多孔白云石颗粒催化剂的研制和评价

GIEC OpenIR > 中国科学院广州能源研究所

	多孔白云石颗粒催化剂的研制和评价
其他题名	Preparation and Experimental Study of the Porous Granular Dolomite
	巩伟
导师	阴秀丽
	2009-05-31
学位授予单位	中国科学院广州能源研究所
学位授予地点	广州能源研究所
学位名称	硕士
关键词	生物质焦油白云石催化裂解动力学模型 Ni基催化剂半焦
摘要	由于传统能源的日趋枯竭和严重的环境问题，生物质作为绿色可再生资源得到了越来越广泛的关注和研究。生物质众多利用技术中，气化是生物质利用的关键技术之一。生物质气化能将各种废弃的固体生物质通过气化装置转化成为可燃气体，这些可燃气体可以通过不同的工艺得到液体燃料、化学品或者通过内燃机、燃气轮机发电。但是气化过程中产生的焦油会降低气化效率、污染设备和管道、影响发电设备正常运行，严重限制气化技术的推广使用。开发高效低成本的生物质焦油脱除工艺是生物质气化研究的热点问题。催化裂解作为一种效果显著的气体除焦净化技术，得到越来越广泛的关注。白云石是一种能有效催化裂解焦油的矿物质，来源广泛，价格低廉，然而白云石作为焦油催化裂解催化剂存在共性问题。即随着白云石的使用，它的机械强度逐步下降，尤其在流化床反应器中更为明显。针对煅烧白云石用于催化裂解焦油时存在的强度低损耗严重等问题，本文利用白云石粉末和其他辅助材料为原材料，经过混合、造粒、干燥、煅烧等步骤，研制成功一种多孔白云石颗粒(porous granular dolomite)。其强度为13.3N，比表面积为17.8m2/g，比孔容为0.78cm3/g。针对多孔白云石颗粒以及选为对比的Ni基催化剂和生物质半焦进行评价实验。考查了反应温度(600℃～900℃)、接触时间(0.3s～2.0s)等反应条件对乙酸、苯转化率和选择性的影响，同时考查了多孔白云石颗粒催化剂、Ni基催化剂的失活和再生性能。实验结果表明乙酸、苯转化率和选择性均随反应温度与接触时间的增加而上升：采用多孔白云石颗粒催化剂，在850℃、接触时间2.0s时乙酸和苯转化率分别达最大值99.8%和18.7%；采用Ni基、半焦催化剂，在850℃、1.1s时苯的转化率分别达最大值90.2%和48.3%。多孔白云石颗粒催化剂在600℃～700℃的温度范围，苯裂解生成的积碳量很少，而850℃时苯裂解生成的积碳占已裂解苯的一半。Ni基催化剂在700℃，接触时间大于0.9s时，生成的积碳占已裂解苯的10%以下；而接触时间0.5s，反应温度大于800℃时，积碳占已裂解苯的20%左右。半焦催化裂解苯选择性远小于转化率，苯裂解得到的主要产物是积碳。对多孔白云石颗粒、Ni基催化剂和生物质半焦进行动力学实验，选取一级反应速率方程结合活塞流模型和阿累尼乌斯方程对焦油催化裂解反应宏观动力学进行数学分析。多孔白云石颗粒催化剂催化裂解乙酸、苯的指前因子（A）分别为6680s-1和2930s-1，活化能分别为71.4kJmol-1和94.5kJmol-1。Ni基催化剂和半焦催化裂解苯的指前因子（A）分别为：1268.77s-1和283.7s-1，活化能分别为50.69kJmol-1和57.27kJmol-1。经检验，模型计算与实验结果能较好吻合。
其他摘要	A great deal of concern and research have been dedicated to biomass which is thought of as a kind of green and renewable resource owning to the drain of traditional fossil energy and drastic environment problems. Among various biomass utilization technologies, gasification process is the key one. Through biomass gasification, various solid biomass could be gasified into combustible gas, which will be transformed into liquid fuel, chemicals or generates electricity using internal combustion engine or gas turbine. However, tar forms during the gasification process that eliminates the gasification efficiency, fouls downstream pipelines and equipments, influences the functions of power generating facilities, and undermines the promotion of biomass gasification technology. So, developing a high-efficiency low-cost process applied to reducing tar is more meaningful than before. As an effective way purifying the product gas, increasing attention has been paid to catalytic decomposition of biomass tar. Dolomite, as a kind of effective catalyst used to catalytic cracking biomass tar, notwithstanding the widely distribution and low cost, a common disadvantage is inevitable that under the working condition, dolomite’s mechanical intensity decreases, especially in the fluidized bed. In order to handle the disadvantages of low intensity, easy wore-out, etc. This dissertation developed the porous granular dolomite (PGD), utilizing dolomite powder and other materials, following the procedures of mix, granulation, desiccation and calcinations. The porous granular dolomite’s intensity was 13.3N, specific surface area was 17.8m2/g, and specific pore volume was 0.78cm3/g. A set of experiments were performance to inspect the catalytic properties of porous granular dolomite, Ni catalyst and biomass tar. These experiments inspected the affects of temperature (600℃～900℃) and contact time (0.3s～2.0s) on the conversion and selectivity rates of acetic acid and benzene as feedstock (tar model compound) using PGD, Ni-based catalyst and char as catalysts; The deactivation and regeneration attributes of Ni-based catalyst and PGD were also tested. Results indicated that the conversion and selectivity rates of acetic acid and benzene increased with increasing temperature and contact time: the acetic acid and benzene conversion rates using PGD as catalyst reached their maximum 99.8% and 18.7% at 850℃, 0.5s, respectively. When using Ni-based catalyst and char, the benzene conversion reached their maximum 90.2% and 48.3% at 850℃, 1.1s, respectively. There generated little carbon deposition when PGD was select as catalyst at 600℃～700℃, while the temperature increased to 850℃, the carbon deposition accounted for almost a half of the total converted benzene. When Ni-based catalyst was selected, the carbon deposition accounted for less than 10% of the converted benzene at 700℃ where contact time was larger than 0.9s, while the carbon deposition accounted for less than 20% at 0.5s where temperature was larger than 800℃. When char was selected as catalyst, values of selectivity rates were quite small, so almost all of the benzene cracked was converted to the form of carbon deposition. A mathematical analyst of the dynamic experiment data was performed; as a result, a macroscopic reaction dynamic model was established, based on the hypothesis that a one-order reaction, plug flow model and Arrhenius equation were acceptable. Results were the active energy of cracking acetic acid and benzene using PGD as catalyst were 71.4kJmol-1 and 94.5kJmol-1, A’s were 6680s-1 and 2930s-1, respectively. The active energy of cracking benzene using Ni-based catalyst and char were 50.69kJmol-1 and 57.27kJmol-1, A’s were 1268.77s-1 and 283.7s-1, respectively. At last, by comparison, the calculated values agreed well with the experimental data.
页数	96
语种	中文
文献类型	学位论文
条目标识符	http://ir.giec.ac.cn/handle/344007/5846
专题	中国科学院广州能源研究所
推荐引用方式 GB/T 7714	巩伟. 多孔白云石颗粒催化剂的研制和评价[D]. 广州能源研究所. 中国科学院广州能源研究所,2009.

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