Monte Carlo simulation for chemical reaction equilibrium of ammonia synthesis in MCM-41 pores and pillared clays

Reactive canonical Monte Carlo (RCMC) method was performed to simulate the chemical reaction equilibrium of ammonia synthesis in two important porous materials: MCM-41 pores and pillared clays. First, our results were compared with those in slit pores in the literature. Then, the effect of other factors such as pore size, pressure and temperature on the chemical equilibrium was investigated. A parameter of the absolute increase of ammonia mole fraction in the pores against that in the bulk phase, Δabs, is introduced to describe the effect of confinement on the chemical equilibrium. The yield of ammonia increases with the decrease of pore size, but this increase becomes pronounced at pore sizes of 1.5 nm for MCM-41 pores and 1.02 nm for pillared clays. The yield of ammonia also increases with pressure. In addition, the maximum ammonia mole fraction is attained at 100 bar and 573 K in both MCM-41 pores and pillared clays. When the feed mole ratio of N:H of the bulk phase declines from 4:13 to 4:15, the yield of ammonia in the pore phase also decreases. In addition, the effect of porosity in pillared clays on the chemical equilibrium was simulated.