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Trimetallic NiMoW unsupported catalysts for HDS

Paper ID Volume ID Publish Year Pages File Format Full-Text
43148 45957 2009 7 PDF Available
Title
Trimetallic NiMoW unsupported catalysts for HDS
Abstract

Trimetallic unsupported NiMoW sulfide catalysts were prepared of by decomposition-sulfidation of bimetallic Mo-W thiosalts precursors impregnated with Ni. The catalytic activity of the catalysts was determined, both in situ and ex situ, in the dibenzothiophene (DBT) hydrodesulfuration (HDS) reaction. The sample with a relative composition R1 = Mo/[Mo − W] = 0.85 and R2 = Ni/[Mo + W] = 0.5 presented a substantial increment (k = 23 × 10−7 mol/s g) with selectivity to hydrogenation by a factor of 1.24 over hydrodesulfuration. Scanning electron microscopy (SEM) micrographs showed changes in morphology as a function of R1 suggesting that distinct crystalline phases were formed. Also, X-ray diffraction (XRD) measurements of precursors and catalysts revealed that the bimetallic thiosalt structure presents the same planes of the rhombohedral structure as ammonium thiomolybdate (ATM) or ammonium thiotungstate (ATT) indicating that redistribution of Mo and W occurred preferably in specific orientations as the (0 0 2), (0 2 0) and (3 1 0). The ammonium thiomolybdate-thiotungstate (ATMW) bimetallic thiosalt with R1 = 0.85 showed very different structure from the original Mo or W single precursors, among all the samples. Extended Hückel calculations revealed that promotion of (Mo-W)S2 precursors with Ni forming trimetallic NiMoWS catalysts after sulfidation, increases the availability of electrons over the Fermi level increasing the metallic character of the catalysts.

Graphical abstractIn this work, the preparation of trimetallic unsupported NiMoW sulfide catalysts by decomposition-sulfidation of bimetallic Mo-W thiosalts precursors impregnated with Ni, presented substantial increments in the activity for the hydrodesulphurization (HDS) of dibenzothiophene (DBT) for catalysts presenting the relative composition R1 = Mo/(Mo − W) = 0.85 and R2 = Ni/Mo + W = 0.5. Their morphology was studied by scanning electron microscopy (SEM), and X-ray diffraction (XRD) measurements of the samples were done. Extended Hückel calculations revealed that promotion of (Mo-W)S2 precursors with Ni forming trimetallic NiMoWS catalysts after sulfidation, increases the availability of electrons over the Fermi level increasing the metallic character of the catalysts.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Trimetallic; HDS of DBT; Extended Hückel calculations; DOS; Energy band
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 352, Issues 1–2, 15 January 2009, Pages 10–16
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us