Evaluation on the characteristics of homogeneous catalytic hydrothermal gasification of waste rubber based on ReaxFF-MD simulation

• Published in: International journal of hydrogen energy 2024-01, Vol.51, p.758-769
• Main Authors: Nie, S.Q., Chen, M.Q.
• Format: Article
• Language: English
• Subjects: Homogeneous catalysts; Hydrothermal gasification; Kinetics; ReaxFF-MD
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2023.10.201

Massive waste tires unrecycled will pose a significant threat to the urban environment. Hydrothermal gasification (HTG) is a promising technology converting polymer wastes into H2-rich syngas. The homogeneous catalytic hydrothermal gasification behavior of natural rubber (NR) and styrene-butadiene rubber (SBR) was estimated based on reactive force field molecular dynamics (ReaxFF-MD). KOH had the highest catalytic performance in enhancing the degradation efficiency (22.5 %) and H2 yield (27.4 %) in HTG of NR, and K2CO3 demonstrated the most optimal alkaline catalyst for SBR to enhance the degradation efficiency (27.2 %) and H2 yield (37.9 %). K2CO3 loading with 6 wt% manifested the optimum amount for lifting DE and H2 yield in HTG of SBR, while 10 wt% K2CO3 loading represented the best effect for lifting DE (26.5 %) and H2 yield (42.6 %) in HTG of NR. The activation energy of SBR in HTG was about 259 kJ/mol, which was about 72 kJ/mol higher than that of NR. With 6 wt% K2CO3, the activation energy of SBR and NR in HTG decreased to about 143 kJ/mol and 122 kJ/mol, respectively. The present work could provide essential theoretical support and fundamental data for the application of the homogeneous catalysts in HTG recycling of waste rubber materials. •Catalytic HTG of rubber polymeric wastes was examined by ReaxFF-MD.•K2CO3 was the optimum catalyst to improve the H2 yield of SBR in HTG.•K-based catalyst was better than Na-based one for hydrothermal gasification of NR.•A better catalystic effect was realized by promoting the formation of OH radicals.•The lowest activation energy of SBR was 143 kJ/mol with K2CO3 addition.