Catalyst Synthesis Via the Strong Electrostatic Adsorption Method

The strong electrostatic adsorption (SEA) method of catalyst synthesis leverages electrostatic attraction to achieve catalysts with a small particle size and high surface area. SEA requires no specialized materials or equipment and is scalable so it is promising for extending lab-scale studies to industry. SEA leverages the pH difference between a metal solution and the point of zero charge (PZC) of a support. While the overall procedure for SEA is gleaned from literature, we address several challenges to adapt this method for use in the Porosoff group. These challenges are determining the PZC of a support, selecting the optimal pH of the metal solution depending on the PZC, and calculating the mass of support needed for synthesis. We find that PZC can be determined by adding support to solutions of different pH, shaking, measuring the final pH of each solution, and finding the intersection between the best fit line of initial vs final pH and ΔpH = 0. Optimal relative pH is calculated using the revised physical adsorption (RPA) method. After addressing these procedural challenges, synthesis is performed on activated carbon as a surrogate for a carbon-based Joule heater monolith. CO chemisorption and temperature programmed desorption are used to characterize the catalyst. Some challenges that occur during synthesis trials are the formation of a precipitate due to a reaction between the metal ions and the acid and base used to adjust pH, high pH causing silica-based supports to dissolve, and small particle sizes making filtration difficult for some syntheses. These studies on activated carbon are important proof of concept for extending our work to Joule heaters, which are promising for industrial decarbonization due to their low energy requirement for heating compared to traditional steam-based heating. SEA is a promising method of catalysis for Joule heaters due to its scalability and applicability to any surface shape.