Technological Applications of Honeycomb Monoliths in Environmental Processes: A review

Abstract Honeycomb monoliths are carbon-based, ceramic or metallic structures, comprising a significant number of packed, small-in-diameter channels. One of the features associated with the honeycomb monoliths is the demonstrated low pressure drops in processes involving high flow rates. Honeycomb monoliths, with a range of structures, have found increasingly promising applications in various industries. Owing to their physical structures, they keep finding new applications in industrial treatment systems. They are mainly fabricated via two different techniques: extrusion and coating. Monoliths fabricated via each of these techniques demonstrate specific characteristics suitable for a certain number of applications. With the presence of cordierite substrate in the coated monoliths, higher mechanical strength of coated honeycomb monoliths is expected when compared to the integral monoliths. The coated monoliths are suitable when mechanical strength is of importance where the adhesion of the thin layer coating on monoliths is a determining factor in the performance of the entire process. The integral monoliths are most-commonly employed in gas-phase processes rather than liquid phase applications due to their high accessible surface area per total weight (or volume) of the monoliths. Embedding mesoporous carbon coating and nanoparticles into honeycomb monoliths has improved the efficiency of monoliths in comparison to the more conventional preparation methods.