Hydrogen Peroxide Direct Synthesis: Selectivity Enhancement in a Trickle Bed Reactor

H2O2 direct synthesis over a palladium catalyst based on sulfated ceria (Pd-CeS) has been studied in a trickle-bed reactor at - 10 degrees C. The combined effect of liquid and gas flow rates was studied by independent variations. The maximum productivity and selectivity was always found at flow rate combinations intermediate within the investigated range. The reactor operated under pressure and its effect was investigated (10 and 20 bar), resulting in a significant gain in selectivity. Selectivity up to 80% has been measured at the highest pressure tested (20 bars), liquid flow rate of 2 mL/min, and 6 mL/min gas flow rate. The maximum production rate measured was 0.0035 mmol/min with 0.5 mL/min liquid flow rate and 2.7 mL/min gas flow rate. Relevance of direct water formation has been isolated by independently investigating H2O2 decomposition and hydrogenation. Results indicate directions of further performance improvements and the importance of reactor type and operation.