New NiMo catalysts supported on ZrO2-modified SBA-15 materials for 4,6-dimethyldibenzothiophene hydrodesulfurization
Introduction
SBA-15-type materials are novel well-ordered mesoporous molecular sieves with high surface area and narrow distribution of pores of about 60-100 Å in diameter [1]. These materials have already been tested in a variety of applications, such as adsorbents, molecular sieves, catalysts and catalytic supports. However, up to now only purely siliceous SBA-15 materials were tested in hydrodesulfurization (HDS) and published information is limited to a few papers 2., 3., 4.. The incorporation of heteroatoms (Al, Ti, Zr, etc.) on the pure siliceous SBA-15 surface should modify dispersion and coordination of the deposited active metal species (Mo, W) and subsequently their efficiency and selectivity in HDS reaction. In the present work, with the aim of searching for new, highly effective HDS catalysts, a series of ZrO2-modified SBA-15 supports and the respective NiMo catalysts were prepared, characterized and evaluated in the 4,6-dimethyldibenzothiophene (4,6-DMDBT) HDS reaction.
Section snippets
Experimental
Purely siliceous SBA-15 was synthesized according to the well-known procedure [1] using the triblock copolymer Pluronic P123 as the structure-directing agent and tetraethyl orthosilicate (TEOS) as the silica source. ZrO2-modified SBA-15 supports with different ZrO2 loadings (12.5, 25, 37.5 and 50 wt %) were prepared by incipient wetness impregnation of zirconium (IV) propoxide solution in dry 1-propanol on pure siliceous parent SBA-15. Zr-containing solids were calcined in air at 550°C for 6 h.
Results and Discussion
The results from textural characterization of the supports indicate that zirconia incorporation on the SBA-15 surface produces a decrease in the SBA-15 textural properties, which is more pronounced at high ZrO2 loading (Table 1). The pore size distributions calculated from the desorption branch of the isotherms show a narrow distributions of mesopores with the maxima at the values shown in Table 1. It can be observed from this table that ZrO2 incorporation into SBA-15 results in a notable
Conclusions
It can be concluded that the modification of SBA-15 supports with ZrO2 species results in high-performance NiMo catalysts for hydrodesulfurization of hindered dibenzothiophenes. Zirconia loading in the catalyst support leads to an increase in the dispersion of oxidic Mo species and promotes the HYD pathway of 4,6-DMDBT hydrodesulfurization.
Acknowledgements
Financial support for this work by CONACyT-Mexico (grant 46354) is gratefully acknowledged. The authors thank I. Puente-Lee, M. Aguilar-Franco and C. Salcedo-Luna for assistance in TEM and XRD characterizations.
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Cited by (10)
Effect of hetero atom on dispersion of NiMo phase on M-SBA-15 (M = Zr, Ti, Ti-Zr)
2013, Catalysis TodayCitation Excerpt :Different materials have been assayed as new supports for hydrotreating catalysts, namely, silica [1,2], zirconia [3–5], titania [1,5,6], carbon [7], mixed oxides (ZrO2–Al2O3 [8–10], ZrO2–SiO2 [10,11], ZrO2–TiO2 [12]), mesoporous materials like MCM-41 [13–17], SBA-15 [17,18] etc. Several reviews are available for detailed analysis of the support effect on hydrotreating activity [19,20]. The catalytic properties of the molybdates are closely related to their structure.
Ordered Mesoporous Materials as Catalysts
2012, Advances in CatalysisCitation Excerpt :Metal oxides and sulfides have also been incorporated as active components into ordered mesoporous structures for use in a variety of catalytic reactions. Many reports concern HDS (507,522,555–571), which is a widely used industrial process to remove sulfur from natural gas and petroleum. For example, Huirache-Acuna et al.(558) prepared an HDS catalyst by immobilization of a ternary cobalt–molybdenum–tungsten oxide on phosphate-loaded mesoporous SBA-15 and SBA-16.
Effect of the support on the high activity of the (Ni)Mo/ZrO <inf>2</inf>-SBA-15 catalyst in the simultaneous hydrodesulfurization of DBT and 4,6-DMDBT
2011, Journal of CatalysisCitation Excerpt :%) were discussed in [41,42]. The application of impregnated ZrO2–SBA-15 as HDS support was studied only for NiMo catalysts in [25]. Here, we report the characterization results that complement previous collaborations and allow us to describe the Mo and NiMo materials in the oxide state (denoted as oxide precursors).
Deep HDS over NiMo/Zr-SBA-15 catalysts with varying MoO<inf>3</inf> loading
2008, Catalysis Today