Effect of pyrolysis temperature and time on catalytic performance of sewage sludge/industrial sludge-based composite adsorbents

Adsorbents for removal of hydrogen sulfide from moist air were prepared from sewage sludge, waste oil sludge and their 50:50 mixture by pyrolysis at 650 and 950 °C for either half an hour or an hour. The resulting materials were characterized using sorption of nitrogen, thermal analysis, pH measurements and X-ray diffraction. Their catalytic performance was evaluated in hydrogen sulfide reactive adsorption via a dynamic test. The adsorbents have high capacity for hydrogen sulfide removal and high selectivity for its conversion to elemental sulfur. That sulfur is stored in the pore system, mainly mesopores. In some cases, after the oxidation, a secondary pore system is formed within the deposited sulfur. Either the capacity or selectivity depends on the pyrolysis temperature, time, and the specific chemistry of the sludge precursors. They govern the development of porosity and formation of new mineral-like catalytic components through solid-state reaction.