Engineering of Nitrogen Oxides Catalytic Removal in Mineral Fertilizer Industry

Removal of nitrogen oxides from the tail gases is a key challenge for manufacturing nitric acid and mineral fertilizers. Application of such high-performance SCR (selective catalytic reduction) catalyst as АОК-78-55 allows to solve the challenges of industrial ecology.

Currently, the only industrial method of producing nitric acid is the catalytic oxidation of ammonia followed by absorption of the resulting nitrogen oxides with water. Non-concentrated nitric acid is further used for manufacturing mineral fertilizers and after the absorption stage the heated residual nitrogen oxides enter the SCR reactor to be mixed with ammonia, and in the result of the SCR process, harmless molecular nitrogen, N2, and water are discharged into atmosphere. Thus, the process of manufacturing the nitric acid and mineral fertilizers is almost harmless to the environment and human health. However, the real situation is quite different. SCR reactors, which must operate efficiently to provide the required residual NO_x amount of 0.006% (vol.) fail to ensure the required removal efficiency (NO_x conversion) as a result of using low quality catalysts.

Since the 1990s, Katalizator JSC has been developing the catalysts for SCR process. In 1995, the first delivery of АОК-78-21 alumina palladium catalyst for high-temperature reduction of nitrogen oxides for the АК-72 unit was made to Azot enterprise in Kemerovo, Russia, as the competitive catalyst to the well-known АPК-2 catalyst. At the same time, AOK-78-55 alumina vanadium catalyst was developed for selective reduction of nitrogen oxides, and in 1999 the first batch of the catalyst was supplied to JSC Nevinnomysskiy Azot. Later, the catalyst АОК-78-55 was modified to improve catalytic activity and reduce pressure loss, and production of four grades of the catalyst started in the form cylindrical extrudates and rings (АОК-78-55, АОК-78-55К, АОК-78-55М, and АОК-78-55КМ), thus providing options to the prospective customer.

Today, the Company has taken the next step – has developed its SCR (DeNO_x) engineering expertise. By using the advanced scientific equipment and based on the SCR reactor process data, our experts can provide calculations and the reactor operation modelling, perform the required measurements and studies, accomplish R&D to address production and environmental challenges. Installation of the research facility with extended configuration has made it possible to test both fresh catalysts and catalysts after long-term operation in the reactors, thus enabling the development of best solution for SCR reactor loading to ensure the required removal efficiency.

Presently, the knowledge of JSC Katalizator allows to develop customized and package solutions to address production challenges in design improvement of the treatment and emission abatement reactors.