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Methanol adsorption and dehydration reactions within zeolites represent important steps in the catalytic conversion process to form long-chain hydrocarbons. Herein, first-principles density functional theory (DFT) is employed in the determination of methanol adsorption and conversion in ferrierite (FER), where we predict the fundamental adsorption geometries and energetics of methanol adsorption. The methanol molecule is shown to physisorb at all explored binding sites, stabilized through hydrogen-bonded interactions with the acid site atOmeth-Hframbond distances ranging from 1.33-1.51 A. We demonstrate that the zeolites' adsorption capability is affected by the silicon/aluminium ratio, with stronger adsorptions predicted in the material with silicon to aluminium fractions of 5 than 8. The adsorption strength is also found to vary depending on the tetrahedral binding site, with the T1O2 site yielding the most stable methanol adsorption structure in the Si/Al ratio = 5(Eads = -22.5 kcal mol-1), whereas the T1O1 site yields the most stable adsorption geometry (Eads = -19.2 kcal mol-1) in the Si/Al ratio = 8. Upon translational and rotational motion, methanol is protonated resulting in the breaking of its C-O bond to form a methoxy species bound to the framework oxygen (O-CH3 distance of 1.37 A), whereas the water molecule is stabilized at the acid site through H-bonding (Owat-H = 2.0 A). Further reaction between the methoxy species and a second methanol molecule results in the formation of ethanol and protonated dimethyl ether, with adsorption energies of -42 and -25 kcal mol-1, respectively. The results in this study provide atomistic insight into the effect of acidity of the FER zeolite on the adsorption and conversion of methanol. Keywords: Zeolites, ferrierite, methanol adsorption, acid sites, density functional theory (DFT).

Detailed insight into molecular diffusion in zeolite frameworks is crucial for the analysis of the factors governing their catalytic performance in methanol-to-hydrocarbons (MTH) reactions. In this work, we present a molecular dynamics study of the diffusion of methanol in all-silica and acidic zeolite MFI and Beta frameworks over the range of temperatures 373&ndash, 473 K. Owing to the difference in pore dimensions, methanol diffusion is more hindered in H-MFI, with diffusion coefficients that do not exceed 10&times, 10&minus, 10&nbsp, m2s&minus, 1. In comparison, H-Beta shows diffusivities that are one to two orders of magnitude larger. Consequently, the activation energy of translational diffusion can reach 16 kJ&middot, mol&minus, 1 in H-MFI, depending on the molecular loading, against a value for H-Beta that remains between 6 and 8 kJ&middot, 1. The analysis of the radial distribution functions and the residence time at the Br&oslash, nsted acid sites shows a greater probability for methylation of the framework in the MFI structure compared to zeolite Beta, with the latter displaying a higher prevalence for methanol clustering. These results contribute to the understanding of the differences in catalytic performance of zeolites with varying micropore dimensions in MTH reactions.

The reactions of furfuryl alcohol with itaconic anhydride can proceed via four plausible pathways – two pathways involving initial Diels-Alder cycloaddition followed by lactonization and two pathways involving initial esterification followed by intramolecular Diels-Alder cycloaddition – to afford two distinct norbornene products bearing either a five- or six-membered butyrolactone ring respectively. DFT calculations reported herein show that the first-step Diels-Alder cycloaddition reactions have barriers of 8.5 and 11.8 kcal/mol which are far lower than the barriers of 29.6 and 36.9 kcal/mol for the esterification pathways. The calculated energies for the experimentally observed five- and six membered oxa-norbornene lactone isomers are exergonic with reaction energies of −17.1 and −12.8 kcal/mol respectively. Thermodynamically the five-membered isomer is more stable adduct than the six-membered adduct. Thus the most preferred pathway is the one involving initial [4 + 2] cycloaddition followed by lactonization to form the five-membered butylrolactone ring. Substitution of methyl groups on the carbon bearing the hydroxyl group shows that the substituents do not affects the reaction pathways markedly.