Wang Lu, Lei Hanwu, Liu Jian, Bu Quan
School of Biological and Medical Engineering, Hefei University of Technology Hefei 230009 China
Bioproducts, Sciences and Engineering Laboratory, Department of Biological Systems Engineering, Washington State University Richland WA 99354-1671 USA
RSC Adv. 2018 Jan 9;8(4):2196-2202. doi: 10.1039/c7ra12187c. eCollection 2018 Jan 5.
In this study, the thermal decomposition behavior and kinetics of pyrolysis and catalytic pyrolysis of Douglas fir (DF) were investigated using thermogravimetric (TG) analysis. It was found that the heating rate was an important factor during the biomass pyrolysis process, it affected the pyrolysis though heat transfer and mass transfer through the biomass particles. The differential thermogravimetric (DTG) curves demonstrated that the role of the catalyst was to slightly reduce the temperature of biomass thermal degradation. We obtained the thermal data including the activation energy, frequency factor and reaction order by Coats-Redfern and Friedman methods. For the Coats-Redfern method, we found that the activation energy of the catalytic pyrolysis was lower than that of the non-catalytic pyrolysis. It means that the ZSM-5 catalyst increased the rate of reaction and reduced the energy required for the decomposition process. Meanwhile, the result from the Friedman method demonstrated that the reaction could be divided into two steps, which were reaction rate between 0.2 and 0.7 and a reaction rate of 0.8 based on parallelism. Addition of the ZSM-5 catalyst reduced the activation energy in the first region then increased it in the second region due to the secondary cracking of intermediate compounds which was highly affected by shape-selective catalysis. Simulation of pyrolysis and catalytic pyrolysis of DF using the obtained kinetic parameters was in good agreement with the experimental data. Py-GC/MS analysis was also carried out and indicated that the ZSM-5 catalyst had a highly positive effect on aromatic hydrocarbon production by significantly reducing oxygen-containing compounds ( acids, esters, ketones/aldehydes and guaiacols) during the catalytic pyrolysis of DF.
在本研究中，采用热重（TG）分析研究了花旗松（DF）热解和催化热解的热分解行为及动力学。研究发现，加热速率是生物质热解过程中的一个重要因素，它通过生物质颗粒的传热和传质影响热解。微商热重（DTG）曲线表明，催化剂的作用是略微降低生物质热降解的温度。我们通过Coats-Redfern法和Friedman法获得了包括活化能、频率因子和反应级数在内的热数据。对于Coats-Redfern法，我们发现催化热解的活化能低于非催化热解的活化能。这意味着ZSM-5催化剂提高了反应速率，降低了分解过程所需的能量。同时，Friedman法的结果表明，反应可分为两步，基于平行性，反应速率分别为0.2至0.7和0.8。由于中间化合物的二次裂解受到择形催化的高度影响，添加ZSM-5催化剂降低了第一区域的活化能，然后在第二区域提高了活化能。使用获得的动力学参数对DF的热解和催化热解进行模拟，与实验数据吻合良好。还进行了Py-GC/MS分析，结果表明，在DF的催化热解过程中，ZSM-5催化剂通过显著减少含氧化合物（酸、酯、酮/醛和愈创木酚）对芳烃生成具有高度积极的影响。
