Liquid‐Phase Oxidation Reaction and Mechanism of p‐Diethylbenzene to p‐Ethylacetophenone with H₂O₂ in a Batch Reactor and a Fixed Bed Reactor

Abstract

Liquid‐phase oxidation of p‐diethylbenzene (PDEB) to p‐ethylacetophenone (EAP) with hydrogen peroxide (H2O2) catalyzed by 5Co/SBA‐15 in a batch reactor and a fixed bed reactor was investigated. Based on the analysis of compositions, a reasonable reaction mechanism was discussed. Results show whether in a batch reactor or a fixed bed reactor, a mixture of EAP, 1‐(4‐ethylphenyl)‐1‐ethanol (EPEA), p‐diacetylbenzene (PDAB), 4‐acetylbenzoic acid (AA) and terephthalic acid (TA) could be detected. The reaction mechanism for oxidation of PDEB based on two reaction pathways for oxidizing ethyl group with H2O2 involving radical intermediates are proposed, PDEB firstly undergoes oxidation to give alkyl benzene carbocation and generates the key intermediate EPEA, which will be converted to EAP through pathway I. EAP can ultimately yield byproducts PDAB, AA and TA with pathway I and pathway II. Besides, diethyl group of PDEB can be tolerated pathway II to generate TA directly. The selectivity of EAP is steady around 68% in the fixed bed reactor, which is 16.52% higher than that in the batch reactor. It is essential to have a further study on the continuous flow process and obtain more data for industrial application.

TS‐1@MCM‐48 Core‐Shell Catalysts for Efficient Oxidation of p‐Diethylbenzene to High Value‐Added Derivatives

“…[6] Sánchez [7] found that Al-MCM-41 showed good catalytic activity in the acylation of ethylbenzene and ethyl acetate with the conversion of ethylbenzene and the selectivity of EAP of more than 40 %. Kenneth [8] used Ce(OTf) 4 (cerium (IV) triflate) as catalyst in acetonitrile solvent to carry out PDEB oxidation at room temperature. Under the condition that the molar ratio of catalyst to PDEB is 4 : 1 and the reaction time is 25 h, the yield of EAP is 61.3 %.…”

“…Among them, EAP and EPEA are fine chemical intermediates, which has widely used in organic synthesis, medicine and cosmetics industries leading to large market demand and high research value [3] . Wang [4] studied the process of liquid phase oxidation of p ‐diethylbenzene (PDEB) to p ‐ethylbenzone (EAP) with hydrogen peroxide (H 2 O 2 ) catalyzed by 5Co/SBA‐15 in batch reactor and fixed bed reactor. It is concluded that the selectivity of EAP in fixed bed reactor is stable at about 68 %.…”

Study on Preparation of Ce/Cu‐BTC and Its Catalytic Oxidation Process of P‐Diethyl benzene to P‐Ethyl acetophenone in the Fixed‐Bed Reactor

“…So study on heterogeneous catalysts for side chain oxidation of aromatic hydrocarbons have received extensive attention. [11,12] Xu et al [13] in our group prepared EAP by oxidizing PDEB with Co/SBA-15 as the catalyst, acetic acid as the solvent and KBr as the promoter. The conversion rate of pdiethylbenzene was up to 85 %, and the yield of EAP was 58 % under the molar ratio of PDEB:KBr:H 2 O 2 :CH 3 COOH of 1:0.3 : 10.9 : 21.8 with the feed volume space velocity of 0.21 h À 1 at 85 °C for 5 h. Among them, the metal organic framework materials (MOF) [14,15] has become a research hotspot of heterogeneous catalysts [16,17] with its large specific surface area, adjustable pore structure and rich catalytic active sites.…”

“…So study on heterogeneous catalysts for side chain oxidation of aromatic hydrocarbons have received extensive attention [11,12] . Xu et al [13] . in our group prepared EAP by oxidizing PDEB with Co/SBA‐15 as the catalyst, acetic acid as the solvent and KBr as the promoter.…”