Catalytic steam reforming of ethanol over W-, V-, or Nb–modified Ni-Al-O hydrotalcite-type precursors

Abstract

2:1 Ni/Al layered double hydroxides (LDH) doped by anions using ammonium salts (NH4)10[W12O41], NH4VO3 or (NH4)3[NbO(C2O4)3] have been prepared by co-precipitation, dried and calcined at 600оС, forming NiO-based solid solutions. Diffraction patterns are typical for the layered Ni-Al-O hydrotalcite-like structure. Anion incorporation into the interlayer space increases the interlayer distance for W- and Nb-containing anions but decreases it for VO3 -1. Broad halos in the diffraction patterns indicate amorphous or strongly disordered phases containing the doping anions. H2 reduction of undoped Ni-Al-O (NA) and those doped by W (NAW) and Nb (NANb) occurred in one step, while that doped by V (NAV) was reduced in two steps. W doping increases the reduction temperature, but Nb doping decreases it. The hydrogen consumed increases in the row: NANb < NAW < NAV < NA. In the ethanol steam reforming reaction, modification by W and Nb anions results in ethanol conversion rates close to that of the unmodified sample, but V increases it nearly twofold.