Vacuum Swing Adsorption on Natural Zeolites from Tuffs in a Prototype Plant Francesco Petracchini,a Valerio Paolini,a Flavia Liotta,a Lucia Paciucci,a and Enrico Faccib a Institute of Atmospheric Pollution Research, National Research Council of Italy, Monterotondo, Rome 00015, Italy;
[email protected] (for correspondence) b AzzeroCO2 s.r.l, Rome 00184, Italy Published online 00 Month 2017 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ep.12530 A vacuum swing adsorption (VSA) prototype plant was developed and tested, based on natural zeolites from tuffs containing Chabazite. The regeneration procedure of natural zeolites was optimized, and the operative pressure resulted to be the most important parameter. The VSA prototype was fed for 3 months with a real biogas, produced by agrozootechnical byproducts in an anaerobic baffled reactor (ABR). Biogas composition from ABR was very stable and allowed to deeply investigate the performances of natural zeolites in real biogas conditions. Biogas was desulfurized and dehydrated before the VSA unit. In our experimental conditions, a biomethane average purity > 98% was achieved, with methane recovery > 95%. CO2 concentration was always lower than 0.3%, while oxygen ranged from 0.2 to 1.5%. A light desulfurization effect was also observed. CH4 concentration C 2017 American Institute of was < 0.1% in the VSA off-gas. V Chemical Engineers Environ Prog, 00: 000–000, 2017 Keywords: biogas, zeolites, adsorption, methane, pressure swing adsorption INTRODUCTION
Biogas from anaerobic digestion is a useful fuel suitable for the production of thermal and electrical energy [1–3]. The composition of biogas, mainly methane (40–75%) and carbon dioxide (15–60%), depends on the feeding and the operational conditions of the anaerobic digester. Trace amounts of others molecules are also present, including water (5–10%), hydrogen sulfide (0.005–2%), siloxanes (
