Abstract
The diffusion in ZSM-5 zeolite of methanol and of two series of promoters of the methanol to dimethyl
ether reaction (linear methyl esters, benzaldehyde, 4-n-alkyl benzaldehydes) has been studied using
classical molecular dynamics in the NVT ensemble. Whereas promoter diffusion coefficients decrease
with increasing alkyl chain length in methyl esters, the aromatic aldehyde promoters all have similar
diffusion coefficients. The lowest diffusion coefficient is that of benzaldehyde. All the promoters
exhibit a preference for moving in the straight pore, a preference that is most pronounced for the
4-n-alkyl benzaldehydes and least for the longest aliphatic esters. A novel diffusion mechanism, a
molecular ’3-point turn’, is observed. The diffusion coefficient of methanol is larger than that of all
the promoters. The more catalytically active aromatic aldehyde promoters limit methanol diffusion less than the aliphatic esters.
Supplementary materials
Title
ESI
Description
Electronic Supplementary Information.
Actions
Title
3-point turn
Description
A video of the molecular 3-point turn described in the paper.
Actions