Abstract
Rhenium is an element that exhibits a broad range of oxidation states. Synthesis paths of selected rhenium compounds in its seventh oxidation state, which are common precursors for organic reaction catalysts, were presented in this paper. Production technologies for copper perrhenate, aluminum perrhenate as well as the ammonia complex of cobalt perrhenate, are thoroughly described. An ion exchange method, based on Al or Cu metal ion sorption and subsequent elution by aqueous perrhenic acid solutions, was used to obtain perrhenates. The produced solutions were neutralized to afford the targeted aluminum perrhenate and copper perrhenate products in high purity. The developed technologies allow one to manage the wastes from the production of these perrhenates as most streams were recycled. Hexaamminecobalt(III) perrhenate was produced by a newly developed method enabling us to produce a high purity compound in a reaction of spent hexaamminecobalt(III) chloride solution with a perrhenic acid. All prepared compounds are the basis for precursor preparation in organic catalysis.
Highlights
Rhenium(VII) compounds, like the commonly known organic catalyst methyltrioxorhenium (MTO), may be applied in various catalytic processes as well as used to prepare active catalytic matrices.NH4 ReO4, Al(ReO4 )3 and HReO4 are used for the preparation of heterogeneous catalysts of the Re2 O7 type, which is embedded on solid carriers, usually Al2 O3 or more rarely SiO2, or another support with a highly developed specific surface area like SiO2 -Al2 O3, Al2 O3 -B2 O3
Rhenium content in product was analyzed using a gravimetric method with tetraphenylarsonium chloride (TPAC) as the precipitating agent, while aluminum and copper(II) were analyzed using flame atomic emission spectroscopy (FAES, spectrophotometer AAS novAA400, Persee, Auburn, AL, USA)
It was determined that aluminum and copper(II) perrhenates of high purity may be produced by the ion-exchange method using the strongly acidic cation-exchange resins PFC 100x10 and
Summary
Rhenium(VII) compounds, like the commonly known organic catalyst methyltrioxorhenium (MTO), may be applied in various catalytic processes as well as used to prepare active catalytic matrices.NH4 ReO4 , Al(ReO4 ) and HReO4 are used for the preparation of heterogeneous catalysts of the Re2 O7 type, which is embedded on solid carriers, usually Al2 O3 or more rarely SiO2 , or another support with a highly developed specific surface area like SiO2 -Al2 O3 , Al2 O3 -B2 O3. Rhenium(VII) compounds, like the commonly known organic catalyst methyltrioxorhenium (MTO), may be applied in various catalytic processes as well as used to prepare active catalytic matrices. The most important Re2 O7 /Al2 O3 system is characterized by high catalytic activity and selectivity in low a temperature (20–100◦ C), which is an important advantage. It is used in the metathesis of gaseous and/or liquid alkenes ( these with various functional groups) and acyclic alkenes with functional groups [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19]. Further research revealed that organic-inorganic compounds that contain a group, or ReO4 −
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