GOALI: STM and AXAFS Studies of Electronic Effects due to Metal Support Interaction on Noble Metal Supported Catalysts

这是一个果利大学与行业合作的项目。沃尔夫教授和米勒博士将测量各种载体上贵金属催化剂的电子性质，并验证这些性质的变化是否与观察到的周转频率和选择性的变化在数量级上相关。模型催化剂将包括沉积在金属氧化物载体薄膜上的铂和钯(沉积或生长在Mo(110)上的氧化铝、二氧化硅、二氧化钛和掺K的氧化铝)。将它们与标准的高表面催化剂进行比较。表面的电子结构将用扫描隧道谱(STS)来探测，它的形态将用扫描显微镜(STM)来探测，以及它与新戊烷氢解和甲烷氧化的反应动力学。将合成不同大小的金属颗粒。STM将被用来确定颗粒的尺寸分布，STS将通过在裸载体和颗粒包裹的催化剂上的I-V曲线来获得电子特性。吸附CO的漫反射红外光谱(DRIFT)将获得结构和电子性质信息。金属和载体的近邻结构将用EXAFS确定。用原子吸收X-射线能谱(AXAFS)测定了铂的原子间相互作用势，并与催化和漂移结果进行了关联。酸度的测定将涉及氨的化学吸附。STM工作将在巴黎圣母院进行，而BP Amoco的EXAFS工作将需要阿贡国家实验室的资源。

This is a GOALI university-industry collabortive project. Prof. Wolf and Dr. Miller will measure the electronic properties of noble metal catalysts on various supports and verify whether changes in those properties are correlated with the observed changes by orders of magnitude in turnover frequency and selectivity. The model catalysts will consist of Pt and Pd deposited on thin films of metal oxide supports (alumina, silica, titania, and K-doped alumina, deposited or grown on Mo (110)). They will be compared with standard high surface are catalysts. The electronic structure of surfaces of surfaces will be probed with scanning tunneling spectroscopy (STS); its morphology with scanning microscopy (STM); and its reactivity with the kinetics of hydrogenolysis of neopentane and oxidation of methane. Metal particles will be synthesized with different sizes. STM will be used to ascertain the particle size distribution and STS will yield the electronics characteristics via I-V curves on the bare support and the particle-coated catalyst. Diffuse reflectance infrared spectroscopy (DRIFTS) of adsorbed CO will yield structural and electronic property information. The near neighbor structure of metals and support will be determined with EXAFS. The interatomic potential of Pt will be determined with atomic absorption x-ray spectroscopy (AXAFS) and correlated with catalysis and DRIFTS results. Acidity determinations will involve ammonia chemisorption. The STM work will be carried out at Notre Dame, while the EXAFS work by BP Amoco will require resources of the Argonne National Laboratory.