科研之友
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摘要
Computational quantum chemistry has been employed to examine the production of ethylene with methanol-to-hydrocarbon (MTH) processes via a carbon pool mechanism. We find that the M05-2X functional performs well for the types of reactions that are involved. The methylation reactions of the aromatic cocatalyst are the most energy-demanding steps in the process. For the subsequent production of C(2)H(4), we have identified a low-energy pathway that involves multiple methyl shifts, followed by concerted deprotonation and C(2)H(4) elimination. The substitutions of the Al and Si atoms in the participating Si-OH-Al moiety of zeolite catalysts with Ga and Ge do not lead to lower barriers for the methylation reactions, nor does the use of a more electron-rich aromatic cocatalyst. However, we find that the use of two cocatalysts, a nucleophile and an aromatic carbon pool, can provide an overall low-energy pathway for the MTH process.
- 出版日期2010-8
