Designing Ti-modified TiO2-Al2O3 composites with engineered acidity, texture, and thermal stability as catalyst for hydrodesulfurization

This study investigates the role of titanium incorporation in tailoring the acidic, textural, and thermal properties of TiO 2 -Al 2 O 3 composite as potential HDS catalyst synthesized via a sol-gel method with varying Ti/Al molar ratios (0.2, 0.4, 0.6, and 0.8). The catalysts were comprehensively characterized using PXRD, N 2 physisorption, NH 3 -TPD, XPS, TGA-DSC, STEM-EDS, and HRTEM. Characterization results demonstrate that Ti incorporation onto γ-Al 2 O 3 effectively modulates the HDS catalyst properties: it enhances mesoporosity, leading to significant increases in surface area, pore volume, and pore diameter, while simultaneously increasing the strength of weak acidic sites, which is generally considered beneficial for HDS performance. Furthermore, Ti integration markedly improves the thermal stability of the material, inhibiting the phase transition from γ- to α-alumina and preserving the mesoporous structure at high temperatures. When materials were evaluated for the hydrodesulfurization (HDS) of dibenzothiophene, the Ti/Al ratio of 0.8 exhibited superior activity. Increased TiO₂ concentration in the carriers improved their weak surface acidity (Brønsted acid) and texture, which enhanced the catalysts' DDS properties. This improved performance is directly correlated with an optimized combination of high surface area, well-developed porosity, and a balanced, moderately acidic site distribution.