Preparation Of Porous Carbon From Rice Husk And Its Preliminary Application In The Catalytic Oxidative Desulfurization Of Oil

As an alternative to the conventional hydrodesulfurization, catalytic oxidative desulfurization(C-ODS), is regarded as one of the most promising desulfurization technique with mild reaction conditions and low production cost. As desulfurization efficiency mainly depends on the properties of catalyst used, the preparation of catalyst with excellent properties should be highvalued. In this paper, porous carbons were prepared from rice husk with NaOH pretreatment, pre-oxidized in the air and finally activated by H3PO4. Catalytic oxidative desulfurization catalyzed by porous carbon from rice husk was used to remove sulfur from DBT contained paraffin oil as simulated diesel oil. The relationships among the preparation parameters and modification of porous carbons, the experimental conditions in catalytic oxidative desulfurization, and the desulfurization efficiency were analyzed. The main conclusions are as follow.NaOH pretreatment on rice husk at high temperature increased the total pore volume and specific surface area of obtained porous carbons, while ash content decreased significantly. As for rice husk treated by NaOH solution at high temperature, the best preparation parameters of rice husk-based porous carbon activated by H3PO4 were as follow. The time of pre-oxidation in the air at 200 oC was 6 h. The mass ratio of activating agent to pretreated rice husk powder and activation temperature were 2.5 and 600 oC, respectively.Higher bath temperature led oxidation of useful components in diesel, so 60 oC and 180 min were used as the bath temperature and the time, respectively. H2O2 solution was added as oxidant with 3:1 mol ratio of H2O2 to sulfur. Acetic acid solution was added to make the pH value of aqueous solution below 2. After catalytic oxidative desulfurization, the sulfur content in model diesel was largely reduced from 261 μg g-1 to 20 μg g-1 with 92.3% of sulfur removal and 94.3% of oil recovery when the dosage of porous carbons prepared with 2.5 mass ratio of activating agent to pretreated rice husk powder at 600 oC was 6 g L-1. After modification with K2S2O8 solution, porous carbons showed better desulfurization performance. The sulfur content in simulated diesel was reduced to 17 μg g-1 from 261 μg g-1 with 93.4% of sulfur removal and 93.8% of oil recovery when porous carbon modified with 5 wt% K2S2O8 solution were used.