Foamed ceramic based γ-Al₂O₃ coated catalysts with different preparation methods for ethyl nicotinate hydrogenation reaction

This study investigated the catalytic hydrogenation of ethyl nicotinate using Pd/Al 2 O 3 -SiO 2 foam ceramic catalysts prepared via sol-gel impregnation (SI), sol-gel precipitation (SP), precipitation-impregnation (PI), and co-precipitation (CP). We aimed to evaluate the performance and stability of these catalysts as coatings on foam ceramic surfaces in a high-pressure hydrogen reactor at 403 K and 5 MPa. Various physicochemical characterization methods were employed to correlate catalytic performance with physicochemical properties. Results indicated that sol-gel prepared supports had higher specific surface areas, more acidic sites, and better metal-carrier interactions compared to the precipitation method. SEM analyses revealed flatter and smoother coatings from the sol-gel method, while TEM showed uniform Pd distribution with impregnation. Ultimately, the SI method provided the best catalytic performance with a conversion of 86.77 %. The conversion of the substrate remained above 80 % after five cycles.