Effect of H₂S and thiophene on the steam reforming activity of nickel and rhodium catalysts in a simulated coke oven gas stream

In the present work the impact of H2S and thiophene on the steam reforming and water-gas shift (WGS) reactions were studied. The activity of three catalysts i.e. Ni/Al2O3, Ni/mayenite and Rh/Al2O3 was evaluated using an atmospheric fixed-bed lab-scale quartz reactor. A simulated coke oven gas (COG) stream was fed to the reactor. The temperature range studied was 675–900 °C. It was found that the temperature had a significant influence on the degree of poisoning of the catalysts and thus their performance. Regeneration of benzene reforming activity of the poisoned Ni/Al2O3 was achieved after exposing the catalyst to up to 200 ppm of H2S. Rh/Al2O3 outperformed the nickel catalysts in the steam reforming of benzene in the presence of thiophene. Ni/mayenite was the only catalyst able to maintain a noticeable WGS activity in the presence of H2S this result was attributed to the presence of CaO on the surface of this catalyst.