Decarbonizing ammonia production requires catalyst and reactor choices that sustain high intrinsic rates under lower and flexible operating conditions typical of green hydrogen supply. Here, a physically grounded Langmuir–Hinshelwood–Hougen–Watson (LHHW) sensitivity framework links descriptor-level catalyst properties to reactor operating choices for green ammonia synthesis. Across 320–440 °C and 25–140 bar, control of ln(rate) is concentrated in a physically interpretable subset of parameters. Global rank-correlation analysis identifies the effective activation energy E a , the pre-exponential factor A 0 for N₂ activation, and the adsorption enthalpy–entropy pairs for H₂ and NH₃ as the dominant kinetic levers. Their mean ∣ PRCC ∣ values are 0.78 for E a , 0.49 for ln A 0 , and 0.40–0.48 for H₂/NH₃ adsorption. Entropy and pre-exponential factors therefore emerge as design handles comparable to adsorption enthalpy, highlighting the importance of supports and promoters that tune adsorbate phase space and effective attempt frequencies, not only binding energies. The same framework also quantifies the leverage of operating variables. Within the selected LHHW ensemble and operating grid, temperature is the dominant control variable, with a Sobol first-order index of 80.7%. NH₃ mole fraction is the second most important variable, with an index of 15.7%. By contrast, pressure and inlet H₂/N₂ ratio contribute only 2.5% and 0.1%, respectively, to the variance of the log-rate index, indicating that they act mainly as weak, nearly additive modifiers. Spatial interpretation in an exothermic adiabatic bed suggests a shift from Eₐ/H₂-controlled kinetics at the cool inlet to NH₃-controlled kinetics at the hot outlet, providing a descriptor-based hypothesis for axially graded catalyst zoning. Together, these results provide a quantitative, physically interpretable map from catalyst descriptors to operating knobs, enabling principled co-design of catalysts and reactors for green ammonia synthesis.
Alsaedi et al. (Thu,) studied this question.