Research on the Production of Methyltrioxorhenium and Heterogenous Catalysts from Waste Materials

This paper presents the research results on the synthesis of rhenium catalysts MTO, Re2O7/Al2O3, and M-Re2O7/Al2O3 (where M = Ni, Ag, Co, Cu) from rhenium compounds (ammonium perrhenate, perrhenic acid, nickel(II) perrhenate, cobalt(II) perrhenate, zinc perrhenate, silver perrhenate, and copper(II) perrhenate) derived from waste materials. Methyltrioxorhenium (MTO) was obtained from silver perrhenate with a yield of over 80%, whereas when using nickel(II), cobalt(II), and zinc perrhenates, the product was contaminated with tin compounds and the yield did not exceed 17%. The Re2O7/Al2O3 and M-Re2O7/Al2O3 catalysts were obtained from the above-mentioned rhenium compounds. Alumina obtained in a calcination process of aluminum nitrate nonahydrate was used as a support. The catalysts were characterized in terms of their chemical and phase composition and physicochemical properties. Catalytic activity in model reactions, such as cyclohexene epoxidation and hex-1-ene homometathesis, was also studied. MTO obtained from silver perrhenate showed >70% activity in the epoxidation reaction, thus surpassing commercial MTO (1.0 mol% MTO, room temperature, and reaction time—2 h). Ag-Re2O7/Al2O3, Cu-Re2O7/Al2O3, and H-Re2O7/Al2O3 catalysts were inactive, while Co-Re2O7/Al2O3 and Ni-Re2O7/Al2O3 showed low activity (<43%) in the hex-1-ene homometathesis reaction. Only Re2O7/Al2O3 catalysts achieved >70% activity in this reaction (2.5 wt% Re, room temperature, and reaction time—2 h). The results indicate the potential of using rhenium compounds derived from waste materials to synthesize active catalysts for chemical processes.