MAl₂O₄ (M: Mg, Ni, and Co) as unique support for Ni active metal to form a catalyst for renewable biohydrogen and syngas production from glycerol reforming over a microchannel reactor

Different mesoporous aluminate MAl₂O₄ spinels (with M: Mg, Ni, and Co) were fabricated via a sol–gel procedure. The fabricated spinels each were then used as support for a Ni active metal to synthesize a catalyst, and the performance of the spinel as part of the catalyst used in glycerol steam reforming (GSR) and dry reforming (GDR), respectively, was investigated. Further, the catalysts were characterized using XRD, EDX-Mapping, H₂-TPR, TEM, NH₃-TPD, and S_BET analyses, respectively. Notably, the catalysts each displayed a high BET specific surface area in the range of 130–190 m²/g. In addition, hydrogen production by GSR and GDR under different synthesized catalysts was evaluated in the temperature ranges of 500–700 °C and 600–800 °C, respectively, in a monolithic reactor. In particular, a high glycerol conversion, H₂ yield, and CO selectivity, and low CO₂ selectivity were achieved using the NiO/NiAl₂O₄ catalyst in GSR. Further, the order of catalytic performances with regard to glycerol conversion, H₂ yield, and CO selectivity was the catalytic performance of NiO/NiAl₂O₄ > NiO/MgAl₂O₄ > NiO/CoAl₂O₄, respectively. Likewise, the H₂/CO ratio in the temperature range of 600–800 °C was closest to ∼ 1 in the case of the NiO/NiAl₂O₄ catalyst used in GDR. Subsequent TGA analysis of each spent catalyst after 32 h of use showed that the amount of coke production in GDR was much higher than that in GSR. In addition, the highest amount of coke deposition was with the use of the NiO/CoAl₂O₄ catalyst in these reformings.