Role of the Si/Al molar ratio and pH in NIW/MCM41-Al2O3 catalystsfor HDS of DBT

This research presents a series of catalytic supports of MCM41 modified with -Al2O3 with a Si/Al molarratio of 10, 25 and 50. These materials were impregnated with Ni +W solutions at pH 7 and pH 9, respectivelyand were evaluated in the hydrodesulfurization (HDS) of dibenzothiophene (DBT) reaction. In orderto modify the low acidity of MCM41, its surface acidity was modified by incorporation of alumina contentin the supports.The sol?gel incorporation method of Al2O3 to the structure of the MCM41 did produce changes in thecharacteristic of hexagonal arrangement of mesoporous materials.The symmetries of the materials were determined through UV?vis where the octahedral and tetrahedralnickel species were found. By Raman, monotungstate (WO4) and polytunsgtate (W12O408?) specieswere observed. The HDS of DBT showed that in the NiW/AMS50 catalyst impregnated at pH 9 presents thehighest reaction rate. And in the case of the catalysts impregnated at pH 7 the highest reaction rate wasachieved by the NiW/AMS10 catalyst. The selectivity was mainly oriented to the production of biphenyl(BP). The low catalytic activity was attributable to low formation NiWS species responsible for the HDSactivity.