▎ 摘　　要

NOVELTY - Method for removing residual chlorine in an inorganic material, involves heat-treating inorganic material in a gas atmosphere containing moisture or soaking the inorganic material having residual chlorine in a base solution for a predetermined time, filtering, and drying. USE - The method is used for removing residual chlorine in inorganic material for producing SCR catalyst for reducing nitrogen oxides (claimed). ADVANTAGE - The method simplifies apparatus, and reduces installation cost, management cost, raw material cost. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a method for producing a selective catalytic reduction (SCR) catalyst for reducing nitrogen oxides, which involves supporting ruthenium and iridium on a support, where the residual chlorine amount of the catalyst is less than or equal to 2 mu mol/mg M per the weight of the supported metal; (2) a SCR catalyst for reducing nitrogen oxides in which ruthenium and iridium are supported on a support, where the residual chlorine amount of the catalyst is less than or equal to 2 mu mol/mg M per the weight of the supported metal; (3) a method for selective reduction of nitrogen oxides, which involves using the catalyst to selectively catalytically reduce nitrogen oxides; and (4) a selective reduction system of nitrogen oxides comprising the catalyst.