Chromium-based MIL-101 metal organic framework as a fully regenerable D4 adsorbent for biogas purification

In this work, the chromium-based MIL-101 metal organic framework has been synthesized and investigated as a fully regenerable, high capacity sorbent for siloxanes, which are common contaminants in raw biogas from anaerobic digestion. Adsorption isotherms of D4, the most common siloxane in waste treatment plants, have been collected at different temperatures and modelled by means of the Langmuir theoretical isotherm. The selected metal organic framework shows a remarkable affinity for siloxane adsorption and an outstanding saturation capacity weakly dependent on temperature. Moreover, repeated adsorption isotherms, collected after a reactivation treatment of the same adsorbent sample, clearly indicate full regeneration capabilities. Considering that chromium-based MIL-101 is also a noticeable H2S adsorbent, the results reported in this work pave the way to its potential application for the simultaneous removal of the two main poisoning compounds contained in biogas.