Honeycomb Supports, Filters and Catalysts for Cleaner Environment

Abstract

The extruded honeycomb supports, porous filters and catalyst monoliths are innovative ceramic products used in environmental protection. The development and applications of these novel materials and products are mainly driven by the environmental legislation in the region, the availability of technology, the mass manufacturing facilities and the cost effectiveness. This paper highlights some of the recent innovations and challenges in ceramic materials and design, and our findings in systematic understanding and applications of the principle of fabrication of honeycomb ceramics for various air pollution control systems in India. The use of locally available platy kaolin and advanced extrusion process control using rheological parameters of the paste are advantageously adopted for production of thin walled and high thermal shock resistant cordierite honeycomb supports for catalytic converters. The low cost design of diesel particulate filter (DPF) with off board electric regeneration system is found to be very effective in reducing the particulate emission in urban transport buses and proven for more than 100,000 km on Indian roads. The Ti-WV based SCR catalyst extruded in the form of honeycomb using high surface area TiO2 has shown high NOX reduction in coal fired boiler exhaust. The preparation of high surface area honeycombs from activated carbon and zeolites with adequate mechanical strength opens up new application areas. Some of the case studies on the above products and applications are presented in this paper.