocarbon. At methanol cost of approximately 35 cents per gallon, this SG could be produced at about half the price of current gasoline. Phase I aims to: (1) show feasibility and substantiating preliminary results; and (2) prepare simulated SG samples of relevant isoalkane compositions and analyzing them for their “gasoline specs” to compare them with conventional gasoline. In Phase II of this project, we will construct and operate a bench-scale methanol conversion apparatus to afford a full technical feasibility study with an eye toward commencing a pilot plant engineering design effort, possibly through partnership with a biomass processing business and/or an oil refining company. Post Phase II, a demonstration-scale facility will be constructed to produce fuels for large-scale engine testing.