Egg-shell Pd@Al2O3 is the most common catalyst for the catalytic hydrogenation of 2-alkylanthraquinone on the industrial scale because of their virtues of maximizing the utilization of the precious metal. The palladium particles preformed by microemulsion method were deposited onto the alumina which differ from the hydrophobic nature and textural properties. In this method polyoxyethylene(7–8) octylphenyl ether was used as surfactants, from which palladium metal nanoparticles (ca. 2.3–2.5 nm) exhibit a narrower size distribution and higher extent of palladium reducibility compared with the typical Pd@Al2O3 currently used in industrial plants. Transmission electron microscopy, digital microscopy, H2–O2 titration, and other chemisorptions results clearly indicate that both the polarity of the support surface and preformed vacancy of the shell thickness affect the palladium migration process, which further determines its final aggregation in the egg shell. Extensive particles were found to be aggregated when palladium ions–water solution was typically employed, yet highly dispersed palladium particles were observed when the microemulsion method was applied due to the inhibition effect on the migration and aggregation process of primary particles. In the obtained 0.3%Pd@Al2O3 pretreated with polyoxyethylene(7–8) octylphenyl ether/cyclohexane microemulsion, a sharp active metal boundary and high dispersion of palladium were observed and hence, the obtained catalyst exhibited profitable activity, selectivity, and product distribution for 2-ethylanthraquinone hydrogenation.

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Hydrogen peroxide is currently manufactured almost exclusively by the cyclic auto-oxidation (AO) process. It is important that the working solution meet the requirement for efficient operations for all steps involved in the cycle and that it chemically produces as great a yield as possible per pass through the cycle. Focusing on these requirements, organic heterocyclic bisamide solvent is proposed and systematically investigated in this work as one working solution component for industrial improvements. Specifically, N,N,N,N-tetrapropyl malonamide is selected as the novel working solution constituent for experimental investigation. From the foregoing experiments, the novel working solutions exhibits a favorable dissolving power for 2-alkylanthraquinones and their corresponding hydroquinone derivatives, great holdup ability for hydrogen, and more advantageous volumetric mass transfer coefficient brought by its physicochemical nature. In favor of these advantages, the kinetics apsect of 2-alkylanthraquinone is observed to be significantly improved. This is characterized by the apparent reaction rate constants, which are substantially in favor of the hydrogenation stage, and in the working compounds hydrogenation is always considered to be the key step for AO process. As a result, improvement in the hydrogenation efficiency of 2-alkylanthraquinone and the hydrogen peroxide yield per cycle are thus obtained in novel working solvents compared with the traditional ones.