China Petroleum Processing & Petrochemical Technology ›› 2021, Vol. 23 ›› Issue (3): 1-11.

• Scientific Research • Previous Articles     Next Articles

Insights into the Reaction Network and Mechanism of Green Aerobic Oxidative Esterification of Methacrolein over Different Heterogeneous Catalysts

Li Chenhao; Xia Changjiu; Liu Yujia; Huang Kaimeng; Peng Xinxin; Liu Jinsheng; Lin Min; Zhu Bin; Luo Yibin; Shu Xingtian#br#   

  1. State Key Laboratory of Catalytic Materials and Reaction Engineering, Research Institute of Petroleum Processing, SINOPEC, Beijing 100083
  • Received:2020-09-01 Revised:2021-05-19 Online:2021-09-30 Published:2021-09-27
  • Contact: XIA Chang-Jiu E-mail:xiachangjiu@yahoo.com.cn; xiachangjiu.ripp@sinopec.com
  • Supported by:
    the National Key Basic Research Development Plan "973" Project;the SINOPEC Project;the SINOPEC Project;The National Natural Science Foundation

Abstract: The oxidative esterification of methacrolein (MAL) is an important way to prepare high-valued methyl methacrylate (MMA), but this process is ultra-complex, due to the highly reactivity of both C=O and C=C bonds within MAL. In order to further improve the selectivity of MMA selectivity, the reaction network and mechanisms over different catalysts have been profoundly investigated in this paper. Five kinds of reactions are involved in this process, including (a) hemiacetal/acetal reaction; (b) aerobic oxidation of aldehyde/alcohol; (c) alkoxylation of C=C double bond; (d) Diels-Alder reaction; (e) hydrogenation reaction of double bond/ carbonyl. Among them, Diels-Alder reaction of MAL is noncatalyzed, and Br?nsted acid sites favor promoting hemiacetal/acetal reaction of MAL with methanol, while alkaline sites enhance the alkoxylation of C=C bond with methanol. In particular, by using Pd-based catalysts, several kinds of hydrogenated products are formed, hence with lower MMA selectivity than those of Au-based catalysts. Notably, it is of necessary to match the hemiacetal reaction of MAL with methanol to and aerobic oxidation of hemiacetal, which is relevant with the amount of Br?nsted acid and redox sites. Consequently, this work provides a good guidance for the further design of both catalysts and processes in future.

Key words: methacrolein, oxidative esterification, mechanism, reaction network, methyl methacrylate