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Effects of reaction conditions on one‐step synthesis of methylal via methanol oxidation catalyzed by Mo:Fe(2)/ HZSM ‐5 catalyst
Author(s) -
Tian Yuanyu,
Yuan Meng,
Li Shen,
Tang Ruiyuan,
Zong Peijie,
Qiao Yingyun
Publication year - 2021
Publication title -
international journal of energy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.808
H-Index - 95
eISSN - 1099-114X
pISSN - 0363-907X
DOI - 10.1002/er.6330
Subject(s) - catalysis , methanol , dimethoxymethane , dehydrogenation , chemistry , space velocity , selectivity , thermal desorption spectroscopy , desorption , inorganic chemistry , chemical engineering , adsorption , organic chemistry , engineering
Summary In the process of one‐step synthesis of methylal via methanol oxidation, the design and research of various dual‐function catalysts are important and studies on the influence of reaction conditions on this type of process are scarce. We explored the influence of reaction temperature, reaction space velocity, and the feed ratio of methanol to air on the catalytic effect of the process based on the Fe‐Mo‐based bifunction catalyst and discovered the most appropriate reaction conditions for the process. Results showed that excessively high reaction temperatures were not conducive to the formation of target product Dimethoxymethane (DMM) and this was verified from the perspective of thermodynamic analysis. At the same time, through Brunaure Emmett Teller (BET), X‐ray diffraction, scanning electron microscope, NH 3 ‐temperature‐programmed chemisorption, and Pyridine Fourier Infrared (PY‐FTIR) characterization, analysis of the microstructure and surface characteristics of the catalyst showed that an excessively high reaction temperature caused accumulation of metal oxides on the catalyst surface to block pores and reduce the specific surface area. This also destroyed the active acidic sites on the catalyst surface and weakened the acidity of the catalyst, thereby reducing catalytic activity. Investigation showed that excessively high reaction space velocity caused most of the formaldehyde obtained by catalyzing the initial oxidative dehydrogenation to fail to undergo polycondensation with methanol after desorption in time to obtain DMM, leading to a significant decrease in DMM selectivity. Investigation of the methanol‐air feed ratio showed that when CH 3 OH:air = 1.5, the methylal selectivity was highest and catalytic activity had improved. Orthogonal experiments showed that optimal reaction conditions of the process were 663 K, 15 000 h −1 and CH 3 OH: air = 0.82. In addition, compared with other bifunctional catalysts of this process, the self‐made Mo:Fe(2)/HZSM‐5 bifunctional catalyst exhibited high stability and carbon deposition resistance under severe operating conditions.