Proton transfer reaction mass spectrometry technique for the monitoring of volatile sulfur compounds in a fuel cell quality clean-up system

• A real biogas digester pilot plant was monitored with PTR-MS technique.
• The behavior of the sub-sections is monitored by an online MS technique.
• VSCs and the other volatile organic compounds were detected and monitored continuously.
• A gas cleaning section was designed and realized experimentally.

Biogas from the dry anaerobic digestion of OFMSW from a pilot plant was analyzed in terms of sulfur compound removal through a gas cleaning section based on activated carbons, from lab. scale to real plant. In general, even the presence of sub-ppm(v) of selected biogas contaminants can hamper the life-time of SOFC systems. For this reason, stringent fuel cell quality requirements apply. The challenge of real-time monitoring of the performance and quality of the fuel feeding the SOFC can be solved through the use of PTR-MS. This technique – once properly and preliminary calibrated as shown in this study – has the capability of rapidly resolving the wide spectrum of contaminants slipping from the clean-up section. A commercial sorbent material was adopted to remove sulfur compounds and was tested for 80 h in a pilot gas cleaning system. H2S, the main sulfur compound detected (99.36% of total sulfurs) was removed to a satisfactory level. The sulfur compounds elute from the cleaning section in the following order: CH3SH, CH3SCH3, CH3CH2CH2SH, CH3(CH2)3SH, CS2 and H2S. The filter section was able to provide a clean biogas (1 ppm(v)) throughout the whole experimental trial (almost 450 h) with an average H2S inlet concentration of 52 ppm(v).