Simultaneous Removal of Toluene, Naphthalene, and Phenol as Tar Surrogates in a Rotating Gliding Arc Discharge Reactor

In this study, a rotating gliding arc (RGA) plasma reactor was investigated for the decomposition of gasification derived tar. Toluene, naphthalene, and phenol were selected as tar surrogates to be simultaneously decomposed. The effects of steam addition, preheating temperature, tar, and CO2 concentration were studied and the decomposition pathways of tar model compounds were proposed. The optimum amount of steam can facilitate tar destruction, enhance H-2 yield, and, importantly, suppress the formation of carbon black. The conversions of toluene, naphthalene, and phenol can be up to 85.8, 76.4, and 93.4%, respectively, when 8-12% steam is applied in the system. As expected, the increase of tar or CO2 concentration reduces the conversions of tar. Interestingly, increasing the preheating temperature to 600 degrees C enhances the tar conversions but is then surprisingly followed by a slight drop with the subsequent increase in temperature. The conversions of the three components decrease in the order of phenol > toluene > naphthalene under the studied conditions. Primary decomposition products of toluene, naphthalene, and phenol are determined to be benzyl, naphthyl, and phenoxy compounds, which would be further degraded by active species such as N-2 (A(3) Sigma(+)(u)), OH radicals, O radicals, etc. into smaller molecules like H-2, CO, and CO2.