Selective Hydrogenation of 1,3-Butadiene and 1-Butyne over a Rh/Chitosan Catalyst Investigated by using Parahydrogen-Induced Polarization

Hydrogenation of 1,3-butadiene and 1-butyne over the Rh/chitosan catalyst in gaseous and liquid phases was investigated by using the NMR and parahydrogen-induced polarization technique. The Rh/chitosan system was a very selective catalyst for the partial hydrogenation of 1,3-butadiene and 1-butyne to 1- and 2-butenes. The catalyst demonstrated high activity in the hydrogenation of 1-butyne after its activation in the hydrogenation of 1,3-butadiene. Therefore, the Rh/chitosan catalyst was used for the catalytic removal of 1,3-butadiene and 1-butyne from gaseous butene streams. Moreover, the syn- and anti-addition of the hydrogen molecule to substrates proceeded in a pairwise manner in the gas phase heterogeneous hydrogenation as was demonstrated by parahydrogen-induced polarization. However, in the liquid phase hydrogenation of 1-butyne, both hydrogen atoms from the same hydrogen molecule were added to 1-butyne only through the syn-addition route.