Selective hydrogenation of furfural over supported nickel and nickel phosphide catalysts

Supported Ni (60 wt% Ni) catalysts were prepared and phosphided into corresponding Ni2P catalysts. They were used for the hydrogenation of furfural as well as for the probe reactions (the hydrogenation of furan and propanal). The results demonstrated that the acidic support promoted the adsorption and hydrogenation of furan ring and aldehyde group over the nickel sites while the basic support played the opposite role. The IR spectra demonstrated that the aldehyde group was more easily hydrogenated than the furan ring at room temperature, implying the sequential hydrogenation of furfural to furfuryl alcohol (FA) and then to tetrahydrofurfuryl alcohol (THFA) over Ni. The microcalorimetric studies revealed that both the aldehyde group and furan ring were strongly adsorbed on Ni so that the Ni catalysts were highly active to hydrogenate the two groups, i.e., the Ni catalysts favored the formation of THFA. On the other side, although the adsorption heats of aldehyde group were much lower on Ni2P than on Ni, the adsorption heats were significantly higher for aldehyde group than for furan ring on Ni2P, implying the high selectivity to FA on Ni2P.