【作者】 张敏；

【导师】 高利珍；

【作者基本信息】 太原理工大学 ， 环境工程， 2017， 博士

【摘要】 中国煤层气(CBM)资源储量丰富(已探明储36.8万亿立方米),排世界第三位,但煤层气综合利用却相当滞后。煤层气的主要成分是甲烷,甲烷催化裂解后一方面可以提供丰富的氢能源,另一方面又可通过一定的催化手段使裂解后的纳米碳变为极具潜在应用价值的新型碳材料(如纳米洋葱碳CNOs、石墨烯Graphene、纳米碳管CNTs等)。对煤层气催化裂解制备氢气和纳米碳材料已成为了众多研究者研究的热点。纳米洋葱碳以其独特的物理和化学结构已经引起了研究机构的重视,尤其是其独特的0维结构、小的直径(<10 nm)、高导电率以及相对于1维纳米管和2维石墨烯而言比较容易分散。CNOs被认为在能源材料、耐高温/耐磨材料、磁性存储媒介材料、超导材料、生物材料、润滑油抗摩剂和低温离子液体电解液活性材料等方面具有广阔的应用前景。甲烷催化裂解制备氢气及纳米碳材料的研究已相对成熟,而对于煤层气催化裂解研究相对较少,本文在甲烷催化裂解的基础上,通过自行设计的“零排放催化裂解制碳-产氢-发电”系统,以煤层气为碳源,采用改进高温水蒸气处理不锈钢载体工艺并担载催化剂,用化学气相沉积法高选择性地合成了纳米洋葱碳。系统地从理论上分析了反应系统的能量效率,采用TPR手段对不锈钢网催化剂载体催化活性进行了分析并优化了制备方法,研究并优化了纳米洋葱碳的纯化方法,最后分析探讨了纳米洋葱碳在超级电容器、电化学传感器及在润滑油中的极压抗摩特性。研究结果表明:(1)通过理论计算得出,发明设计的“零排放催化裂解制碳-产氢-发电”系统,催化裂解温度为800℃时,整个系统净能量产出为20.2%;(2)通过高温水蒸气工艺处理不锈钢网载体,提高不锈钢网比表面积(4.45m2/g)近8倍,以此担载催化剂,经H2气900℃还原1.5h后在800℃下催化裂解煤层气,转化效率达到70%左右;替代H2还原过程,以催化剂经过煤层气热裂解后产生的氢气在线自还原后进行裂解反应,其催化裂解效率达到88%,接近理论转化率(91.3%),且持续裂解60小时后无下降趋势;(3)催化剂具有高的选择性,裂解制备纳米碳90%以上是石墨化程度高的圆球状CNOs,粒径在5~200nm,是内嵌催化剂颗粒的CNOs与中空CNOs的混合物。通过“酸洗-500℃氧化-再酸洗”的工艺,可以将内嵌催化剂移除,纳米洋葱碳的回收率不足50%。通过磁学性能分析发现,内嵌催化剂CNOs具有铁磁性,可通过“酸洗-磁选”将内嵌催化剂CNOs与中空CNOs有效分离。(4)纳米洋葱碳与super-p按照比例1:0、1:3、1:5和0:1加入到超级电容器电极材料中,以TEA-BF4为电解液组装超级电容器并测试其电化学性能发现,CNOs取代super-p以后其比容量达到142.31F/g,提高近17.14%,且经过1000转循环的循环稳定性有所提高。(5)通过旋转圆盘(SDP)制备了CNOs-M(M=Pt,Au)CNOs-Pt/GCE和CNOs-Au电化学传感器,并分别对甲醛和葡萄糖进行电化学检测。结果表明,CNOs-Pt/GCE对甲醛具有好的电化学反应活性,相对高的灵敏度和精确度。CNOs-Au传感器能很好的检测葡萄糖并表现出相应时间快,稳定性高和再生性能好,能够用于血液葡萄糖检测。(6)纳米洋葱碳在润滑油中具有较好的油溶性,饱和油溶量为0.1wt%,加入量0.01wt%以下时基本不影响原油品的表观颜色,纳米洋葱碳含量在0.002wt%以上时,表现出优异的极压抗磨性能,且随着加入量的增加抗磨性能增加。更多还原

