Co₃O₄-g-C₃N₄ catalysts for 1-octene transformation to nonanol: Structure, activity and mechanism

Hydroformylation reactions of olefins are one of the important applied transformations in the syngas industry, mainly using homogeneous noble catalysts. Here the composite of zeolitic imidazolate framework (ZIF-67) derived Co3O4 with g-C3N4 for catalyzing 1-octene transformation under pressured syngas has been investigated. Using 5 wt% Co3O4-g-C3N4 in the reaction at 150 degrees C and 7 MPa for 8 h, 1-octene conversion and nonanol selectivity reached 99.9 % and 77.8 %, respectively. At 110 degrees C, a nonanal selectivity of 90 % was achieved. TEM, CO-/H-2-TPD, XPS, in situ XRD and in situ DRIFTS characterization indicated that as-synthesized Co3O4 precursor showed dominantly exposed (2 2 0) and (3 1 1) crystal planes. The oxygen vacancy proportion on 5 %Co3O4-g-C3N4 reached 56 %, which enhanced the CO adsorption, in addition to Co3O4 dispersion on the g-C3N4 surface for raising turnover frequency. Electron transfer on the Co3O4-g-C3N4 interfaces promoted the reduction of Co3O4 to active Co. The successive hydroformylation-hydrogenation pathway was discussed for the promoted production of nonanol.