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

Abstract

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.