Hydrodesulphurization and hydrodenitrogenation of light gas oil using NiMo catalyst supported on functionalized mesoporous carbon

The effect of functionalization on the hydrotreating activity of NiMo catalysts supported on mesoporous carbon supports (mC) was studied. mC support was prepared by volume templating of alkali modified SBA-15 using sucrose as carbon source. The mC supports were functionalized using nitric acid of various concentrations (upto 8 M HNO3). The supports and catalysts were characterized by N2 physisorption, SAXS, XRD, FTIR, TGA, Raman spectroscopy, SEM, TEM, and HRTEM. SAXS results showed the changes in structural orderliness of virgin and functionalized mC supports. Physisorption analysis indicated progressive reduction in surface area (SA) and pore volume with the increase in nitric acid concentration. Enhancement of surface functional groups after functionalization was observed through FTIR. SEM images showed that the carbon supports retain needle like morphology even after nitric acid etching. As seen by HRTEM, qualitatively Type-II like NiMoS phase (lower support metal interaction (SMI)) is generated on functionalized mC supported catalysts, which is active for hydrotreating. Hydrotreating activity study of these NiMo catalysts were carried out under industrial operating conditions in a laboratory trickle bed reactor using coker light gas oil feed and it was found that NiMo supported on 6 M acid treated mC showed the highest activity. Based on equal catalyst mass, the hydrodesulphurization and hydrodenitrogenation activities of NiMo/mC catalyst were higher than that of NiMo/γ-Al2O3 owing to lower SMI and higher SA. This study reveals that the functionalized mCs can become potential alternative catalyst support to conventional γ-Al2O3, for the hydrotreating of gas oil feedstocks.

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► Effect of nitric acid functionalization on mesoporous carbons and NiMo catalysts.
► Optimum between functional groups and textural properties is established.
► NiMo over 6 M HNO3 treated mesoporous carbon exhibits highest HDS & HDN activity.
► Lower support metal interaction helps to form active, Type-II like NiMoS phase.
► HDS & HDN activity of NiMo/mC ≫ NiMo/γ-Al2O3 under industrial operating conditions.