Preparation and Characterization of Metakaolin-Based Catalysts for Gasoil Hydrodesulfurization Purposes

The present study investigates preparation of alumina metakaolin (AMK) from Iraqi kaolin clays and supporting of AMK by active metals to manufacture new catalysts applied for hydrodesulfurization (HDS) of the raw gasoil with 12,600-ppm sulfur content. Alumina metakaolin (AMK) was created with high acidity and a high surface area after destroying a crystallite structure of kaolin clays by activating H2 ions through an ion exchange method and then cementing with gamma alumina (γ/Al2O3) as a composite support. The significant increase in the surface area and pore size of the prepared catalyst combined with the strength, density and accessibility of the catalyst sites (i.e., Bronsted and truly Lewis acid sites) leads to an increase in its performance efficiency. The hydrodesulfurization efficiency (HDS%) over the prepared catalyst was evaluated in a fixed-bed reactor, which was operated at 24–320 C, 2–6 h−1 weight hourly space velocity (WHSV), and 3–12 bar. Catalysts activity tests were performed after loading different percentages of three active metals to find the best results were obtained at 10% of each Mo, Co, and Ni with an HDS% of 47.8, 43.6, and 40.8%, respectively. A comparative study of the catalyst activity was conducted between the bi-functional laboratory-prepared CoMo/AMK catalyst and the commercial CoMo/Al2O3 one. At the same optimum operating conditions, the percentage of HDS was 80.5 and 72.3% of the CoMoA/MK and CoMo/Al2O3, respectively.