Periodic open cellular structures (POCS) as enhanced catalyst supports: Optimization of the coating procedure and analysis of mass transport

Aluminum periodic open cellular structures (POCS) of cylindrical shape (9 mm diameter and 4−25 mm length) manufactured by investment casting were investigated as potential enhanced catalyst carriers. Samples with an ideal cubic cell geometry and different cell sizes - namely 1.5, 1.75 and 2.25 mm - were tested. First, coating experiments were performed aiming at understanding the wet coating deposition process: the influence operative spin coating parameters (i.e. spinning speed, time, acceleration) on final coating thickness was studied using glycerol solutions of different viscosity. Based on this preliminary investigation, POCS were activated by depositing a Pd/CeO2 catalyst by slurry coating techniques and tested under mass-transfer limited conditions in CO oxidation, used as a test reaction for gas/solid limited heterogeneous processes. A correlation for mass transfer performances of these structures in function of the Reynolds number is herein presented and used to compare these novel materials against conventional catalyst supports.