Synthesis of trioxane catalyzed by [Ga]-MFI zeolites

ZSM-5 is considered to have great potential in the catalytic synthesis of Trioxane (TOX), and the effect of acidity on TOX selectivity was explored. [Al]-MFI-50, [B]-MFI-50, Platelike [Ga]-MFI-50 and a series of [Ga]-MFI-y materials were investigated by XRF, XRD, XPS, SEM, NH 3 -TPD, BET, Py-FTIR, 71  Ga MAS NMR and 1 H MAS NMR. According to the results, it is clear that the Ga-MFI have a better effect on the selective of TOX compared with the [Al]-MFI, Platelike [Ga]-MFI-50 and [B]-MFI. This is mainly due to the change in the ratio of Brønsted acid density to Lewis acid density (B/L ratio), and the selectivity of TOX increases with the B/L ratio. Moreover, the percentage increase in density of Brønsted acid is less than that of Lewis acid when the ratio of Si atoms to Ga atoms is decreased. So the ratio of Brønsted acid density to Lewis acid density(B/L ratio) decreases. [Ga]-MFI-50 exhibited better catalytic performance among all catalysts with a selectivity of 97.79% for TOX.