Study of Silane Decomposition during the Combustion of Renewable Natural Gas

Abstract

The decomposition of silane (SiH4), as a model silicon-containing trace compound in renewable natural gas (RNG), has been studied during RNG combustion at ambient pressure conditions, using the opposed-jet, flat-flame experimental configuration. Silane flame concentration profiles were obtained, which indicate that complete SiH4 oxidation occurs in the preflame and luminous flame regions. The laser-extinction technique was used to measure particle volume fractions in the flame, and scanning electron microscopy and energy dispersive analysis by X-ray were used to study the morphology (size and shape) and the elemental composition of the particles formed. It was shown that pure solid silica (SiO2) particles are generated and carried out with the gaseous combustion products into the postflame region. The experimental data were modeled using two detailed SiH4 decomposition models, and the major SiO2 production channels have been identified for both these models via sensitivity and reaction path analyses. It was determined further that a first-order global decomposition reaction rate can describe adequately the experimental data.