III International Conference

PP-II-524% and higher. Apparently the catalyst is involved only in CHHP decomposition and does notaffect the process of cyclohexane oxidation.Cyane conversion (mol. %)Selectivity for CHHP (mol. %)Selectivity for side products (%)129630302520151050302520151050Blank run0 wt.% of Au0.11 wt.% of Au1.2 wt.% of Au2.1 wt.% of Au3.9 wt.% of Au0 20 40 60 80 100 120Time on stream (min)Blank0 wt.% of Au0.11 wt.% of Au1.2 wt.% of Au2.1 wt.% of Au3.9 wt.% of Au0 5 10 15Cyane conversion (mol.%)0 5 10 15Cyane conversion (mol.%)Blank run0 wt.% of Au0.11 wt.% of Au1.2 wt.% of Au2.1 wt.% of Au3.9 wt.% of AuFig. 1. Effect of Au content inAu/silicalite catalysts on performance ofcyclohexane oxidation by molecularoxygen. (Reaction conditions: 70 ml ofC 6 H 12 , 0.5 wt. % of catalyst, air stream75 cc/min, stirring rate 600 rpm).As Au content in the catalystsincreased their activity in CHHPdecomposition also increases, achievinga plateau at the Au concentration about1.2 wt %. As the fraction of CHHPdecomposed over the catalyst increases,the selectivity for side productsformation decreases. It means thatCHHP decomposition over the catalystproceeds with a higher selectivity thanthermal or non-catalytic CHHPdecomposition. Independent experimentsperformed in a flow reactordemonstrated that gold catalystdecomposes CHHP with selectivityclose to 100 %. Therefore, the main roleof Au/silicalite catalysts in cyclohexaneoxidation consists in highly selectiveCHHP decomposition to ketone andalcohol.References1. Schuchardt, Ulf, et al., Cyclohexane oxidation continues to be a challenge, Applied Catalysis A:General 211, pp. 1-17, 2001.2. Druliner, J. D., et al., Direct oxidation of cycloalkanes // US patent No 6160183.3. Fan, Fengwen, et al., Environmentally Benign Oxidation of Cyclohexane and Alkenes with Airover Zeolite-Encapsulated Au Catalysts, 1 sheet (front and back), 4.sup.th World Congress onOxidation Catalysis, Sep. 16-21, 2001, Berlin/Potsdam, Germany.259