Long-term evaluation of NiMo/alumina–carbon black composite catalysts in hydroconversion of Mexican 538 8C+ vacuum residue E. Lo ´pez-Salinas * , J.G. Espinosa, J.G. Herna ´ndez-Cortez, J. Sa ´nchez-Valente, J. Nagira Instituto Mexicano del Petro ´leo, Eje Central 152, G.A. Madero, Me ´xico 07730 D.F., Mexico Available online 13 October 2005 Abstract Alumina with (8–18 wt.%) carbon black composite (AMAC) supports was prepared as bimodal extrudates, containing 11–20% of total pore volume as macropores (i.e. >1000 A ˚ ). These supports, in spite of containing carbon black and macropores, showed good side crushing strength (0.67–1.19 kg/mm) after pyrolysis in 6% O 2 /N 2 . AMAC-catalysts were obtained after impregnating these alumina–carbon black supports with Ni and Mo, to obtain 3.5 wt.% NiO and 15 wt.% MoO 3 . These catalysts were evaluated for about 700 h in the hydroconversion of a Mexican vacuum residue (538 8C+) at 415 8C, 200 kg/cm 2 ,H 2 /HC = 6000 ft 3 /barrel in a pilot plant equipped with a Robinson–Mahoney reactor. In comparison with a commercial bimodal alumina-based catalyst (ComCat), AMAC catalysts showed much fewer sediments and less Conradson carbon formation. Initial HDS in AMAC containing macropores can be as high as 92%, while that in a ComCat is 86%. On average, yields of naphtha and kerosene were 2.6 and 1.34 times higher with AMAC catalysts than those with ComCat, while diesel yields were similar. # 2005 Elsevier B.V. All rights reserved. Keywords: Hydroconversion; Hydrodesulfurization; Hydrodenitrogenation; Vacuum residue; H-oil; Carbon-black; Alumina support; Macropores 1. Introduction Petroleum residues are the heavy fraction remaining after distilling petroleum crudes at atmospheric pressure (atmospheric residue) or at reduced pressure of 25–100 mmHg (vacuum residue). Residues have high molecular weight (1000 amu number average for vacuum residue) and contain polynuclear aromatics, also termed asphaltenes. Because of their high thermal stability, asphaltenes having 3–4 rings provide the greatest limitation to the conversion of residue. In addition, the high concentrations of heteroatoms (sulfur, nitrogen, vanadium, and nickel) in petroleum residue act along with asphaltenes to poison catalysts. No matter which type of process is used, a substantial fraction of residue molecules can be cracked off as fragments to become liquids in the transportation fuel and vacuum gasoil boiling ranges. However, one should not try to overly convert residues because asphaltene content can force the selectivity to go to the thermodynamically favored, but lower valued, products: coke and/or sediments and/or hydrocarbon gases. One of the processes designed to convert heavy oil residue to lighter fractions is the so-called H-Oil TM , which typically operates at 410–420 8C, 120 kg/cm 2 , LHSV: 0.5 h 1 ,H 2 /HC: 3500 ft 3 /barrel, and uses an ebullated bed reactor. Maya crude oil is classified as heavy oil, and it accounts for more than 50% of the total crude oil production in Mexico. In terms of environmental problems, catalytic hydrodesulfurization (HDS) and hydrocracking (HC) technologies are important to produce low sulfur fuel oils by upgrading residues from Mexican crude oil which contain not only high concentrations of sulfur compounds (around 4.5 wt.%), and catalyst-deactivating vana- dium compounds (around 400 ppm), but also asphaltenes. At present, Mexican refineries operate with crude oil blends, that is, 55–60% Isthmus (e.g., the Mexican light blend), and 45–40% Maya (e.g., the Mexican heavy blend) crude oils; but since heavy oils tend to become relatively abundant, an unavoidable situation for the Mexican oil industry in the near future will be to refine Maya crude oil richer blends. Two H-Oil TM plants, which have been operating for more than 30 years in the Salamanca, Gto. refinery (18,500 BPD designed capacity), and more recently in the Tula, Hgo. refinery (50,000 BPD designed capacity), transform Mexican heavy vacuum residue into more valuable oil fractions, such as gasoil and diesel, removing great amounts www.elsevier.com/locate/cattod Catalysis Today 109 (2005) 69–75 * Corresponding author. Fax: +52 55 9175 8429. E-mail address: esalinas@imp.mx (E. Lo ´pez-Salinas). 0920-5861/$ – see front matter # 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.cattod.2005.08.011