A super-growth carbon nanotubes-supported, Cs-promoted Ru catalyst for 0.1–8 MPaG ammonia synthesis

• Published in: Journal of catalysis Vol. 413; pp. 623 - 635
• Main Authors: Nishi, Masayasu, Chen, Shih-Yuan, Tateno, Hiroyuki, Mochizuki, Takehisa, Takagi, Hideyuki, Nanba, Tetsuya
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.09.2022
• Subjects: Cs-Ru active components; In situ characterization; Mild ammonia synthesis; Ru catalyst; Super-growth carbon nanotube; Cs-Ru active components; Mild ammonia synthesis; Ru catalyst; In situ characterization; Super-growth carbon nanotube
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2022.07.015

[Display omitted] •A super-growth carbon nanotubes-supported, Cs-promoted Ru catalyst was synthesized.•This catalyst gave high performance in mild ammonia synthesis (≤400 °C and 10 MPaG).•The active sites are metallic Ru particles with homogeneously dispersed CsOH species.•The cooperation of CsOH and Ru at the active sites reduced H2 poisoning and facilitated N2 dissociation.•This catalyst would be a potential candidate for green ammonia synthesis using electrolytic hydrogen. For the decarbonization of ammonia industry, a super-growth carbon nanotube (SGCNT)-supported, Cs-promoted Ru catalyst (Cs-Ru) was developed for mild ammonia synthesis (≤400 °C and ≤8 MPaG), particularly under intermittent operation conditions. This catalyst with well-dispersed Cs-promoted Ru particles was superior to previously reported analogs in ammonia synthesis concerning activity and stability. It produced ≈ 15 vol% of ammonia (rate ≈ 35 mmol g−1 h−1) at 380–400 °C and 5 MPaG (an H2/N2 molar ratio of 3 and a GHSV of 7000 h−1) that was close to thermodynamic equilibrium. The active components of Cs-promoted Ru particles confined in the nanospace of SGCNTs facilitated the adsorption of hydrogen and nitrogen during the ammonia synthesis. Hence, it exhibited high resistance to hydrogen inhibition in H2-rich ammonia synthesis conditions, particularly under pressurization, and facilitated nitrogen dissociation, resulting in high activity and stability in 0.1–8 MPaG ammonia synthesis at ≤400 °C.