Towards the "pressure and materials gap": Hydrogenation of acrolein using silver catalysts

The hydrogenation of acrolein has been studied over various Ag/SiO2 catalysts in a pressure range from 50 mbar to 20 bar. Increasing partial pressures of acrolein and/or hydrogen lead to increasing selectivities of allyl alc. The selectivity towards allyl alc. also depends on the structural features of the Ag/SiO2 catalyst. Larger particles seem to favor the prodn. of propanal. This observation is discussed in view of the different plane-to-edge-ratio of the different catalysts. The interaction of hydrogen with silver samples has been studied with TAP at very low pressures as well as with calorimetry at ambient pressures. Both methods indicate, that also the hydrogen adsorption is structure-sensitive. No interaction of hydrogen with electrolytic silver or the support material alone was obsd. IR spectroscopy has been used to elucidate the interaction of acrolein with Ag/SiO2 catalysts. A strong interaction with the support material was found, hindering the observation of probable silver-acrolein interaction