Propenal hydrogenation

A study concerning the lowermost particle size necessary for admitting a reaction to occur is provided by Amiridis et al. [55] in their investigations of propene hydrogenation. For metal particle sizes greater than 2nm, hydrogenation of simple olefins is considered to be structure insensitive... 

Amiridis followed that also in propene hydrogenation over Pt-Au/Ti02 a minimum ensemble of Pt atoms is necessary for a successful concomitant adsorption of olefin and hydrogen. However, beside this dilution effect of gold on the bimetallic particles, an electronic impact can not be excluded. An application of Amiridis ... 

Fig. 2. Dependence of basicity and catalytic activity on calcination temperature of CaO (O) Basic sites with > 15 ( ) relative activity for Tishchenko reaction of benzaldehyde ( ) number of reducing sites ( ) activity for styrene polymerization and (A) relative propene hydrogenation activity ( ).

Panjabi, G., Argo, A. M., and Gates, B. C., Supported iridium cluster catalysts for propene hydrogenation Identification by X-ray absorption spectra measured during catalysis. Chem. Eur. J. 5,2417 (1999). 

A brief study of the direct photolysis of propyne at 2062 A has been made by Galli et The major gas-phase products are 1,5-hexadiyne, propene, hydrogen and acetylene, while smaller quantities of methane and compounds of the formulae C4H6, CgHg and CgHio were observed. The gas-phase products represented about... 

The experiments were conducted in a fully automated flow reactor. The gas compositions were analyzed by a GC (see [8] for details). The reactor was fed with a mixture of propane, propene, hydrogen and nitrogen to achieve differential conditions. This was desired to avoid changes in the gas compositions along the bed leading to a non-uniform coke profile, and also to reduce the computational effort. The gas flow rates were controlled by mass flow controllers. The temperatures were 780,800 and 820 K, and the total pressure was 1.5 bar. 

ARCO Chem Tech (now Lyondell) has reported catalysts that show enhanced selectivity and yield for PO [24]. Again, the catalyst was made of Pd impregnated over TS-1, but the addition of either NH4OH, benzothiophene or triphenylphosphine in the reaction medium enabled an increase in the PO yield with respect to propene and H2. Selectivity was also improved due to the suppression of the propene hydrogenation reaction. 

Competing side reactions include propene hydrogenation to propane, and pro-pene combustion to carbon dioxide and water. Additional hydrogen and oxygen consumption occurs to form water. 

Fig. 7 The dependence of the photocatalytic activity (mmole/hr/gr) for propene hydrogenation on Ti02/Al203 particle size.

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