PURIFYING METHOD OF EXHAUST GAS FROM INNER COMBUSTION ENGINE AND CATALYST

摘要

PROBLEM TO BE SOLVED: To provide a catalyst with which NOx in a combustion exhaust gas of an inner combustion engine can be purified with high efficiency and which is hardly contaminated with SOx. SOLUTION: The catalyst used contains at least one element selected from alkali metals and alkaline earth metals in a form of a multiple oxide having lower standard free energy of formation than the standard free energy of formation when a sulfate is formed from the element. By using this catalyst, NOx in a lean-burn exhaust gas is chemically adsorbed or absorbed to the multiple oxide. Thereby. NOx can be purified with high efficiency and the catalyst is hardly contaminated with SOx.