三维有序大孔–介孔Pt基纳米催化剂的可控制备及其对多组分VOC氧化的催化性能研究

Three-Dimensionally Ordered Macroporous-mesoporous (3DOMacro-meso) catalytic materials have the advantage of macroporous or mesoporous materials, which can improve the catalytic performance. But it is very difficult to prepare 3DOMacro-meso transition-metal oxides. Based on the nationwide urgent need of highly efficient catalysts for VOC removal and to realize the great need of the efficient utilization of nonferrous metal in guangxi and rare-earth resources in yulin city, this project is proposed. We shall adopt the templating methods to make the rare-earth metal oxides doped in situ in the 3DOMacro-meso SiO2 skeleton, and fabricate the highly dispersed Pt−Pd nanoparticles doped with the transition-metal oxides by the modified polyvinyl alcohol-protected reduction strategies, so that the Pt-based nanocatalysts with high surface areas, good thermal stability, and high catalytic performance can be generated. A number of characterization techniques will be used to determine the physicochemical properties of the Pt-based nanocatalysts, and their catalytic activities for the oxidative removal of the multicomponent VOC closer to the real environment (e.g., xylene, acetone and ethyl acetate, etc.) will be evaluated. By so doing, we can elucidate the “structure-performance” relationship, clarify the involved catalytic mechanisms, and establish the corresponding catalytic reaction kinetic models. It is envisioned that the results obtained in the proposed project will provide the experimental and theoretical basis on designing, preparing novel catalytic materials with high performance and the related catalytic process parameters for the practical application, and provide a new way to utilize efficiently the nonferrous metal in guangxi and the rare-earth resources in yulin city.

三维有序大孔–介孔（3DOMacro-meso）催化材料兼有大孔和介孔的优势，有利于提高催化性能，但目前很难制备3DOMacro-meso过渡金属氧化物。基于我国对挥发性有机物（VOC）治理高效催化剂的迫切需求以及实现广西有色金属和玉林稀土资源高效利用的重大需要，本课题拟通过模板法合成3DOMacro-meso Ce1-xZrxO2-SiO2，采用改进的聚乙烯醇保护还原法在Pt−Pd纳米粒子中掺入过渡金属，进而制得高比表面积、高稳定性和高活性的多级孔Pt基纳米催化剂。利用若干表征技术测定催化剂的物化性质，研究其对接近真实环境的多组分VOC（如二甲苯、丙酮和乙酸乙酯等）氧化的催化行为，揭示构效关系，探明催化作用机制，建立反应动力学模型。研究结果可为新型高性能催化材料的设计、制备和实际应用中催化工艺参数提供实验和理论基础，为广西有色金属和玉林稀土资源高效利用提供新途径。

氧化消除挥发性有机物催化剂的研究取得较大进展，但在提高催化剂性能、降低成本和实际应用等方面，仍然存在问题和挑战。广西具有丰富的有色金属矿产资源，玉林市是我国南方离子型稀土资源富集区，围绕扩大桂东南优势矿产资源的深度开发和利用而展开科学研究，有助于服务地方经济社会可持续发展。为此，探究了三维有序大孔-介孔SiO2基或Al2O3基载体材料及负载合金纳米粒子催化剂的制备，且应用在催化消除甲苯的反应。为了简化制备和降低成本，通过简便易行的共沉淀法制备铈锆铝复合材料，探究了其在催化消除汽车尾气中还原性气氛对材料结构和性能的影响。鉴于催化消除废水中有机污染物的实际需求，也研究开发了制备简便的光催化材料。 研究结果表明，成功制备M/3DOMacro-meso SiO2 (M = Pd, Pt, PdPt2)和M/3DOMacro-meso Ce0.75Zr0.25O2-Al2O3 (M =Au, Pt, AuPt2)，且M理论负载量为0.5 wt%，其中PdPt2/3DOMacro-meso SiO2和AuPt2/3DOMacro-meso Ce0.75Zr0.25O2-Al2O3具有更好的催化氧化甲苯活性；采用共沉淀法（CZA）、沉淀悬浊液混合法（CZ+A）、分步沉淀法Ⅰ（CZ-A）和分步沉淀法Ⅱ（A-CZ）四种不同沉淀方法制备铈锆铝复合氧化物（Ce、 Zr、Al 摩尔比为 1 : 1 : 2），发现共沉淀法制备的CZA 样品具有更好的结构、织构、储氧、还原和耐热性能；采用沉淀前驱物混合法制备铈锆铝复合氧化物（CZ+A(pm)）和沉淀机械研磨混合法制备铈锆铝（CZ+A(mm)）(Ce、Zr、Al 摩尔比为 1 : 1 : 2)，CZ+A(mm)样品中铈锆和氧化铝粒子更大，相互之间间隔更远，经还原热处理时能抑制CeAlO3的形成，从而改善材料在还原气氛下的储氧和还原性能；采用共沉淀法制备铈锆铝CZxA（Ce、Zr、Al 摩尔比为 1 : x : 2，其中 x = 0、0.5、1、1.5、2），发现CA 样品经还原热处理更易生成CeAlO3，而在CA中掺杂一定量Zr元素后的CZ1.5A、CZ2A 样品能抑制CeAlO3的形成，从而显著改善材料的储氧性能和H2-TPR耗氢量，且铈锆铝材料经还原热处理，均具有更好的低温还原性能。这些研究结果为催化剂的实际应用提供了重要的参考价值。