Cu-ZSM-5 as a regenerable adsorbent for removal of low-concentration methyl mercaptan

Regeneration of desulfurizer is a difficult topic because the bond is strong between the adsorptive site and the Scontaining gas. This work synthesized a regenerable desulfurizer by dispersing Cu into ZSM-5, which removed 8.84 mg center dot g-1 of methyl mercaptan by Cu2+ and CuO sites. Both N2 and H2 were feasible to regenerate the used adsorbent at 500 degrees C. N2 was a better choice since the adsorptive capacity maintained at 6.23-6.40 mg center dot g-1 even after five-cycle regenerations. On the contrary, the adsorptive capacity was decreased to 4.58 mg center dot g-1 after three H2-regeneration cycles. H2 regeneration reduced the Cu2+ sites, which were oxidized to CuO after being exposed to air. Methyl mercaptan was inclined to be oxidized to SO42- on CuO during the thermal regeneration. CuO sites were thus occupied by SO42-, which decreased the adsorptive capacity. Residual S content was increased to 3.74 wt.% after the forth H2 regeneration. In comparison, the S content was only 1.26 wt.% after the sixth N2 regeneration. Therefore, this work put forward a regenerable desulfurizer together with a regeneration method, which is in favor of sustainable adsorption of refractory sulfur-containing odorous gas.