Hydrocracking of Maya Vacuum Residue with NiMo Catalysts Supported on Mesoporous Alumina and Silica–Alumina

Abstract

Hydrocracking of heavy oils poses greater challenges than that of lighter feeds in terms of catalyst properties and resistance to deactivation. The development of larger pore size catalysts may be beneficial to improve their effectiveness toward cracking the larger molecules present in these feedstocks. Mesoporous alumina and mesoporous silica−alumina (MSA) with different textural properties were used as supports to prepare NiMo-based catalysts. These catalysts were tested in the hydrocracking of a vacuum residue (VR) from Maya crude oil and compared against a commercial Al 2 O 3 catalyst. The conversion of VR and asphaltenes into lighter hydrocarbons obtained with supports and catalysts was determined, and the coke deposition process was studied. The in-house developed catalysts were utilized for two consecutive runs with fresh feed to evaluate coke deposition during reutilization of the materials. It was found that coke deposition occurred mainly in the first run, with carbonaceous deposits stabilizing for all the catalysts during their reutilization. Reaction temperature had an important impact on conversions and product distributions, with higher reaction temperatures accounting for higher VR and asphaltene conversions at the expense of a large increase in gas yields. Although the NiMo/Al 2 O 3 catalyst achieved similar VR conversion to the other catalysts, it displayed higher asphaltene conversion with lower coke deposition and a reduced gas yield. The effectiveness of this catalyst can be attributed to its larger pores that can allow better diffusion of asphaltene molecules than MSA or NiMo/MSA as well as the commercial catalyst.

Macroporous NiMo/alumina catalyst for the hydrocracking of vacuum residue

“…The impregnation of NiMo phases reduces the pore volumes and surface areas of the alumina supports (Table 1). This is consistent with previous reports [14,24]. After Ni and Mo impregnation, the pore volumes of Me-Al and Ma-Al are decreased by 24.1 % and 11.4 %, respectively.…”

“…Alumina has been widely used as a conventional catalytic support for hydrocracking processes. Recently, mesoporous alumina has been applied for hydrocracking studies due to its great capability to disperse Mo species, achieving higher activity during the hydrodesulfurization [14][15][16][17]. With these mesoporous catalysts, higher yields of liquid products have been obtained in the hydrocracking of residual oils [17].…”

Carbon nanofibres coated with Ni decorated MoS2 nanosheets as catalyst for vacuum residue hydroprocessing

“…An alumina support with large surface area and pore volume was synthesized according to a procedure [23] modified from the literature [24].…”

“…Liquid products were recovered after each reaction and fractioned into maltenes (heptane soluble) and asphaltenes (heptane insoluble, toluene soluble) following a procedure previously described [23]. Afterwards, the maltene fraction was analyzed by Gas Chromatography (GC).…”

“…0.50), and slightly lower than that obtained for NiMo/Al 2 O 3 (0.55). It has been reported that the upgrading of the >450 °C fraction in VR can be mainly considered as a thermally driven process [23,48] thus explaining the small differences observed between catalysts.…”