fulltext.study @t Gmail

Gas phase hydrogenation of nitrocyclohexane over supported gold catalysts

Paper ID Volume ID Publish Year Pages File Format Full-Text
40094 45843 2013 10 PDF Available
Title
Gas phase hydrogenation of nitrocyclohexane over supported gold catalysts
Abstract

•First report of gas phase nitrocyclohexane hydrogenation over supported Au.•Activity/selectivity dependent on oxide (Al2O3, TiO2, CeO2 and ZrO2) carrier.•Au/Al2O3 exhibits highest selectivity to the target oxime.•Cyclohexanone predominant over Au/CeO2, ketone and amine over Au/TiO2 and Au/ZrO2.•Surface interaction between imine, H and –OH governs selectivity.

We report the first continuous (gas phase) hydrogenation of nitrocyclohexane over oxide (Al2O3, TiO2, CeO2 and ZrO2) supported Au catalysts. Thermochemical analysis has established possible thermodynamic constraints and product distribution at equilibrium. The catalysts have been characterised by temperature-programmed reduction (TPR), H2/O2 chemisorption/temperature-programmed desorption (TPD), BET surface area/porosity, X-ray diffraction (XRD) and scanning/transmission electron microscopy (STEM/TEM) measurements. The effects of space velocity (2–6 × 104 h−1), temperature (353 and 473 K) and H2 partial pressure (8 × 10−4–0.93 atm) on catalyst performance have been examined. Selectivity to the target cyclohexanone oxime is sensitive to H2 pressure, where an increase in temperature favours cyclohexanone with amine/ketone condensation and subsequent reduction to dicyclohexylamine. An increase in turnover frequency was observed with decreasing (surface area weighted) mean Au size (from 7.0 to 4.3 nm) but a lower value was obtained for 3.0 nm Au (on CeO2) that is linked to suppressed H2 chemisorption (under reaction conditions) resulting from strong interaction with the partially reduced support. We establish a critical surface interplay between imine, H and –OH that governs selectivity. Au/Al2O3 exhibited the highest activity and oxime selectivity (maximum = 95%), Au/CeO2 promoted near exclusive production of cyclohexanone whereas Au/TiO2 and Au/ZrO2 generated a cyclohexylamine/cyclohexanone mixture.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (223 K)Download as PowerPoint slide

Keywords
Gas phase hydrogenation; Nitrocyclohexane; Cyclohexanone oxime; Supported Au catalysts; Thermochemical analysis; Hydrogen partial pressure
First Page Preview
Gas phase hydrogenation of nitrocyclohexane over supported gold catalysts
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 A: General - Volume 467, 2 October 2013, Pages 575–584
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