TY - JOUR
T1 - Ammonia synthesis via chromium-based nitrogen carrier looping
AU - Sun, Zhao
AU - Li, Ke
AU - Toan, Sam
AU - Zhang, Rongjun
AU - Li, Hongwei
AU - Wu, Yu
AU - Sun, Zhiqiang
N1 - Publisher Copyright:
© 2023 Elsevier B.V.
PY - 2023/11/15
Y1 - 2023/11/15
N2 - Redox nitrogen fixation-nitride hydrolysis looping provides a promising pathway for ammonia synthesis; however, high N fixation temperature and low N3−lattice supplement efficiency limit its further development and application. In this regard, a two-step chemical looping ammonia synthesis route, chromium-based nitrogen carrier enabled low-temperature N fixation and nitrogen carrier hydrolysis, is proposed to intensify ammonia generation. In the N fixation step, the effects of carbon species on the carbothermal reduction performance are investigated. Results reveal that decreasing the graphitization degree of the carbon species can effectively reduce the nitrogen activation temperature from 1054 °C to 948 °C. Meanwhile, the C/Cr2O3 ratio required is correlated with the amount of oxygen in carbon species, and the appropriate active carbon/biochar-to-Cr ratios are 4.00 and 3.25, respectively. In the ammonia synthesis step, the nitrogen carrier hydrolysis rate is mainly limited by the diffusion of reactive species. The ammonia formation rate reaches 0.127 mmol·h−1·g−1 nitrogen carrier at 1100 °C. XRD retrieve refinement results reveal that the utilization of the lattice nitrogen decreases with the increase in the ammonia releasing temperature. This study provides new implications for advanced nitrogen carrier exploitation, which will substantially promote the development of chemical looping ammonia synthesis technologies with lowered energy consumption.
AB - Redox nitrogen fixation-nitride hydrolysis looping provides a promising pathway for ammonia synthesis; however, high N fixation temperature and low N3−lattice supplement efficiency limit its further development and application. In this regard, a two-step chemical looping ammonia synthesis route, chromium-based nitrogen carrier enabled low-temperature N fixation and nitrogen carrier hydrolysis, is proposed to intensify ammonia generation. In the N fixation step, the effects of carbon species on the carbothermal reduction performance are investigated. Results reveal that decreasing the graphitization degree of the carbon species can effectively reduce the nitrogen activation temperature from 1054 °C to 948 °C. Meanwhile, the C/Cr2O3 ratio required is correlated with the amount of oxygen in carbon species, and the appropriate active carbon/biochar-to-Cr ratios are 4.00 and 3.25, respectively. In the ammonia synthesis step, the nitrogen carrier hydrolysis rate is mainly limited by the diffusion of reactive species. The ammonia formation rate reaches 0.127 mmol·h−1·g−1 nitrogen carrier at 1100 °C. XRD retrieve refinement results reveal that the utilization of the lattice nitrogen decreases with the increase in the ammonia releasing temperature. This study provides new implications for advanced nitrogen carrier exploitation, which will substantially promote the development of chemical looping ammonia synthesis technologies with lowered energy consumption.
KW - Ammonia synthesis
KW - Carbothermal reduction
KW - Chemical looping
KW - Chromium-based nitrogen carrier
KW - Lattice nitrogen
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U2 - 10.1016/j.cej.2023.146643
DO - 10.1016/j.cej.2023.146643
M3 - Article
AN - SCOPUS:85174836847
SN - 1385-8947
VL - 476
JO - Chemical Engineering Journal
JF - Chemical Engineering Journal
M1 - 146643
ER -