Real Time Phase Imaging AFM of Palladium-Decorated Membranes for Hydrogenation

Heterogeneous catalysis for hydrogenation in the liquid phase is important in many industrial processes, and in emerging areas in bio-based renewable energy. Hydrogen mass transfer through the liquid phase to the catalytic sites is hampered by the low solubility of hydrogen in liquids. Hydrogen starvation of the catalyst can cause unwanted reactions, poor selectivity, and coking. Hydrogen supply directly to the catalyst palladium deposited on an integral-asymmetric membrane can alleviate mass transfer issues and decouple the liquid-phase hydrostatic pressure from the hydrogen supply to the catalyst. Phase imaging atomic force microscopy (AFM) can detect the appearance of hydrogen on the palladium in the liquid phase in real time, and is applied to track a hydrogenation reaction. This application of AFM opens new avenues to study liquid-phase catalysis over metals in real time, with nanometer-scale resolution.