The nitrogen cycle needed for scaled agriculture relies on energy- and carbon-intensive processes and generates nitrate-containing wastewater. Here we focus on an alternative approach-the electrified co- electrolysis of nitrate and CO2 to synthesize urea. When this is applied to industrial wastewater or agricultural runoff, the approach has the potential to enable low-carbon-intensity urea production while simultaneously providing wastewater denitrification. We report a strategy that increases selectivity to urea using a hybrid catalyst: two classes of site independently stabilize the key intermediates needed in urea formation, *CO2NO2 and *COOHNH2, via a relay catalysis mechanism. A Faradaic efficiency of 75% at wastewater-level nitrate concentrations (1,000 ppm NO3- [N]) is achieved on Zn/Cu catalysts. The resultant catalysts show a urea production rate of 16 mu mol h(-1) cm(-2). Life- cycle assessment indicates greenhouse gas emissions of 0.28 kg CO(2)e per kg urea for the electrochemical route, compared to 1.8 kg CO(2)e kg(-1) for the present-day route.

Selective electrochemical synthesis of urea from nitrate and CO2 via relay catalysis on hybrid catalysts / Y. Luo, K. Xie, P. Ou, C. Lavallais, T. Peng, Z. Chen, Z. Zhang, N. Wang, X.-. Li, I. Grigioni, B. Liu, D. Sinton, J.B. Dunn, E.H. Sargent. - In: NATURE CATALYSIS. - ISSN 2520-1158. - 6:10(2023 Oct), pp. 939-948. [10.1038/s41929-023-01020-4]

Selective electrochemical synthesis of urea from nitrate and CO2 via relay catalysis on hybrid catalysts

I. Grigioni;
2023

Abstract

The nitrogen cycle needed for scaled agriculture relies on energy- and carbon-intensive processes and generates nitrate-containing wastewater. Here we focus on an alternative approach-the electrified co- electrolysis of nitrate and CO2 to synthesize urea. When this is applied to industrial wastewater or agricultural runoff, the approach has the potential to enable low-carbon-intensity urea production while simultaneously providing wastewater denitrification. We report a strategy that increases selectivity to urea using a hybrid catalyst: two classes of site independently stabilize the key intermediates needed in urea formation, *CO2NO2 and *COOHNH2, via a relay catalysis mechanism. A Faradaic efficiency of 75% at wastewater-level nitrate concentrations (1,000 ppm NO3- [N]) is achieved on Zn/Cu catalysts. The resultant catalysts show a urea production rate of 16 mu mol h(-1) cm(-2). Life- cycle assessment indicates greenhouse gas emissions of 0.28 kg CO(2)e per kg urea for the electrochemical route, compared to 1.8 kg CO(2)e kg(-1) for the present-day route.
Settore CHIM/02 - Chimica Fisica
ott-2023
11-set-2023
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/1022515
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