Application Of Activated Carbon Fiber In Removal Of Sulfur-Containing Compounds From Oils

Deep desulfurization of transportation fuels is receiving increasing attention in theresearch community worldwide due to increasingly stringent regulations and fuelspecifications in many countries for environmental protection purpose. The traditionalhydrodesulfurization process (HDS) is highly efficient in removing thiols and sulfides, but itis less effective for thiophenes and thiophene derivatives. Ultra-deep desulfurization isbecoming even more formidable challenge for HDS with the decreasing lower sulfur in fuels.Therefore, non-hydrodesulfurization technique of liquid fuels has caused intensive concernsfor ultra-deep desulfurization. Recently, the adsorption desulfurization technique and catalyticoxidation-adsorption desulfurization technique have drawn much attention at home andabroad due to its mild reaction condition, low production cost and little environmentalpollution. This thesis focuses on the researches of application of activated carbon fiber inadsorption and oxidation-adsorption removal of thiophenic sulfur compounds from oils.In the first part of the thesis, the capability of activated carbon fiber (ACF) treated bydifferent kinds of acids for adsorption removal of thiophenic sulfur compounds was evaluatedin the batch-type adsorption process. The results show that the as-received ACF adsorbentefficiently adsorbs the bigger size sulfur compounds, and the removal efficiency for the sulfurcompounds follows in the order of 4,6-DMDBT＞DBT＞BT＞T. Effect of treatmenttemperature and time by SN acid (ratio of volume of H₂SO₄ to HNO₃ is 3:1) on ACFadsorption removal of thiophenic sulfur compounds was studied. The results show thatoxidation with SN acid at room temperature can remove the ashes or inorganic components ofthe ACF adsorbent as well as change in the surface chemistry, introduce theoxygen-containing functional groups such as carboxyl and hydroxyl, improve the adsorptioncapability of ACF for removal of thiophenic sulfur compounds.In the second part of the thesis, the oxidation and adsorption removal of DBT overHPW/ACF catalysts in model oils containing 5 wt% naphthalene was studied. The catalystswere characterized by XRD,SEM and low temperature nitrogen adsorption. The results showthat the HPW/ACF catalysts have excellent oxidation and adsorption performance for DBT ascompared with unsupported phosphotungstic acid (HPW) with hydrogen peroxide as theoxidant. Under the optimized process conditions, the sulfur content in the model oils could bereduced to 0μg/g from 900μg/g, i.e. the removal efficiency of DBT over HPW/ACF catalysts could reach 100%. The process for the oxidation and adsorption removal of DBTover HPW/ACF catalyst is that DBT is oxidized to form sulfone, then sulfone adsorbed on theACF, thus DBT is removed from fuel oils, in which ACF has dual functions: support andadsorbent.