炭基双金属催化剂对松木催化热解生物油酚类组分的影响研究

Effect of Carbon-based Bimetallic Catalysts on Phenolic Components in Bio-oil from Pine Sawdust Catalytic Pyrolysis

摘要:

富酚生物油为高附加值化学品的重要来源，具有广泛的应用前景。为了提高催化热解所得生物油中酚类物质的相对含量，以松木为原料，通过制备炭基双金属催化剂进行催化热解，选取了催化剂类型、热解温度、松木与催化剂比例以及双金属负载比例为实验变量，探讨炭基双金属催化剂上酚类物质生成机理。实验结果表明，松木热解所得酚类物质相对含量从14.61%提高到69.42%~83.32%。通过不同工况研究发现，松木催化热解制备酚类的最优条件为：催化剂类型为Fe-Cu催化剂，热解温度为550°C，生物质与催化剂质量比为1：1，双金属负载比为5：5，此时酚类物质的相对含量为83.32%。经过金属改性后的催化剂比表面积都有大幅度提高，有利于负载更多的活性位点参与反应；经过改性后，Fe成功负载到了碳载体上并且经过烧不同金属以合金的形式存在；单金属催化剂表面的颗粒更加聚集，相比之下，双金属催化剂表面的分散性得到提升，有利于催化反应的进行。铜负载在碳载体上转化形成了CuFe/Cu/CuO混合价态异质结构，提高了催化剂的催化性能，促进热解中间体通过脱氧和重组反应生成酚类物质。

Abstract:

Phenol-rich bio-oils served as an important source of high value-added chemicals and held great potential for a wide range of industrial applications. In order to improve the relative content of phenolic compounds in bio-oil produced from catalytic pyrolysis, pine sawdust was used as the feedstock and prepared carbon-based bimetallic catalyst for catalytic pyrolysis. The catalytic types, pyrolysis temperature, pine sawdust to catalyst ratio and bimetallic loading ratio were selected as experimental variables and the mechanisms of phenolic compound formation over carbon-based bimetallic were investigated. The results showed that the relative content of phenolic compounds in bio-oil was from 14.61% to 69.42%~83.32%. Studies revealed that the optimal conditions for preparation of phenolics were under Fe-Cu catalyst at 550°C, the biomass-to-catalyst ratio of 1:1 and bimetallic loading ratio of 5:5. Under these conditions, the relative content of phenolic compounds in the bio-oil reached 83.32%. The specific surface area of the catalyst significantly increased after metal modification, facilitating the loading of more active sites for enhanced reaction participation. After modification, Fe was successfully anchored onto the carbon carrier, and upon calcination, different metals formed an alloy. The particles on the surface of the monometallic catalyst tended to aggregate more, whereas the bimetallic catalyst exhibited improved dispersion, which was beneficial for catalytic reactions. Cu loaded onto the carbon carrier was transformed into a CuFe/Cu/CuO mixed valence heterostructure, which enhanced the catalytic performance of the catalyst and facilitated the generation of phenolics from pyrolysis intermediates through deoxygenation and rearrangement reactions.