贵金属－过渡金属磷化物有效接触双功能催化剂的可控制备及其生物油中酚类化合物加氢脱氧构效关系研究

It is difficult for bio-oil to be used as transportation fuel due to high oxygen content, viscosity and acidity. Hydrodeoxygenation of biomass oil has been a hot piont in biomass ewnergy research. The dual functional catalyst with uniform nano particle size and the effective contact between Ni2P and noble metal becomes most likely a new generation of the catalyst which has high acitivity and selectivity for biomass oil upgrading. However, the traditional impregnant method can not ensure the effective contact between Ni2P and noble metal and further lead to waste of noble metal.In the previous study, the applicant found that using the reductive metal support to reduce noble metal precursor in situ can result in the effective contact between Ni2P and noble metal and the appropriate synergy effect and further contribute to excellent performance for hydrogenation and dehydrogenation. In this work, the sol-gel- temperature-programmed reduction and in situ conversion are used to prepare the dual functional catalyst material with the uniform nano particle size and effective contact between Ni2P and noble metal (MNPS) and this catalyst will also be used to catalyze hydrodeoxygenation of phenolic compounds in biomass oil. On the basis of experimental and calculation results,the principle of in situ conversion for noble metal precursor on phosphide support is explored and synergetic effect between noble metal and phosphide is explained. Further,structure-function relationship between structure and component of MNPS and biomass oil upgrading also is unveiled. Through this work, it is expecting that in theory the scientific basis for biomass oil upgrading can be provided. In application aspect, the scientific fundamental can be offered to meet the needs of national energy.

由于含氧量高、粘度大和酸性强，难以直接用作运输燃料，目前生物油加氢提质已成为生物质能源研究的热点。粒度均匀可控、贵金属与Ni2P有效接触双功能催化剂极可能成为生物油加氢提质的高效催化剂。然而目前普遍采用的浸渍法难以确保Ni2P和贵金属之间的有效接触、且造成贵金属浪费。在前期的研究中，申请者发现以还原性载体原位还原贵金属产生的载体和贵金属间有效接触能够带来的适宜协同效应，进而产生优异的加、制氢性能。本项目采用溶胶凝胶－程序升温还原、原位转化法制备粒度均匀可控、贵金属与Ni2P有效接触双功能催化剂（MNPS），并将其应用于酚类化合物加氢脱氧反应。基于实验和模拟结果，探索贵金属前驱体在磷化物载体上的原位可控转化规律和贵金属与Ni2P间的协同效应，进而揭示MNPS的结构组成和生物油加氢提质间的构效关系。该研究在理论上期望为生物油高效加氢提质提供科学依据，在应用上以期为满足国家能源需求提供科学支撑。

生物质是唯一可大量再生的碳氢资源。对于生物质的高效利用一直是研究者关注的焦点。本研究以贵金属-金属磷化物紧密结合双功能催化剂对生物质基酚类化合物的选择性高效加氢脱氧进行了深入研究，主要研究结论如下：.本项目研究表明，相比与溶剂相合成法,溶胶-凝胶法准备Ni2P/SiO2具有较高的苯酚加氢脱氧活性，这归结于作为路易斯酸和金属位点的高浓度低价Ni物种,以及较高的Ni2P结晶度。与单纯的负载型Ni2P或贵金属催化剂及其物理混合物相比，三种贵金属(Pd,Pt,Ru)-Ni2P催化剂中,Pd-Ni2P/SiO2的转化率和环己烷选择性最高。表征表明，由于Ni2P与贵金属之间的密切接触，催化剂上的活性位点增多，电子从Ni2P转移到贵金属。Ni2P脱氧与Pd加氢的协同作用提高了催化剂的催化活性和选择性。稳定性研究表明，Pd-Ni2P/SiO2催化剂的稳定性最高。在0.1g催化剂，2MPa和493 K和4个反应循环中，苯酚转化率为100.0%-93.0%，环己烷选择性为94.2%-83.1%。Pd在催化剂上高度分散并与Ni2P强烈相互作用，导致金属的聚集、损失和积碳可以忽略。相比之下，Ni2p/SiO2的失活是由于在H2O存在下，磷的损失、磷化物的氧化和碳的沉积。通过对反应工艺条件的考察发现，在Ni2P/SiO2下，苯酚、苯甲醚和愈创木酚在较低的反应温度和较高的H2压力有利于这些模型化合物加氢生成环己烷，而较高的反应温度和较低的H2压力有利于苯的生成。在1.5 MPa、573 K、0.5 MPa和673 K时，苯甲醚或苯酚的加氢脱氧中环己烷和苯的收率分别为89.8%和96.0%。稳定性实验表明，在36h内，苯甲醚的活性和苯选择性稳定。此外，在温和的反应条件下，含氧缺陷的复合NiOx-Ni2P/SiO2(0.43<x<1)催化剂比单纯Ni2P、NiOx催化剂和大多数文献值显示出高的苯酚加氢脱氧性能。这主要是因为NiOx中氧缺陷和Ni2P的酸性导致苯酚吸附构型和加氢脱氧能力的协同效应。.本课题通过对生物质基酚类化合物的研究，在不同反应条件下，分别高选择的得到了环己烷、环己醇和苯类化合物。这为生物质的开发利用提供了理论依据和科学借鉴。