无水、贫氧条件下模型纳米石墨烯材料活化低碳烷烃脱氢反应的研究

Water is one of the most important resources in people’s everyday life. However, it combusts larger amount of water in the present chemical production process. Styrene is one of the most important precursors in chemical industry, which can be produced by a catalytic dehydrogenation process using Fe based catalysts under the protection of steam. Therefore, this technique requires huge amount of water. Recently, nanocarbon material as a metal free catalyst catalytic dehydrogenation of ethylbenzene to styrene has attracted a growing interest for researchers. Comparing with the traditional metal catalyst, the nanocarbon material presents the higher catalytic performance and the robust catalytic stability, especially it did not generate cook on the carbon surface during the dehydrogenation reaction, which can avoid using steam in the whole dehydrogenation process. In this project, we will design a model nanographene catalyst with a novel core-shell structure. This model nanographene catalyst is composed by a nanodiamond core and one or two layer ultra-thin graphene nanoshell. We want to investigate the catalytic performance over this model nanographene material under lean oxygen and the absence of steam. We want to combine the oxidative dehydrogenation and direct dehydrogenation on the model nanographene surface in order to enhance the styrene yield. Meanwhile, we want to understand the effect of the gaphene layer, the surface structure and the doped atom on the catalytic performance. Hopefully, it can explore a new way to catalytic dehydrogenation of ethylbenzene to styrene over the nanographene catalyst under the lean oxygen and the absence of steam.

水是人类赖以生存的重要资源，然而现有大部分的化工过程都需要消耗大量的水。苯乙烯是重要的化工原料之一，目前工业生产苯乙烯主要是使用铁基催化剂在大量水蒸气保护下由乙苯高温脱氢制备，该工艺需要消耗大量的水蒸气。最近纳米碳材料非金属催化乙苯脱氢已经成为研究的焦点。与传统的金属催化剂相比，纳米碳材料在脱氢反应中具有较好的催化活性、选择性和长期稳定性，尤其是纳米碳表面不易产生积碳，因而可以避免水蒸气的使用。本项目以一种具有复合结构的模型纳米石墨烯材料为研究对象，该材料以纳米金刚石为核，1-2层石墨烯为壳。重点考察在无水蒸气下，利用贫氧气氛，在纳米石墨烯表面有机结合乙苯的氧化脱氢反应和直接脱氢反应的发生过程，保证乙苯高转化率的同时，进一步提高产物苯乙烯的选择性。此外，还将考察石墨烯的壳层层数、表面结构、掺杂原子的种类和数量对脱氢性能的影响，为探索无水、贫氧气氛下乙苯脱氢工艺开辟一条新的途径！

为了开发高效、节能的乙苯脱氢工艺，本项目以一种具有复合结构的模型纳米石墨烯材料为研究对象，该材料以纳米金刚石为核，1-2层石墨烯为壳结构均一可控。通过在乙苯直接脱氢反应气氛中加入少量的氧气，利用少量的氧气首先诱导乙苯分子在纳米石墨烯表面发生氧化脱氢反应，由于乙苯氧化脱氢过程是一个放热反应，该过程会产生大量的热量，借助于石墨烯表面是热的良导体，故在纳米石墨烯表面可以将该部分热量快速的传递给其它乙苯分子用于参与直接脱氢反应，进而抑制目的产物苯乙烯的过渡氧化。在贫氧气氛下利用纳米石墨烯表面乙苯氧化脱氢和直接脱氢反应的耦合，实现乙苯分子具有高转化率的同时进一步提高苯乙烯的选择性。此外，通过本项目的实施考察了纳米石墨烯的壳层层数、表面结构、掺杂原子的种类和数量对贫氧气氛下乙苯脱氢性能的影响，为开发新型无水蒸气、贫氧气氛下纳米石墨烯材料催化乙苯脱氢制苯乙烯工艺提供了充分的理论指导。