AVT - Research - Research project

Siloxanes can be removed from gas streams using membrane technology. The selective removal of the silicon-containing molecules from gases such as air or biogases down to levels below a few ppms is possible. The process is continuous.

Siloxanes are a group of molecules containing alternating silicon and oxygen atoms. If present in fuel gases used in combustion processes, siloxanes can oxidise to SiO2, i.e. sand. These deposits pose a serious problem, for example, in gas engines of co-generation units or microturbines, as they promote mechanical wear and cause more frequent oil changes. In addition, gas pollutant emissions usually increase when siloxane concentrations in fuel gas exceed about 5 mg/Nm3 CH4.

Conventional methods of siloxane removal include condensation and sorption. The AVT.CVT has identified gas permeation as a potential new method and is currently testing the applicability of new membrane materials. Several membrane materials were found to be suitable. First field trials with landfill gas showed that the tested membranes are relatively selective for siloxanes. Currently, a membrane module of 1m² is built with which the applicability of different operating modes (3-end or 4-end) at different temperatures will be tested. The technology is interesting for other siloxane-related applications, such as mechanical-biological waste treatment (MBT) or the protection of expensive catalysts used to purify engine exhaust gases.