生物质热解油的化学组成及其研究进展

综述了生物质热解油的研究现状及应用前景,重点介绍了生物质热解油化学组成的分析方法,总述了生物质热解油的物化性质,进而归纳了几种常见生物质热解油,特别是城市污水污泥热解油、城市垃圾热解焦油、工业废油热解油、林业废料热解生物油和农作物热解油的化学组成及其性质;讨论了生物质热解油常见的改性办法,如催化加氢处理、沸石分子筛处理、催化裂解和乳化工艺的过程及其特点;展望了生物质热解油的研究前景,提出了相关建议。     

典型废弃生物质的热解特性研究

对6种典型废弃生物质(锯末、稻壳、纸屑、橱芥、废塑料、废橡胶)进行热重实验分析及热解动力学分析;同时,利用TG/DTG曲线分析了它们的基本热解特性,包括热解区间、最大热解速率的温度、不同加热速度等对热解进程的影响等;通过热解动力学分析,给出了基本的热解动力学方程,研究了各种原料在不同升温速率下的热解动力学参数,为废弃生物质制取生物质能源技术提供基础数据.     

木材热解及金属盐催化热解动力学特性研究

通过不同升温速率下杉木的热重实验,对比分析钾盐催化杉木热裂解动力学特性.借助于DTG重叠峰的分离以及分布活化能模型计算不同转化率条件下的反应活化能,得到钾盐对生物质中半纤维素的低温段分解、纤维素的整个热裂解过程存在催化效果,使失重曲线(200~270℃)肩状峰衰退乃至消失,并促进脱水和交联反应,导致焦炭产率的提高和残碳的有序化,体现为焦炭产量从16.3%提高到25.3%(质量分数),而且80%转化率后残碳分解活化能的急剧提高.基于三组分平行反应机理,采用非线性回归法拟合计算杉木热解动力学参数,得到纤维素的热裂解基本上属于一阶反应,而且钾盐对纤维素和半纤维素的热裂解具有较大程度促进,活化能分别从148.12和235.43kJ/mol下降到108.84和171.41kJ/mol,但对木质素的催化影响并不显著.     

生物质的裂解及液化

综述生物质热化学加工技术中的裂解和液化最新研究进展及裂解、液化产品的改性方法,并预测了今后的研究方向。     

竹材居里点快速热裂解研究

利用JHP-5型居里点裂解仪,在358、445、590和670℃4种居里点温度下快速热裂解竹材,通过GC-MS在线分析裂解产物。结果表明竹材居里点裂解液相主要产物为糠醛和酚类物质,其中445℃时2,3-二氢苯并呋喃的相对含量多达21%,并且液相主要产物的相对含量随温度的提高呈现先增后减的变化规律,裂解温度为445~590℃更利于液相产物的生成。裂解机理分析得知糠醛是由纤维素和半纤维素裂解产生,而酚类物质则来源于木质素。     

Application and verification of simultaneous determination of cellulose δ13C and δ18O in Picea shrenkiana tree rings from northwestern China using the high-temperature pyrolysis method

Stable isotopes in tree-ring cellulose provide important data in ecological, archaeological, and paleoenvironmental researches, thereby, the demand for stable isotope analyses is increasing rapidly. Simultaneous measurement of cellulose δ¹³C and δ¹⁸O values from tree rings would reduce the cost of isotopic commodities and improve the analytical efficiency compared with conventional separate measurement. In this study, we compared the δ¹³C and δ¹⁸O values of tree-ring α-cellulose from Tianshan spruce (Picea schrenkiana) in an arid site in the drainage basin of the Urumqi River in Xinjiang of northwestern China based on separate and simultaneous measurements, using the combustion method (at 1050°C) and the high-temperature pyrolysis method (at 1350°C and 1400°C). We verified the results of simultaneous measurement using the outputs from separate measurement and found that both methods (separate and simultaneous) produced similar δ¹³C values. The two-point calibrated method improved the results (range and variation) of δ¹³C and δ¹⁸O values. The mean values, standard deviations, and trends of the tree-ring δ¹³C obtained by the combustion method were similar to those by the pyrolysis method followed by two-point calibration. The simultaneously measured δ¹⁸O from the pyrolysis method at 1400°C had a nearly constant offset with that the pyrolysis method at 1350°C due to isotopic-dependence on the reaction temperature. However, they showed similar variations in the time series. The climate responses inferred from simultaneously and separately measured δ¹³C and δ¹⁸O did not differ between the two methods. The tree-ring δ¹³C and δ¹⁸O values were negatively correlated with standardized precipitation evapotranspiration index from May to August. In addition, the δ¹⁸O was significantly correlated with temperature (positive), precipitation (negative), and relative humidity (negative) from May to August. The tree-ring δ¹³C and δ¹⁸O values determined simultaneously through the high-temperature pyrolysis method could produce acceptable and reliable stable isotope series. The simultaneous isotopic measurement can greatly reduce the cost and time requirement compared with the separate isotopic measurement. These results are consistent with the previous studies at humid sites, suggesting that the simultaneous determination of δ¹³C and δ¹⁸O in tree-ring α-cellulose can be used in wide regions.     

浅析生物质快速热裂解反应器

[目的]研究生物质快速热裂解反应器。[方法]根据文献资料对现行几种主流热裂解反应器做了详细的介绍,并对新兴的斜板槽式反应器做了简要介绍。[结果]反应器是生物质快速热裂解液化技术的核心,不同的反应器类型决定了不同的工艺类型和工艺参数,目前热裂解反应器普遍还存在一些问题,实现工业化高效节能生产还不容易;斜板槽反应器作为一种新的尝试,其有一定的优势,但也存在着许多问题,需要进一步改进。[结论]该研究为生物质能代替常规能源提供理论依据。     

生物质居里点热裂解研究

[目的]为生物质裂解的机理分析提供理论基础。[方法]利用JHP-5型居里点裂解仪,在不同的居里点温度下研究杨木屑及其磨木木质素的裂解。同时,在试验的裂解温度范围内研究温度对主要裂解液相产物的影响。[结果]通过GC-MS在线分析裂解的液相产物显示2,种原料的液相产物都为酚类物质,产物基本相同,只是杨木屑的酚类物质种类较多,并且有糠醛产生。液相产物的相对含量随温度的升高都表现为先增加后减少的变化规律,温度为445～590℃时液相主要产物的相对含量较大。[结论]居里点热裂解与气质联用分析技术已成为木质化学研究领域一个固定的技术。     

Microwave pyrolysis of cellulosic materials for the production of anhydrosugars

Large-scale microwave rapid pyrolysis of cellulosic materials has been investigated. Levoglucosan (1,6-anhydro--d-glucopyranose) was obtained from a larch log as the main anhydrosugar in 2.6% yield on the basis of dry wood weight. This yield would be much higher than that obtainable by conventional pyrolysis in the largescale reaction. Levoglucosenone (1,6-anhydro-3,4-dideoxy--D-glycero-hex-3-enopyranos-2-ulose) was found to be produced in one-quarter the amount of levoglucosan. Other anhydrosugars, such as mannosan (1,6-anhydro--D-mannopyranose), galactosan (1,6-anhydro--d-galactopyranose), and xylosan (1,4-anhydro--d-xylopyranose), were also confirmed to be produced as minor components depending on the proportion of the monosaccharide content in the larch. When microwave pyrolysis of used papers and filter papers was performed, the yields of levoglucosan were about 6% and 12%, respectively, suggesting that a higher content of cellulose gives a larger amount of levoglucosan.