NiW/AMBT catalysts for the production of ultra-low sulfur diesel

A series of hydrodesulfurization (HDS) catalysts of NiW supported on γ-Al2O3–MB–TiO2 (denoted as AMBT) composites with various amounts of TiO2 were prepared, in which zeolite MB was synthesized from kaolin mineral. The samples were characterized by means of N2 physisorption, XRD, UV–vis DRS, TPR, NH3-TPD, XPS, HRTEM and NO-DRIFT. The characterization results showed that, compared with NiW/Al2O3, the additions of MB and TiO2 reduced the interaction between the metal components and the composite support, and also made the active metal phase of WS2 existing as larger slabs on the surface of the composite support. Meanwhile, the layer number of the active metal clusters became greater. Furthermore, the incorporation of MB into the support tuned the overall acidity of the NiW catalysts. The active metal species of W and Ni exhibited higher sulfidation extents in NiW/AMBT catalyst than those in NiW/Al2O3 and NiW/AMB catalysts. The HDS activities of FCC diesel changed with the addition amounts of TiO2 in the NiW/AMBT catalysts. Higher HDS efficiencies were achieved over NiW/AMBT5 and NiW/AMBT9 than that of traditional NiW/Al2O3 catalyst, and the optimal TiO2 content was 9 m% in the AMBT composite supports. The reason of NiW/AMBT catalyst with higher HDS activity was attributed to the enhanced hydrogenation activity. The ultra deep desulfurization of FCC diesel oil, in which the sulfur content was below 10 ppm, could be obtained under the operation conditions of 350 °C, 5 MPa, 1 h−1 and 600 mL/mL.