title: Investigation of thermochemistry associated with the carbon-carbon coupling reactions of furan and furfural using ab initio methods.
abstract: Upgrading furan and small oxygenates obtained from the decomposition of cellulosic materials via formation of carbon-carbon bonds is critical to effective conversion of biomass to liquid transportation fuels. Simulation-driven molecular level understanding of carbon-carbon bond formation is required to design efficient catalysts and processes. Accurate quantum chemical methods are utilized here to predict the reaction energetics for conversion of furan (C4H4O) to C5-C8 ethers and the transformation of furfural (C5H6O2) to C13-C26 alkanes. Furan can be coupled with various C1 to C4 low molecular weight carbohydrates obtained from the pyrolysis via Diels-Alder type reactions in the gas phase to produce C5-C8 cyclic ethers. The computed reaction barriers for these reactions (∼25 kcal/mol) are lower than the cellulose activation or decomposition reactions (∼50 kcal/mol). Cycloaddition of C5-C8 cyclo ethers with furans can also occur in the gas phase, and the computed activation energy is similar to that of the first Diels-Alder reaction. Furfural, obtained from biomass, can be coupled with aldehydes or ketones with α-hydrogen atoms to form longer chain aldol products, and these aldol products can undergo vapor phase hydrocycloaddition (activation barrier of ∼20 kcal/mol) to form the precursors of C26 cyclic hydrocarbons. These thermochemical studies provide the basis for further vapor phase catalytic studies required for upgrading of furans/furfurals to longer chain hydrocarbons.
authors.affiliation: Materials Sciences Division, Argonne National Laboratory , Lemont, Illinois 60439, United States.
authors.forename: Cong
authors.initials: C
authors.lastname: Liu
authors.forename: Rajeev S
authors.initials: RS
authors.lastname: Assary
authors.forename: Larry A
authors.initials: LA
authors.lastname: Curtiss
mesh_terms: D002241:Carbohydrates / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D002482:Cellulose / Q000737:chemistry; D003198:Computer Simulation; D061565:Cycloaddition Reaction; D004987:Ethers / Q000737:chemistry; D005662:Furaldehyde / Q000737:chemistry*; D005663:Furans / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D011789:Quantum Theory; D013816:Thermodynamics
chemical_list: D002241:Carbohydrates; D004987:Ethers; D005663:Furans; D002244:Carbon; D002482:Cellulose; D005662:Furaldehyde; C039281:furan