Catalytic fructose dehydration to 5-hydroxymethylfurfural over sulfonated carbons with hierarchically ordered pores

Sulfonated carbons with hierarchically ordered pores (SCHOP) were prepared by means of dual template self-assembly, carbonization, HF etching, and sulfonation. The effect of carbonization temperature on microstructure of the prepared carbons as well as the SCHOPs were surveyed at 500-700℃. Using fructose dehydration to 5-hydroxymethylfurfural as a probe reaction, catalytic performance of SCHOPs was examined. The results show that SCHOP-500 carbonized at 500℃ exhibits the highest catalytic activity. SEM and TEM characterization as well as N₂ adsorption desorption show that all of the SCHOPs possess hierarchically ordered macropores and mesopores, but high carbonization temperature damages the regularity of carbon materials slightly. FT-IR, EDS and -SO₃H determination confirm that sulfonic acid group could be successfully introduced to carbon materials by sulfonation. However, high carbonization temperature lowers aromaticity of the carbon materials, and as a result leading to low sulfonation degree. Under the catalysis of SCHOP-500, as high as 93.4% of 5-HMF yield with 96.1% fructose conversion rate is achieved after reacting at 130℃ for 20 min, indicating that SCHOP-500 is a highly effective and efficient solid acid catalyst.