Preparation, Characterization Of Metal Supported Mesoporous Materials And Adsorptive Desulfurization Performance In Fuels

Deep desulfurization of transportation fuels, particularly of diesel and gasoline,has attracted considerable attention worldwide not only due to heightened interest forcleaner air but also because of the great significance for making ultra-low-sulfur fuelsfor fuel cell applications. Various techniques and adsorbents have been reported toremove sulfur compounds from commercial fuel; however further research isnecessary.This dissertation presents our efforts to develop novel sorbents for adsorptivedesulfurization （ADS） of commercial and simulated fuels. Nickel particles weresupported on mesoporous MCM-41or AlMCM-41（SiO₂/Al₂O₃=30,50） by incipientwetness impregnation （IWI） using nickel nitrate and the ultra-deep desulfurizationperformances properties for simulated fuels or diesel were evaluated under ambientconditions. Among the tested sorbents,15%Ni-AlMCM-41（30） presented the highestsulfur adsorption capacity toward thiophene, benzothiophene and commercial diesel.The pore structure, acidic sites and surface features of the sorbents were characterizedby means of Brunaur-Emmett-Teller （BET）, X-ray diffraction （XRD）,Temperature-programmed desorption of ammonia （NH3-TPD）, pyridineadsorbed-Fourier transform infrared spectroscopy （Py-FTIR） and X-ray photoelectronspectroscopy （XPS） techniques, it revealed that Lewis acidic sites played importantrole in the removal of organic sulfur compounds over reduced15%Ni-AlMCM-41（30）. After regeneration of used sorbent, approximately100%of organic sulfuradsorption capacity was recovered.Owing to the high surface area, a big pore volume and acidic sites, MCM-41orAlMCM-41（SiO₂/Al₂O₃=30,50） were also tested as a support for Lanthanum.Mesoporous La/MCM-41and La/AlMCM-41（SiO₂/Al₂O₃=30,50） sorbents wereprepared by an incipient wetness impregnation or ion-exchange （IE） process, anddesulfurization performances were investigated for commercial diesel containing totalsulfur of560ppmw at ambient temperature and pressure. The high surface area, a big pore volume and diameter of sorbents played important role in sulfur removalefficiency. The sorbents were characterized and the results of N2-adsoption isotherms,XRD, High resolution transmission electron microscopy （HRTEM） and FT-IRrevealed that no structure deterioration occurred during the wet impregnation. Theinteraction between sulfur in thiophene and HO-La（OSiAl） was crucial for theremoval of sulfur compounds.High performance nickel-based micro-mesoporous silica （Ni/MMS） sorbent wasprepared by incipient wetness impregnation with ultrasonic aid （IWI-u） for adsorptivedesulfurization （ADS） of commercial gasoline or simulated fuels. The sorbents werecharacterized with BET, XRD, TPR, SEM, HRTEM and TG/DTG. The results showthat20wt%Ni/MMS （IWI-u） can still retain the framework of MMS and nickelparticles were homogeneously distributed in the MMS channels without anyaggregation, which improved significantly the ADS performance of the sorbent. Thestudies on the ADS kinetics indicate that the adsorption behaviour of thiophene （T）,benzothiophene （BT） and dibenzothiophene （DBT） over20wt%Ni/MMS （IWI-u） canbe described appropriately by pseudo second-order kinetic model. The intraparticlediffusion model verified that the steric hindrance and intraparticle diffusion were therate controlling step of the adsorption process of DBT molecules. Langmuir modelcan be used to describe the adsorption isotherms for T, BT and DBT due to lowcoverage. The regeneration sorbent maintains the sulfur removal efficiency of85.9%for6cycles.