Continuous recycled packed bed reactor technology: effect of liquid flowrate on arabinose oxidation

The catalytic oxidation of arabinose to arabinonic acid was investigated in a recycled packed bed reactor to address pH control issues in continuous processes. Packed bed reactors are pivotal in the valorization of biomass, making the shift from batch to continuous systems critical for industrial applications. The setup used 2.1% Au/γ-alumina catalyst extrudates and incorporated a tandem reactor system with a liquid recycling loop to maintain a controlled pH of 8, ensuring optimal reaction conditions. Experiments were conducted at a reactor temperature of 70 °C, with liquid flow rates of 40 and 70 mL/min. The results demonstrated that the liquid flow rate significantly influences the arabinonic acid production, particularly during the initial stages, where the overall reaction rate is flow rate dependent. The higher flow rate (70 mL/min) resulted in faster arabinonic acid formation, attributed to increased reactant-catalyst contact and improved mass transfer, which also mitigated potential catalyst deactivation. These findings highlight the importance of flow rate optimization for enhanced sugar acid yields in continuous reactor systems and underscore the need for further research to optimize the reactor design and operation.