Synthesis of iminodiacetic acid in a microchannel reactor

The features of the iminodiacetic acid (HIDA) synthesis by ehydrogenation of diethanolamine (DEA) on the Cu/ZrO2 catalyst in flow microchannel reactor in comparison with the synthesis in the autoclave are studied. It was found that the specific performance of reactors in terms of the reaction volume and weight of the catalyst in a microchannel reactor are 4,38 gHIDA/(cm3·h) and 0,49 gHIDA/ (g cat·h), respectively, while in an autoclave – 0,018 gHIDA/(cm3·h) and 0,46 gHIDA/(g cat·h). Analysis of kinetic data indicates that the synthesis of HIDA proceeds in two stages with the formation of an intermediate N-(2-hydroxyethyl)glycine (Bicine). A formal two-step kinetic scheme of this process and calculated apparent rate constants of stages are proposed. It was found that the apparent constants of rate of stages are magnitude greater in several orders for the microchannel reactor than the corresponding constants for the autoclave synthesis. Specific productivity, calculated for the reaction volume for the microchannel reactor, also higher in two orders of magnitude than for the autoclave, what is indicating that a substantial intensification of the process in the channels of sub-millimeter sizes due to the high efficiency of heat and mass transfer.

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