Sergio Fuentes Moyado
Departamento de Nanocatálisis, Centro de Nanociencias y Nanotecnología
Universidad Nacional Autónoma de México, campus Ensenada.
The environment protection in the case of air requires the production of ultra low sulfur fuels for use in transportation. In Mexico the required level of sulfur in fuels is regulated by NOM 086 that indicates that gasoline has to be less than 30 ppm and 10 for diesel. Therefore the Pemex refineries need to improve catalysts used in hydrodesulfurization units to reach those levels. Indeed, the challenge is even more demanding for Mexican refineries that process stocks derived from heavy oil as the Maya which contain more than 3 wt %.
This work presents results about the development of scalable prototypes of CoMo and NiMo catalysts both in bulk form or suported on gamma-alumina designed to process heavy oil fractions derived from maya crude oil.
The bulk catalysts were prepared by decomposition of alkylammonium thiosalts of Mo and W, including Ni or Co as promoters. The obtained catalysts presented high surface area, high catalytic activity, high carbon content and they were very selectives for hydrogenation path.
In the case of supported catalysts three cases were investigated:
a) Silica based mesoporous materials SBA-15 and KIT-6 covered by alumina or titania which improve the dispersión of MoS2 nanostructures and ameliorate the catalytic activity favoring the direct hydrodesulfurization path.
b) Alumina nanorods which induce the formation of low dimensionality WS2 and improve the catalytic activity for reactions HDS of DBT y 4,6 DM-DBT.
c) Alúmina promoted with Y zeolite for preparation of CoMo and NiMo catalysts used in the hydrotreating of heavy oil fractions as light gasoil (LGO) to produce ultra low sulfur fuels. Pilot plant results show that prototypes developed are able to produce ultra low sulfur diesel under similar conditions as those in refinery plants even in the case where high contents of refractory charges as light cycle oil (LCO) are introduced.
Coautores:G. Alonso, T. Zepeda Partida, J. N. Díaz de León, E. Smolentseva