Bio-waste glycerol steam reforming to hydrogen through membrane reactor: Application of computational fluid dynamics technique

This study investigates the simultaneous production and purification of hydrogen from bio-waste glycerol, a byproduct of biodiesel production, through steam reforming in membrane reactor. To analyze the process, two-dimensional axisymmetric computational fluid dynamics model was developed in COMSOL Multiphysics. The model was designed and validated to examine the distribution of chemical species concentrations under operational conditions, including a steam-to-glycerol ratio of 6, pressure of 1 atm, and sweep gas ratio of 10. The performance of Ni/Al 2 O 3 , Co/Al 2 O 3 , and Ru/Al 2 O 3 catalysts was compared to evaluate their effects on conversion, hydrogen yield and recovery. The results showed conversion of 56.43 % at 673 K and 87.7 % at 773 K. These results closely align with experimental data for nickel catalyst (60 % and 87.9 %, respectively), with relative errors of 5.95 % and 0.23 %, respectively. The Ru/Al 2 O 3 catalyst exhibited superior performance in terms of activity and stability. The Ru/Al 2 O 3 catalyst achieved a maximum hydrogen yield of 93 % at 973 K and, under baseline conditions of S/C = 6, 1 atm pressure, and SF = 10, outperformed Ni/Al 2 O 3 (85 %) and Co/Al 2 O 3 (80 %). This superior activity, along with enhanced resistance to coking, reinforces Ru/Al 2 O 3 as an efficient option for sustainable hydrogen production from biodiesel byproducts. Increasing temperature improved glycerol conversion and hydrogen recovery, while higher pressure enhanced hydrogen permeability through the membrane. Optimizing operational pressure is essential, as it may negatively affect reaction equilibrium. The results of this study highlight the potential of using the Ru/Al 2 O 3 catalyst and determining optimal operational conditions to achieve efficient and sustainable hydrogen production from bio-waste glycerol. • A numerical model of glycerol conversion to hydrogen was developed. • Membrane-assisted steam reforming of glycerol is an efficient pathway for H 2 production. • Performance of Ni/Al 2 O 3 , Co/Al 2 O 3 , and Ru/Al 2 O 3 catalysts in process was evaluated. • Ru/Al 2 O 3 catalyst exhibited superior performance in terms of activity and stability. • Higher pressure enhanced hydrogen permeability through the membrane.