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Hanson DS, Wang Y, Zhou X, Washburn E, Ekmekci MB, Dennis D, Paripati A, Xiao D, Zhou M. Catalytic Urea Synthesis from Ammonium Carbamate Using a Copper(II) Complex: A Combined Experimental and Theoretical Study. Inorg Chem 2021; 60:5573-5589. [PMID: 33826330 DOI: 10.1021/acs.inorgchem.0c03467] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The synthesis of urea fertilizer is currently the largest CO2 conversion process by volume in the industry. In this process, ammonium carbamate is an intermediate en route to urea formation. We determined that the tetraammineaquacopper(II) sulfate complex, [Cu(NH3)4(OH2)]SO4, catalyzed the formation of urea from ammonium carbamate in an aqueous solution. A urea yield of up to 18 ± 6% was obtained at 120 °C after 15 h and in a high-pressure metal reactor. No significant urea formed without the catalyst. The urea product was characterized by Fourier transform infrared (FT-IR), powder X-ray diffraction (PXRD), and quantitative 1H{13C} NMR analyses. The [Cu(NH3)4(OH2)]SO4 catalyst was then recovered at the end of the reaction in a 29% recovery yield, as verified by FT-IR, PXRD, and quantitative UV-vis spectroscopy. A precipitation method using CO2 was developed to recover and reuse 66 ± 3% of Cu(II). The catalysis mechanism was investigated by the density functional theory at the B3LYP/6-31G** level with an SMD continuum solvent model. We determined that the [Cu(NH3)4]2+ complex is likely an effective catalyst structure. The study of the catalysis mechanism suggests that the coordinated carbamate with [Cu(NH3)4]2+ is likely the starting point of the catalyzed reaction, and carbamic acid can be involved as a transient intermediate that facilitates the removal of an OH group. Our work has paved the way for the rational design of catalysts for urea synthesis from the greenhouse gas CO2.
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Affiliation(s)
- Danielle S Hanson
- Department of Natural Sciences, Lawrence Technological University, 21000 West Ten Mile Road, Southfield, Michigan 48075, United States
| | - Yigui Wang
- Center for Integrative Materials Discovery, Department of Chemistry and Chemical Engineering, University of New Haven, 300 Boston Post Road, West Haven, Connecticut 06516, United States
| | - Xinrui Zhou
- Department of Natural Sciences, Lawrence Technological University, 21000 West Ten Mile Road, Southfield, Michigan 48075, United States
| | - Erik Washburn
- Department of Natural Sciences, Lawrence Technological University, 21000 West Ten Mile Road, Southfield, Michigan 48075, United States
| | - Merve B Ekmekci
- Department of Natural Sciences, Lawrence Technological University, 21000 West Ten Mile Road, Southfield, Michigan 48075, United States
| | - Donovan Dennis
- Department of Natural Sciences, Lawrence Technological University, 21000 West Ten Mile Road, Southfield, Michigan 48075, United States
| | - Amay Paripati
- Department of Natural Sciences, Lawrence Technological University, 21000 West Ten Mile Road, Southfield, Michigan 48075, United States
| | - Dequan Xiao
- Center for Integrative Materials Discovery, Department of Chemistry and Chemical Engineering, University of New Haven, 300 Boston Post Road, West Haven, Connecticut 06516, United States
| | - Meng Zhou
- Department of Natural Sciences, Lawrence Technological University, 21000 West Ten Mile Road, Southfield, Michigan 48075, United States
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Voronin GF, Genkin MV, Kutsenok IB. Virial equations of state for gaseous ammonia, water, carbon dioxide, and their mixtures at elevated temperatures and pressures. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2015. [DOI: 10.1134/s0036024415110229] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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