Study on the optimization of hydrothermal liquefaction performance of tobacco stem and the high value utilization of catalytic products

The major objective of this paper was to explore the hydrothermal liquefaction (HTL) characteristics of tobacco stem (TS) and increased the possibility of using TS. The optimum reaction conditions were determined by discussing the reaction temperature, initial pressure and residence time. HCl, KOH and Na2CO3 catalysts were added to compare and analyze the products of bio-oil, biochar and gas (Characterized and analyzed via GC-MS, FT-IR, SEM and GC). Research has found that the best bio-oil yield was 14% under the conditions of reaction temperature 300 °C, initial pressure 6Mpa and residence time 30min. However, the relative content of phenolic compounds in bio-oil was the highest at 320 °C, which is 17.46%. The relative yield of nicotine was the maximum at 280 °C, which was 9.21%. With the increased of reaction temperature, the nicotine content gradually reduced. The addition of HCl could completely decompose nicotine, so that the relative yield of phenolic compounds increased to 24.01% in bio-oil, and valeric acid could be found in bio-oil. Through the investigation of HTL of TS, it was found that TS have a wide application prospect in the preparation of high-value nitrogen-containing compounds and phenolic compounds.