Hydroprocessing of heavy gas oils using FeW/SBA-15 catalysts: Experimentals, optimization of metals loading, and kinetics study

Abstract

In the present work, a series of FeW/SBA-15 catalysts were prepared and screened for their hydrodesulfurization and hydrodenitrogenation activities using bitumen-derived heavy gas oil from Athabasca. A systematic process optimization study has been conducted to investigate the optimum process conditions required to evaluate kinetic parameters for these reactions. Catalyst metal loadings were varied from 0 to 5 and 15 to 45wt.% for Fe and W, respectively; resulting in an optimum catalyst (Cat-5) with metal loadings of 3.0 and 30.0wt.% for Fe and W, respectively. Several techniques were employed to characterize the prepared catalysts and activity results have been correlated with that obtained from characterization. Hydrotreating experiments were performed in a continuous flow micro trickle-bed reactor at the temperatures, pressures, and LHSVs of 633–693°K, 7.6–9.6MPa, and 0.5–2h−1, respectively, with H2 flow rate and catalyst weight maintained constant at 50mL/min and 1.5g, respectively, in all cases. Three kinetic models were applied to fit experimental data obtained from HDS and HDN reaction studies evaluated within temperature range of 633–693°K. The optimum operating conditions for maximum sulfur and nitrogen conversions occurred at temperature, pressure, and LHSV of 673°K, 8.8MPa, and 1h−1, respectively. Experimental data fitted with the Power Law model yielded reaction orders of 2.0 and 1.5 for HDS and HDN reactions, respectively; and activation energies of 129.6kJ/mol and 150.6kJ/mol, respectively. By fitting a modified power law model (Multi-parameter model) to the kinetic data yielded hydrodesulfurization (HDS) and hydrotreating (HDN) reactions orders of 2.2 and 1.8, with respective activation energies of 126.7kJ/mol and 118.8kJ/mol.