Insight into the efficient oxidation of methyl-ethyl-ketone over hierarchically micro-mesostructured Pt/K-(Al)SiO2 nanorod catalysts: Structure-activity relationships and mechanism

• Published in: Applied catalysis. B, Environmental Vol. 226; pp. 220 - 233
• Main Authors: Jiang, Zeyu, He, Chi, Dummer, Nicholas F., Shi, Jianwen, Tian, Mingjiao, Ma, Chunyan, Hao, Zhengping, Taylor, Stuart H., Ma, Mudi, Shen, Zhenxing
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.06.2018
• Subjects: Activation mechanism; Al-K decorated silica; Catalytic oxidation; Methyl-ethyl-ketone; Monodispersed Pt sites; Al-K decorated silica; Catalytic oxidation; Activation mechanism; Methyl-ethyl-ketone; Monodispersed Pt sites
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2017.12.007

[Display omitted] •Hierarchically micro-mesostructured K-(Al)SiO2 supports were successfully prepared.•Monodispersed Pt was created by ethylene glycol reduction and colloid impregnation.•Pt/K-Al-SiO2 nanorod catalysts exhibit superior performance for MEK oxidation.•Role of K and Al and structure-activity relationships of catalysts were studied.•MEK destruction mechanism was investigated and proposed by in situ DRIFTS and DFT. Hierarchically micro-mesostructured Pt/K-Al-SiO2 catalysts with regular nanorod (Pt/KA-NRS) and spherical nanoflower-like (Pt/KA-SNFS) morphologies were prepared. The existence of Al atoms generates Brønsted acid sites and reduces silanol groups over the supports, promoting the dispersion of Pt nanoparticles and stability of catalysts. Potassium atoms balance the negative charge of supports and enhance O2 mobility. The Pt/KA-NRS catalysts exhibit unexceptionable low temperature activity, CO2 selectivity, and stability for MEK oxidation. Amongst, 0.27 wt.% Pt/KA-NRS completely converts MEK at just 170 °C (activation energy as low as 37.22 kJ·mol−1), more than 100 °C lower than other typical Pt/Pd supported catalysts reported in the literature. Diacetyl and 2,3-butandiol are the main intermediates during MEK activation, which convert into H2O and CO2 through aldehydes and acids. The excellent catalytic activity of Pt/KA-NRS is ascribed to their regular morphology, high Pt0 content and dispersion, excellent MEK adsorption capacity and superior O2/CO2 desorption capability under low temperature.