fulltext.study @t Gmail

Synergy effect in the HDO of phenol over Ni–W catalysts supported on active carbon: Effect of tungsten precursors

Paper ID Volume ID Publish Year Pages File Format Full-Text
47074 46458 2010 12 PDF Available
Title
Synergy effect in the HDO of phenol over Ni–W catalysts supported on active carbon: Effect of tungsten precursors
Abstract

The aim of this study was to detect any synergistic effect between nickel and tungsten oxide species supported on activated carbon as well as to study the effect of tungsten precursor (silicotungstic (HSiW), phosphotungstic (HPW), and tungstic (HW) acids) on the activity of partially reduced Ni–W/AC catalysts in phenol hydrodeoxygenation (HDO). The catalytic tests were performed in a flow fixed-bed reactor set-up at a hydrogen pressure of 1.5 MPa, temperatures ranging from 423 to 573 K and weight hourly space velocities of 0.5 gphenol/(gcatalyst h). Before reaction, the catalysts were heat treated in H2 flow at soft conditions (T = 673 K for 4 h). The XPS analysis of spent catalysts revealed that this pre-treatment led to W(VI) species and a mixture of metallic and NiO species. Moreover, XPS and HRTEM analyses of the spent catalysts indicated that the nickel incorporation into W/AC catalysts led to a substantial improvement in surface exposure of the metal oxide species. All catalysts were active in the HDO of phenol and the most active catalysts were those prepared from heteropolyacids (HPAs). Regardless of the tungsten precursor, after Ni incorporation to the base W/AC system, a large enhancement in catalyst performance was observed. Moreover, supporting Ni and W phases on AC induced some beneficial effect because of the lower coke formation on the surface of AC with respect to classical alumina support. Regardless of the reaction temperature, analysis of the products suggests that reaction occurs via two direction pathways: (I) a hydrogenation (HYD) of phenol's aromatics ring (main reaction route) leading to formation of cylohexane, cyclohexene, cyclohexanol and methylcyclopentane and (II) a direct cleavage of the C–O σ bond leading to benzene formation. Total elimination of the O-containing compounds was archived in the HDO reaction at 573 K over oxide Ni–W(P)/AC and Ni–W(Si)/AC catalysts.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights▶ Ni–W oxide catalysts supported on carbon perform successfully phenol HDO. ▶ Large Ni promotion effect on W/AC catalysts was measured in HDO (as in HDS). ▶ More active Ni–W HDO catalysts can be prepared increasing W dispersion using non-conventional precursors.

Keywords
Biomass; Phenol; Hydrodeoxygenation; Nickel; Tungsten; Carbon-supported; Heteropolyacids
First Page Preview
Synergy effect in the HDO of phenol over Ni–W catalysts supported on active carbon: Effect of tungsten precursors
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
Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 101, Issues 1–2, 22 November 2010, Pages 1–12
Authors
, , , , ,
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