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Study on the influence of small molecular gases on toluene reforming in molten salt

Yang, Fu, Hu, Hongyun, Gao, Qiang, Yang, Yuhan, Tang, Hua, Xie, Kang, Liu, Huan, He, Yao, Yao, Hong
Renewable energy 2020 v.153 pp. 832-839
benzaldehyde, carbon monoxide, carbonates, catalytic activity, free radicals, gases, heat, hydrogen, hydroxyl radicals, ions, metals, methane, models, phenylacetaldehyde, polycyclic aromatic hydrocarbons, polymerization, pyrolysis, renewable energy sources, thermal cracking, toluene, wastes
The upgrading of tar is a key issue for the sufficient application of biowaste pyrolysis technology. Molten salt, with high migration and diffusion of ions to prevent the deactivation of coke deposition of tar reforming functional metals, is considered as a feasible catalytic reaction medium and heat carrier for the upgrading of tar. The present study investigated the interactions between small molecular pyrolysis gases (including H₂, CO, CH₄) and main tar model compound in ternary carbonate eutectics (Li₂CO₃–Na₂CO₃–K₂CO₃). The results demonstrated that H₂ could be decomposed to produce H radicals, promoting the conversion of toluene into gaseous products. CO₃²⁻ could consume H radicals required by toluene cracking, making the process toluene polymerized to polycyclic aromatic hydrocarbons be strengthened. On the other hand, CO would react with OH radicals to produce H radicals and could enhance gas-generating process. In addition, toluene could react with CO to form benzaldehyde and phenylacetaldehyde. With the addition of CH₄, more H radicals were supposed to be consumed, and toluene cracking process was further inhibited. Finally, the effect sequence of small molecular gases (H₂ > CH₄ > CO) on toluene reforming reaction was authenticated by investigating the impacts of introducing any two gases in toluene reforming.