Approaches concerning siloxane removal from biogas * A review

Soreanu, G., M. Béland, P. Falletta, K. Edmonson, L. Svoboda, M. Al-Jamal and P. Seto. 2011. Approaches concerning siloxane removal from biogas * A review. Canadian Biosystems Engineering/Le génie des biosystèmes au Canada. 53: 8.1 8.18. One of the major barriers to the use of biogas as an alternative renewable energy source is the presence of siloxanes. At combustion temperatures, siloxanes are converted to silicon dioxide (SiO2), which forms deposits on the combustion surfaces (pistons and cylinders) of gas processing equipment, thus reducing engine life and increasing overall operational and maintenance costs. This paper presents key multidisciplinary information with respect to siloxane removal, aimed at evaluating various treatment options and identifying future research needs. Current removal methods are typically based on the adsorption process, while others employ gas liquid absorption and refrigeration/ condensation. Otherwise these methods are appropriate for siloxane removal with regard to siloxane physical chemical characteristics (for example, low solubility in water, high solubility in organic solvents, volatility, chemical resistance) their application in practice is cost-limited. Adsorption and absorption methods become inappropriate when applied to moisture-rich biogas, and are often used in combination with a pre-treatment stage. Development of more cost-effective technologies, such as membrane separation and biofiltration is in progress, and initial findings suggest that these methods could represent an attractive alternative.