Catalytic Activity of Heteropoly Tungstophosphoric Acid supported on Partially Reduced Graphene Oxide Prepared by Laser and Microwave Irradiation
The solid acid catalyst of the Keggin-type 12-tungstophosphoric acid (H3PW12O40, HPW) is supported on partially reduced graphene oxide (PRGO) nanosheets for acid-catalyzed reactions. HPW is a new class of catalyst with a good thermal stability and high Bronsted acidity in order to replace common min...
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Format: | Others |
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VCU Scholars Compass
2014
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Online Access: | http://scholarscompass.vcu.edu/etd/3671 http://scholarscompass.vcu.edu/cgi/viewcontent.cgi?article=4697&context=etd |
Summary: | The solid acid catalyst of the Keggin-type 12-tungstophosphoric acid (H3PW12O40, HPW) is supported on partially reduced graphene oxide (PRGO) nanosheets for acid-catalyzed reactions. HPW is a new class of catalyst with a good thermal stability and high Bronsted acidity in order to replace common mineral acids. However, it has low specific surface area (1-5 m2/g). Therefore, the possibility of PRGO as a catalytic support for HPW is investigated due to its high surface area (2630 m2/g) and good thermal stability. The synthesis of HPW-GO catalyst is prepared using microwave and laser irradiation without using any chemical reducing agents. The HPW-GO catalysts are characterized by Ultraviolet-visible spectroscopy (UV-Vis), Fourier Transform Infrared Spectroscopy (FT-IR), Raman Spectroscopy, X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD) techniques, and Transmission Electron Microscopy (TEM). Also, the surface acidity is measured by a non-aqueous titration of n-butyl amine. Furthermore, the application for catalysts is tested by three acid-catalyzed reactions: Esterification, Friedel-Crafts acylation, and Pechmann condensation. The greatest acidity for the microwave irradiation method is with the loading of 85 wt% HPW-GO and 60wt% HPW-GO for laser irradiation. The results observed provide an excellent opportunity for PRGO as a catalytic support for HPW for acid-catalyzed reactions. |
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