A pervaporation photocatalytic reactor for the green synthesis of vanillin

Pervaporation is the ideal membrane separation process to be coupled with photocatalysis for the green synthesis of vanillin from ferulic acid. In fact the operative conditions of the two processes are absolutely congruent and the integration is straightforward even operating with separate equipments. The utilization of a highly selective membrane allows the continuous recovery of vanillin by pervaporation from the reacting solution, so that its oxidative degradation is largely avoided and the yield is substantially enhanced. The effects of the main parameters are analyzed resorting to a mathematical model, which is validated by a comparison with the experimental data. In particular it is demonstrated that an optimal value of the ratio of the rate of pervaporation to the rate of reaction maximizes the “intensification” of the process. Other benefits of the integrated process, such as the complete retention of the photocatalytic powder in the reacting solution and high degree of purification of the product are presented and discussed.

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► Photocatalysis and pervaporation can be straightforwardly coupled in an integrated “green” process to produce vanillin.
► Vanillin is recovered by pervaporation while it is produced to prevent its oxidative degradation.
► The yield of the process is highly enhanced.
► The permeate is enriched in vanillin and is absolutely free of the photocatalytic fine particles.
► The ratio of the characteristic rate of pervaporation to the one of reaction is a key parameter.