Synergistic Effects of Tungsten and Sulfate Species on the Structural Evolution and Acidity of Titania for High-Efficiency Transesterification

Abstract

The innovation for highly effective solid acid catalysts that resist impurities is crucial for enhancing sustainable esterification and transesterification processes, which are vital for biofuel production and green chemistry. In this work, tungsten-modified sulfated titania (WO₃/SO₄²⁻/TiO₂) catalyst was prepared through the impregnation method and subsequently calcined at 550 °C to assess the impact of tungsten impurity on its structural and catalytic properties. The catalyst was characterized through FT-IR, XRD, NH₃-TPD, and BET surface area analysis. These analyses revealed that the presence of sulfate and tungsten species inhibited TiO₂ crystallization, improving the textural properties and increasing surface acidity. The 5 wt.% WO₃/SO₄²⁻/TiO₂ catalyst demonstrated the largest surface area (35.99 m²/g) and total acidity (1.20 mmol NH₃/g). This catalyst achieved 86.4% conversion in the reaction of transesterification of ethyl acetate and n-butanol at 100 °C for 3 h. The enhanced catalytic performance and selectivity were attributed to the synergistic interaction between WO₃ and SO₄²⁻, resulting in the formation of Lewis-Bronsted acid sites. This study provides important insights into how tungsten affects the structure and acidity of sulfated titania, which could guide the design of more efficient, impurity-tolerant solid acid catalysts for environmentally sustainable chemical processes.

Graphical Abstract