Hydrogen production through ammonia decomposition: comparative modelling analysis of conventional and membrane reactor configurations

Ammonia (NH 3 ) is a promising hydrogen (H 2 ) carrier, but achieving high conversion and H 2 purity at moderate conditions remains challenging. A one-dimensional non-isothermal model coupling mass, momentum, and energy balances for retentate and permeate sides was used to compare a benchmark packed-bed tubular reactor with four Pd-membrane-reactor configurations (IN-OUT vs OUT-IN at co-current and counter-current). The parametric study varied wall temperature, inlet pressure, NH 3 feed flow rate, and feed-to-sweep ratio, assuming an ideally H 2 -selective dense Pd layer. A membrane-type influence (permeability/Pd thickness) was also assessed. The OUT-IN counter-current configuration delivered the best performance, combining high NH 3 conversion, H 2 recovery, and energy efficiency. Under optimised conditions ( T wall ≈ 655 K, P inlet = 7 bar, F N H 3 / F sweep gas ≈ 0.32, and F N H 3 , 0 = 0.0001 mol·s −1 ), a 99.6% NH 3 conversion and H 2 recovery above 95% were achieved. These results provide clear guidance for compact, energy-efficient H 2 production from NH 3 . • A 1D model of NH 3 decomposition in Pd membrane reactors (MRs) is developed. • Four MR configurations, IN–OUT/OUT–IN and co-/counter-current, are compared. • The MR outperforms the conventional packed-bed reactor in NH 3 conversion. • Wall temperature, pressure, NH₃ feed rate and feed/sweep ratio effects are analysed. • Results offer guidance for designing efficient MRs for H 2 production.