Patent ID: 6866834

Claim:
A NOx reduction catalyst for exhaust gas discharged from a combustion device operable in a lean region and in a range including a stoichiometric region and a rich region, the NOx reduction catalyst comprising: a refractory inorganic substrate; a catalytic noble metal; a NOx absorbing material which is a metal comprising barium and magnesium, supported on said refractory inorganic substrate, at least a part of said metal comprising barium and magnesium forms a double carbonate represented by the following general formula: Ba x Mg y (CO 3 ) 2 where x and y are atom ratios in which x=0.5 to 1.999; y=0.001 to 1.5; and x+y=2.0; and an oxygen adsorbable and releasable material which carries at least a part of said catalytic noble metal, wherein said catalytic noble metal carried on the oxygen adsorbable and releasable material adsorbs SOx in the exhaust gas, in a form of at least one of sulfate and sulfite.