CATALYST FOR CLEANING EXHAUST GAS AND EXHAUST GAS CLEANING

摘要

PROBLEM TO BE SOLVED: To maintain the NOx cleaning performance at a high level over the range of temperatures from high to low by preventing alkali metals from being transpired in vapor when exposed to high temperatures. SOLUTION: This catalyst for cleaning an exhaust gas absorbs NOx contained in an exhaust gas in an oxygen-rich atmosphere and cleans by reducing NOx absorbed at a chemical equivalent point or in a reductive atmosphere with the help of a reductive component. In addition, the catalyst is composed of a porous carrier and at least, either of Zr or Si and a catalytic noble metal carried on the porous carrier and Cs. The content ratio of Zr to Cs is 0.05-2 in terms of molecular ratio, and that of Si to Cs is 0.003-1. Since Zr or Si is compounded with Cs, the transpiration of Cs in vapor at high temperatures can be prevented from occurring.