UNS:High Surface Free Energy Anchoring of Bimetallic Core Shell Particles

UNS：双金属核壳颗粒的高表面自由能锚定

• 批准号: 1511615
• 负责人: John Monnier
• 金额: $ 45万
• 依托单位: University of South Carolina at Columbia
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-15 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1511615&HistoricalAwards=false
• 关键词: UNS; Surface; Free; Energy; Anchoring

Metallic catalysts for today's applications must be capable of stable operation at extreme conditions of feed compositions and temperatures. Thus, catalyst design and synthesis have become increasingly important to ensure catalyst particles which efficiently use expensive metals such as platinum group metals, and maintain an active surface at high temperatures and atypical feed compositions.The proposed work will create bimetallic catalyst particles dispersed on a carbon catalyst support that have improved resistance to particle coarsening under reaction conditions compared to the active metal component alone. The particle stabilization is achieved by depositing a surface shell of the active (gold, Au) catalyst on a core of a higher surface free energy core material (platinum (Pt), or various earth-abundant transition metals). The concept will be tested in the Au-catalyzed selective hydrochlorination of acetylene with gas-phase hydrochloric acid to produce vinyl chloride (an important intermediate in bulk chemical production). Preliminary work has shown dramatic stabilization of Au particles by depositing the Au on small Pt clusters prepared by atomic layer deposition. In this study, the Pt(core)-Au(shell) bimetallic particles will be further optimized and lower-cost earth-abundant copper (Cu), nickel (Ni), and cobalt (Co) will be evaluated as stabilizing core materials.This is a hypothesis driven proposal based on the simple idea that a higher surface free energy core material in a small core-shell particle can stabilize a lower surface energy shell material that otherwise would sinter rapidly under reaction conditions. The PIs have already obtained data indicating the concept works for two-nanometer Pt(core) particles (prepared by strong electrostatic adsorption) surface-coated with Au (prepared by atomic layer deposition). The further work will compare homogeneous alloys to core-shell catalysts of the same nominal composition, and will also examine the effects of shell thickness and core particle size on acetylene hydrochlorination activity and durability. The potential of nano-scale multi-metallic particles for improved catalytic performance and selectivity is a growing area of interest in catalysis, as is understanding of the working composition and structure of such catalysts. This proposal takes important steps toward optimizing the structure of bimetallic catalyst particles under reaction conditions with an eye toward ensuring long-term catalyst stability in realistic high-temperature reaction environments. Although much attention is being directed towards novel ways of creating supported catalysts containing active metal nano-clusters, few studies have gone beyond initial synthesis and testing to examine long-term stability under reaction conditions. Thus, the present proposal is a welcome addition to research in this area, with expected results that could impact a broad range of catalyst systems beyond the specific ones addressed here. In addition, the proposal offers a route to lower-cost catalysts based on sparing utilization of expensive precious, or noble, active metal components by utilizing core components that are low in cost such as Cu, Ni, and Co. The research will provide opportunities for both graduate and undergraduate students to participate in research directed towards industrial applications utilizing advanced synthesis techniques that can potentially enhance a broad range of catalytic processes.

当今应用的金属催化剂必须能够在饲料成分和温度的极端条件下稳定运行。因此，催化剂的设计和合成对于确保有效使用昂贵的金属（例如铂类金属），并在高温和非典型进料组成下保持活跃的表面变得越来越重要。拟议的工作将产生Bimetallic催化剂颗粒在碳催化剂支撑上分散在碳纤维支持下与颗粒反应的不受欢迎的反应相比，将其产生的型催化剂颗粒。 通过将活性（金，AU）催化剂的表面壳沉积在较高的表面自由能核心材料（铂（PT）或各种含量含量的过渡金属）的核心上，可以实现粒子稳定。该概念将在Au催化的乙二醇与气相盐酸的选择性盐氯化中进行测试，以产生氯化乙烯基氯化物（散装化学生产中的重要中间体）。 初步工作表明，通过将AU沉积在原子层沉积中制备的小PT簇上，通过将AU沉积在Au颗粒上进行了巨大的稳定。 In this study, the Pt(core)-Au(shell) bimetallic particles will be further optimized and lower-cost earth-abundant copper (Cu), nickel (Ni), and cobalt (Co) will be evaluated as stabilizing core materials.This is a hypothesis driven proposal based on the simple idea that a higher surface free energy core material in a small core-shell particle can stabilize a lower surface energy shell material that otherwise would sinter rapidly under reaction 状况。 PI已经获得了表明该概念对两纳米PT（核心）颗粒（由强静电吸附）表面涂层的数据（由原子层沉积制备）。 进一步的工作将将同质合金与同一名义组成的核壳催化剂进行比较，还将检查壳厚度和核心粒径对乙炔盐水活性和耐用性的影响。纳米级多金属颗粒对提高催化性能和选择性的潜力是催化中感兴趣的增长领域，对这种催化剂的工作组成和结构的理解也是如此。该建议采取重要步骤，以在反应条件下优化双金属催化剂颗粒的结构，以确保在现实的高温反应环境中确保长期催化剂稳定性。尽管人们对创建含有活性金属纳米群体的支持的催化剂的新型方法进行了很多关注，但很少有研究超越初始合成和测试，无法在反应条件下检查长期稳定性。因此，本提案是该领域研究的可喜补充，预期的结果可能会影响此处涉及的特定催化剂系统的广泛催化剂系统。此外，该提案通过利用诸如CU，NI和CO等成本较低的核心组件（例如CU，NI和CO）的核心组件来提供较低成本的催化剂的途径。研究将为研究生和本科生提供有关利用高级合成技术的研究的机会，以提供对培养工业应用程序的研究的机会。