Continuous Operation of Upflow Reactors for Hydrogenolysis in Gas-Liquid-Liquid-Solid Four Phases.

Abstract

We have observed deprotection of amino acid in a four-phase stirred tank reactor (Yamada et el., 1996) and in a four-phase trickle-bed reactor, that is, a gas-liquid cocurrent downflow tubular reactor (Yamada and Goto, 1997). The reactant could be dissolved in an organic phase and hydrogenated to a product using a Pd/C solid catalyst. The product had to transfer to an aqueous phase from the catalyst because it could not dissolve in the organic phase. In continuous operation of the trickle bed reactor, the product was deposited on the catalyst surface because organic and aqueous solutions flowed in separate rivulets. Some sections of catalyst could not come into contact with distilled water. Catalytic activity decreased with time due to the deposition. Periodic operation was adopted to solve this problem. Continuous operation is superior to periodic operation in industrial applications. For this purpose, in this work, deprotection of amino acid in a gas-liquid cocurrent upflow tubular reactor is investigated. We expected that organic and aqueous solutions can flow homogeneously in this type of reactor and that deposition will not occur.