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At least 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Mathematical Modeling of Liquid-Phase Alkylation of Benzene with Ethylene Considering the Process Unsteadiness

Ethylbenzene is a key intermediate in the manufacture of styrene that is an important industrial monomer. Ethylbenzene is produced by benzene alkylation using either gas-phase or liquid-phase methods. The liquid-phase alkylation that uses liquid acidic catalysts needs to be improved. We develop a mathematical model for the liquid-phase benzene alkylation. The reaction scheme, designed with a due analysis of desired and side reactions, and with the analysis of the formation of deactivating agents, reflects, in particular, the influence of the concentration of heavy hydrocarbons on the catalyst activity. The account of the catalyst deactivation by heavy alkylaromatics allows predictions of the temporal changes in the outputs of the alkylation process. In particular, the decrease of the ethylbenzene concentration by 2–3 wt % and increase of the polyalkylate outlet concentration by 1.5–2 wt % are the results of the catalyst deactivation. These effects, however, can be compensated by 1.3-time increase of polyalkylate supply and by the temperature increase up to 398 K. Finally, the calculations also show that it is possible to decrease the supply of fresh catalyst from 0.498 to 0.472 t/hour without loss in the yield of ethylbenzene.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Microwave-Driven Nonoxidative and Selective Conversion of Methane to Ethylene over Mn-Based Catalysts

Recent advancements in microwave-driven nonoxidative catalytic synthesis of C 2 H 4 from CH 4 coupling offer a promising, energy-efficient, and eco-friendly alternative to conventional methods, where selective heating under microwave irradiation enables comparable conversions at substantially lower bulk temperatures and shorter reaction times. This study explores the performance of an MnO X -based catalyst supported on CeO 2 and HY zeolite (silica-toalumina ratio = 5.1) for the nonoxidative coupling of CH 4 (NOCM) under microwave irradiation. Inspired by the well-established efficacy of MnO X catalyst in oxidative CH 4 coupling (OCM), their application in NOCM has also shown significant performance. The catalytic system achieved 15% CH 4 conversion and 99% selectivity toward C 2 hydrocarbons and maintained 64% selectivity toward C 2 H 4 surpassing the yields reported in the literature even at higher temperatures (700−1000 °C). Catalyst performance was correlated with measurements by in situ Raman spectroscopy, and additional characterizations were performed using H 2 −temperature programmed reduction , NH 3 −temperature programmed desorption, and BET surface area analysis to understand structural changes during the reactions. These findings suggested that Mn functions as active sites for CH 4 activation in nonoxidative environments while also promoting efficient C−C coupling under microwave irradiation.

Catalysts↗