ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

The influence of NO_x presence on the catalytic N₂O decomposition over the supported double-promoted cobalt spinel catalyst

Marek Inger, Jakub Rajewski, Monika Ruszak, and Marcin Wilk

New Chemical Syntheses Institute, Puławy, Poland

E-mail: jakub.rajewski@ins.pulawy.pl

Abstract: The supported double-promoted cobalt spinel catalyst has been tested for N₂O decomposition in the model and real gas streams (tail gas) from nitric acid plant. Activity tests carried out in the model gas stream showed a high activity of the developed supported catalyst. However, during catalytic investigations performed under real industrial conditions it was found that this catalyst is very sensitive to NO_x poisoning. The negative influence of these oxides is visible even at their low concentration. However, the stability tests performed in real nitric acid plant gas streams showed that the developed catalyst preserves its initial activity for at least 40 days. Therefore, the authors propose to apply it in a dual-bed catalytic system consisting of deNO_x and deN₂O catalyst beds. At the first stage, tail gas is purified from NO_x in the NH₃-SCR process in the presence of commercial catalyst and at the second stage, catalytic decomposition of N₂O into N₂ and O₂ takes place over the developed supported cobalt spinel catalyst. The deNO_x catalyst bed applied in the proposed dual-bed catalytic system allowed for the complete conversion of NO_x from the tail gases. After installation of the supported cobalt spinel catalyst downstream of the deNO_x catalyst bed, a significant increase in deN₂O catalyst activity in the real tail gas stream was observed. Under optimal conditions, this system (F = 150 L/h; T = 425–450 °C) allowed for the complete reduction of N₂O emission. It is shown that the proposed catalytic system is robust and allows to obtain high conversions of both NO_x and N₂O.

Keywords: Low-temperature N₂O decomposition ; Supported cobalt spinel catalyst ; Dual-bed catalytic reactor 

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-019-00750-9

Chemical Papers 73 (8) 1979–1986 (2019)