催化剂与催化方式对生物质/塑料共热解的影响

Effects of catalyst and catalytic mode on co⁃pyrolysis characteristics of biomass and plastics

首先使用HZSM-5作为催化剂,探究原位与异位催化方式对生物质与塑料共热解过程的影响。之后对HY、HZSM-5和Fe/HZSM-53种催化剂进行全面表征,进一步对比研究三者对生物质与塑料共热解过程的影响,并对3种催化剂积炭失活行为进行了分析。结果表明,原位催化生物油产率高于异位催化,但是异位催化方式强化了“双烯合成”和芳构化等反应,显著提升了芳烃的选择性,高达82.8%。过渡金属Fe的引入提高了催化剂抑制积炭的能力,Fe/HZSM-5催化剂结焦量远少于HY和HZSM-5催化剂,仅为3.77%。同HZSM-5相比,Fe/HZSM-5中Bronsted酸强度减弱,略微降低了碳氢化合物的选择性,但是将碳氢化合物中芳烃的选择性提高了16.7%。由于焦炭的附着,反应后的催化剂比表面积、孔容和酸强度均有所降低,进而降低了其催化活性。

Catalytic co‑pyrolysis of biomass and plastic is a promising way to improve bio‑oil quality and mitigate the environmental issues caused by the disposal of petroleum‑based waste plastics.In this study,the effects of in‑situ and ex‑situ catalytic modes on the performance of co‑pyrolysis were investigated using HZSM‑5 as a catalyst.Three types of catalysts,HY,HZSM‑5 and Fe/HZSM‑5,were then thoroughly characterized,and their effects on the performance of copyrolysis were also investigated.The in‑situ mode resulted in a higher bio‑oil yield compared to the ex‑situ mode.However,the Diels‑Alder and aromatization reactions were promoted in the ex‑situ pyrolysis,leading to a higher aromatic selectivity of 82.8%.The introduction of transition metal Fe improved the anti‑coking ability;therefore,Fe/HZSM‑5 had the least coke amounts of 3.77 wt%among the three catalysts.Compared to HZSM‑5,Fe/HZSM‑5 had a lower Brönsted acid density,thus leading to a slight decrease in the selectivity of hydrocarbons but a dramatic increase in the selectivity of aromatics by 16.7%.Owing to the coke deposition,the BET surface area,pore volume,and there was a decrease in the acidity of the three post‑catalytic catalysts,lowering their catalytic ability.