No. 321: A new material for the purification catalyst for exhaust gas from a diesel engine (October 3, 2011)

The existing catalyst has a low purification rate in engine starting when exhaust gas temperature is, and the purification rate becomes stable when exhaust gas temperature grows high between 300-400 degrees centigrade. Mitsubishi Plastics developed a material for the catalyst that increases the ability to purify nitrogen compound in a low temperature between 150-200 degrees centigrade to 1.5 and 2.0 times higher than the existing catalyst. The purification rate is higher than 95% in a temperature higher than 200 degrees centigrade.

The new material is a kind of zeolite with tiny gaps, and it changes NOx into nitrogen as it works as a catalyst when it unites with a metal catalyst. The material is a kind of AQSOA, which is a Mitsubishi’s self-developed zeolitic absorption agent. The new material is being used as a water vapor absorption agent, and the company optimized it as the catalyst to be used for the urea SCR system, one of the exhaust gas purification technologies. The company found that it provides a higher NOx purification rate in low temperature than the supported-iron based catalyst. It is currently working on the combination between AQSOA and iron. The auto industry is energetically trying to find practical solutions for the control of NOx at low temperature to prepare for scheduled more stringent regulations on exhaust gas.