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

Abstract

Hexaaluminates of lanthanum, lanthanum/cerium and calcium were prepared by coprecipitation method and used as supports for nickel catalysts, with 6 and 14wt% 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 14–18m2g−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 16h of toluene steam reforming, which is coherent with their higher resistance to coke formation.