Highly-efficient hydrogen production through the electrification of OB-SiC nickel structured catalyst: Methane steam reforming and ammonia cracking as case studies

The aim of this work is the preparation and the electrification of Ni_CeO2_Al2O3/OBSiC (Oxygen Bonded SIlicon Carbide) based foams used in two different endothermic reactions for H2 production: methane steam reforming and ammonia cracking. In particular, the heating of the catalytic foams occurs by the Joule effect, and to guarantee a uniform temperature profile in both the axial and radial direction, two different heating resistances were used. In addition, the high tortuosity together with the very high thermal conductivity of the OBSIC carrier, allow to overcome the heat and mass transfer limitations achieving a better control of the reaction behavior. Wet impregnation method was adopted for the Ni and Ce deposition, while the final catalysts was characterized through Hg penetration technique, Scanning Electron Microscope (SEM), N2 adsorption @77 K for the specific surface areas (SSA) determination and X-ray diffraction (XRD). The methane steam reforming and ammonia cracking tests were both carried out, in the same reactor, but at different space velocity values (WHSV). The results obtained are exciting, not only in terms of equilibrium approach and hydrogen production, but also in terms of energy consumption as kWh/Nm3 of H2 produced. In particular, in the case of methane steam reforming the results showed an energy consumption E [kWh/Nm3 H2] equal to 1.21 obtained at WHSV equal to 6.2 h−1, very close to the theoretical limit of 0.98 kW h/Nm3 H2. Also, for ammonia cracking, the energy consumption was very promising considering the scale of our reactor, with 1.5 kW h/Nm3 H2 obtained at a WHSV of 2.27 h−1, considering the theoretical limit equal to 0.71 kW h/Nm3 H2.