金属/纳米氮化硼催化剂的可控制备及其催化性能的研究

Nanostructured hexagonal boron nitride (h-BN) is a promising catalyst support since it has a large surface area, high mechanical strength, good thermal stability, and excellent resistance to oxidation, acid or base. Upon manipulating microstructures or doping with other elements, the electronic characteristics and properties of nanostructured h-BNs might be altered. A reliable technique for producing nanostructured h-BNs and subsequently loading mono- or bimetallic nanoparticles onto them is pursued in this proposal, targeting high-performance heterogeneous catalysts for common organic reactions. Specifically, the exfoliation of bulk h-BNs and pyrolysis of B- & N-containing precursors will be used to prepare nanostructured h-BNs, followed by the partial substitution of B and N atoms with other elements (P, C, or Si) at high temperature. In addition, incorporation of other elements into pyrolytic precursors is another useful method to synthesize doped nanostructured h-BNs. Metallic nanoparticles will be prepared and loaded onto nanostructured h-BNs with the impregnation-reduction and the vapor deposition methods. The catalytic activities and recycling abilities of aforementioned catalysts will be evaluated in the classic reactions (including the coupling and selective hydrogenation reactions). During these processes, we shall correlate the composition, microstructures and surface moieties of nanostructured h-BNs with the morphology, stability and activity of metallic nanoparticles. Moreover, we shall also elucidate the structure-activity relationship among the nanostructured h-BN supports, metal nanoparticles and catalytic properties, seeking novel catalysts with high activity, selectivity and stability. These studies allow the controllable production of nanostructured h-BNs-supported catalysts and a deep understanding of their surface structures and interfacial interactions.

纳米六方氮化硼具有大比表面积、高机械强度、热稳定、抗氧化、耐酸碱等优良性能，经过微结构的调控和其他原子的掺杂可改变其电子性质和特征，因此在催化剂载体领域有良好的应用前景。本项目拟制备纳米氮化硼负载的金属催化剂并研究它的催化性能。利用块体原料的剥离和B、N前驱体的热解两种方法合成各种结构的纳米氮化硼，再由P、C、Si等原子的原位取代或前驱体组分的改变制备掺杂的纳米氮化硼。以浸渍还原法和气相沉积法在氮化硼载体上负载单或多金属纳米粒子，测试催化剂在模型反应（包括偶联和选择性加氢）中的催化活性和循环性能。考察纳米氮化硼的组成、微观结构、表面基团的调控对金属纳米粒子的形态、稳定性及催化性能的影响，总结氮化硼载体、金属粒子和催化性能三者之间的相互作用及构效关系，寻求具有优良活性、高选择性和稳定性的新型催化剂。通过上述研究深刻理解纳米氮化硼材料及催化剂的可控制备、表面、界面以及性能调节等重要科学问题。

六方氮化硼纳米材料具有很多优良的性质，如化学惰性、大比表面积、高熔点、低密度、高稳定性、憎水性等，而且氮化硼与负载其上的过渡金属存在相互作用（如金属dz轨道和N、B的pz轨道交盖）。这些特性使其成为一种良好的催化剂载体。因此，本项目主要发展氮化硼纳米材料的制备方法并在其上负载金属纳米粒子，探索它们非均相催化领域的应用。.首先用液相剥离法制备氮化硼纳米片，再由沉淀沉积法负载了Pd、Pd-Fe、Pd-FeNi(OH)x、CuI等纳米粒子，系统地表征了它们的形貌、组成和结构等性质，评估它们在模型反应中（如选择性加氢、醇氧化酯化、二氟甲基化反应）的催化性能。接着，合成新型的碳纳米材料及其复合材料，例如将环境废弃物（烟蒂）转化为多孔碳材料载体、制备还原氧化石墨烯与金属有机框架的复合材料，并以其作为电极材料和催化剂载体分别应用于苯二酚同系物的检测和氯苯酚的脱氯反应，借此获得了碳材料的合成工艺参数对其表面官能团、形貌、成分的影响规律，为掺杂氮化硼材料的制备积累了数据。随后，采用含碳、氮、硼或磷等元素的前驱体，由高温热解法合成掺杂的纳米碳材料和氮化硼材料，如碳杂介孔氮化硼、碳杂氮化硼纳米管、氮磷掺杂碳纳米片、氮掺杂还原氧化石墨烯、氮化碳纳米片等材料，重点研究了前驱体及合成工艺条件对这些材料的形貌、组成、结构、比表面积、带隙等物化性质的调控作用。以掺杂材料为载体负载了Pd、RuNi、NiCoMo、CuFOx纳米粒子，所得催化剂分别在产氢、有机污染物降解反应中表现出良好的催化活性和循环性，部分催化剂的TOF超过文献报道值。而且碳杂氮化硼纳米管、氮磷掺杂碳纳米片作为无金属催化剂在电化学氧还原反应中呈现出优于Pt/C的催化能力。通过上述研究，探究了纳米氮化硼及其掺杂材料的合成、修饰条件对其结构的调控机制，进而改善载体与金属粒子间的相互作用，实现了二者的协同效应，获得了一系列综合性能优良的金属/纳米氮化硼催化剂。