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 beta 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.