Preparation, characterization and application of sulfonated mesoporous hollow carbon microspheres

Abstract

Mesoporous hollow carbon microspheres (MHCM) with high specific surface area was prepared by using a core–shell structured mesoporous material of SiO2@SBA-15 as hard template, sucrose as carbon precursor via inverse replica method. Then, MHCM was sulfonated by diazonium coupling to synthesize sulfonated mesoporous hollow carbon microspheres (MHCM-DS). TEM images showed that hollow carbon microspheres were successfully formed. The small angle XRD patterns of SiO2@SBA-15 and MHCM confirmed these two materials were ordered mesoporous material. BET surface area and pore diameter distribution results indicated that MHCM had an area of 620 m2/g and a double mesoporous with 2.7 nm and 3.4 nm pore diameter, respectively. After the MHCM being sulfonated, the area was reduced to 446 m2/g. In addition, pore diameter distributions of 2.7 nm and 3.4 nm were weakened, and new pore diameter distributions in the range of 5–10 nm were appeared meanwhile. Surface acid amount of sulfonated carbon microspheres (2.8 mmol H+/g) was higher than unsulfonation carbon microspheres (2.2 mmol H+/g). Besides, the FTIR result also demonstrated the existing of –SO3H. The catalytic activity of MHCM-DS was observed for transesterification and epoxidation reaction, respectively. For transesterification reaction, the highest yield of fatty acid methyl esters was 93 wt% at 180 °C in 6 h with 0.6 g catalyst amount. For epoxidation reaction, when reaction temperature was 40 °C and reaction time was 6 h, conversion and yield could both reach up to 50%.