The influence of solvent polarity on the dehydrogenation of isoborneol over a Cu/ZnO/Al2O3 catalyst
Autor: | Mengchan Wang, Liu Jie, Wu Dan, Suying Zhao, Jingjing Chen, Lin Yi, Huidong Zheng, Guanghua Yin, S. Ted Oyama |
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Rok vydání: | 2019 |
Předmět: |
Inorganic chemistry
Oxide chemistry.chemical_element Nanoparticle 02 engineering and technology General Chemistry Zinc 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Copper Catalysis 0104 chemical sciences Solvent chemistry.chemical_compound Dehydration reaction chemistry Dehydrogenation 0210 nano-technology |
Zdroj: | Catalysis Today. 323:44-53 |
ISSN: | 0920-5861 |
Popis: | Several Cu/ZnO/Al2O3 catalysts with high Cu and ZnO contents were used to study the influence of solvent polarity on the dehydrogenation and dehydration of isoborneol. The employment of a polar solvent enhanced the activity for the main dehydrogenation reaction, while the use of a non-polar solvent favored the dehydration side-reaction. Different techniques were employed to characterize the fresh, treated, and spent catalysts. X-ray powder diffraction (XRD) showed that the copper was in metallic form and zinc in oxide form, transmission electron microscope (TEM) showed differences in catalyst morphology that depended on the polarity of the solvent used, N2O titration gave the Cu active site density, and temperature-programmed desorption of NH3 (NH3-TPD) provided the acidity of the materials. The characterization results indicated that in non-polar solvents the copper nanoparticles were sintered and this may have been due to the enhanced activity of adventitious water in those solvents or simply because of interactions between the solvents and the copper and zinc oxide components. The sintering resulted in a decrease in the number of active sites and an increase in acidic sites, which enhanced the undesired dehydration reaction. Based on the results of inductively coupled plasma (ICP) and TEM, a model of the catalyst was proposed to illustrate the effect of solvent polarity on the dehydrogenation of isoborneol. |
Databáze: | OpenAIRE |
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