Preparation Of Molybdenum Oxide-Based Micro-Nano Materials And Their Application On Catalytic Oxidative Desulfurization Of Fuel

With the development of society,the demand for energy,especially traditional fossil fuels,still dominates.Sulfur oxides?SOx?produced by fuel combustion are one of the main sources of environmental pollutions.The produced SOx would induce many environmental issues,such as acid rain,fog and haze,etc.In addition,the produced SOx would cause a threat to ecosystems and human health.Now,hydro-desulfurization?HDS?method used in modern industry could remove aliphatic sulfur compounds and thiophene effectively,but the removal of benzothiophenic sulfur compounds is unsatisfied.Moreover,the reaction is carried out under high pressure and high temperature?> 300?,> 2MPa?harsh operating conditions.Thus,it is urgent to suit for a desulfurization method which could remove benzothiophenic sulfur compounds effectively under relatively moderate reaction conditions.Currently,oxidative desulfurization?ODS?method has attracted considerable interest owing to its mild reaction conditions,low energy consumption,and excellent desulfurization efficiency.At present,related research shows that molybdenum oxide?MoOx?,as a transition metal oxide?TMOs?,can be efficiently active oxygen?O₂?.Here,in this paper,MoOx was selected as the catalytic active center.Catalysts were synthesized by different method to enhance the aerobic oxidative catalytic performance of MoOx,realizing deep desulfurization of benzothiophenic sulfur compounds.?1?The as-prepared oxygen-deficient MoOx catalyst was obtained by high temperature calcination under nitrogen atmosphere.Then,the catalysts were characterized by O₂-TPD,EPR,etc,the results indicate that the synthesized MoOx enriched oxygen vacancies.Sulfur removal could reach up to 100% after reaction for 4 h under 120? environment by using O₂ in air as oxidant.Excellent sulfur removal could also be achieved with oils of different substrates.At the same time,the experimental results show that MoOx has excellent recyclability and stability.?2?Graphene-like hexagonal boron nitride?h-BN?with large specific surface area and high chemical stability was selected as carrier.Then,supported catalyst MoOxNPs/h-BN was prepared by a simple one-step method.The as-prepared catalysts were characterized by FT-IR,UV-Vis,Raman,XRD,XPS,SEM and HR-TEM.All the results indicate that MoOx is dispersed uniformly on the surface of h-BN,and the structure of h-BN is kept after the immobilization of MoOx.In addition,the particle size of MoOxNPs can be controlled by changing the amount of precursor.The DBT in oil could be removed completely only after reaction for 3 h.The mechanism of desulfurization of MoOxNPs/h-BN was investigated by selective quenching experiments and ESR characterization.?3?The molybdenum-based ionic liquid?C16mim?2Mo2O11 was selected as the molybdenum source,and the supported catalyst MoO₂/h-BN was prepared by the impregnation method combined with the high-temperature calcination method.The characterization results indicate that MoO₂ is dispersed uniformly on the surface of hBN,and electron transfer could be found between h-BN and MoO₂.Then,the oxidative desulfurization performance of MoO₂/h-BN was investigated.Hydrogen peroxide?H2O₂?was used as the oxidant,excellent sulfur removal could also be achieved with oils of different substrates,such as,4,6-DMDBT,4-MDBT and DBT.The optimal reaction conditions are as follows: m?catalyst?= 0.05 g,T = 60?,n?O?/n?S?= 4.Finally,selective quenching experiments and ESR characterization were applied to analyze possible catalytic oxidative mechanism.Conclusions could be drawn as: H2O₂ reacts with MoO₂/h-BN to generate HO⁺ species,and the HO⁺ species could oxidize DBT to DBTO₂.