Effect of pH on Activity of NiMo/Al.sub.2O.sub.3 Catalysts Prepared with Citric Acid in Simultaneous Hydrodesulfurization and Hydrodenitrogenation Reactions

NiMo/alumina catalysts were prepared by impregnation of metal precursors in the presence of citric acid (CA) at different pHs. Catalysts were characterized by nitrogen physisorption, X-ray diffraction, temperature programmed reduction of sulfided catalysts (TPR-S), temperature programmed sulfidation...

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Bibliographic Details
Published in:Catalysis letters 2017-05, Vol.147 (5), p.1104
Main Authors: Braggio, Flávia A, Mello, Matheus D, Magalhães, Bruno C, Zotin, José L, Silva, Mônica A. P
Format: Article
Language:English
Subjects:
Catalysts
Citric acid
Hydrogen sulfide
Quinoline
Thiophene
X-ray diffraction
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Summary:NiMo/alumina catalysts were prepared by impregnation of metal precursors in the presence of citric acid (CA) at different pHs. Catalysts were characterized by nitrogen physisorption, X-ray diffraction, temperature programmed reduction of sulfided catalysts (TPR-S), temperature programmed sulfidation (TPS) and NO chemisorption of sulfided catalysts. Catalytic activity for dibenzothiophene (DBT) hydrodesulfurization (HDS) was studied in a trickle-bed reactor, with and without quinoline in the reaction feed. Results suggest that HDS of DBT occurs mainly by direct desulfurization route and CA addition at pH 3 was detrimental, resulting in a less active catalyst, which was confirmed by TOF calculations. Furthermore, TPR-S results show that the catalyst prepared at pH 3 presented less coordinatively unsaturated sites (CUS), being less active than the one synthesized at pH 1. Besides that, the catalyst prepared at pH 1 was less inhibited at higher quinoline concentrations.
ISSN:1011-372X
1572-879X
DOI:10.1007/s10562-016-1903-6