基于TG-FTIR联用的污水污泥热解实验研究

采用TG-FTIR联用技术研究了污水污泥热解,结果表明.污泥热解分为3个阶段,污泥热解的主要产物有脂肪烃、芳香烃及其化合物、酯类、羧酸、含氮化合物、酚、醇、醛、酮、水、CO2、CH4、CO和NH3,这些热解产物随热解温度的改变呈规律性变化.     

纸塑铝复合包装材料各组分共热解行为研究

以用甲酸分离枕型利乐包所得的纸、聚乙烯、铝作为实验材料,采用热重红外联用(TG-FTIR)分析技术,研究了各组分在热解过程中的协同作用,以探索纸塑铝复合包装各组分共热解机理,为实现废弃利乐包材料的资源化利用提供科学参考和实验依据。结果表明:共热解时纸和聚乙烯之间存在协同作用,在失重峰位置表现得尤为明显;铝在共热解时具有一定的催化作用,在反应的不同阶段起到了相应的促进或者抑制热解的作用。     

纸塑铝复合包装材料各组分共热解产物分析

以甲酸分离枕型利乐包所得的纸、聚乙烯、铝作为实验材料,使用热重红外联用(TG-FTIR)分析技术,研究了单一组分热解产物特性和组分共热解机理。结果表明:共热解时纸和聚乙烯之间存在协同作用,且在TG-FTIR失重峰位置附近产生的影响尤为明显;铝在共热解时具有催化剂的作用,会促进聚乙烯的分解。为实现废弃纸塑铝复合包装材料的资源化利用提供科学参考和实验依据。     

利用TG-FTIR研究造纸黑液碱木质素的热解机理

采用热重-傅里叶红外光谱（TG-FTIR）联用的分析方法对造纸黑液碱木质素的热解失重特性和产物生成特性进行了研究。结果表明：碱木质素热解失重过程可分为3个阶段,其中200~500℃是碱木质素主要的热解挥发阶段,反应符合一级反应动力学模型,利用Coats-Redfern动力学模型计算得出不同升温速率下热解主反应的表观活化能为39.3~43.1 kJ/mol。FTIR的实时分析结果表明：碱木质素热解的气态产物主要有H₂O、CO₂、CO、CH₄、甲醇、酚类和N₂O;产物中的CH₄、甲醇、酚类和N₂O主要在300~500℃区间内释放,随着热解温度的升高,这些气态产物在420℃附近集中释放,且产量达到最大。     

热重红外联用多组分混合气体产物定量分析

为了定量分析热反应过程中连续或彼此重叠产生的多组分混合气体产物,提出依据气体混合物的红外吸收特征谱带强度时间分布确定热重-红外联用中多组分气体产物逸出体积流量的定量计算方法.以氧气气氛中炭黑固体样品反应生成二氧化碳、一氧化碳、二氧化硫等气体的热重-红外联用实验为例,重点讨论载气流速的选择对多组分气体产物定量结果的影响.计算结果表明,在适当的载气流速下,可忽略反应气体的消耗以及微量气体产物的析出对多组分气体产物逸出体积流量定量计算的影响.当热反应过程中逸出的混合气体存在弱吸收红外、甚至不吸收红外的气体时,可采取近似定量方法实现多组分气体产物逸出体积流量快速定量表征.     

Mechanism study on cellulose pyrolysis using thermogravimetric analysis coupled with infrared spectroscopy

Based on the investigation of the polysaccharide structure of cellulose by using Fourier transform spectrum analysis, the pyrolysis behaviour of cellulose was studied at a heating rate of 20 K/min by thermogravimetric (TG) analysis coupled with Fourier transform infrared (FTIR) spectroscopy. Experimental results show that the decomposition of cellulose mainly occurs at the temperature range of 550–670 K. The weight loss becomes quite slow when the temperature increases further up to 680 K and the amount of residue reaches a mass percent of 14.7%. The FTIR analysis shows that free water is released first during cellulose pyrolysis, followed by depolymerization and dehydration. Glucosidic bond and carbon-carbon bond break into a series of hydrocarbons, alcohols, aldehydes, acids, etc. Subsequently these large-molecule compounds decompose further into gases, such as methane and carbon monoxide. __________ Translated from Journal of Zhejiang University (Engineering Science), 2006, 40(7): 1 154–1 158 [译自: 浙江大学学报 (工学版)]     

