Synthesis and Characterization of Trimetallic Ni(Co)-Mo-W HDS Catalysts Supported on Al-HMS Substrates

HDS Catalysts Supported on Al-HMS Substrates

R. Huirache-Acuña¹, B. Pawelec², E.M. Rivera-Muñoz³, R. Nava⁴

B. Torres⁵, G. Alonso-Núñez⁶, J.A. Cortés¹ and J.L.G. Fierro²

¹Facultad de Ingeniería Química, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, 58060, Morelia, Michoacán, Mexico.

²Instituto de Catálisis y Petroleoquímica, CSIC, c/ Marie Curie, 2, Cantoblanco, 28049 Madrid, Spain. ³Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, A.P. 1-1010, 76000. Querétaro, Qro., Mexico.

⁴Facultad de Ingeniería, Universidad Autónoma de Querétaro, Centro Universitario, Cerro de las campanas, 76010, Querétaro, Mexico.

⁵University of Texas at El Paso, Materials Research Technology Institute, El Paso, TX ,79968, USA.

⁶Centro de Nanociencias y Nanotecnología, UNAM, Ensenada, B. C., 22800, Mexico.

E-mail: rafael_huirache@yahoo.it

Abstract

Traditionally, the removal of sulfur from petroleum-derived feedstocks has been achieved by a hydrodesulfurization (HDS) process using alumina-supported Mo or W catalysts promoted by Co or Ni. However, to satisfy new stringent environmental restrictions on the sulfur content of fuels [1], more active HDS catalysts are being requested by the industry. The new generations of catalysts, such as NEBULA®, which are based on totally different concept of bulk-like materials [2] are more expensive than alumina-supported ones. Thus, the challenge is to design novel cost-effective and active supported catalysts.

Many different approaches have been taken to achieve this goal, including varying the catalyst support and catalyst synthesis methods. Considering the new supports, recently, the use of mesoporous silica materials for supporting hydrotreating catalysts has attracted interest of the research community [3-11]. In particular, the use of hexagonal mesoporous molecular sieves such as HMS and SBA-15 are intensively studied [3-9,11,12] because of their hexagonal array of uniform mesopores, a narrow pore size distribution, high surface area, high sorption capacity and thermal stability. In addition, the former could be improved by support modification with different cations such as Al, Ti, Zr [11].

To the best our knowledge there are no references in the literature about the use of the Al-HMS material for supporting trimetallic Co(Ni)MoW catalysts. All investigations are on the monometallic [4, 5] or bimetallic catalysts [3, 6-9]. In order to clarify the effect of promoter (Co vs Ni) on the HDS activity of ternary systems, the Al-HMS supported catalysts were synthesized by simultaneous impregnation. Prior to the catalytic test, the catalytic materials were sulfided ex situ at atmospheric pressure in a tubular furnace heated up 673 K under a flow of H₂S in hydrogen (15%) and kept under those conditions for 4 h. The sulfided catalysts were tested in the HDS of dibenzothiophene (DBT) performed in a batch reactor at 623 K and total pressure of 3.1 MPa. The calcined and fresh sulfide catalysts were characterized by a variety of techniques (N₂ adsorption–desorption isotherms, XRD, DRS UV–vis spectroscopy and HRTEM).

Keywords: HDS, Catalysts, Trimetallic.

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