基于TG-FTIR的圆柏心、边材热解研究

生物质热解是实现生物质废弃物有效处理及生物质材料高效利用的重要途径之一,因此对生物质热解过程及其机理进行研究具有极大的现实意义。木材作为一种来源广泛的可再生材料也是众多生物质热解原料中的一种,由于组成成分等多方面的差别,不同树种的热解特性具有明显差异。然而,同一种木材的心材与边材由于在组织构造、化学组成及其含量等方面有着明显不同,因此在热解特性和产物方面也存在一定的差异,该工作即对此进行深入研究。试验以心、边材区分明显的常见园林绿化物圆柏为试验材料,通过TG-FTIR联用技术分别得到其心、边材热解过程中的热重曲线和挥发分的红外光谱谱图并对其进行分析。结果表明,纤维素、半纤维素、木质素和抽提物含量对心、边材热解特性影响显著。由于圆柏心材半纤维素、木质素含量较高,在热解前期和热解后期具有比边材更大的失重率,而较高的抽提物含量则在一定程度上增加了其在反应中期的失重率,减小了该范围内心、边材失重率的差异;边材纤维素含量较高,因此其在300~380℃,失重明显,在DTG曲线中的最大失重速率也较高。在红外图谱中,心、边材热解所产生的挥发分种类几乎相同,但在数量上有差异,当热解达到最大失重速率时,所产生的挥发分明显增加,且整个过程中边材产生的有机酸类化合物更多,而心材相对产生更多的水和CO2。

Study of Sabina Chinensis Heartwood and Sapwood Pyrolysis with TG-FTIR Analysis

Biomass pyrolysis is one of the most important means to realize effective treatment and efficient utilization of biomass wastes and materials.Therefore,it has great practical significance to research the pr ocess and mechanism of biomass pyrolysis.Wood,as a renewable material with a r ich source,is a kind of pyrolysis raw material among lots of biomass.As we al l know,because of the difference of composition and other aspects,pyrolysis ch aracteristics of different tree species have obvious differences.However,e ven the same kind of wood such as the heartwood and sapwood of lumber show diffe rent pyrolysis characteristics and products in the process of pyrolysis,due to the significant differences in such aspects as microstructure,chemical composit ion and the amount of each component,which is studied feild in this paper.In the experiment,sabina chinensis,a kind of common landscaping,are taken as te st material,whose heartwood and sapwood are clearly distinct.In order to resea rch the pyrolysis differences between heartwood and sapwood,TG-FTIR method is used to obtain the thermogravimetric curves and volatile spectrograms during the process.Results elucidated that the content of cellulose,hemicellulose,ligni n and extracts have a remarkably effect on both heartwood and sapwood.On accoun t of higher content of hemicellulose and lignin,the heartwood of sabina chinens is showed higher weight loss ratio than sapwood during the early and late stages.What's more,higher content of extracts increased the weight loss ratio of he artwood in the medium stage,which reduced the differences between heartwood and sapwood.On contrary,sapwood with more cellulose had more obvious weight loss during 300～380 ℃ and higher weight loss ratio in the DTG curve.In addition,th e infrared spectrum indicated that both heartwood and sapwood produced almost sa me volatiles,but there were differences in amount.And when the pyrolysis came to the maximum weight loss velocity,volatiles produced increased significantly.Moreover,sapwood produced more organic compounds,while heartwood produced mor e water and CO2.