The Effect of Surface Functional Groups on the Dispersion, Chemical Properties, and Catalytic Behavior of Carbon- Supported Pd and Pt-Sn Catalysts Prepared from Metal Cluster

本文研究了不同含氧官能团对钯对碳和铂锡对碳的分散、烧结性能和催化性能的影响。该策略是以一种可控的方式改变高纯度碳上羧基、内酯、羰基、羟基和酚基的浓度。从历史上看，这样做的尝试由于难以表征碳表面而受挫。在本研究中，在1000>下处理去除所有表面基团后，在空气、硝酸和过氧化氢中处理后选择性恢复某些基团，通过反射红外光谱、热重分析/质谱和差示微量热法对碳表面进行了表征。制备金属/碳催化剂的新方法包括钯和铂锡有机金属配合物的合成和浸渍，这些配合物在低温下很容易还原。钯晶大小对磁性和化学性质的影响由磁化率测量、金属对氧、一氧化碳和氢的吸附热、化学吸收一氧化碳的红外光谱、以及化学吸附氢和钯-105的固态魔角旋转核磁共振。这项工作直接解决了碳负载贵金属催化剂的性能，但结果也与碳电极的生产和使用、煤气化和石油重整有关。碳载贵金属催化剂广泛应用于特种化工和石油化工行业。

This is a study of the effects of different oxygen-containing functional groups on the dispersion, sinter resistance, and catalytic behavior of palladium on carbon and of platinum-tin on carbon. The strategy is to alter, in a controlled way, the concentrations of carboxyl, lactone, carbonyl, hydroxyl, and phenolic groups on a high-purity carbon. Historically, attempts to do this have been frustrated by the difficulty of characterizing carbon surfaces. In this study, carbon surfaces are characterized by reflection infrared spectroscopy, thermal gravimetric analysis /mass spectrometry, and differential microcalorimetry after treatment at 1000> to remove all surface groups and after treatments in air, nitric acid, and hydrogen peroxide to selectively restore certain groups. Novel approaches to the preparation of metal/carbon catalysts involve the synthesis and impregnation of palladium and platinum-tin organometallic complexes that can be easily reduced at low temperatures. The influence of palladium crystallite size on magnetic and chemical properties is determined by magnetic susceptibility measurements, heats of adsorption for oxygen, carbon monoxide, and hydrogen on the metal, infrared spectra of chemisorbed carbon monoxide, and solid-state magic-angle-spinning nuclear magnetic resonance of chemisorbed hydrogen as well as palladium-105. The work addresses directly the performance of carbon- supported noble-metal catalysts, but the results are also relevant to production and use of carbon electrodes, coal gasification, and petroleum reforming. Carbon-supported noble-metal catalysts are widely used in the specialty chemicals and petrochemicals industries.