Dye Adsorption And Catalytic Oxidation Desulfurization Properties Of Trinuclear Chromium Cluster Complexes

Transition metal carboxylate complexes are widely used in the synthesis of metal-organic frameworks coordination polymer. Molecular sieve type organic carboxylic acid complexes can be synthesized by adjusting the size and the structure of the carboxylic acid ligand.Heteropoly acid(HPA) as a sold acid catalyst has been widely used in the acid catalysis and oxidation reduction catalysis by its excellent catalytic properties. This paper selected the trinuclear chromium to build structural unit, and then combined with anion to produce metal organic gel and highly active oxidative desulfurization catalysts. Details are as follows:(1) The gel was synthesized using the trinuclear chromium by solvothermal method and characterized by FT-IR, XRD, TG and physical adsorption. The results show that the gel has a real pore structure. The gel composed of a cationic framework which was proved by adsorption experiments. The gel can selectively adsorb the anionic dye in a mixed solution,which means a general absorbing effect for anionic dyes. The methyl orange(MO) in wastewater can also be cleared by this gel. The adsorbed anions can be displaced by ion exchange method and after activation the gel can be repeated use and the capacity of adsorption does not decrease. It is stable in water and hydrophobic.(2) The complex material was prepared by co-precipitation method and use as oxidative desulfurization catalyst. The material was then characterized by IR, Raman, UV-vis and XRD,which show that the catalysts remain the skeleton structure of HPA. The catalysts have large specific surface area and easily separated from the reaction system, compared to the HPA.Organic sulfides text ethyl mercaptan, benzothiophene and dibenzothiophene were selected to dissolve in hexane solution to study the performance of the series catalyzed oxidative desulfurization reaction as a probe reaction. The effects of reaction temperature, catalyst type and reaction time on the catalytic oxidation desulfurization were discussed. The results showed that the optimal reaction temperature was 70 ℃, the optimum reaction time was 3 h.Under these conditions the trinuclear chromium binding two substituents of phosphomolybdic acid express the best catalytic effect, and the desulfurization rate up to 99% for three model oils. Sulfur content of the products reduced to below 1.0 ppm from raw material of 100 ppm.The catalysts can be reused five times and the catalytic effect is not reduced.