Amorphous Cr/SiO2 Materials Hydrothermally Treated: Liquid Phase Cyclohexanol Oxidation

Abstract

Amorphous Cr-SiO 2 materials were synthesized by the sol-gel method and hydrothermally treated at temperatures between 150 and 220 °C. These materials were used as catalysts for cyclohexanol oxidation with H 2 O 2 as oxidant and CH 3 CN as a solvent. They were responsible for the decomposition of H 2 O 2 , which triggers, by a free radical mechanism in the homogeneous phase, the oxidation or degradation of the hydrocarbon chain. Metal leaching causes a drop in catalytic activity when the material is recycled. Studies on the hydrothermal treatment effect on the leaching process have demonstrated that the higher the hydrothermal treatment temperature, the higher the metal/support interaction, leading to a diminution of the leaching process. Under mild reaction conditions, and using TBHP as oxidant, leaching was reduced, and improvements were obtained on the selectivity towards the formation of cyclohexanone. The use of these catalysts in the oxidation of verbenol, an allylic alcohol, showed a significant increase in the substrate conversion and in the selectivity to carbonyl derivative formation.

Recent Progress in Adipic Acid Synthesis Over Heterogeneous Catalysts

“…Metal oxides are widely studied for oxidation reaction (Fang et al, 2013;Hao et al, 2013;Zhang et al, 2013;Li et al, 2014;Qadir et al, 2014;Gui et al, 2015;Imanaka et al, 2015;Wang et al, 2016;Shiraishi et al, 2017). The nature of the metal oxides as support or as active species influenced the catalytic performance of the catalysts significantly (Unnarkat et al, 2016;Ribeiro de Sousa Martins et al, 2017;Yang et al, 2017;Feliciano Miranda et al, 2018). Acharyya et al (2015) synthesized Cr 2 O 3 supported Cu nanoclusters with hydrothermal method which converted cyclohexane to cyclohexanone with high yield, but failed to produce any AA.…”