Effect of potassium in CoMo/γ-Al2O3-K(x) catalysts on naphtha hydrotreating

CoMo catalysts supported on γ-Al2O3 modified with potassium (K, 1, 3 and 5 wt%) were prepared and evaluated in simultaneous hydrodesulfurization (HDS) of 2-methyltiophene and hydrogenation of olefins (trimethyl-1-pentene to trimethyl-2-pentene ratio) reactions. The acid-base properties of the catalysts were measured by ammonia temperature-programmed desorption (TPD) and by the decomposition reaction of 2-propanol. Results showed that the BET surface area and the acidity of catalysts modified with potassium decreased when the potassium concentration increased as long as hydrodesulfurization/ hidrogenation (HDS/HYD of internal olefins increased. However, the activity of the modified catalysts decreased for all reactions. Comparison with literature information allowed establishing that modifications in the structure and dispersion of the active phase caused by the introduction of potassium are not the responsible for the activity decrease.