Patent ID: 8048390

Claim:
A process for selective catalytic reduction of nitrogen oxide which is present in exhaust gas of a motor vehicle, by ammonia, comprising catalytically decomposing at least one guanidine salt with an ammonia formation potential of from 80 g/kg to 850 g/kg in solution, in the presence of a catalytically active oxidation inactive coating of at least one oxide selected from the group consisting of titanium dioxide, aluminum oxide, and silicon dioxide, or a hydrothermically stable zeolite to form ammonia, and contacting said ammonia to said exhaust gas, upstream of an SCR catalyst, and downstream of an engine, wherein said guanidine salt has the formula: wherein R is H, NH, or C 1 -C 12 -alkyl, and X − is selected from the group consisting of acetate, cyanate, formate, hydroxide, methoxide and oxalate.