The Preparation of Reverse Micellar Polyoxometalates and Catalytic Oxidative Desulfurization of Dibenzothiophene with Dioxyge
|School||Northeast Normal University|
|Keywords||Desulfurization Dibenzothiophene Polyoxometalates Reverse-micelles|
Deep desulfurization of fuel oils has been paid more attention due to urgently environmental problem. More and more stringent regulation limits the sulfur content in gasoil and diesel. The conventional method for removing sulfur in industry is catalytic hydrodesulfurization （HDS） process, which can desulfurize aliphatic and acyclic sulfur compounds. This process, however, is limited when treating some refractory sulfur compounds such as dibenzothiophene （DBT） and its derivatives. In order to achieve deep desulfurization, severe operating conditions such as high temperature, high pressure and high hydrogen consumption are required, leading to high instrumental cost. Therefore, there is an essential demand for developing alternative non-HDS methods to achieve deep desulfurization to produce clean diesel containing low sulfur concentration. Among them, oxidative desulfurization （ODS） combined with extraction is considered to be one of the most promising process, because it can be performed under mild conditions to remove the refractory sulfur compounds. In ODS, molecular oxygen is the most economical and environmental benign oxidant that might be used in desulfurization of fuels. The oxidation of DBT by oxygen under mild conditions would be of great significance in industry due to its lower costs and green chemical advantage.Amphiphilic quaternary ammonium of polyoxometalate（POM） can form supramolecular reverse micellar assemblies ranging from nanoscale to microscale sizes in non-polar solvent. This structure could possibly afford high local reactant concentrations near the catalysts, helping to enhance the catalytic rate. Therefore, seeking of active and durable catalyst under mild temperature and atmospheric pressure is the main task.Here, we report the oxidation of DBT with molecular oxygen as the oxidant using reverse micellar system, where an amphiphilic catalyst acts as both the catalyst and the surfactant. The oxidation rate of DBT could accelerate in this reverse micellar system and the catalyst did not need any treatment for reused.1. Preparation of polyoxometalate reverse micellar catalysts: [C18H37N（CH3）3]7[PW10Ti2O38（O2）2](C18PW10Ti2（O2）2)、[C16H33N（CH3）3]5[PMo10V2O38（O2）2](C16PMo10V2（O2）2). And they were characterized by elements analysis, IR, UV, XRD, TEM, EDS, XPS, MALDI-TOF and DLS measurements. 2. The catalytic activity of C18PW10Ti2（O2）2 was investigated for the oxidation of DBT by oxygen. The influences such as catalyst amount, reaction time, reaction temperature, the DBT concentration, absorption of DBT, oxidation efficiency of DBT by different catalysts, influence of length of chain of [（CnH2n+1）N（CH3）3]7PW10Ti2O38（O2）2 on oxidation of DBT, reuse of catalyst were done to study the catalytic activity.3. The catalytic activity of C16PMo10V2（O2）2 was investigated for the oxidation of DBT by oxygen. The influences such as catalyst amount, reaction time, reaction temperature, the DBT concentration, absorption of DBT, oxidation efficiency of DBT by different catalysts, influence of length of chain of [（CnH2n+1）N（CH3）3]5PMo10V2O38（O2）2 on oxidation of DBT, reuse of catalyst were done to study the catalytic activity.4. According the references, the possible mechanism of the oxidation of DBT to sulfone with O2 and catalyst is speculated.