Effect of titania grafting on behavior of NiMo hydrodesulfurization catalysts supported on different types of silica

• Published in: Fuel (Guildford) Vol. 100; pp. 100 - 109
• Main Authors: Mendoza-Nieto, J. Arturo, Puente-Lee, Ivan, Salcedo-Luna, Cecilia, Klimova, Tatiana
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Kidlington Elsevier Ltd 01.10.2012; Elsevier
• Subjects: 4,6-Dimethyldibenzothiophene; Applied sciences; Crude oil, natural gas and petroleum products; Deep hydrodesulfurization; Dibenzothiophene; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fuels; NiMo catalysts; Processing of crude oil and oils from shales and tar sands. Processes. Equipment. Refinery and treatment units; Titania; 4,6-Dimethyldibenzothiophene; NiMo catalysts; Titania; Deep hydrodesulfurization; Dibenzothiophene; Desulfurization; Hydrotreating; Catalyst selectivity; Molybdenum; Silica; Supported catalyst; Characterization; Nickel; Surface area; X ray diffractometry; Titanium oxide; Catalyst activity; Nanostructured materials; Comparative study; Hydrodesulfurization
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2012.02.005

► A comparison study of NiMo/silica and NiMo/titania-silica catalysts was undertaken. ► Different types of silica (MCM-41, SBA-15, amorphous silica) were modified with TiO2. ► Titania addition to the silica supports increased the dispersion of the NiMo species. ► Catalytic activity was tested in HDS of dibenzothiophene (DBT) and 4,6-dimethyl-DBT. ► NiMo/Ti-SBA-15 catalyst showed the highest activity in HDS of 4,6-dimethyl-DBT. In the present work, a comparison study of the NiMo hydrodesulfurization catalysts supported on different types of silica supports (nanostructured supports of MCM-41 and SBA-15-types and commercial amorphous silica) and the same ones modified by TiO2 grafting was undertaken. The aim of this study was to inquire on the effect of the characteristics of the primary silica supports on the activity and selectivity of the NiMo catalysts modified with titania in deep HDS. Supports and catalysts were characterized by nitrogen physisorption, small-angle and powder XRD, TPR, UV–vis DRS, and HRTEM, and tested in the simultaneous HDS of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). It was found that titania grafting on all silica supports resulted in a slight decrease of BET surface area and total pore volume. However, the characteristic p6mm hexagonal pore arrangement of the used nanostructured silica materials was not affected. Powder X-ray diffraction pointed out a good dispersion of Mo and Ni oxide species in all prepared catalysts. TPR characterization of the NiMo catalysts revealed some increase in the metal-support interaction after titania grafting on the silica surface. Further DRS characterization indicated that the best dispersion of Mo oxide species was obtained on the TiSBA-15 support. Titania addition to the silica supports also produced an increase in the dispersion of the sulfided NiMo phase, which was more marked for SBA-15 and commercial silica supports than for the MCM-41 (HRTEM). In line with the characterization results, titania addition to all silica supports resulted in an increase in the HDS activity of NiMo catalysts. However, this increase was smaller for the MCM-41 support than for the SBA-15 and amorphous silica supports used. The most active NiMo/Ti-SBA-15 catalyst resulted to be significantly more active (∼40%) than the reference NiMo/γ-Al2O3 catalyst in HDS of 4,6-DMDBT.