. . . "The selective non-catalytic reduction (???SNCR???) of NOx with a reducing agent such as ammonia or urea requires a relatively high temperature, e.g., in the range of from about 1600??? F. to about 2100??? F. [0006] Alternatively, the reduction of NOx with ammonia can be performed catalytically at a much lower temperature, e.g. from about 500??? F. to about 950??? F., in a process known as selectiv" . .