Influence of the Nanostructure of Gallium Oxide Catalysts on Conversion in the Green Synthesis of Carbamates

Abstract

Abstract:The nanostructure of β-gallium oxide crystals influences the conversion to carbamates; specifically, for the synthesis of alkyl carbamates (like propyl N-octylcarbamate) from CO 2 and n-propanol in the absence of phosgene. The nanostructures with variable aspect ratios (length (L)/width (D); from 2 to 18) were prepared by the controlled addition of neutral and cationic surfactants during gallium oxide synthesis. These catalysts displayed selectivities to the corresponding carbamates as high as~70%, superior to non-nanostructured Ga 2 O 3 catalysts. The conversion was found to be inversely proportional to the square of the relative crystallinity. The catalysts retained their structure and catalytic performance upon recycling.

Effective Synthesis of m-Xylylene Dicarbamate via Carbonylation of m-Xylylene Diamine with Ethyl Carbamate over Hierarchical TS-1 Catalysts

“…Over the past few years, carbamate syntheses over several homogeneous and heterogeneous catalysts have been reported, such as Mg 2 Zr x Al 1– x –MMO, 11 Ga 2 O 3 , 12 Mg–Al–Y, 13 Cu-CPO-27, 14 alkali-treated zeolites, 15 Ce–Zn, 16 tungstophosphoric acid (TPA/K30), 17 Mn(OAc) 2 , 18 Pd/ZrO 2 , 19 NaOCH 3 , 20 CuCl 2 /ionic liquids, 21 [BSO 3 HMIm][OTf], 22 Se, 23 AlSBA-15, 24 Zn/SiO 2 , 25 and 3-amino-1,2,4-triazole potassium (KATriz). 26 However, difficulties in homogeneous catalyst separation and low catalytic activity for the heterogeneous catalysts resulted in difficulties in the scale-up process.…”