Coking resistance evaluation of tar removal catalysts

• Ni catalysts supported on hexaaluminates of La, La/Ce and Ba were evaluated.
• Cyclohexane dehydrogenation indicates the tendency of coke formation.
• Coking rates were calculated using thermogravimetric experiments with synthetic mixtures.
• The catalysts were tested in steam reforming of toluene at 500 and 650 °C.

The tendency towards coke formation on nickel catalysts supported on hexaaluminates of barium, lanthanum and lanthanum/cerium was evaluated by two different methods: model reaction of cyclohexane dehydrogenation and thermogravimetric analysis using a synthetic gas composition. The ratio between hydrogenolysis and dehydrogenation rates provided a good indication of the potential for coke formation on the catalyst and is correlated to the nickel particle size. Thermogravimetric analysis was performed using a synthetic mixture containing H2, CO, CO2 and CH4, and also in the presence of C2H4. The catalyst supported on barium hexaaluminate presented lower coking rate and higher activity in toluene steam reforming, with preferential formation of filamentous carbon.