Urea Complete Conversion to Compound Fertilizer in Industrial‐scale Tandem Reactors

A compound fertilizer with NH4H2PO4 and KH2PO4 offer significant advantages in enhancing both crop yield and quality. Ammonia (NH₃) is essential for the synthesis of the compound fertilizer, which was produced by an energy intensive chemical process. Developing efficient and environmental friendly methods to produce ammonia‐containing compound fertilizers is crucial and extremely challenging. Here, we present a tandem catalysis system capable of achieving complete conversion of abundant urea into compound fertilizer in industrial‐scale reactors by combining electrochemical and subsequent chemical processes. In a typical cycle, with the use of 200 g urea, 1580 g of solid compound fertilizer (KH2PO4 and NH4H2PO4) and 232 L of pure H2 are produced without any further separation process. The key to the realization of this system is to precisely control the rate of urea consumption and NO2‐ formation in electrochemical process. By maintaining a precise molar concentration ratio of urea to NO2‐ at ½ in electrolyte, urea can completely react with NO2‐ to form N2, while CNO‐ can be converted into NH4+ to form compound fertilizer in the second step of H3PO4 treatment, achieving complete conversion of urea without by‐products formation.