Reaction rate enhancement of three‐phase hydrogenation using the Taylor flow reactor

Abstract

AbstractA gas–liquid–solid three‐phase reaction was conducted in a Taylor flow reactor to improve the apparent reaction rate by enhancing the mass transfer rate of the gas component to the surface of the solid catalyst through the liquid. Hydrogenation of α‐methyl styrene (AMS) was the model reaction. The reactor was an aluminum tube with a length of 300 mm and an inner diameter of 4 mm. A thin alumina layer was formed on the inner wall and palladium was used as the catalyst. Hydrogen and AMS were introduced into a T‐joint installed at the upper stream of the reactor to form a gas–liquid Taylor flow. The AMS conversion obtained using the Taylor flow was higher than that obtained without the flow. To examine the effect of the hydrogen absorption promotion by the circulating flow in the AMS slug, the total flow rate of the reactants was varied whereas the length of the gas and liquid slugs was maintained. Although the absorption increased owing to the faster surface renewal, only a slight improvement was observed. Conversely, when the total flow rate was fixed and the ratio of the gas slug length to the liquid slug length was increased, the apparent reaction rate improved significantly. These results indicate that diffusion in the thin liquid film directly toward the solid catalyst on the reactor wall was dominant for enhancing the reaction rate.