Effect of supports and Ni crystal size on carbon formation and sintering during steam methane reforming

Steam methane reforming was studied at 823 K, a total pressure of 20 bar and steam to carbon ratios from 0.08 to 2.4 over conventional NiO/α-Al2O3 and NiO/CaO-Al2O3 catalysts as well as catalysts supported on hydrotalcite derived materials. Catalyst activity, coke formation and deactivation at steam reforming conditions were studied using the tapered element oscillating microbalance (TEOM). Nickel supported on hydrotalcite derived materials had a smaller crystal size and a higher resistance to coke formation than the conventional NiO/α-Al2O3 and NiO/CaO-Al2O3. The higher resistance to carbon formation could be due to a higher saturation concentration of carbon in the smaller nickel crystals. Sintering experiments were performed at 903 K and 20 bar on the hydrotalcite derived catalysts and compared with an industrial NiO/CaAl2O4 catalyst. The particle growth for the hydrotalcite derived catalysts was larger than for the industrial catalyst, but the hydrotalcite derived catalysts had the smallest size of stabilized Ni crystals.