Effects of ball-milling treatment on physicochemical properties and solid base activity of hexagonal boron nitrides. Issue 2 (19th November 2018)

• Record Type: Journal Article
• Authors: Namba, Shoichiro; Takagaki, Atsushi; Jimura, Keiko; Hayashi, Shigenobu; Kikuchi, Ryuji; Ted Oyama, S.
• Is Part Of: Catalysis science & technology. Volume 9:Issue 2(2019)
• Page Start: 302
• Page End: 309
• Publication Date: 2018-11-19
• Subjects: Catalysis -- Periodicals; 541.395
• DOI: 10.1039/c8cy00940f
• Languages: English
• ISSNs: 2044-4753

Abstract

Abstract : Hexagonal boron nitride solid base catalysts were prepared by simple ball-milling at various rotation speeds of a commercial low-surface area boron nitride. Abstract : Hexagonal boron nitride (h-BN) was ball-milled at various rotation speeds (150–600 rpm) using a planetary ball-mill. Ball-milling disrupted the layered structure of the h-BN, resulting in significant increases of surface area. Ball-milling at 400 rpm gave the highest surface area of 412 m 2 g −1 while higher rotation speeds decreased the surface areas due to agglomeration. Moreover, ball-milling resulted in the emergence of amino- and hydroxyl groups on the surface which were observed by Fourier transform infrared spectroscopy, and partial oxidation of the surface boron by the formation of B–OH groups was confirmed by X-ray photoelectron spectroscopy. The appearance of trigonal B–O and tetrahedral B–O was observed by boron-11 magic-angle spinning nuclear magnetic resonance spectroscopy. The number of base sites was increased with the increase of rotation speeds of milling, corresponding to the formation of amino groups. The ball-milled h-BN showed catalytic activity for the nitroaldol reaction between nitromethane and benzaldehyde in which the h-BN milled at 400 rpm exhibited the highest reaction rate and turnover frequency. In addition, the ball-milled h-BN could convert glucose with the formation of fructose at 40 °C whereas pristine h-BN showed no activity. The base sites were mainly responsible for the catalytic activity.