The role of Zn in the Cu-Zn-Al mixed oxide catalyst and its effect on glycerol hydrogenolysis

• Published in: Molecular catalysis 2022-12, Vol.533, p.112796, Article 112796
• Main Authors: Frolich, Karel, Kocík, Jaroslav, Mück, Jáchym, Kolena, Jiří, Skuhrovcová, Lenka
• Format: Article
• Language: English
• Subjects: 1,2-propanediol; Catalysis; Cu surface; CuZnAl mixed oxides; Glycerol
• ISSN: 2468-8231; 2468-8231
• DOI: 10.1016/j.mcat.2022.112796

•Glycerol hydrogenolysis to propylene glycol on reduced Cu-Zn-Al oxides was studied.•Zn presence influenced Cu particles size as well as their surface.•Zn effect had its maximum at the molar ratio of Zn/(Cu+Al) = 0.35.•Excess of Zn led to the formation of ZnO and deterioration of Cu surface.•Acidic centres were not primarily important for the reaction mechanism. A series of Cu-Zn-Al oxide catalysts reduced in H2 was tested in glycerol hydrogenolysis in a stirred batch autoclave at 230°C. The catalysts were prepared by the precipitation – calcination method from layered double hydroxides (LDH) structures. The oxide forms of the catalysts were obtained by calcination of these structures at programmed temperatures, up to 350°C. The catalysts were characterized by the following methods: X-ray diffraction (XRD), temperature-programmed reduction (TPR), thermogravimetric analyses (TGA), N2-physisorption and temperature programmed desorption of ammonia (NH3-TPD). It was found that Zn plays acts as a structure modifier, influencing Cu dispersion and particle size. Consequently, Zn has an impact on the catalyst activity. In particular, the Zn effect had its maximum at the concentration corresponding to a ratio of Zn/(Cu+Al) = 0.35 where conversion of 65% and the selectivity to 1,2-propanediol of 70% was achieved after 60 min of reaction time. [Display omitted]