Synthesis of durene by methylation of 1,2,4-trimethylbenzene with syngas over bifunctional CuZnZrOx–HZSM-5 catalysts

1,2,4,5-Tetramethylbenzene (durene) is a value-added aromatic used in producing high-end polyesters. The known synthesis routes of durene by 1,2,4-trimethylbenzene (1,2,4-TriMB) methylation with methanol or direct conversion from syngas suffer from low alkylation efficiency and diverse product distr...

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Bibliographic Details
Published in:Catalysis science & technology 2022, Vol.12 (8), p.2555-2565
Main Authors: Wen, Danlu, Zuo, Jiachang, Han, Xiaoqin, Liu, Jia, Ye, Linmin, Yuan, Youzhu
Format: Article
Language:English
Subjects:
Alkylation
Carbon monoxide
Catalysts
Catalytic activity
Direct conversion
Disproportionation
Durene
Methanol
Methylation
Polyester resins
Reagents
Selectivity
Solid solutions
Stability
Synthesis
Synthesis gas
Trimethylbenzene
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Summary:1,2,4,5-Tetramethylbenzene (durene) is a value-added aromatic used in producing high-end polyesters. The known synthesis routes of durene by 1,2,4-trimethylbenzene (1,2,4-TriMB) methylation with methanol or direct conversion from syngas suffer from low alkylation efficiency and diverse product distribution. Here, we show a novel pathway to synthesize durene by coupling 1,2,4-TriMB methylation with syngas conversion over a bifunctional catalyst ZnZrOx–HZSM-5 (ZZO–Z5). Over 90% durene selectivity in tetramethylbenzene and 56.5% tetramethylbenzene selectivity in hydrocarbons with 21.3% 1,2,4-TriMB conversion were obtained at 320 °C and 3.0 MPa. Upon further doping of 5 wt% Cu into ZZO, the resultant 5CuZZO–Z5 gave comparable 1,2,4-TriMB conversion (21.2%) compared with ZZO–Z5 at 290 °C. When syngas was used as a methylation reagent instead of methanol, the methylation rather than the disproportionation of 1,2,4-TriMB was the main process for durene production and the durene selectivity improved significantly. Results revealed that the synergistic interaction within CuZnZr ternary solid solution was necessary to advance the catalytic activity and stability. The introduction of Cu reduced the apparent activation energy but increased the adsorption of CO and the formation of intermediate CHxO* (x = 1–3). The mechanism involved CO hydrogenation on 5CuZZO to generate the reactive methylation species CHxO*, which migrated to the Z5 pore for 1,2,4-TriMB methylation to form durene. The two bifunctional catalysts ZZO–Z5 and 5CuZZO–Z5 exhibited excellent stability within 100 h.
ISSN:2044-4753
2044-4761
DOI:10.1039/d2cy00037g