Kinetics of hydrogenation of acetic acid over supported platinum catalyst

Petroleum is non-renewable and contributes to environmental pollution, thus bio-oil can be substituted as a potential alternative. However, bio-oil in its crude form cannot be used directly as fuel since it contains high proportion of oxygenated, acidic and reactive compounds such as carboxylic acids. These are known to cause corrosion of vessels and pipework, instability and phase separation. The heating value of bio-oil can be improved through hydrodeoxygenation (HDO). In this study, HDO of acetic acid is presented, being a typical model compound found in bio-oil. Kinetic data were obtained over the range of temperature: 175 - 210 ºC, hydrogen pressure: 20-50 bar, initial acetic acid concentration: 0.16-0.521 M and catalyst loading: 0.2-0.5 g, in a 100mL batch reactor using 4% Pt/TiO2. It was found that catalyst particle sizes < 65 μm and a stirring speed of 1000 min-1 were sufficient to overcome internal and external mass transfer resistances and ensure that the reaction is within the kinetic regime. A Langmuir-Hinshelwood model, assuming competitive adsorption of dissociative H2 and acetic acid, fitted the experimental data.