Kinetics of hydrothermal reactions of n-butanol over Pt/Al2O3 catalyst for biopropane fuel gas production

• Kinetics of n-butanol hydrothermal reactions over 5 wt% Pt/ A l 2 O 3 were investigated. • Propane, C O 2 and hydrogen obtained as main products in 1:1:2 molar ratios. • Deformylation and/or decarbonylation of n-butanol as dominant reaction mechanisms. • N-butanol first-order reaction with activation energy values of 62 - 70 kJ m o l - 1 . • Potential to develop a large-scale high-yielding biopropane production process. Energy defossilisation using drop-in biofuels is an important step towards Net Zero. Producing low-carbon clean-burning propane fuel from biomass provides such additional sustainability benefits. In this work, kinetics of hydrothermal reactions of n-butanol, a biomass-derived feedstock, to produce propane over 5 wt% Pt/ A l 2 O 3 catalyst have been studied from 523- 573 K. Experimental data revealed negligible internal and external mass transfer effects and, when fitted to an integral power-rate law equation, gave activation energy of 70 kJ mol −1 (n-butanol reaction order = 1). Furthermore, an appropriate Langmuir-Hinshelwood model was developed, which predicted similar activation energy 62 kJ mol −1 . Low adsorption enthalpies for n-butanol (–33.51 kJ mol −1 ) and water (−18.16 kJ mol −1 ) indicated weak interactions on the catalyst surface. These agreed with the fast reaction rate of ≈1.0 x 10 -5 mol g cat -1 s −1 obtained at ≥ 548 K. As a new research area, generation of such accurate kinetics data will contribute to process development for large-scale biopropane production.