Steam reforming of tar using toluene as a model compound with nickel catalysts supported on hexaaluminates

•Hexaaluminates of La, La/Ce and Ca are a mixture of phases after calcination at 1200 °C.•Ni supported on hexaaluminates presented low reduction temperature.•Coking rates are related to Ni particle sizes.•La/Ce support presented higher stability during steam reforming of toluene at 650 °C.

Hexaaluminates of lanthanum, lanthanum/cerium and calcium were prepared by coprecipitation method and used as supports for nickel catalysts, with 6 and 14 wt% of NiO. After calcination at 1200 °C the hexaaluminate supports consisted of different crystalline phases, including α-alumina, perovskites and oxides, with specific surface areas of 14–18 m2 g−1. All the catalysts exhibited nickel reduction peaks in the range of 360–500 °C. Coking rates measured in thermogravimetric experiments using a synthetic mixture were directly correlated with Ni particle sizes. Catalysts with lower Ni dispersion exhibited lower initial toluene conversion at 650 °C. Ce-containing catalysts presented higher stability during 16 h of toluene steam reforming, which is coherent with their higher resistance to coke formation.

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