(589b) Catalytic Hydrodeoxygenation (HDO) of Acetic Acid over Carbon-Supported Metals

With fast pyrolysis of biomass [1], bio-oils can be obtained that contain many oxygenated components that include carboxylic acids [1,2].  From carboxylic acid feeds, desirable products such as alcohols and hydrocarbons can be obtained through hydrodeoxygenation (HDO). These methods consist of feeding the reactant (e.g. carboxylic acid) with hydrogen to facilitate hydrogenolysis and hydrogenation reactions required for the removal of oxygen. This process results in the production of liquids with high energy density that are similar to those of conventional fossil fuels. When the HDO process is applied, the feed is heated in a presence of a heterogeneous catalyst to produce the deoxygenated stream.  The HDO pathways consist of hydrogenation, decarbonylation and decarboxylation for organic acids [3]. This study will explore the catalytic chemistry of HDO of acetic acid over noble metals on activated carbon and multiwall carbon nanotube supports. These catalysts are synthetized using strong electrostatic adsorption. Transition metals supported on C supports yield primarily alkane products in the HDO of acetic acid, making them promising candidates for production of liquid fuels from organic acid feeds. The reactions are evaluated in a continuous plug-flow reactor operated between 200-400ºC under atmospheric pressure with concentrations of 1% acetic acid/20%H₂/balance He. The gaseous products were analyzed by an on-line gas chromatograph. The activation energies and kinetics involving the reaction rate orders with respect to acetic acid and H₂ are being studied as a function of support and metal particle size. Furthermore, the reaction activity, expressed as turn over frequency (TOF), is used to compare intrinsic activities between various supported metal species.

References

[1]       Hydrogenation of Acetic Acid and Its Promotional Effect on p -Cresol Hydrodeoxygenation, Energy Fuels. 27 (2013)

 [2]      Z. He, X. Wang, Required catalytic properties for alkane production from carboxylic acids: Hydrodeoxygenation of acetic acid, J. Energy Chem. 22 (2013) 883–894.

 [3]      Y.K. Lugo-José, J.R. Monnier, C.T. Williams, Gas-phase, catalytic hydrodeoxygenation of propanoic acid, over supported group VIII noble metals: Metal and support effects, Appl. Catal. Gen. 469 (2014) 410–418.