Influences of iron additives on microwave-assisted pyrolysis of woody biomass and microwave-induced discharge with spherical bio-char
Longzhi Li, Kangqi Cao, Dongqiang Cai, Zhonglei Zhang, Zhiyang Zhao, Miao Yu, Lianjie Zhang, Qiang Zhang, Guifu Zou, Cuiping Wang
Abstract
Microwave-assisted pyrolysis with iron additives is a promising method for biomass utilization . The bio-char from this method can induce microwave discharge. However, the influencing mechanism of iron additives on microwave-assisted pyrolysis and subsequent microwave-induced discharge is unclear. Therefore, the work focuses on the influences of various iron additives on microwave-assisted pyrolysis of woody biomass and microwave-induced discharge with spherical bio-char. It was revealed that Fe 2 (SO 4 ) 3 and Fe 2 O 3 mainly impose the catalytic effect at the second pyrolysis stage, reducing activated energies by 35.5% and 77.3%, respectively. The addition of Fe(OH) 3 , Fe 2 (SO 4 ) 3 and Fe 2 O 3 is conducive for the generation of bio-char, bio-oil and synsgas, respectively. The iron additives effectively promote initial discharge intensity, which is enhanced by 87.6% with Fe 2 (SO 4 ) 3 . Besides, Fe 2 (SO 4 ) 3 and Fe(OH) 3 prolong the discharge duration to twice and triple of that in free of additives. Additionally, microwave discharge raises the temperature of bio-char bed layer, reaching the maximum temperature of 834.4 °C. This paper provides new insights into the value-added utilization of biomass.