Bio-hydrogen production based on catalytic reforming of volatiles generated by cellulose pyrolysis: An integrated process for ZnO reduction and zinc nanostructures fabrication

The paper presents a process of cellulose thermal degradation with bio-hydrogen generation and zinc nanostructures synthesis. Production of zinc nanowires and zinc nanoflowers was performed by a novel processes based on cellulose pyrolysis, volatiles reforming and direct reduction of ZnO. The bio-hydrogen generated in situ promoted the ZnO reduction with Zn nanostructures formation by vapor-solid (VS) route. The cellulose and cellulose/ZnO samples were characterized by thermal analyses (TG/DTG/DTA) and the gases evolved were analyzed by FTIR spectroscopy (TG/FTIR). The hydrogen was detected by TPR (Temperature Programmed Reaction) tests. The results showed that in the presence of ZnO the cellulose thermal degradation produced larger amounts of H₂ when compared to pure cellulose. The process was also carried out in a tubular furnace with N₂ atmosphere, at temperatures up to 900 °C, and different heating rates. The nanostructures growth was catalyst-free, without pressure reduction, at temperatures lower than those required in the carbothermal reduction of ZnO with fossil carbon. The nanostructures were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). The optical properties were investigated by photoluminescence (PL). One mechanism was presented in an attempt to explain the synthesis of zinc nanostructures that are crystalline, were obtained without significant re-oxidation and whose morphologies are dependent on the heating rates of the process. This route presents a potential use as an industrial process taking into account the simple operational conditions, the low costs of cellulose and the importance of bio-hydrogen and nanostructured zinc.     

基于热重红外联用分析的纤维素热裂解机理研究

在用红外固体压片法研究纤维素多糖结构的基础上,利用热重红外联用技术在线分析研究了纤维素在20 K/min升温速率下的热裂解行为.结果表明,纤维素的热分解主要发生在550~670 K,680 K以后热失重很缓慢,在此温度下固体残留物的质量分数为14.7%.在线红外分析结果表明,纤维素热裂解过程中先析出游离水,随后发生解聚和脱水反应,主要的苷键和碳碳键断开形成各种烃类、醇类、醛类和酸类等物质,随后这些大分子物质二次降解为甲烷和一氧化碳为主的气体产物.     

桉木化学机械浆碱木素热解特性初步研究

采用酸析法分离桉木碱性过氧化氢法(APMP)制浆废液中的碱木素,应用热重红外联用(TG-FTIR)分析方法对碱木素的热解特性进行初步研究,并对热解过程中挥发性产物释放规律进行追踪。热重分析(TG)结果表明,热解主要分为玻璃态转化、主要热解、残留物质缓慢分解3个阶段;傅里叶红外光谱(FTIR)分析结果表明,热解阶段可挥发性产物有H2O、CO2、CO、CH4、酚醇类化合物和醛酮类化合物,反应时间在2000 s以后的高温阶段热解产物主要为CO和CO2。其中,CH4、醛酮类化合物、酚类和醇类化合物释放主要集中在300～600℃之间,且产率均较高。     

分级处理秸秆的热解过程

利用热重-傅立叶红外联用分析仪(TG-FTIR)研究了麦秸、汽爆麦秸、发酵麦秸的热失重特性及其气体析出行为. 实验表明,热失重过程主要分4个阶段：干燥阶段(30~150℃)、过渡阶段(150~200℃)、热解阶段(200~600℃)、炭化阶段(600~900℃);析出挥发分的机理过程分为2步：热解初始阶段发生脱羟基、脱羧基、脱烷基和解聚反应,析出含C?O?C基团、醇、醛、酸、酮和CO2, CO, H2O, CH4等气体化合物,炭化阶段发生脱烷基、羰基等反应,先后依次析出CH4, CO2, CO等气体. 汽爆、固态发酵分级处理麦秸不仅使热解干气的产率降低约20%~30%,热解液的产率增加,而且热解液中羧酸类产量分别减少了30%和50%左右.