Glucose Oxidation in Slurry Reactors and Rotating Foam Reactors

Abstract

Glucose oxidation using platinum promoted by bismuth was studied as a three-phase model reaction. Using catalyst nanoparticles and measuring the oxygen concentration in the bulk liquid, the kinetic parameters and mass transfer characteristics were determined at a temperature of 333 K. The overall reaction rate was studied experimentally using three different support types: slurry catalysts, pellets, and a solid foam stirrer. The glucose conversion rate and the deactivation rate of the catalyst depend strongly on the ratio between mass transfer and reaction rate. At low catalyst concentrations, the glucose oxidation process is liquid–solid mass-transfer-limited. The block stirrer shows a superior performance over the slurry catalysts due to the high liquid–solid volumetric mass transfer coefficient. The bimodal pore size distribution of the catalyst layer further increases the conversion rate. Using slurry catalysts, a loading of 1 wt % in combination with pure oxygen feed is required to achieve acceptable conversion rates. Under these conditions, the gas–liquid mass transfer and partially the liquid–solid mass transfer are the rate-limiting steps. The foam block stirrer shows good gas–liquid mass transfer rates and high liquid–solid mass transfer rates, which still increase at high power input. Working under external mass transfer control and using this stirrer type, the catalyst loading can be strongly reduced to loadings less than 0.4 wt %, while the conversion rate remains comparable to slurry particles with loadings of 1 wt %. As the catalyst is fixed, attrition and agglomeration in high viscosity liquids are circumvented. There is further no need for filtration, and the catalyst can simply be reused.

Micromixing efficiency in a multiphase reactor with a foam block stirrer

“…In recent years, RFR has received a lot of research interest due to its higher mass transfer rates between gas‐liquid and liquid‐solid phases compared to the Rushton stirrer reactor and slurry reactors . Tschentshcer et al showed that the RFR achieved a gas‐liquid mass transfer rate of 0.19 s −1 of k GL a GL using the oxygen‐water system, which was 50 % better than that obtained in the Rushton stirrer.…”

Deactivation of solid catalysts in liquid media: the case of leaching of active sites in biomass conversion reactions

“…This is the case in some reactions of oxidation of alcohols in liquid medium. 43,44 Occasionally, a change of phase 35 of the support during the reaction can have a beneficial effect, as in the case of alumina-supported Ptplatinum catalyst in APRthe aqueous phase reforming of glycerol. Here, the initial alumina forms bohemite, which is active in the reaction of dehydration of glycerol.…”

Kinetic Study of Heterogeneously Catalyzed Glucose Oxidation in a Stirred Cell

“…The formation of fructose can be neglected below a reaction temperature of 70°C [11]. A control sample analyzed by HPLC (RI and UV/Vis detector) showed no fructose or other by-products.…”

“…Kinetic performances are mainly investigated in slurry reactors [11 -14], but spinning disc reactors [15], rotating foam reactors [11], or internal loop airlift reactors [16] are also used. Tschentscher et al [11] showed the influence of process conditions on the reactor performance. Due to the low solubility of oxygen in water solutions, the mass transfer of the oxygen to the catalyst is often rate determining.…”