摘 要：
以不同热解温度下制备的生物质半焦作为催化剂,在二段固定床反应器中考察木质素模型化合物(丁香酚)的转化行为,利用气相色谱质谱仪分析液体产物的成分及含量,进而考察催化反应过程中的转化路径;通过对催化反应前后的半焦结构表征,探究其结构变化对催化作用的影响。结果表明,热解温度400℃时制备的半焦(400BC)能够显著促进丁香酚向异丁香酚转化,其相对含量占热解产物的66.7%,而600℃的半焦(600BC)催化效果明显较弱。通过X射线光电子能谱和傅里叶变换红外光谱表征分析发现:400BC表面含氧官能团—OH和—COO含量高于600BC,表明半焦表面含氧官能团对丁香酚异构化反应起重要作用,且—OH的催化效果优于—COO。拉曼光谱分析则表明:生物质半焦中小芳环结构与大芳环结构I(GR+VL+VR)/ID比值从400BC的1.64下降到600BC的1.46,且催化反应后其比值进一步变小,说明半焦炭结构中的小芳环具有一定的催化活性,随着半焦制备温度的升高及催化反应的进行,半焦中小芳环逐级向大芳环转化,石墨化程度增大,从而导致活性降低。此外,笔者构建出生物质半焦对丁香酚的催化机理,即半焦表面含氧官能团与丁香酚中羟基/苯环形成氢键,以及半焦炭结构中小芳环与丁香酚苯环通过π-π堆积效应相互作用。
译 名：
Catalytic conversion of eugenol over bio-char
作 者：
HUANG Yong;LIU Shasha;WU Yishuang;ZHOU Jianbin;ZHANG Shu;College of Materials Science and Engineering,Nanjing Forestry University;
关键词：
bio-char;;lignin;;eugenol;;catalytic conversion
摘 要：
Carbon-based catalyst has recently attracted a lot of attention because of its low cost,environmental friendliness,and easy modification.To investigate the catalytic performance of biomass derived char on lignin decomposition,the conversion behavior of eugenol as a typical lignin model compound was thoroughly studied in a two-stage fixed bed reaction system,using pinewood derived bio-chars prepared at different pyrolysis temperatures as catalysts.The resulting liquid products were qualitatively and semi-quantitatively analyzed by the gas chromatography/mass spectrometer(GC/MS),and then the conversion pathways of eugenol during the catalytic reaction were proposed.To further understand the mechanism of bio-char catalysis,a series of characterization methods was employed to illustrate the effect of the chemical structure of bio-char on the eugenol conversion based on the structural changes before and after the catalytic reactions.The results indicated that the bio-char prepared at a pyrolysis temperature of400℃(400 BC) could significantly promote the conversion of eugenol to isoeugenol,and the relative content of isoeugenol was accounted for 66.1% of the total pyrolysis products,while the catalytic performance of bio-char prepared at 600℃(600 BC) was obviously deteriorated.Both the X-ray photoelectron spectroscopy(XPS) and Fourier transform infrared spectroscopy(FT-IR) characterization results suggested that the contents of surface oxygen containing functional groups(mainly —OH and —COO) in 400 BC were higher than that in 600 BC,indicating that the surface oxygen containing functional groups played a very important role in the isomerization of eugenol.The Raman analysis of bio-chars showed that the I_((GR+VL+VR))/I_D decreased from 1.64(400 BC) to 1.46(600 BC),and further reduced to1.35(400 BC) and 1.04(600 BC) after the catalytic reaction,indicating that the small aromatic rings in the carbon structure of bio-char exhibited a certain catalytic activity.As the preparation temperature of bio-char catalysts raised and the catalytic reactions proceeded,the small aromatic rings in the carbon structure of bio-char were gradually converted to large aromatic rings,and the graphitization degree of the bio-char carbon increased,resulting in the decrease in bio-char activity.Finally,the catalytic mechanism of eugenol conversion by the bio-char prepared from low temperatures(e.g.,400 ℃) was proposed,that was,hydrogen bond formation took place between the surface oxygen containing functional groups(mainly —OH and —COO) in bio-char and the hydroxyl group and/or benzene ring in eugenol,and π-π stacking interactions also occurred between the small aromatic rings in the carbon structure of bio-char and benzene ring in eugenol.
