Selective liquid phase oxidation of cyclohexane over Pt/CeO2-ZrO2-SnO2/SiO2 catalysts with molecular oxygen

Abstract

Partial oxidation of cyclohexane into cyclohexanone and cyclohexanol (KA-oil) is an industrially significant reaction for producing precursors for the synthesis of ε-caprolactam and adipic acid, which are the building blocks of nylon. However, to date, the cyclohexane conversion ratio has usually been limited to less than 6% to prevent further oxidation of the cyclohexanol and cyclohexanone targets. In this study, we report that Pt/CeO 2 -ZrO 2 -SnO 2 /SiO 2 , in which CeO 2 -ZrO 2 -SnO 2 provide reactive oxygen molecules from inside the bulk, can act as efficient catalysts. Optimization of the catalyst composition and reaction conditions provided a cyclohexane conversion ratio of 24.1% and a total selectivity for cyclohexanol and cyclohexanone of 83.4% at 130 ℃ in 0.5 MPa (4.9 atm) air for 7 h over a 5wt%Pt/16wt%Ce 0.68 Zr 0.17 Sn 0.15 O 2.0 /SiO 2 catalyst. This catalyst has significant advantages over conventional catalysts because the reaction proceeds at a lower pressure, and there is no need for toxic radical initiators or free-radical scavengers.

Cerium Oxide Nanoparticles Inside Carbon Nanoreactors for Selective Allylic Oxidation of Cyclohexene

“…This behavior makes ceria extremely useful for oxygen storage and release applications, as well as in other important chemical reactions, such as the preparation of imines, the oxidation of CO to CO 2 , and the hydrogenation of CO 2 to methanol . However, a less explored and often disregarded application of ceria is its ability to initiate radical-mediated organic transformations, which often commence in the homolytic cleavage of organic peroxides by Ce 3+ , as demonstrated in the oxidation of cyclohexene, the products of which represent important intermediates in the chemical industry . Akin to the structure–function relationships observed in ceria nanocatalysis, the shape and size of ceria nanoparticles are expected to modulate its efficiency as an initiator; , however, further research is critically required to probe how the physical and chemical properties of CeO 2 influence the yields and distribution of products of radical-based chemical reactions.…”

“…14 However, a less explored and often disregarded application of ceria is its ability to initiate radical-mediated organic transformations, which often commence in the homolytic cleavage of organic peroxides by Ce 3+ , as demonstrated in the oxidation of cyclohexene, 15 the products of which represent important intermediates in the chemical industry. 16 Akin to the structure−function relationships observed in ceria nanocatalysis, the shape and size of ceria nanoparticles are expected to modulate its efficiency as an initiator; 17,18 however, further research is critically required to probe how the physical and chemical properties of influence the yields and distribution of products of radicalbased chemical reactions. Despite the breadth of ceria-based nanostructures synthesized to date, the controllable preparation of monodisperse ultrasmall CeO 2 nanoparticles remains a significant challenge.…”

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).…”

Bi/Bi2O3 sensor for quantitation of dissolved oxygen in molten salts

“…Although the latter parameter significantly affects molten salt processing [7], posing a number of safety threats to operating molten salt reactors (such as reducing the solubility of nuclear fuel and promoting the slow precipitation of uranium oxide), no corresponding uniform and universal quantitation methods exist [8][9][10].…”