新颖纳米金刚石基整体式催化剂催化乙苯直接脱氢制苯乙烯研究

Styrene is considered as one of the most important polymer monomers, and also serves as raw material for fine chemicals. More than 90% of its total output throughout the world has been produced through the catalytic direct dehydrogenation of ethylbenzene over Fe-based catalysts. Unfortunately, this production process suffers from the sharp deactivation of catalysts by coke deposition. The introduction of excess steam into feed can efficiently inhibit deactivation by suppressing the coke-formation, but which inevitably results in huge energy consumption and also in significant decrease in reactor volume efficiency. To replace the metallic catalysts with nanocarbons is a quite promising and practical approach for clean and energy-saving styrene production. The nanocarbon-based monolithic catalysts can efficiently overcome the existing issues of the application of nanocarbon powder catalysts in fixed-bed and fluidized-bed reactors, besides the significantly intensified heat and mass transfer. However, their catalytic activity and adhesion still remains urgent to be further improved. Therefore, the proposed work is to study the fabrication and manipulation of the novel nanodiamond-based monolithic catalysts towards the direct dehydrogenation of ethylbenzene under the oxidant- and steam-free conditions. The purpose is to resolve the open problems of the existing supported nanodiamond monolithic catalysts for direct dehydrogenation of ethylbenzene to styrene through increasing the amount of exposed active sites to reactants and their nucleophilicity via steric hindrance effect, the surface edge-corner and structural defect effect, synergism and the support effect resulted from the deagglomeration, inhibition of reagglomeration of the commercially available nanodiamond agglomerates, controllable fabrication of nanodiamond-based hybrids, heteroatoms-doping, surface defect production, and manipulation of support microstructure of monolithic catalysts. The manipulating rules and promoting mechanism of the as-developed monolithic catalysts towards direct dehydrogenation of ethylbenzene to styrene would be explored and the structure-performance relationship of the developed catalysts would be revealed by correlating the characterization results of catalysts to the catalytic reaction data. The main objective of this proposed work is to lay a solid foundation for the highly-efficient, energy-saving and clean production of styrene.

苯乙烯是重要高分子单体和精细化工原料，其总产量90%以上经由铁基催化剂催化乙苯直接脱氢制得，但存在催化剂积炭失活难题。引入过量水蒸气可有效抑制积炭，却又造成巨大能耗和反应器容积效率显著降低。纳米碳替代金属催化剂，颇具前景。整体式催化剂克服了纳米碳粉体用于固定床、流化床反应器所存在的问题并强化传热传质，但催化活性和活性单元抗脱落性仍亟待提升。为此，拟研究乙苯直接脱氢用新颖纳米金刚石基整体式催化剂的构筑与调控。通过纳米金刚石解聚和再团聚抑制、杂化体构建、控制氧化、掺杂、缺陷化及载体调控，发挥物理隔离效应、边角缺陷效应、协同作用及载体效应，提高暴露活性位数目、亲核性及活性单元抗脱落性，解决现有担载纳米金刚石整体式催化剂催化该反应所存在的问题。关联反应数据和催化剂表征结果，探究所构筑的新颖整体式催化剂在该反应中的调控规律和促进作用机制并揭示构效关系。本项目旨在为苯乙烯高效、节能、清洁生产奠定基础。

苯乙烯是重要高分子单体和精细化工原料，其总产量90%以上经由铁基催化剂催化乙苯直接脱氢制得，但存在催化剂积炭失活难题。引入过量水蒸气可有效抑制积炭，却又造成巨大能耗和反应器容积效率显著降低。纳米碳替代金属催化剂，颇具前景。整体式催化剂克服了纳米碳粉体用于固定床、流化床反应器所存在的问题并强化传热传质，但催化活性和活性单元抗脱落性仍亟待提升。为此，本项目针对现有整体式纳米碳催化剂的不足，主要开展以下几个方面的工作：1）针对纳米金刚石团聚所致的催化活性低的问题，开展了纳米金刚石团聚体的解聚、分散新方法及新型纳米金刚石基杂化体的制备研究，建立了有效的纳米金刚石解团聚新方法，显著提高纳米金刚石基纳米碳催化剂的乙苯脱氢催化活性；2）针对现有金刚石基整体式纳米碳催化剂低活性、活性单元易脱落的问题，开展了新型高效纳米金刚石基整体式纳米碳催化剂的研究。3）还开展了纳米金刚石基颗粒状纳米碳催化剂及其催化乙苯直接脱氢反应研究，将纳米金刚石解团聚、分散并植入氮掺杂碳网状结构，制备了新型纳米金刚石基颗粒状催化剂，为粉末纳米碳催化剂的工业应用瓶颈问题的解决开辟了新途径；4）还开展了廉价非纳米金刚石基纳米碳催化剂的制备及其催化乙苯直接脱氢的研究，探索了苯乙烯生产用非纳米金刚石基纳米碳催化剂的可行性。开展了烯基化合物选择氧化制羰基化合物的研究，为苯乙烯下游应用提供借鉴。还开展了氮化碳和载金属催化剂的研究，为乙苯直接脱氢用新型高效纳米金刚石基整体式纳米碳催化剂的制备和调控提供了技术支撑。通过本项目研究，制备了系列高效乙苯直接脱氢纳米碳催化剂，催化性能得到了显著提升。关联乙苯脱氢反应数据和催化剂的表征结果，探究所构筑的新型催化剂在乙苯直接脱氢反应中的构效关系和催化剂的调控规律，揭示了这些催化剂具有优良的乙苯直接脱氢催化性能的原因和机制。本项目的研究成果，为苯乙烯的高效、节能、清洁生产奠定了基础。