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Development of processes that utilize heterogeneous catalysis in environmentally beneficial media is of fundamental and practical importance. The oxidation of 2,6-di-tert-butylphenol (DTBP) to 2,6-di-tert-butyl-1,4-benzoquinone (DTBQ) and 3,5,39,59-tetra-tert-butyl-4,49-diphenoquinone (TTBDQ) has been investigated to evaluate the factors necessary to achieve high product conversion and selectivity in various media. A series of porous materials with immobilized Co(II) complexes served as catalysts and their reactivities using O 2 as the terminal oxidant were screened in neat acetonitrile, supercritical carbon dioxide (scCO 2 ), and CO 2 -expanded acetonitrile. The highest conversions were found with the catalysts that had high affinity for dioxygen. Moreover, the greatest conversions (y60%) were obtained when reactions were done in scCO 2 , which is attributed to improved mass transfer of O 2 and substrates through the porous catalysts. Furthermore, the heterogeneous catalysts can be recycled with some loss of activity (y30%) after three cycles; nonetheless these results suggest that the polymer hosts efficiently protect the immobilized catalytic sites from destructive bimolecular routes.

The present work was aimed at investigating activity and selectivity of various catalysts for the partial oxidation of propane in sc‐CO2 atmosphere. Catalytic experiments were performed in a stirred batch reactor. This paper reports on the used reactor system and first results of a catalyst screening using different metal (oxide) catalysts as well as the variation of the reaction conditions.

Development of processes that utilize heterogeneous catalysis in environmentally beneficial media is of fundamental and practical importance. The oxidation of 2,6-di-tert-butylphenol (DTBP) to 2,6-di-tert-butyl-1,4-benzoquinone (DTBQ) and 3,5,39,59-tetra-tert-butyl-4,49-diphenoquinone (TTBDQ) has been investigated to evaluate the factors necessary to achieve high product conversion and selectivity in various media. A series of porous materials with immobilized Co(II) complexes served as catalysts and their reactivities using O 2 as the terminal oxidant were screened in neat acetonitrile, supercritical carbon dioxide (scCO 2 ), and CO 2 -expanded acetonitrile. The highest conversions were found with the catalysts that had high affinity for dioxygen. Moreover, the greatest conversions (y60%) were obtained when reactions were done in scCO 2 , which is attributed to improved mass transfer of O 2 and substrates through the porous catalysts. Furthermore, the heterogeneous catalysts can be recycled with some loss of activity (y30%) after three cycles; nonetheless these results suggest that the polymer hosts efficiently protect the immobilized catalytic sites from destructive bimolecular routes.