【作者】 王光学；

【导师】 吴琪琳；

【作者基本信息】 东华大学 ， 物质智能系统， 2011， 硕士

【摘要】 板栗壳的大量废弃及直接燃烧,己造成了一定程度的环境污染和资源浪费。对板栗壳的资源化利用,具有一定的社会效益、经济效益和环境效益。本论文针对板栗壳自身具有的碳含量及燃烧热值较高的特点,以及内部多孔分层结构,利用预氧化、炭化工艺在有无催化剂两种情况下制备出了具有较高燃烧热值的栗壳基生物质炭材料,并通过多种分析测试方法对板栗壳的热裂解情况及在制备过程中的结构性能演变做了研究。本论文利用热重分析仪和气相色谱-质谱联用仪对板栗壳热裂解行为进行了研究,发现板栗壳热解过程存在三个失重区,随升温速率增加,热解滞后。加入催化剂后,相同升温速率下热解提前,热解区变宽；随裂解温度上升,裂解产物中CO2比重增大,乙酸和左旋葡聚糖的出峰时间提前,呋喃类化学物有较明显下降,催化剂的加入抑制了板栗壳裂解过程中左旋葡聚糖的产生,升高温度后呋喃类化合物增加。本论文利用元素分析仪、红外光谱仪和X-ray衍射仪研究了有无催化剂两种情况下板栗壳在预氧化、炭化过程中各温度阶段的元素组成、基团和晶型演变。随着温度升高,C元素含量逐步增加,碳网结构逐渐增大,催化剂的加入,改变了各阶段的元素组成含量,H、O元素更多地以H20的形式脱除,产物提前形成碳网结构。本论文利用扫描电子显微镜研究了板栗壳在有无催化剂两种情况下预氧化、炭化过程中各温度阶段微观结构的演变。随着温度升高,样品表面孔洞变得萎缩,断面孔隙率增大,网络结构逐渐规整,催化剂的加入,使断面网络结构规整化提前,并使表面出现龟壳现象。本论文进一步研究了有无催化剂两种情况下预氧化、炭化过程中各温度阶段样品的得率及密度变化,并通过氧弹量热仪研究了燃烧热值的变化。样品得率随温度升高明显下降,密度随温度升高呈波浪形变化,预氧化阶段燃烧热值缓慢上升,进入炭化阶段之后,燃烧热值有了大幅增加。在750。C制备出得率为38.17%、燃烧热值为30.75MJ/Kg的生物质炭；催化剂的加入,提高了各阶段的样品得率,燃烧热值也有了进一步提升,在750℃制备出得率为44.31%、燃烧热值为35.48MJ/Kg的生物质炭。更多还原

【Abstract】 The discarding and directly burning of a large number of chestnut shell, have caused some environmental pollution and resources waste, so it will be benefit to our society, economy and environment to make good use of the abandoned chestnut shell. Chestnut shell based biochar with high calorific value has been made through pre-oxidation and carbonization in two cases, without and with catalyst, according to the innate advantages of chestnut shell at carbon content and calorific value. The pyrolysis behaviors and the transmutation of both the structure and properties during the carbonization were investigated.The pyrolysis behaviors of chestnut shell have been studied by TG and GC-MS. Results show that there are three stages of pyrolysis of the chestnut shell and the TG curve slightly shifts to higher temperature as the heating rate increases. With catalyst, the TG curve slightly shifts to low temperature at the same heating rate. With the pyrolysis temperature increasing, the weight proportion of CO2 in pyrolysis products goes up, acetic acid and levoglucosan emerge earlier, while furans decrease obviously. The catalyst restrains the levoglucosan’s generation, and helps furans increase when temperature goes up.The transmutation of elements composition, groups and crystalline structure in pre-oxidation and carbonization have been investigated by element analysis tester, FT-IR and XRD respectively. As the process temperature increases, carbon element content increases gradually and carbon network grows up. When adding catalyst, element contents of every stage change, hydrogen and oxygen eliminate more often by the form of H2O, and the carbon network forms earlier.The microstructure of samples, without or with catalyst, in pre-oxidation and carbonization has been studied by SEM. As the process temperature increases, the holes on surface shrinks and the porosity of cross section become bigger, while network structure grows to be regular. The catalyst makes the network structure of cross section emerge earlier and the surface becomes turtle shell shape. The yield and density of samples in pre-oxidation and carbonization, without or with catalyst, have been studied, and the transmutation of calorific value has been investigated by oxygen bomb calorimeter. Results show that the yield decreases as the process temperature increases, and the transformation of density is undulation. Calorific value goes up slowly in pre-oxidation process, while in carbonization, it increases quickly. The chestnut shell based biochar with 38.17% yield and 30.75MJ/Kg calorific value has been prepared at 750℃. Adding catalyst has improved the density, yield and calorific value. With the catalyst, the chestnut shell based biochar with 44.31% yield and 35.48MJ/Kg calorific value has been obtained at 750℃.更多还原