Optimizing pyrolysis of herbal tea and Salvia miltiorrhiza residues for sustainable energy and product recovery
Yan Chen, Jingyong Liu, Liangzhong Li, Xin Chen, Ziting Lin, Chunxiao Yang, Fatih Evrendilek, Weixin Li, Wenxiao Huang, Yao He, Sheng Zhong, Zuoyi Yang
Abstract
With the global shift to renewable energy and a circular economy, the pyrolysis of traditional Chinese medicine residues offers a promising alternative for resource recovery. This study characterized the pyrolysis behaviors and products of herbal tea residues (HBR) and Salvia miltiorrhiza residues (SMR) in the N 2 and CO 2 atmospheres. A three-stage pyrolysis process was identified for both fuels, with the primary reaction occurring between 180–620 °C for HBR and 170–600 °C for SMR. Kinetic analysis demonstrated that CO 2 reduced the activation energy of pseudo-components in HBR but increased it for SMR. Under N 2 , slow pyrolysis produced eicosane (C 20 H 42 ) as the main product for HBR (32.90 %) and dodecanoic acid (C 12 H 24 O 2 ) for SMR (26.61 %). In CO 2 , 1-nonadecene (C 19 H 38 ) was the primary product for HBR (45.22 %), and 1-tetradecanol (C 14 H 30 O) for SMR (42.17 %). Fast pyrolysis in N 2 predominantly produced acetic acid (C 2 H 4 O 2 ) for both HBR (16.40 %) and SMR (18.70 %). These findings offer new insights into the valorization of both fuels as a sustainable energy source and provide a basis for further exploring their scalability and economic feasibility.