Читать книгу Handbook of Biomass Valorization for Industrial Applications - Группа авторов - Страница 84

Glycerol dehydration is a promising technique for converting glycerol into useful chemicals such as acrolein and hydroxyacetone. Acrolein is used as a reactant for producing acrylic acid, while hydroxyacetone is used for the manufacturing of propanediol. The process is carried out either in the gas phase or in the liquid phase. Figure 4.8 depicts that the presence of a suitable acidic catalyst is necessary for the reaction. Several reports have shown that solid acid catalysts exhibit a higher selectivity towards acrolein; however, catalysts deactivation is the main problem [55]. Deactivation study indicates that polycondensed and cyclic C₆₊ generated due to reaction of glycerol with acrolein deposited inside the pores and block the active acidic sites. Therefore, the growth of a highly efficient and stable heterogeneous catalyst for the long-term stable transformation of glycerol to acrolein is still required.

Figure 4.8 Glycerol dehydration in the presence of acidic catalyst [55].

Very few studies have been reported on the carbon-based catalyst for glycerol dehydration. Lili et al. have utilized activated carbon-supported silicotungstic acid catalyst for the glycerol dehydration into acrolein. Activated carbon was selected as support due to its high surface area, superior stability over a wide pH range, and strong interaction with acidic silicotungstic material. The activity of the catalyst depends upon the loading of silicotungstic acid, its dispersion, and the relative amount of acidic sites. The catalyst with 10% loading showed the highest activity and selectivity [56].