Patent ID: 7635593

Claim:
A test module for evaluating localized catalytic activity in a selected section of a solid catalyst layer in a selective catalytic NO x reduction (SCR) unit, said test module comprising: first and second sampling probes, means for mounting said first and second sampling probes to said SCR unit upstream and downstream, respectively, of said catalyst section, and means for drawing samples of gas through said first and second sampling probes for analysis; a reductant supply probe, means for mounting said reductant supply probe to said SCR unit upstream of said catalyst section at a location causing reductant from said reductant supply probe to selectively strike said catalyst section, and means for supplying reductant to said reductant supply probe; and barrier walls forming a lateral enclosure sized to encircle said catalyst section and to thereby prevent reductant flow from said reductant supply probe from diverging from said catalyst section.