Unlocking dynamics of compact methanol reformers during on‐line catalyst activation using transient computational fluid dynamics simulation

On‐board methanol reforming is a practical solution to supply hydrogen for fuel cell vehicles (FCVs). For commonly employed Cu‐based reforming catalysts, activation has a profound influence on subsequent reaction performance. However, tailoring of this process at the reformer level has received little research attention. Herein, we present the dynamics of compact methanol reformers with Cu/ZnO/Al 2 O 3 catalysts during in situ H 2 /N 2 pre‐activation as a preliminary step of online catalyst activation by computational fluid dynamics simulations. Raising inlet temperatures or hydrogen fractions is demonstrated to accelerate activation while generating a high‐temperature band within the catalyst bed, which hampers effective activation. Increasing the reductant flow rates improves the homogeneity of activation thanks to enhanced convective heat and mass transfer. Notably, we revealed that inlet reductants exceeding 453 K trigger temperature runaway that may severely damage the reformer. These new insights will enlighten optimization of operation and control of on‐board methanol reforming for FCVs.