Surface chemistry of propanal, 2-propenol, and 1-propanol on Ru(001)
Adsorption and thermal chemistry of propanal, 2-propenol, and 1-propanol on Ru(001) were studied using temperature programmed reaction spectroscopy (TPRS) and reflection absorption infrared spectroscopy (RAIRS). The results show that each molecule adsorbs molecularly at 90 K and displays the same spectral features as observed for the corresponding liquids after 1.0 L exposures. 2-Propenol was found to molecularly desorb at 200 K, dehydrate to yield propene around 130 K, isomerize to propanal at 180 K, and hydrogenate to 1-propanol at 220 K. Propanal, however, does not undergo isomerization on the surface but desorbs molecularly at 175 and 280 K. Similarly, 1-propanol also desorbs molecularly with two peaks centered at 227, and 298 K. Formaldehyde desorption was observed for each molecule. Furthermore, a reversible hydrogenation-dehydrogenation process was observed between propanal and 1-propanol in the range of 200 to 320 K. These results provided further insights into previous studies on hydrogenation pathways of acrolein on the Ru(001) surface and into the challenges of selectively increasing the yield of the unsaturated alcohol.