Catalytic Cracking Of Coal Bed Methane For Carbon Nano Onions And Their Application Research

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.