Mesoporous tin phosphate as an effective catalyst for fast cyclodehydration of bio-based citral into p-cymene

Effective synthesis of aromatic compounds from renewable biomass is highly important yet challenging. p -Cymene is an attractive aromatic compound with various promising applications in the manufacture of fine chemicals. In this study, a novel and effective catalytic system based on mesoporous tin phosphate (M-SnPO) with Lewis-Brønsted dual acidity was developed for the fast synthesis of p -cymene from the cyclodehydration of bio-based citral. Up to 78.5% yield of p -cymene was achieved from the cyclodehydration of citral at 180 °C within only 0.5 h, superior to the results reported for benchmark homogeneous acid catalysts. Characterization of as-prepared M-SnPO catalyst via various techniques indicates that the synergic effect of Lewis and Brønsted acidic sites, large pore-sized structure, and high surface area are responsible for its remarkable catalytic performance. In addition, the effectiveness of the M-SnPO catalyst could be almost sustained over multiple cycles without significant loss. The work herein is the first example of developing a Lewis-Brønsted dual acidic heterogeneous catalyst for the fast synthesis of p -cymene from the cyclodehydration of citral.