Preparation of Ni-B/MgAl 2 O 4 catalysts for hydrogen production via steam reforming of methane

In this paper, a series of B doped Ni/MgAl2O4 catalysts for hydrogen production via steam reforming of methane (SRM) were prepared, and their catalytic activities and stability were evaluated. The characterization of XRD, XPS, TPR, BET, TPO, and TEM revealed that the addition of B could promote Ni dispersion, which lead to the reduce of Ni particle size. 0.5 wt% B was incorporated into Ni/MgAl2O4 would increase Ni particle dispersion rate from 11.2% to 14.8%, which caused Ni particle average size was decreased from 8.78 to 6.96 nm. At the same time, 0.5% B doped would increase the chemisorbed oxygen content of the catalyst, and more oxygen vacancies were formed. Thus, Ni particles sintering and carbon deposition during SRM was suppressed, and the catalytic activity and stability were promoted. Ni-B0.5/MgAl2O4 could achieve 90.2% methane conversion rate and 85% H2 yield under 700 degrees C with a WHSV of 36,000 mL center dot(gh)-1 during SRM process, and only a marginal reduction (2%) of methane conversion rate was observed after 48 h reaction. The total carbon content on the used Ni-B0.5/MgAl2O4 catalyst was approximately 0.031 gc center dot gcat- 1, which was three times lower than that of Ni/ MgAl2O4. However, the excess B doping into Ni/MgAl2O4 had a negative effect on the catalytic activity and stability.