Synergistic Effect between Ultrasmall Cu(II) Oxide and CuCr₂O₄ Spinel Nanoparticles in Selective Hydroxylation of Benzene to Phenol with Air as Oxidant

Abstract

Phenol is an important commodity chemical and the catalytic conversion of benzene to phenol by molecular oxygen with minimum waste production is of high significance from an academic as well as industrial point of view. We have developed a facile synthesis method for the preparation of 2-8 nm Cu (II) oxide nanoparticles supported on CuCr 2 O 4 spinel nanoparticles (with size ~55 nm).Detailed characterization of the material was carried out by XRD, SEM, TEM, XPS, FTIR, TGA, TPR, BET surface area, XANES and ICP-AES. XRD and XPS analyses revealed that the main phase is CuCr 2 O 4 spinel, where small amount of CuO is dispersed on it. The catalyst was highly active for selective oxidation of benzene to phenol with air as oxidant. The influence of reaction parameters was investigated in detail. The high catalytic performance of the catalyst is due to ultrasmall size of Cu (II) oxide nanoparticle and the strong synergy between ultrasmall Cu(II) oxide and CuCr 2 O 4 spinel nanoparticles that plays pivotal role in activating air to generate active oxygen species which accomplishes benzene to phenol conversion (36%) with very high selectivity (78%) in a continuous process.

CuCr2O4@rGO Nanocomposites as High-Performance Cathode Catalyst for Rechargeable Lithium–Oxygen Batteries

“…The pure KB electrode provided the poorest electrochemical performance because of its low ORR and OER catalytic activity. Benefiting from the spinel structure of CCO nanoparticles and the synergistic effect from the bimetallic of Cu and Cr, the cycle stability and cycle life were certainly enhanced [17, 24, 32]. Owing to the superhigh surface area and the excellent electronic transmission ability of rGO, the cycleability was significantly enhanced further [30].…”

Bio‐Oil as a Potential Biomass‐Derived Renewable Raw Material for Bio‐Phenol Production

“…Phenol has been widely used in the syntheses of resins, plastics, pharmaceuticals, agrochemicals, and various special chemicals such as bisphenol, caprolactum, aniline, alkylphenol, and chlorophenol salicylic acid . In the industry, phenol is majorly produced by the well‐known cumene process .…”

NH3‐Driven Benzene C−H Activation with O2 that Opens a New Way for Selective Phenol Synthesis

“…Acharyya et al. reported a benzene conversion of 36 % with a phenol selectivity of 78 % over ultrasmall Cu(II) oxide nanoparticles supported on CuCr 2 O 4 spinel nanoparticle catalyst, but the use of high pressure, production of several liquid by‐products and toxic chromium metals inhibits the process from its industrialization.…”

“…According to the conventional concept of catalysis, selective oxidation reactions do not proceed significantly on acid−base catalysts, such as zeolites, Brønsted and Lewis acidic/basic metal oxides, etc., but they proceed on redox catalysts, such as precious and transition metals, reducible metal oxides, etc . Typically, the gas‐phase selective oxidation of benzene to phenol with O 2 , N 2 O and H 2 /O 2 has been observed with metal and metal oxide catalysts of V, Fe, Cu, Mo, Pd, W, Re, etc . These catalysts possess moderate redox potentials and sufficient M−O bond strengths to provide active lattice oxygen and reactive oxygen intermediates.…”