HYDRODESULFURIZATION OF THIOPHENE OVER COMO/ AL2O3 CATALYST USING FIXED- AND FLUIDIZED-BED REACTORS

Abstract

The present work reports a direct experimental comparison of the catalytic hydrodesulfurization ofthiophene over Co-Mo/Al2O3 in fixed- and fluidized-bed reactors under the same conditions. Anexperimental pilot plant scale was constructed in the laboratories of chemical engineering department,Baghdad University; fixed-bed unit (2.54 cm diameter, and 60cm length) and fluidized-bed unit (diameter of 2.54 cm and 40 cm long with a separation zone of 30 cm long and 12.7 cm diameter). The affectingvariables studied in the two systems were reaction temperature of (308 – 460) oC, Liquid hourly spacevelocity of (2 – 5) hr-1, and catalyst particle size of (0.075-0.5) mm. It was found in both operations that theconversion increases with increasing of reaction temperature, slightly decreases with increasing of liquidhourly space velocity and not affected by particle size. Also a kinetic analysis was performed for thiophenehydrodesulfurization reaction in fixed bed reactor and the results indicate that the reaction kinetics are not affected by pore and film diffusion limitations. The results of the comparison between the two reactors indicate that a low conversion was obtained in a fluidized bed than in fixed bed over the range of conditions studied. The lower conversion can be attributed to the gas that bypasses the bed in the form of bubbles or channels.