Mono- and bimetallic catalysts for the steam reforming of glycerol based on (Cox,Ni1-x)3Si2O5(OH)4 phyllosilicate nanoscrolls

Glycerol steam reforming is one of the potential method for hydrogen production is. Nanocomposites based on transition metal phyllosilicates may serve as promising candidates for the role of catalysts in this process. In the present work, Ni- Co-phyllosilicates with a pecoraite-like structure were studied. For the first time, a monometallic Co-catalyst (x = 1) and a bimetallic Ni-Co-catalyst (x = 0.4) were obtained and compared in a catalytic reaction of steam reforming of glycerol with a monometallic Ni-catalyst (x = 0) based on a nanotubular phyllosilicate with the general stoichiometric formula (Co_x,Ni_1-x)₃Si₂O₅(OH)₄. A series of physicochemical methods revealed differences in crystalline and porous structure, morphology of phyllosilicates, stability of porosity during reduction, and size and localization of metal nanoparticles. The catalysts were metal particles with dimensions of 9.6 ± 0.1 nm (x = 0), 11.2 ± 0.1 nm (x = 0.4), and 18.8 ± 0.4 nm (x = 1), dispersed in a phyllosilicate matrix as the support. For the sample with x = 0.4, the metal particles were a homogeneous NiCo alloy. This sample demonstrated a synergistic effect, which was manifested in an increase in glycerol conversion and hydrogen yield over time-on-stream at 600 °C as well as in higher stability and a lower tendency to coking in compared to monometallic samples. The identified features of the studied systems (increase in the homogeneity of the NiCo alloy during the test, oxidation and blocking of Co nanoparticles inside the phyllosilicate channels) made it possible to explain the observed differences in the catalytic behavior in the steam conversion of glycerol.