基于TG-FTIR的雷尼镍催化乙醇木质素热解特性研究

Raney Nickel Catalyzed Pyrolysis Mechanism of Ethanol Organosolv Lignin Based on TG-FTIR

采用热重红外联用仪(TG-FTIR)对雷尼镍催化的乙醇木质素(EOL)热解过程进行实验研究,考察雷尼镍催化剂对木质素热解过程失重特性及挥发性产物释放规律的影响作用,推断其催化作用机理。实验结果表明:雷尼镍催化EOL热解提升木质素结构单体间烷基醚键断裂,导致酚类、烷烃类和CO2产物释放量明显增加;EOL最大失重速率对应温度降低50℃,CH4的释放峰值温度升高。

The depleting stocks of fossil fuels have forced researchers to investigate renewable fuels and chemicals as an alternative to petrochemical products. Recently,more and more attentions have been paid to lignin for product bio-fuels. However,lignin as a by-product of black liquor discharged from industrial pulping process has not been used reasonably. It is the only renewable resource that can direct provide aromatic ring in nature. Lignin is an amorphous and highly branched polymer through C—O or C—C bonds,and the polymer molecular structure of lignin is very difficult to be degraded into phenyl propane monomers. Therefore,the selective depolymerization of lignin structure into smaller molecular units is the major challenge for converting it to value-added chemicals. In order to study the catalytic depolymerization mechanism of ethanol organosolv lignin（EOL） by raney nickel, the pyrolysis experiment of pure EOL and raney nickel loading EOL were investigated by a Fourier transform infrared spectrometry（TG-FTIR）. Then the effect of raney nickel on the thermogravimetric characteristics and the releasing ways of the volatiles products were analyzed. The results suggested that the raney nickel catalysis improved the breakage of ether bond between lignin structure unite,and then led to the formation of phenols,hydrocarbons and CO2 products increased and the release of CH4 and ketones products decreased. Meanwhile,the DTG peak temperature of raney nickel loading EOL was 50℃ lower than that of pure EOL,while the formation temperature of CH4 was increased.