Synthesis and testing of porous carbon composites supported catalysts for environmental and refining applications

Abstract

Porous carbon-TiO2 & carbon-Al2O3 composite supports were prepared and tested for NO reduction via NH3-SCR and hydrotreating of vacuum gas oil (VGO) respectively. The effects of type of porous carbon (activated carbon, graphite, and carbon black), amount of carbon loading and calcination temperatures on the textural properties of carbon-TiO2 & Al2O3 composite supports prepared by mulling and extrusion were studied. Using high surface area porous carbons with TiO2 precursors significantly increased the surface area and pore volume of supports calcined at 300oC. The % NO reduction of x wt% V2O5/ (10 & 30 wt%) Carbon-TiO2 catalysts calcined at 300o C shows significant higher (> 50 %) activity than the reference catalyst in absence of H2O. This increase in catalytic activity can be attributed to combined contribution from increased dispersion of V2O5 on the supports, reduced diffusion limitations of NH3-SCR reaction and surface functional groups on porous carbons acting as catalyst. In case of Carbon-alumina composites textural properties were minimally affected at low carbon loadings (≤30wt%) at different calcination temperatures. Carbon black-alumina composites supported NiMo catalysts tested for hydrotreating of vacuum gas oil (VGO) shows activity comparable to reference catalysts. Activated carbon-alumina composites show decrease in catalytic activity which could be due to sintering of NiMoS phase into large crystals thus reducing the number of active sites.