中文摘要
根据不同材料物理化学性质，成功制备了多壁CNTs内组装金属或金属氧化物的纳米复合催化材料，利用EXAFS、ESR、XPS、Raman、CV、TPR、TG等技术，测定和比较管内组装和管外负载复合材料的电学性能，热稳定性，氧化性能等，并通过探针反应（苯加氢生成环己烷、乙苯脱氢生成苯乙烯和苯羟基化生成苯酚等）研究了活性组分Ni、Co、Ce等在碳管不同位置的催化性能。研究结果发现：1）相对于管外，管内的金属氧化物更易还原或金属更易氧化；2）高温条件下，管内金属作为催化剂能使碳管在临氢条件下部分还原成甲烷；3）碳管的限域效应包括管内浓度提高、压力增加、加速电子转移，增加扩散阻力等；4）内组装样品在苯加氢反应中出现明显的诱导期；5）多壁碳管的空缺结构减少了扩散阻力，有利于反应分子的吸附和产物分子的脱附；6）相对于碳管的管径大小对催化性能的影响，碳管空缺密度的影响更大。进一步的研究发现，CNTs的结构缺陷的自发还原作用提供了促进低价或还原态金属的便利合成，CNTs上形成Fe2+、Cu+等低价活性物种的初步研究结果表明，它们在苯羟基化反应以及苯加氢反应中体现了优于其他方法得到的催化剂的活性和选择性。
英文摘要
Based on the physicochemical properties of different materials, the nanocomposites of metal or metal oxide filled inside multi-walled carbon nanotubes (CNTs) were prepared successfully. The electrical properties, thermal stability, redox of the activated composition inside or outer of CNTs were investigated by means of EXAFS, ESR, XPS, Raman, CV, TPR and TG etc., and the catalytic performance of them also was investigated via these prob reactions such as benzenen hydrogenation to hexane, ethylbenzene dehydrogenation to styrene and benzen hyoxylation to phenol. It is found that 1) relative to the outer of CNTs, the metal oxide or metal located inside CNTs is more easily reduced or oxidized; 2) the metal inside CNTs may as a catalyst to make CNTs reduce partly into methane at high temperature; 3) the confinement effect of CNTs includes the increased concentration or pressure, accelerated electron transfer, and the diffusion resistance inside CNTs; 4) the induction period appears during the benzene hydrogenation when the activated composiotion located insides CNTs; 5）the struture defects in CNTs reduce the diffusion resistance and is beneficial to the adsortion and desorption of reaction molecules during reaction process; 6) relative to the diameter size of CNTs, the effect of defect density is greater for the catalytic performance of benzene hydrogenation. In addtion, a further study found that the spontaneous reduction of CNTs with higher defect density provided a facile synthesis route for the synthesis of metal or metal oxside with low-valence. The preliminary results indicated that Fe2+ and Cu+ deposited on CNTs obtained by spontaneous reduction exhibite the superior catalytic activity and selectivity than that obtained by other methods.
结题摘要
根据不同材料物理化学性质，成功制备了多壁CNTs内组装金属或金属氧化物的纳米复合催化材料，利用EXAFS、ESR、XPS、Raman、CV、TPR、TG等技术，测定和比较管内组装和管外负载复合材料的电学性能，热稳定性，氧化性能等，并通过探针反应（苯加氢生成环己烷、乙苯脱氢生成苯乙烯和苯羟基化生成苯酚等）研究了活性组分Ni、Co、Ce等在碳管不同位置的催化性能。研究结果发现：1）相对于管外，管内的金属氧化物更易还原或金属更易氧化；2）高温条件下，管内金属作为催化剂能使碳管在临氢条件下部分还原成甲烷；3）碳管的限域效应包括管内浓度提高、压力增加、加速电子转移，增加扩散阻力等；4）内组装样品在苯加氢反应中出现明显的诱导期；5）多壁碳管的空缺结构减少了扩散阻力，有利于反应分子的吸附和产物分子的脱附；6）相对于碳管的管径大小对催化性能的影响，碳管空缺密度的影响更大。进一步的研究发现，CNTs的结构缺陷的自发还原作用提供了促进低价或还原态金属的便利合成，CNTs上形成Fe2+、Cu+等低价活性物种的初步研究结果表明，它们在苯羟基化反应以及苯加氢反应中体现了优于其他方法得到的催化剂的活性和选择性。