291475 Effect of Solvents On the Activity of Palladium Catalysts for the Hydrodeoxygenation of Organic Esters

Monday, October 29, 2012
Hall B (Convention Center )
Ryan McLay, Chemical Engineering, Florida Institute of Technology, Melbourne, FL

Conventional biomass to lipid conversion techniques leave highly oxygenated bio-oil.  This bio-oil must be deoxygenated to remove oxygen which is highly corrosive and unfavorable in a process called hydrodeoxygenation (HDO).  This study investigates the effects of various solvents on the activity of palladium (111) catalysts for the HDO of the ester methyl propionate (MP).  Advanced quantum-chemical computational methods using implicit solvation techniques (COSMO and COSMO-RS) based on density function theory (DFT) were implemented on Turbomole 6.0 to calculate the free energies of liquid phase MP in solvent medium.  Polar protic solvents (water and butanol), a polar aprotic solvents (acetonitrile), and a non-polar solvent (octane) were studied.  Microkinetic modeling was then implemented to calculate turnover frequencies (TOF) and surface coverage of all intermediates to validate the results.  Understanding the solvent effect allows researchers to choose solvents that will aid in the synthesis of deoxygenated hydrocarbons from MP more efficiently under realistic reaction conditions.  It was found that the overall free energy of the dominant pathway was reduced the most when polar solvents were used.  Water was the best solvent at lowering the free energy of the overall reaction pathway.  However, polar solvents have a reverse effect on the activation barrier of the rate-determining step in solvents.  Less polar solvents do not increase the activation barrier of the rate determining step as much as polar solvents.  Consequently, less polar solvents (octane and butanol) have a higher turnover frequency.

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