Deep Desulfurization Of Gasoline By Selective Catalytic Oxidation-Adsorption Intergration

Sulfur compounds in gasoline not only cause pollution to the environment but also damage our human health. Meanwhile, more and more strict regulations to limit sulfur content in fuels have been enacted worldwide. Therefore, Ultra-deep desulfurization of gasonline has become a challenging subject to the global refining industries. Aiming to tackle the bottleneck of high energy consumption and low selectivity during the desulfurization of gasoline, this work develops a series of novel catalytic and adsorptive bi-functional materials for selective desulfurization under ambient conditions, and explores a new intergrated catalytic oxidation and adsorption strategy for ultra-deep desulfurization technology under ambient conditions.In this work, we synthesized a series of Ti-Si-O material using sol-gel method and investigated its UV photocatalysis-assisted adsorptive desulfurization (PADS). Results showed that the highest desulfurization rate of around 96% was reached at the Ti/Si ratio of 3:7, which is much higher than the single TiO2 and SiO2.The PADS involves photocatalytic oxidation of thiophenic compounds to sulfone by Ti-Si-O, which was subsequently adsorbed on the Ti-Si-O surface. Cyclic regeneration tests suggested that the Ti-Si-O processed superior regenerability. With the PADS of real gasoline using Ti-Si-O, the sulfur concentration can be decreased to< 10 ppm.A new catalytic and adsorptive bi-functional material——AgxO@SBA-15 was synthesized by the incipient wetness impregnation method assisted by ultrasound. It can achieve the goal of desulfurization using a new catalytic oxidation-adsorption intergration strategy with the employment of earth-urbandant and widely-available air under ambient conditions. The results of desulfurization performance tests showed that:fresh AgxO@SBA-15 can rapidly and efficiently remove the organic sulfur compounds in the fuel without the introduction of air, the desulfurization rate reached 90% and above in 10 mins; aged AgxO@SBA-15’s desulfurization rate was also above 90% with the introduction of air, meanwhile, the desulfurization capacity was 4 times of that without the air. The desulfurization isotherms of AgxO@SBA-15 at different states could be well fitted to the Langmuir model, and the desulfurization capability of different sulfur compound followed the order of DMDBT>MDBT>DBT>BT. More importantly, AgxO@SBA-15 had a ultrahigh adsorptive selectivity and capacity of BTO2 than aromatic hydrocarbons, which means by chemical transformation of thiophenic compounds to sulfones on AgxO@SBA-15, the desulfurization selectivity was dramatically enhanced.The AgxO@SBA-15’s catalytic oxidation-adsorption desulfurization mechanism and its regeneration performance were analyzed through the pore structure and surface state of the materials. The results showed that the Ag species in the fresh AgxO@SBA-15 is AgO, which has oxidation function, so the fresh AgxO@SBA-15 could directly oxidate the BT to BTO2 wihout the air. The Ag species in the aged AgxO@SBA-15 is Ag2O, which has catalysis function, so the aged AgxO@SBA-15 can use the O2 in the air as the oxidant and turn BT to BTO2. In the process of regeneration, the Ag species in the material was losing and agglomerated, so AgxO@SBA-15 showed poor regenerability after cyclic usage, which should be improved to be considered in real applicationsTo tackle the challenge of poor regenerability, the Ag/Ti-Ce-O and Ag/TiO2 materials were synthesized. From our initial results, the Ag/Ti-Ce-O showed high desulfurization uptake as well as good regeneration performance, better than the Ag/TiO2.The silver loading and Ti/Ce ratio in Ag/Ti-Ce-O were optimized to be 15% and 9:1, respectively.