Selective catalytic reduction articles and systems

A method for identifying a catalytic material that is stable toward aging, the method comprising:

• providing a plurality of samples that each comprise particles of a copper-containing molecular sieve in a fresh state containing ion-exchanged copper as Cu+2 cations and as Cu(OH)+1 cations;
• subjecting the particles of the copper-containing molecular sieve in a fresh state to Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy so as to evaluate perturbed T-O-T asymmetric stretching vibrational peaks corresponding to the Cu+2 cations in the copper-containing molecular sieve and perturbed T-O-T asymmetric stretching vibrational peaks corresponding to the Cu(OH)+1 cations in the copper-containing molecular sieve;
• and
• selecting one or more of the samples wherein the copper-containing molecular sieve in a fresh state exhibits a ratio for an integrated peak area of the perturbed T-O-T asymmetric stretching vibrational peak corresponding to the Cu+2 cations to an integrated peak area of the perturbed T-O-T asymmetric stretching vibrational peak corresponding to the Cu(OH)+1 cations that is ≥1.

A method of manufacturing a catalytic article, the method comprising

• developing a process for preparing a first composition comprising copper-containing molecular sieves in a fresh state;
• analyzing at least a sample of the first composition using DRIFT spectroscopy to determine the relative amount of Cu+2 and Cu(OH)+1 in the first composition based on a comparison of intensities of perturbed T-O-T asymmetric stretching peaks corresponding to the Cu+2 and Cu(OH)+1;
• selecting the process for commercial manufacturing of the first composition if the contribution by the perturbed T-O-T asymmetric stretching peak corresponding to Cu+2 to the total integrated peak areas of the perturbed T-O-T asymmetric stretching peaks is ≥50%;
• and
• applying the commercially manufactured first composition made by the process to a substrate to produce the catalytic article.