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The influence of citric acid on the synthesis and activity of high surface area MoP for the hydrodeoxygenation of 4-methylphenol

Paper ID Volume ID Publish Year Pages File Format Full-Text
41033 45875 2012 15 PDF Available
Title
The influence of citric acid on the synthesis and activity of high surface area MoP for the hydrodeoxygenation of 4-methylphenol
Abstract

Unsupported, high surface area MoP was synthesized by adding citric acid (CA) to solutions of ammonium heptamolybdate and diammonium hydrogen phosphate followed by drying (397 K), calcination (773–973 K), and reduction in H2 (923 K). A tetrameric Mo citrate precursor was formed after drying which decomposed into a monomer of the form, Mo(C4H5O3CN)O2·HPO4 following calcination. Reduction of this monomer produced CH4, CO, CO2, NH3, H2O, and MoP. The C content of the reduced MoP-CA catalysts decreased from 12.8 to 4.0 wt% as the calcination temperature increased from 773 to 973 K, whereas the surface area decreased from 136 m2/g to 53 m2/g and the MoP particle size increased from 5 to 9 nm, respectively. The residual C acted as a structural promoter of the calcined samples, limiting agglomeration of the MoP crystallites during reduction so that nanoparticles (5–9 nm) of MoP were produced. The HDO of 4-methylphenol over the MoP-CA catalysts was found to be structure insensitive with an initial turnover frequency (TOF) of 0.079 s−1 at 623 K and 4.4 MPa H2. The ratio of hydrogenation to direct deoxygenation of 4-methylphenol (TOFHYD:TOFDDO = 0.78:1) was independent of the MoP particle size and greater than that observed over MoS2.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (225 K)Download as PowerPoint slideHighlights► High surface area MoP was prepared by mixing citric acid with metal salt solutions. ► Mo(C4H5O3CN)O2·HPO4 was produced following calcination. ► Reduction of Mo(C4H5O3CN)O2·HPO4 yielded MoP nanoparticles and residual C. ► C acted as a structural promoter to limit agglomeration of the MoP crystallites. ► The hydrodeoxygenation of 4-methylphenol is shown be structure insensitive over MoP.

Keywords
Hydrodeoxygenation; Hydrogenation; 4-Methylphenol; Structure sensitivity; Molybdenum phosphide; Catalyst preparation; Citric acid; Molybdenum citrate; Unsupported catalyst
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The influence of citric acid on the synthesis and activity of high surface area MoP for the hydrodeoxygenation of 4-methylphenol
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volumes 419–420, 29 March 2012, Pages 111–125
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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Price was $35.95
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Price after discount Only $4.95
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