Effect of cobalt modification onto a Beta zeolite for the direct catalytic decomposition of dimethyl sulfide

For the development of small-scale desulfurization processes such as fuel cell systems, catalytic decomposition of dimethyl sulfide (DMS) to H₂S without H₂ addition was investigated using a Co/H-Beta zeolitic catalyst, with its acidity controlled via post-synthesis modification. The protonated zeolite (H-Beta) exhibited little catalytic activity at 400 °C, but Co modification significantly promoted DMS decomposition, with a high H₂S yield of 50% observed. The optimum Co amount was equivalent to half of the ion-exchange capacity of the original H-Beta zeolite. While the Co/SiO₂ did not display catalytic activity, and thus, the coexistence of acid and Co ion sites is necessary in DMS decomposition. The Co species were introduced at the cation sites of the zeolite, suppressing Co sulfurization, which contributed to the high catalytic activity.