Periodic DFT Study of the Opening of Fructose and Glucose Rings and the Further Conversion of Fructose to Trioses Catalyzed by M‑BEA (M = Sn, Ti, Zr, or Hf)

Periodic density functional theory calculations with long-range corrections were used to analyze the opening of fructose and glucose rings catalyzed by metal-substituted β zeolites (M-BEA). The reaction mechanisms were systematically analyzed on BEA substituted with tin (Sn), titanium (Ti), zirconium (Zr), and hafnium (Hf). Here, we proposed a mechanism for the conversion of fructose to dihydroxyacetone and glyceraldehyde and a novel mechanism for the glucose ring opening. The preferential site of substitution of the metals in BEA was reported. The adsorption energies of fructose and glucose through their different oxygen atoms on M-BEA were also reported. The transition state energies were calculated using the nudged elastic band and dimmer methods. Among the zeolites studied, Sn-BEA displays the lowest energies barriers for the conversion of the fructose to its trioses and for the glucose ring opening.本研究采用带长程校正的周期性密度泛函理论（periodic density functional theory）计算，分析了金属取代β沸石（M-BEA）催化果糖（fructose）与葡萄糖（glucose）的开环过程。系统探究了经锡（Sn）、钛（Ti）、锆（Zr）及铪（Hf）取代的BEA沸石上的反应机理。本文提出了果糖转化为二羟基丙酮（dihydroxyacetone）与甘油醛（glyceraldehyde）的反应机理，以及全新的葡萄糖开环反应机理；同时报道了金属在BEA沸石中的优先取代位点，以及果糖与葡萄糖通过不同氧原子在M-BEA上的吸附能。过渡态势能通过nudged弹性带法（nudged elastic band）与二聚体法（dimmer method）计算获得。在所研究的沸石材料中，Sn-BEA催化果糖转化为丙糖以及葡萄糖开环的能垒均为最低。