摘要随着全球化石能源的不断消耗，新能源得到大力发展，生物质能作为一种重要的新能源，其综合利用日益成为热点。生物质CO2气化不仅可以充分利用能源，还能够保护生态环境，符合可持续发展。此外，生物质CO2气化技术的发展直接推动铁矿石气基直接还原的进程。在全面了解国内外生物质CO2气化相关理论及技术的基础之上，本文以锯木屑和毛竹屑为实验原料，利用TGA-DSC1热重分析仪，研究不同升温速率、气化时间、7种不同催化剂、不同催化剂负载方式和负载量对两种生物质气化特性的影响。并采用均相模型和未反应核模型对锯木屑快速热解阶段和气化阶段进行动力学分析，并计算其指前因子与表观活化能。84587

研究结果表明，毛竹屑的热解速率要大于锯木屑，而在同等气化条件下，锯木屑的气化效果要好于毛竹屑。升温速率和气化温度都能影响生物质CO2气化效果，升温速率越快，气化过程将向高温区移动；而随着气化温度升高，热力学条件得到改善，反应时间明显缩短。但随着温度继续升高，气化速率没有明显提高，这是因为在反应后期，气孔堵塞甚至坍塌，动力学成为限制性环节。

从催化角度分析，碱金属盐K2CO3和Na2CO3对生物质热解有明显催化效果；在生物质焦气化阶段，碱金属盐K2CO3和Na2CO3的催化效果最好，其次分别是Fe2O3、MnO2、MgO和TiO2。CaO因高温失活，生成的CaCO3在高温区分解，吸收热量甚至会抑制气化反应的进行。在一定范围内，增加催化剂负载量都会增强催化活性。浸渍法对生物质热解气化特性的影响要比机械混匀法更显著。

研究还表明，无论是热解还是气化阶段，生物质气化反应机理都趋向未反应核模型。在相同温度区间内，碱金属盐K2CO3和Na2CO3能降低生物质热解阶段的表观活化能；在气化阶段，MgO、MnO2、Fe2O3、TiO2与生物质反应生成中间体，使反应更容易进行，从而降低表观活化能。而CaO因CaCO3高温区分解强吸热使表观活化能提高。另外，在生物质热解气化的过程中，总是存在一定的动力学补充。

毕业论文关键词：生物质；CO2气化；热解；催化；动力学

Abstract With the consumption of global fossil energy, new energy has been developed vigorously, As an important new energy, the comprehensive utilization of biomass energy gradually become a hot spot。 Biomass gasification CO2  can not only make full use of energy, but also can protect the ecological environment,  which is consistent  with sustainable development。  In addition, the development of biomass CO2  gasification technology directly promote the process of direct reduction of iron ore。 In this paper, on the basis of a comprehensive understanding of the theory and  technology of biomass CO2 gasification at home and abroad, the influence of different condition (different heating rate, different gasification temperature, seven different catalysts, different catalyst loading capacity and catalyst loading methods) on  the characteristics of the two kinds of biomass gasification(sawdust, bamboo powder) were investigated using the thermo  gravimetric analyzer  (TGA-DSC)。 In addition,  the mechanism of biomass catalytic gasification was also studied in this paper,  the  homogeneous model  (HM)  and  the shrinking core model (SCM) were employed to carry out  dynamics simulation  for sawdust fast  pyrolysis  and char  gasification phase, and to calculate the apparent activation energy and  the pre-exponential factor。 

The experimental results  showed that:  The pyrolysis rate  of bamboo powder  was greater than the sawdust, and under the same conditions, the gasification effect of sawdust was  better than that of  bamboo powder。  Both the heating rate and the gasification temperature could  influence  the efficiency of biomass CO2  gasification,  the gasification process would  move to high temperature zone  as the heating rate increased。 With the increase of gasification temperature, the thermodynamic conditions were improved and the reaction time was shortened。 However, with increasing  the temperature, the gasification rate was not significantly improved。 The pore was blocked or even collapsed in the end of the reaction and the dynamic conditions became the restrictive step。