Search

A series of Cu–Ca–Al hydrotalcite derived catalysts were prepared by the co-precipitation method. Their catalytic activities were evaluated in the hydrogenolysis of glycerol. The catalysts were characterized by XRD, SEM, TEM, ICP, NH3-TPD, CO2-TPD and H2-TPR. It was observed that the incorporation of calcium and aluminum in the Cu–Ca–Al catalyst improved the conversion of glycerol and promoted the generation of 1,3-PDO. This is due to the appropriate acidity and basicity of the catalyst, which is confirmed by NH3-TPD and CO2-TPD. The conversion of glycerol over the catalyst with a Cu–Ca–Al mole ratio of 1:3:5 was up to 73.2 % with 42.6 % selectivity to 1,2-PDO and 9.1 % selectivity to 1,3-PDO. Effects of the reaction time, reaction temperature and initial hydrogen pressure on the conversion and selectivity were systematically investigated.

By combing ZnO with the silicon hydroxyl in USY, a series of Cu/ZnO-USY catalysts with both acid and base sites were prepared with the precipitation method and used in the hydrogenolysis of glycerol to propanediol. The Cu/USY and Cu/ZnO catalysts were also prepared with the same method and used as blanks. These catalysts were fully characterized with TEM, SEM, BET, XRD, NH3-TPD, CO2-TPD and H2-TPR. The combination of ZnO with the surface silicon hydroxyl of USY generated new “core–shell like” structure and introduced base sites. This newly formed structure made the Cu particle (10 nm) highly dispersed on the catalyst and the acid–base co-operativity accelerated the glycerol dehydration and led to higher glycerol conversion and 1,3-propanediol (1,3-PDO) selectivity with much short time (5 h). Catalyst deactivation was also investigated, mainly caused by the increase of the Cu particle size during the hydrogenolysis process.

A series of dealumination ultrastable Y-type zeolite (DUSY) supported Cu catalysts with different Cu loadings were prepared, characterized and tested in the hydrogenolysis of glycerol. The results showed that DUSY retained the Y zeolite structure and generated abundant of secondary mesoporous, which not only facilitated the 1,2-propanediol (1,2-PDO) to diffuse out the catalyst, but also improved the dispersion of Cu. Cu/DUSY catalyst exhibited single weak acid sites and unique reduced structure of Y type zeolite and resulted in a more concentrated product distribution, primarily 1,2-PDO with few glycols.