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

• A mesoporous solid (MCM41) was synthesized by using an organic template method.
• The modification of MCM41 was made by using the sol–gel alumina incorporation method.
• Catalysts were synthesized varying the Si/Al molar ratio (10, 25 and 50).
• The aqueous solution method was used to impregnate NiW species on the supports.
• The catalytic activity was evaluated in the HDS reaction of dibenzothiophene.

This research presents a series of catalytic supports of MCM41 modified with γ-Al2O3 with a Si/Al molar ratio of 10, 25 and 50. These materials were impregnated with Ni + W solutions at pH 7 and pH 9, respectively and were evaluated in the hydrodesulfurization (HDS) of dibenzothiophene (DBT) reaction. In order to modify the low acidity of MCM41, its surface acidity was modified by incorporation of alumina content in the supports.The sol–gel incorporation method of Al2O3 to the structure of the MCM41 did produce changes in the characteristic of hexagonal arrangement of mesoporous materials.The symmetries of the materials were determined through UV–vis where the octahedral and tetrahedral nickel species were found. By Raman, monotungstate (WO4) and polytunsgtate (W12O408−) species were observed. The HDS of DBT showed that in the NiW/AMS50 catalyst impregnated at pH 9 presents the highest reaction rate. And in the case of the catalysts impregnated at pH 7 the highest reaction rate was achieved 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 HDS activity.

DBT hydrodesulfurization conversion and product selectivity with NiW/AMS catalysts.Figure optionsDownload high-quality image (120 K)Download as PowerPoint slide