Tandem catalytic conversion of glycerol using solid catalysts followed by transesterification to produce alkyl lactate

Abstract

This study investigated alkyl lactate production from glycerol by tandem processes which included glycerol conversion to calcium lactate using solid catalysts and subsequent transesterification of calcium lactate to alkyl lactate using methanol/ethanol and carbon dioxide. The effect of reaction conditions on alkyl lactate production was systematically investigated. A central composite design (CCD) and response surface methodology were used to design the experiments and evaluate the optimum process conditions. At the optimum condition, the methyl lactate yield reached 57 mol% with a glycerol conversion of 94 mol% using refined glycerol. A yield of approximately 42 mol% for ethyl lactate was obtained using refined glycerol at the optimum condition. Similar glycerol conversion and alkyl lactate yields were obtained using crude glycerol, indicating that the impurities in the crude glycerol had no significant effects on alkyl lactate production. The examination of regenerated catalysts that had been reused twice showed no negative effects on glycerol conversion and methyl lactate production.Compared to the traditional lactic acid and alkyl lactate production, this two-step process for alkyl lactate production from glycerol is both economical and environmentally benign since no gypsum was produced and the solid catalysts can be regenerated and reused.

Fe-Doped SnO2catalysts with both BA and LA sites: facile preparation and biomass carbohydrates conversion to methyl lactate MLA

“…In view of these drawbacks, it is important to develop heterogeneous catalytic routes for the production of MLA from biomass. It has a higher rate of reaction and allows the use of more types of biomass feedstocks such as glycerol, 19 fructose,…”

Glycerol in subcritical and supercritical solvents

“…Further experiments allowed the authors to solve the problem by reducing water to the role of an additive. The same group subsequently developed a method using a glycerol solution, with only 33 wt% of water, and a catalytic system with NaOH and CuO, always in a batch reactor . Ye and co‐workers afforded 96% conversion at only 473 K, with good selectivity, and then partially extracted the intended product by transesterification.…”

The conversion of glycerol to methyl lactate catalyzed by tin‐exchanged montmorillonite‐supported gold catalysts

“…Therefore, one‐pot direct conversion of glycerol into methyl lactate with methanol as solvent is a very attractive process. Yet only a limited number of works have been reported so far on the direct transformation of glycerol to methyl lactate in methanol …”

“…Yet only a limited number of works have been reported so far on the direct transformation of glycerol to methyl lactate in methanol. [20][21][22] Nevertheless, the advancement in efficiency for the direct conversion of glycerol to methyl lactate in methanol requires more active, cost-effective and environmentally-friendly metal-acid bifunctional catalysts. Montmorillonite (Mt) is a low-cost layered material with high specific surface area, outstanding adsorption ability, great cation-exchange capacity, and flexible and tunable acidity.…”