Selective catalytic reduction with ammonia (NH3-SCR) is an effective method to eliminate nitrogen oxides (NOx) in oxygen excess for stationary and mobile applications. Titaniasupported vanadia catalysts, promoted by tungsten, are traditionally used for NH3-SCR. This type of catalyst is effective in the temperature range 300-450°C, however, the efficiency to reduce NOx decreases at both lower and higher temperatures. The efficiency of the NH3-SCR process can be significantly improved by using catalysts based on copper-exchanged zeolites and zeotypes, due to their high activity around 200°C. This type of catalysts can efficiently be prepared by solid-state ion-exchange in a mixture of copper oxide and zeolite/zeotype, however the process usually requires high temperatures, typically above 700°C. The ion-exchange can be considerably affected by appropriate choice of atmosphere during the process [1-4]. Here we show that the copper-exchange is possible at unprecedented low temperatures, as low as 250°C, in presence of ammonia. The influence of the treatment conditions on the copper-exchange and the mechanism of the reaction-driven ion-exchange process will be presented and discussed. Such copper-exchanged zeolite/zeotype structures with high copper loading are potentially interesting catalysts for a number of technical applications.

Copper mobility in zeolite-based SCR catalysts

2019 Spring National Meeting

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