【Abstract】 There is plentiful of coal bed methane(CBM)reserves in China(about 36.8trillion cubic meters that have been proved),ranked third in the world.However,the comprehensive utilization of CBM is still lagging behind in China.As we all know,the main component of CBM is methane.CBM catalytic cracking to produce hydrogen and nano carbon materials has become a hot spot for many researchers,due to hydrogen and carbon nano materials(such as carbon nano onions CNOs,Graphene and carbon nano tubes CNTs etc.)these two important products can be produced together through methane catalytic cracking process.Carbon nano onions have attracted great interest in the research community since they exhibit unique chemical and physical properties.Especially due to their unique 0D,small diameter(less than 10 nm),high conductivity and easy to be dispersed compared with 1D CNTs and 2D graphene.Carbon nano onions have been expect to have good prospect in some aspects of energy materials,high-performance/high temperature wear resistant materials,composites materials,magnetic storage media,super conductive materials,biomaterials,lubricating oil anti-friction agent and Low temperature ionic liquid electrolyte materials.The research of methane catalytic cracking for hydrogen and carbon nano materials producing is relatively mature,rarely the catalytic cracking of CBM.In this paper we based on the methane catalytic cracking technology,through the system “ catalytic cracking carbon production-hydrogen generation-electricity” designed by ourselves,choosing CBM as carbon source,by using the improved high temperature water vapor technology for stainless steel mesh treating and catalyst loading and followed by chemical vapor deposition high selectively synthesized CNOs.In this paper,the net energy efficiency of the reaction system has been analysis theoretically,TPR methods have been introduced for the catalytic active analysis of stainless steel mesh supports and the prepare route has been optimized,the purification methods of the as-harvested carbon nano onions have been researched and optimized also.Finally,the application of CNOs in the supercapacitors,electrochemical sensors and lubricating oil anti-friction has been discussed.The results showed that:(1)The net energy efficiency of as designed “catalytic cracking carbon production-hydrogen generation-electricity” is 20.2% theoretically.(2)The surface area of the stainless steel mesh has been improved almost 8times after been treated by high water vapor technology,catalyst loaded on thesetreated supports and then reduced by H2 at 900℃ for 1.5 hrs and then using for the CBM catalytic cracking at 800℃,the methane conversion efficiency up to about 70%.Instead of H2 reducing process,using H2 produced from CBM thermal cracking for catalyst online self-reduction,the catalytic cracking efficiency is up to 88% as high as the theoretical conversion efficiency 91.3%,and this efficiency did not show any decline trend lasted 60 hrs.(3)The catalysts have high selective and as harvested carbon nano onions from cracking process are high graphite phase and appeared spherical shape,the diameter is between 5nm and 200 nm.Both CNOs with catalyst inside and hollowed are all existed in the raw products.The catalyst in the CNOs can be removed through “Acid wash-500℃ oxidation-acid wash again” process and the harvest rate of CNOs only below 50%.The CNOs with catalyst inside performed ferric magnetic property.The CNOs with and without catalyst inside can be separated efficiently.(4)CNOs and super-p with the ratio of 1:0,1:3,1:5 and 0:1 was introduced into supercapacitors acted as electrodes materials.The supercapaciors were assembled using TEA-BF4 as electrolyte.The electrochemical performance of as assembled supercapacitors showed that the specific capacity reached to142.31F/g has been improved about 17.14% when the super-p has been all instead by CNOs,and the cycle stability also has been improved after 1000 cycles.(5)CNOs-Pt/GCE electrodes and CNOs-Au electrodes were made through spinning disc processor used as formaldehyde and glucose electro-chemical sensors and their performance have been estimated.The results showed that the CNOs-Pt/GCE has good electric catalytic activity to formaldehyde,and has relatively high sensitivity and accuracy when test formaldehyde.The CNTs-Au sensors for glucose concentration detection have good characteristics;the response fast,have good stability and reproducibility,and it can be applied for blood glucose testing.(6)Carbon nano onions performed excellent oil soluble properties in lubricant oil and the maximum adding amount is 0.1wt%.The apparent color of the lubricant oil will not be affected when the adding is below 0.01wt%.The lubricant oil performed a outstanding extreme pressure anti-friction property when the CNOs added beyond 0.002wt% and the anti-friction property will be improved with the increase of the adding.更多还原