Deactivation mechanisms and anti-deactivation strategies of molecular sieve catalysts for NOx reduction

Molecular sieve catalysts, owing to their unique chemical properties, are widely used as catalysts among various catalytic reactions. Abundant Brønsted acid sites in molecular sieve catalysts usually enable active components to disperse well on the catalyst surface, and help to adsorb a large number of gas molecules to achieve maximum catalytic performance. Therefore, a variety of molecular sieve catalysts have been developed and used in the selective catalytic reduction of NOx by NH3 (NH3-SCR). For example, Cu molecular sieve catalysts such as Cu-SSZ-13 and Cu-SAPO-34 with wide temperature windows and stable structure are considered and applied as commercial catalysts for NOx removal in diesel vehicles for a long time. Although molecular sieve catalysts possess many advantages, they still cannot avoid the serious deactivation caused by various factors in practical applications. In this review, reasons leading to the deactivation of molecular sieve catalysts for NOx reduction in actual working conditions were concluded. The deactivation mechanisms of molecular sieve catalysts for NOx reduction were analyzed and the corresponding anti-deactivation strategies were summarized. Finally, challenges and prospects of molecular sieve catalysts for NOx reduction were also proposed.