Catalytic ammonia decomposition to COx-free hydrogen over ruthenium catalyst supported on alkali silicates

A series of alkali metal silicates A(2)SiO(3) (A = Li, Na and K) were synthesized by a sol-gel method route and employed as support for Ru nanoparticles to catalyze NH3 decomposition. The NH3 conversion can be ranked as the order of Ru/K2SiO3 > Ru/Na2SiO3 > Ru/Li2SiO3 > Ru/SiO2 at the same conditions, and Ru/K2SiO3 displays the highest NH3 conversion of 60.5% with the TOF (H2) of 2.03 s(-1) under the weight hourly space velocity (GHSV) of 30,000 mL.g(cat)(-1).h(-1) at 450 degrees C. The combination results of different characterization indicate that the formation of alkali metal silicates can increase the strength and number of basic sites, and the strong electronic metalsupport interaction (EMSI) would appear between Ru particles and oxygen vacancies in A(2)SiO(3) structure at reduction conditions. The presence of EMSI can result in the higher Ru dispersion and enhanced electronic density of Ru particles over A(2)SiO(3), greatly facilitating the decomposition of NH3 to COx-free hydrogen.

Automated summary

The study found that the formation of alkali metal silicates can increase the number and strength of basic sites on the catalyst material, thus improving the efficiency of NH3 conversion.