Synthesis Of Tungsten-substituted Mesoporous Aluminophosphates And Their Performance In The Oxidative Desulfurization Of Dibenzothiophene

Mesoporous materials are expected to show potential values in many fields such as adsorption,catalysis,optics,nano-technology,electronics,magnetics and chemical sensors because they have a readily tunable pore size in a wide range,high surface area and thermal stability,and become one of the research focuses of numerous fields.Tungsten-substituted hexagonal mesoporous aluminophosphates with oxide tungsten content 1,3 and 5 wt%(W-AlPO-1,W-AIPO-3 and W-A1PO-5)were synthesized hydrothermally using cetyltrimethylammonium bromide(CTAB)as the structure-directing agent and aluminium triisopropoxide,followed by a temperature-programmed calcination method.UV-Vis results indicated that tungsten species were highly dispersed in W-AIPO and were mainly in the form of tetrahedral[WO₄]^2-.The maximum tetrahedral[WO₄]^2-content was observed in W-AIPO-3.ODS usually used H₂O₂ as a oxidant,and the operation is in a batch type.Because H₂O₂ is soluble and need for sufficient mixing.The thesis used cumene hydroperoxide(CHP)and tert-butyl hydroperoxide(TBHP)as oxidation and the operation is in a continuous reactor.All the W-AlPO samples exhibited high activity in the oxidative desulfurization(ODS)of dibenzothiophene(DBT),then the active site of W-A1PO is covered by organic matter from reaction system,so activity of W-AIPO decline,such as the adsorption of the phenol.Using TBHP is better.At 40℃the conversion of DBT over W-A1PO-3 was up to 100%within 21h. The mesoporous framework does not collapse obviously by compare XRD.In addition,the characterization and catalytic performance suggest that the active site of ODS might be related to the tetrahedral[WO₄]^2-in W-AlPO.