Strategy to produce highly loaded alumina supported CoMo-S catalyst for straight run gas oil hydrodesulfurization

Abstract

A simple postmodification synthesis is proposed to produce large pore volume alumina, with addition of a porogen during the peptization step, which is an industrial process preceding alumina shaping. By adjusting the synthesis parameters, obtained alumina present improved textural properties compared to conventional ones: specific surface areas between 380 à 430m2g−1, large pore diameters between 12 and 20nm and consequently large pore volumes. This allowed to prepare highly loaded catalysts, at a density of 4atMo.nm−2, without the formation of undesirable bulk molybdenum-cobalt oxide species despite the high molybdenum content. Catalysts performance were evaluated in thiophene HDS, where the activity varied by a factor 1.5. The most performant solid of the series was then tested in the HDS of a straight run gas oil under industrial conditions: it showed significantly improved activity compared to that of a catalyst prepared from a commercial alumina with the same molybdenum density, with a temperature gain of 17°C at 100ppm residual sulfur. Moreover, the catalyst activity remained stable after one week of testing. This work thus evidences that the development of alumina supports with enhanced textural properties is an efficient way to improve the performance of HDS CoMo catalysts.