doi:10.16186/j.cnki.1673-9787.2022030006

Received:2022/03/02

Revised:2023/02/27

Published:2024/01/25

Catalysis effect of nano-magnetite on methane production from microbial degradation

ZHAO Fajun1,2,3, DENG Qigen1

1.College of Safety Science and Engineering，Henan Polytechnic University，Jiaozuo  454000，Henan，China;2.State Key Laboratory Cultivation Base for Gas Geology and Gas Control，Henan Polytechnic University，Jiaozuo  454000，Henan，China;3.Collaborative Innovation Center of Coal Work Safety，Henan Province，Henan Polytechnic University，Jiaozuo  454000，Henan，China

Abstract: Objective To study the catalytic effect of nano-Fe₃O₄ on producing methane（CH₄）in the process of microbial degradation of coal， Methods  two types of microbial communities，which were come from the mine water from Jincheng mining area and soil from Zhongyuan oilfield，were used to anaerobic digest coal samples from Yima mining area.The effects of temperature and nano Fe₃O₄ addition quantity on the molar concentration of CH₄ produced in the reaction system were investigated.The changes of the molar concentrations of CO₂ and H₂ were also analyzed during the process of CH₄ production； their effects on the molar concentration of CH₄ were evaluated.The role and maximum loading of iron were also evaluated in the anaerobic digestion reaction system and CH₄ production. Results Basing on analysis of co-cultivation results of anaerobic methanogenic archaea and polycyclic aromatic hydrocarbon decomposing bacteria；it was believed that the anaerobic reaction of coal degradation and methanogenesis were consisting of two main steps，the first step was the carboxylation reaction of fused-ring aromatic hydrocarbon activation，which degraded coal into pmethylphenol and 2-naphthalenecarboxylic acid-；the second step was that organic acids，methyl groups and gases produced by coal decomposition were used to generate methane through the biochemical reaction of coenzymes，the yield of methane in this process increased with the increasing of temperature，and a large amount of CO₂ had been existed in the initiating reaction of the process.The production of methane gas increased 39.6%~50.8% after adding nano-Fe₃O₄ into the bacteria co-cultivation system.The catalytic effect of nano-Fe₃O₄ on the process of production of methane gas was to promote the production of intermediate products（hydrogen，CO₂ etc.），which were consumed by methanogenic archaea and liquid water was generated to reduce the gas pressure of the reaction system，so the catalytic reaction could continue in a positive direction. Conclusion The catalytic effect of nano-Fe₃O₄ on microbial degradation of coal producing CH₄ requires a multi-bacterial environment，and there is an optimal loading amount during the catalytic process.

Key words:residual coal in goaf;nano-magnetite;methanogenic archaea;bacteria co-cultivation;coalbed methane;catalysis