Synergistic effect between CO 2 and H 2 O 2 on ethylbenzene oxidation catalyzed by carbon supported heteropolyanion catalysts

Green Processing and Synthesis

article

Abdullah Al Kahtani¹  Naaser A.Y. Abduh¹  Ahmed Aouissi¹ 

[1] Department of Chemistry, College of Science, King Saud University

关键词: activated carbon;    carbon dioxide;    heteropolyanions;    hydrogen peroxide;    oxidation;   

DOI  :  10.1515/gps-2018-0003

来源: De Gruyter

【 摘 要 】

A series of Keggin heteropolytungstate salts (M 1.5 PW 12 O 40 , M=Cu, Co, Zn and Fe) were prepared and characterized utilizing inductively coupled plasma spectrometry (ICP), Fourier transform infrared (FTIR) spectra, and ultraviolet-visible (UV-Vis) light spectroscopy. The as-prepared catalysts were tested for the oxidation of ethylbenzene by using carbon dioxide/hydrogen peroxide (CO 2 /H 2 O 2 ) as the oxidizing agent system under solvent-free conditions. The results indicated that the heteropolytungstates catalyzed the side chain oxidation of ethylbenzene leading to acetophenone as a major product. The effect of various reaction parameters on ethylbenzene oxidation over the best catalyst of the series, namely Co 1.5 PW 12 O 40 loaded on activated carbon (AC), was investigated. It was found that the selectivity depends strongly on the reaction temperature. Higher reaction temperatures reduce the conversion due to the decomposition of H 2 O 2 . Oxidation by a large amount of H 2 O 2 decreases the conversion owing to a decrease of the solubility of ethylbenzene in an aqueous medium, and favors the oxidation of the reaction products, which are more soluble in an aqueous medium. The increase of the CO 2 pressure improves both the conversion and the selectivity of acetophenone due to the involvement of the percarbonate species (HCO 4 − ) responsible for oxidation by oxygen transfer.

【 授权许可】

CC BY