Siloxanes in Biogas: Approaches of Sampling Procedure and GC-MS Method Determination

Abstract

A new approach of siloxane sampling based on impinger, micro-impinger, adsorption on active carbon, and direct TedlarBag methods followed by gas chromatography-mass spectrometry (GC-MS) was developed for the analysis of three linear (L2–L4) and four cyclic (D3–D5) volatile methyl siloxanes (VMSs). Three kinds of organic liquid-medium characterized by different polarities, namely acetone, methanol, and d-decane as siloxanes trap were arranged in the experiment which is widely discussed below. Thus, the GC-MS equipped with SUPELCOWAX-10 capillary column was employed to perform monitoring of VMS content in the analyzed biogas samples originating from landfill, wastewater treatment plants, and agriculture biogas plants. In all samples that have undergone the analysis, cyclic and linear VMSs were found in quantities exceeding 107.9 and 3.8 mg/m3, respectively. Significant differences between siloxanes concentrations depending on biogas origin were observed. Moreover, the high range of linearity (0.1 to 70.06 mg/m3), low LoD (0.01 mg/m3), low LoQ (0.04 mg/m3), and high recovery (244.1%) indicate that the procedure and can be applied in sensitive analyses of silica biogas contaminants. In addition to the above, the impinger method of sampling performed better than active-carbon Tube and TedlarBag, particularly for quantifying low concentrations of siloxanes. Overall, the evaluation of sampling methods for biogas collection simplified the analytical procedure by reducing the procedural steps, avoiding the use of solvents, as well as demonstrated its applicability for the testing of biogas quality.

Biogas/Biomethane Quality and Requirements for Combined Heat and Power (CHP) Units/Gas Grids with a Special Focus on Siloxanes-a Short Review

“…In Table 5 physical and chemical properties of siloxanes presented in biogas/biomethane are presented. 12 In the biomethane context, the initially pre-treated biogas (with low humidity) requires strong purification to be forwarded to the membrane upgradation system. Moreover, it must be taken into account that there are several local and EU standards to describe the purity of biomethane originating from biogas upgrading, which refers to the limitation of biomethane impurities in detail.…”

Integration of biogas systems into a carbon zero and hydrogen economy: a review

“…Because siloxanes are insoluble in water, they are frequently affixed to sludge mass, where the larger molecules may degrade into minor particles or volatile substances that are then released into raw biogas (Cabrera-Codony et al 2014). In raw biogas, siloxanes are difficult to remove and have the most detrimental effect on biogas utilisation (Nyamukamba et al 2020;Piechota 2021). For instance, biogas utilisation in solid fuel cells is restricted by the production of silicon dioxides, which obstructs bioanode pores (Papurello et al 2018).…”

A Critical Overview of the State-of-the-Art Methods for Biogas Purification and Utilization Processes

“…Whereas during the biogas combustion process, oxygen reacts with the VMS under high temperature and pressure, the white SiO 2 deposits are formed in different morphological forms (white, glassy, crystal, microcrystalline, and amorphous deposits) [62,63]. In some cases, these deposits are associated with other components like calcium or sulfur [64]. These deposits can generate abrasive and thermal insulating properties, that can cause damage to turbines, reduce engine life and efficiency, and cause damage to their accessories such as valves, engine heads, and spark plugs.…”