Coke deposition is a critical issue for catalysts in tar reforming. Steam is conducive to tar removal and hydrogen production in biomass pyrolysis, while its effect on coke formation is not well known. Thus, a two-stage fluidized bed/fixed bed reactor was used to study the effect of steam addition on coke deposition. The primary conclusions are as follows: combining steam and biochar, the tar removal efficiency is more than 90% within 20 min of time on stream (TOS). After the TOS reaches 30 min, the biochar surface is saturated with coke deposition and the specific surface area of the biochar stops decreasing. The addition of steam leads to a reduction in the combustion reactivity of the biochar. Besides, the aromatization of the biochar increase and the number of O-containing structures decreases. For the tar, the addition of steam reduces the aliphatics content and increases the O-containing aromatics content. For the gas composition, the addition of steam results in the decrease of CH₄ yield while the H₂ yield increases to 0.12 L/g. The H/C atomic ratio of the gas composition decreases while the O/C atomic ratio increases. The active coke is consumed and decomposed after the introduction of steam. The remaining coke is dominated by inert coke. This contributes to the relatively developed pore structure but a weakened combustion reactivity of biochar.

焦炭沉积是焦油重整催化剂的关键问题。蒸汽有利于生物质热解过程中焦油的去除和制氢，但其对焦炭形成的影响尚不清楚。因此，使用两级流化床/固定床反应器来研究蒸汽添加对焦炭沉积的影响。主要结论如下：蒸汽和生物炭相结合，在运行时间（TOS）20分钟内焦油去除效率超过90%。TOS 达到 30 分钟后，生物炭表面被焦炭沉积饱和，生物炭的比表面积停止减少。蒸汽的加入导致生物炭的燃烧反应性降低。此外，生物炭的芳构化增加，含氧结构的数量减少。对于焦油，蒸汽的加入降低了脂肪族化合物的含量并增加了含 O 的芳香族化合物的含量。对于气体成分，蒸汽的加入导致 CH 的减少₄产量，而 H ₂产量增加到 0.12 L/g。气体成分的 H/C 原子比降低，而 O/C 原子比增加。活性焦在引入蒸汽后被消耗和分解。剩余的焦炭以惰性焦炭为主。这有助于相对发达的孔隙结构，但削弱了生物炭的燃烧反应性。