Preparation Of Dawson Type Multicomponent Heteropoly Compounds And The Research In Catalytic Oxidative Desulfurization

Sulfur is the main harmful substances in the oil, Hydrogen sulfide, iron sulfide, ferric sulfate, sulfurous acid or sulfuric acid, etc which from crude oil in the machining process serious corrode equipment, pollute the environment. Sulfur-containing compounds will be converted into SOx gas after burning in general when the fuel oil is in use, this is one of the main reasons for the formation of acid rain. Sulfur-containing compounds which polluting our environment has caused great harm to many countries.1. The ammonium of molybdophosphate catalyst was synthesized, and further was characterized by X-ray diffraction and FT-IR. The catalyst was tested for oxidative desulfurization using acetonitrile as solvent. The effect of different additives on catalytic activity was investigated, and hydrochloride, sulphuric acid and phosphoric acid were used as the additive. The results show that the acid additives can inhibit the valid decomposing of hydrogen peroxide, help to form the more peroxoheteropolyacid species, accelerate the reaction processes. Under the conditions of reaction temperature 70 ℃, catalyst/n-octane quality 1%, O/S molar ratio 5, phosphoric acid 1.752 mmol, the desulfurization rate for DBT reached 98.2%. Also, the acid initiated reaction mechanism was investigated.2. The different vanadium content molybdovanaphosphoric acid catalyst was synthesized, and further was characterized by X-ray diffraction, ICP and FT-IR. On this basis, the molybdovanadophosphoric acid was modified by using of rare earth elements Ce, La, Pr and Nd. Molybdovanadophosphoric acid catalysts, and rare earth elements modified molybdovanadophosphoric acid catalysts has better catalytic performance to oxidative desulfurization reaction. Molybdovanadophosphoric acid catalyst desulfurization rate of over 84% after 180 min,and rare earth elements modified molybdovanadophosphoric acid catalysts has a further improve performance, reach more than 90%.3. The catalysts were prepared by impregnation when selection of the most active catalyst which is rare earth elements modified molybdovanadophosphoric acid and activated carbon as a carrier. They were characterized by X-ray diffraction and FT-IR,which make the reaction heterogeneous. The desulfurization rate of catalysts reach 87%. Catalyst also exhibited high operational stability with no dramatic loss of catalytic activity even after three successive times.