role of the surface chemistry of activated carbon in the adsorption of siloxanes for biogas purification: an approach using infrared spectroscopy
Résumé
Taking into account the continuous increase concern over greenhouse gases, such as methane and carbon dioxide, the biogas mixture produced in landfills or waste water treatment plants can be collected and utilized as a fuel for producing energy. However, the use of biogas as an energy source sets various design requirements for gas quality and gas cleaning systems. A special issue regarding biogas concerns the presence of traces siloxanes, semi-volatile methylated organosilicon compounds containing Si–O bonds. Originating from hygiene, health care and industrial products, siloxanes are converted during biogas combustion process into crystalline silica inducing the engine damage.
This study aims to investigate the adsorption of siloxane compounds over different activated carbon (AC) solids. The objectives are to test octamethylcyclotetrasiloxane (D4) adsorption capacity of the ACs from different sources under dry/humid atmosphere, deeply characterize the solids and then search the dependence between the D4 adsorption capacity and the AC surface chemistry and textural characteristics. To reach these goals, the following characterization techniques were used: N2 adsorption–desorption isotherms, chemical analysis, XRD, TG-DTA, SEM, TEM, XPS, Raman and FTIR. The adsorption experiments were performed under dry or humid atmosphere by contacting the powders with siloxane vapors in a DRIFTS cell, connected to a conventional gas manipulation apparatus, which allows in situ preconditioning and adsorption studies at variable temperatures