5. Conclusions

The metal-support interaction is one of the most important parameters in the design of HDS catalysts. The use of silicon in the preparation of HDS catalyst support has been showed to weak the metal interaction, generating type II Co(Ni)- Mo(W)-S structures, which are characterized by: (i) a complete sulfidation of the oxidized phase, weakening the electronic interaction with the support or (ii) stacked structures so that the upper crystallites in the structure Mo(W)S2 have a low interaction with the support. The so-called type II Co(Ni)-Mo(W)-S structures are more active than the partially sulfide type I. The use of mesoporous silicates such as MCM-41 and SBA-15 has been proposed in the literature, with the intention to increase the active phase, acidity, the type II structures, and the dispersion of the active phase (Mo(W)S2). In the case of the MCM-41 support, the preparation conditions such as pH and the Si/Al molar ratio increase the number of oxidized species in octahedral coordination, which are precursors of the type II structures. However, these materials did not show better HDS performance in the DBT molecule compared with the alumina support. It would be very useful to evaluate this type of catalyst support (MCM-41) in a molecule more refractory to HDS, such as 4,6-DMDBT, and see if it is possible to increase the catalytic performance compared to the catalyst supported in alumina, since the 4,6-DMDBT molecule is more sensitive to the geometry of the Co(Ni)-Mo(W)-S structure than the DBT molecule. On the other hand, SBA-15 mesoporous silicate doped with a certain amount of Ti (Si/Ti = 60 molar ratio) showed to improve the catalytic performance in the HDS of the DBT molecule, through generating a greater population of type II structures; therefore, these materials are useful as HDS catalyst support.

Silicon Materials

Grafting SiO2 on the surface of γ-alumina or the use of mixed support (Al2O3-SiO2) are other alternatives to promote the formation of so-called type II Co (Ni)-Mo(W)-S structures. It has been reported that a small amount of SiO2 is enough to weaken the metal-support interaction and thus increase the extent of sulfidation and level promotion, which are fundamental parameters to improve the performance of HDS catalysts. So, it can be concluded that the use of silicon in the preparation of HDS catalyst support is a promising alternative to get better performance in HDS catalysts.

References

acscatal.6b02735

10.1021/ja2072719

03.005

Energeticos1.pdf

cattod.2010.05.011

19

[1] Rangarajan S, Mavrikakis M. On the preferred active sites of promoted MoS2 for hydrodesulfurization with minimal organonitrogen inhibition. ACS

DOI: http://dx.doi.org/10.5772/intechopen.84724

The Silicon on the Catalysis: Hydrodesulfurization of Petroleum Fractions

2015;5:7276-7287. DOI: 10.1021/acscatal.

[8] Vít Z, Gulková D, Kaluza L, Kupcik J. Pd-Pt catalysts on mesoporous SiO2- Al2O3 with superior activity for HDS of 4,6-dimethyldibenzothiophene: Effect

[9] Xiangchen F, Rong G, Chengmin Y. The development and application of

hydrodesulfurization of diesel. Chinese Journal of Catalysis. 2013;34:130-139. DOI: 10.1016/S1872-2067(11)60506-8

[10] Sh R, Li J, Feng B, Wang Y, Zhang W, Wen G, et al. Catalysis Today. 2015; 263:136-140. DOI: 10.1016/j.cattod.

[11] Xu J, Huang T, Fan Y. Highly efficient NiMo/SiO2-Al2O3

10.1016/j.apcatb.2016.10.078

for dibenzothiophene

S0277-5387(97)00074-0

[14] Song C. An overview of new approaches to deep desulfurization for

[12] López-Benítez A, Berhault G, Guevara-Lara A. Addition of manganese to alumina and its influence on the formation of supported NiMo catalysts

hydrodesulfurization application. Journal of Catalysis. 2016;344:59-76. DOI: 10.1016/j.jcat.2016.08.015

[13] Gates BC, Topsøe H. Reactives in deep catalytic hydrodesulfurization: Challenges, opportunities, and the importance of 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene. Polyhedron. 1997;16:3213-3217. DOI:

hydrodesulfurization catalyst prepared from gemini surfactant-dispersed Mo precursor. Applied Catalysis B:

Environmental. 2017;203:839-850. DOI:

of metal loading and support composition. Applied Catalysis B: Environmental. 2015;179:44-53. DOI:

10.1016/j.apcatb.2015.04.057

catalysts for ultra-deep

2015.06.023

5b01806

Catalysis. 2016;7:501-509. DOI: 10.1021/

[2] Fu W, Zhang L, Tang T, Ke Q, Wang S, Hu J, et al. Extraordinarily high activity in the hydrodesulfurization of 4,6-dimethyldibenzothiophene over Pd supported on mesoporous zeolite Y. Journal of the American Chemical Society. 2011;133:15346-15349. DOI:

[3] Egorova M, Prins R. Competitive

methylpyridine, and hydrogenation of naphthalene over sulfide NiMo/γ-Al2O3. Journal of Catalysis. 2004;224: 278-287. DOI: 10.1016/j.jcat.2004.

[4] Recursos energéticos globales, Encuesta 2013: Resumen. World Enegy council. Available from: https://www. worldenergy.org/wp-content/uploads/ 2014/04/Traduccion-Estudio-Recursos-

[5] Stanislaus A, Marafi A, Rana SM. Recent advances in the science and technology of ultra low sulfur diesel (ULSD) production. Catalysis Today. 2010;153:1-68. DOI: 10.1016/j.

[6] ENI. 2016. O&G World oil and gas review 2016. Avaliable from: https:// www.eni.com/docs/en\_IT/enicom/ company/fuel-cafe/WOGR-2016.pdf

[7] Van Haandel L, Bremmer M, Kooyman PJ, Van Veen JAR, Weber T,

Hensen EJM. Structure-activity correlations in hydrodesulfurization reactions over Ni-promoted MoxW (1-x)S2/Al2O3 catalysts. ACS Catalysis.

hydrodesulfurization of 4,6 dimethyldibenzothiophene, hydrodenitrogenation of 2-
