Propionaldehyde, adsorbed

Fig. 6 shows the IR-TPR of CsHb partial oxidation over Au/Ti0x-Si02. The interaction of Ar/C3He/H2/02 with the catalyst surface at 50 °C led to decrease in the band intensity of OH vibration at 3741 cm and the formation of a 1662 cm (C=0 of adsorbed acetone) band. Mass spec, results in Fig. 7 shows the reaction produced propionaldehyde, acetone, and CO2. The rate of product formation peaked at 140 °C. 

Yoshida et al. [356] show the presence of O" and OJ on V2Os supported by Si02. With strong reduction, it is mainly O. It was proved that reaction of 02 with propene gives rise to aldehydes (propionaldehyde, acrolein and formaldehyde) at temperatures below 150°C. Yoshida et al. [357] confirm this and find that oxygen at room temperature is mainly adsorbed as molecular oxygen, only 10% is the sum of O and 02. O" is the oxygen species reactive towards carbon monoxide, 02 is not. 

Takeda N, Ohtani M, Torimoto T, Kuwabata S, Yoneyama H. Evaluation of diffusibility of adsorbed propionaldehyde on titanium dioxide-loaded adsorbent photocatalyst films from its photodecomposition rate. J Phys Chem B 1997 101 2644-2649. 

For the hydrogenation of propionaldehyde (CH3CH2CHO) to propanol (CH3CH2CH2OH) over a supported nickel catalyst, assume that the rate-limiting step is the reversible chemisorption of propionaldehyde and that dihydrogen adsorbs dissociatively on the nickel surface. 

Qualitatively similar results were obtained for reaction and desorption of normal and iso-propanol on the 011 [-faceted TiO2(001) surface. In the case of normal propanol, almost half of the molecules initially adsorbed desorbed as the parent molecule at 370 K, while half of the remaining surface species reacted to form propanol at 580 K. The ratio of propene to propionaldehyde generated at 580 K was 10 1. Desorption of isopropanol quantitatively mirrored the desorption of normal propanol in two desorption states at 365 and 512 K. Isopropanol did not generate any dehydrogenation products (e.g., acetone), and the surface did not generate any bimolecular coupling products for any of the probe alcohol molecules. The absence of ether formation on the (Oil [-faceted surface is consistent with the need for double-coordination vacancies to facilitate that reaction, and the absence of such sites on this surface of titanium dioxide [80]. 

During the purification step, especially in the purification of polyethers with adsorbents (for example with aluminium silicates) a specific odour appears due to a cyclic compound, which was identified as cyclic acetal of dipropyleneglycol with propionaldehyde (2-ethyl-4,7-dimethyl-1,3,6-trioxacane) (Figure 4.35). 

An analysis, made in 1 and 2 N solution of cadmium sxilfate, showed the absence of propionaldehyde and a practically quantitative yield of allyl alcohol. The change in the behavior of organic compounds when they are adsorbed on the modified palladium surface is xzndoubtedly due to an energetic hindrance to the /J — a phase transition. The preferential hydrogenation of acetylene derivatives before ethylene derivatives is determined by the greater exothermic nature of adsorption and hydrogenation in acetylene derivatives [3]. 

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