Ni-supported catalysts on mesoporous carbon modified by Al(H2PO4)3 to obtain 1-propanol

Abstract

The aim of this work was to investigate the catalytic properties of nickel over a carbon-based support modified with phosphorus for the hydrogenolysis of glycerol to obtain 1-propanol. For this, a series of nickel phosphide catalysts with different compositions were prepared employing Al(H2PO4)3 and NiCl2 supported on mesoporous carbon and characterized by N2 adsorption-desorption, acid-base properties measurements, TEM, XRD and XAFS analysis. These Ni catalysts presented different phases (NixPy, NiPOx, AlPOx), responsible of the increase in surface acidity, which depended on the Al(H2PO4)3 content. For Al(H2PO4)3 contents between 4 and 10 wt.%, an increase in surface acidity occurs that favors both the conversion and the selectivity of glycerol towards 1-propanol. These results show that the presence of the phosphates is necessary to reach high levels of catalytic activity. However, for Al(H2PO4)3 contents higher than 10 wt.%, a fall or loss of selectivity was produced due to the strong contribution of dehydration reactions on the support acid sites. The Ni/CPAl(10) catalyst, allows reaching 97 % conversion of glycerol with a selectivity of 74 % towards 1-propanol, employing an 80 wt.% glycerol aqueous solution, after 6 h of reaction.