Abstract:
The catalysts of CuZnAl-1, CuZnAl-2 and CuZnAl-3 were prepared by the co-precipitation method using NaOH, Na
2CO
3 and Na
2CO
3/NaOH, respectively, as the precipitant. They were characterized by X-ray diffraction (XRD), N
2 adsorption-desorption, H
2-temperature programmed reduction (H
2-TPR), TGA, and NH
3-temperature programmed desorption (NH
3-TPD); the effect of precipitant on the performance of CuZnAl catalysts in the gas phase selective hydrogenation of furfural to furfuryl alcohol was then investigated in a fixed bed reactor. The results illustrate that all three catalysts exhibit high furfural conversion, whereas the CuZnAl-3 catalyst gives the highest selectivity to furfuryl alcohol. The precipitant has a great impact on the phase structure, surface area, acidity and redox property of the resultant CuZnAl catalysts. The CuZnAl-3 catalyst prepared with Na
2CO
3/NaOH precipitant exhibits proper specific surface area, CuO crystalline phase, weak acid sites and easily reducible CuO on the catalyst surface, which are conducive to produce furfuryl alcohol for the hydrogenation of furfural. Under the optimizing reaction condition, viz., atmospheric pressure, 180℃, hydrogen to furfural molar ratio of 5 and furfural volume space velocity of 0.3h
-1, the conversion of furfural over the CuZnAl-3 catalyst reaches 99.4%, with a selectivity of 98.3% to furfuryl alcohol.