DEVELOPMENT OF THERMAL CONVERSION TECHNOLOGY FROM WOOD CHARCOAL TO CARBON NANOTUBES

基于生物质资源生产新型碳材料的可能性及其作为先进碳材料的应用意味着能够控制其织构、微结构、表面化学，并提出强调其特性的实验和工艺。为了在炭化木材表面形成碳纳米管，研究了氧化铝、三异丙醇铝、快速热解、二氧化硅、正硅酸乙酯、铜铬砷等炭化木材的各种炭化前处理方法。得到的木炭被碾磨，然后在40%的三异丙醇铝的异丙醇溶液中浸泡。干燥后，在高达1300℃的脉冲电流烧结机中碳化5min。这种碳化木材在没有催化剂的情况下，经过“经典”碳化处理后，就形成了一种具有高度多孔结构的非石墨化碳。在本实验中，由于催化剂的加入，Al_2O_3与碳的中间反应生成片状的Al_4C_3，然后在适当的CO压力和温度下分解，在低温下形成Al蒸气和有序的石墨化碳。对碳化后的样品进行了织构、微结构和结构的改性，并用扫描和透射电子显微镜对其进行了表征。在碳化后的样品上，我们证明了催化多壁碳纳米管的生长是可能的。实验先在N_2/H_2气氛下进行，再在N_2/C_2H_4气氛下进行，反应时间为650℃。制备了直径约50 nm的多壁碳纳米管。可能的应用可能是锂离子电池。

The possibility of producing new carbon materials based on biomass resources and their applications as advanced carbon materials imply to be able to control their texture, microtexture, surface chemistry, and to propose experiments and processes emphasizing their characteristics. Various pretreatment methods for carbonized wood such as catalytic carbonization with Alumina, Aluminium triisopropoxide, fast pyrolysis, silicon oxide, TEOS, cupper-chromium-arsenic, have been investigated in order to form carbon nanotubes on the surface of carbonized wood.Japanese cedar, i.e. Sugi (Cryptomeria japonica), was at first carbonized in an electric furnace at 700 ℃ under N_2 flow, at 4 ℃/min heating rate, for one hour. The resulting charcoal was milled and then soaked in a 40 % isopropyl alcohol solution of Al-triisopropoxide. After drying, the specimen was carbonized in a pulse current sintering apparatus up to 1300 ℃ for 5 min. Without catalyst and after "classical" carbonization, such carbonized-wood consists in a non-graphitizing carbon with a highly porous texture. In our experiment, due to catalyst addition, the intermediate reaction of Al_2O_3 with carbon leads to the formation plate-like Al_4C_3. Then this latter compound dissociates under the proper CO pressure and temperature, leading to the formation of Al vapor and well-ordered graphitizing carbon at low temperature. The modification of the texture, microtexture and structure of such carbonized samples was followed by scanning and transmission electron microscopies and will be presented.Subsequently, on this carbonized then sintered samples, we demonstrated that growth of catalytic multiwall carbon nanotubes was possible. Experiments were performed at 650 ℃ under N_2/H_2 then N_2/C_2H_4 atmospheres. Multiwall carbon nanotubes with a diameter of about 50 nm were produced. Possible applications can be lithium ion batteries.