Promotional effect of CeO2 and Fe2O3 species on mesoporous silica as efficient catalysts for the vapor-phase dehydration of iso-butyl alcohol to isobutylene

Abstract

CeO₂–Fe₂O₃ binary oxides were effectively incorporated into mesoporous spherical silica (MCM-41) via a sol–gel technique. The resultant CFO/MCM-41 nanocomposites, with metal loadings ranging from 3 to 30 wt%, were subsequently calcined at 550 °C and assessed as catalysts for the gas-phase dehydration of isobutyl alcohol. Structural and surface analyses using XRD, TG-DTA, ATR-FTIR, BET, TEM, EDX, XPS, and pyridine-adsorbed FTIR confirmed the formation of thermally stable, well-dispersed active phases, as well as the presence of both Lewis and Brønsted acid sites. The differences in catalytic activity among these nanocomposites were closely linked to variations in their acidity. Among all the catalysts, the 10 wt% CeFeO₃/MCM-41 sample demonstrated the best performance at 350 °C, achieving approximately 92 % isobutanol conversion, 100 % selectivity toward isobutylene, and a butene production rate of 45.10 mmol g⁻¹ h⁻¹ . The catalyst also showed excellent stability across five reuse cycles. The outstanding catalytic performance and stability were directly correlated with the material's enhanced structural integrity and optimized textural properties. Furthermore, XPS analysis revealed that the Ce^3 +/Ce⁴⁺ and Fe²⁺/Fe³⁺ redox states, modulated by Ce–Fe interactions, played a crucial role in tuning the catalyst’s acidity and catalytic performance.