Structure-activity correlations of LiNO3/Mg4AlO5.5 catalysts for glycerol carbonate synthesis from glycerol and dimethyl carbonate

MgAl hydrotalcite synthesized via co-precipitation method from magnesium and aluminum nitrates was calcined to produce Mg4AlO5.5 mixed oxides. The oxides were modified by introducing LiNO3 and applied to the synthesis of glycerol carbonate from glycerol and dimethyl carbonate. The research results indicated that LiNO3/Mg4AlO5.5 was an efficient catalyst for the synthesis of glycerol carbonate. The full conversion of glycerol and 96.28% yield of glycerol carbonate were obtained after reacting at 80 °C for 1.5 h in the presence of LiNO3/Mg4AlO5.5. The structure and properties of the catalysts were studied by means of XRD, TGA, BET, CO2-TPD and Hammett indicator method. It was found that the basic strength and the basicity of the catalysts were enhanced after addition of LiNO3. Over Mg4AlO5.5 oxides, LiNO3 was easily converted to LiAlO2 which constituted new strong basic sites. Too high basic strength and basicity of catalysts may improve the conversion of glycerol at the cost of GC selectivity reduction.