Gates Bruce C, Katz Alexander, Liu Jingyue
Department of Chemical Engineering, University of California, Davis, Davis, California 95616, United States.
Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, United States.
Precis Chem. 2023 Feb 15;1(1):3-13. doi: 10.1021/prechem.2c00011. eCollection 2023 Mar 27.
Supported catalysts that are important in technology prominently include atomically dispersed metals and metal clusters. When the metals are noble, they are typically unstable-susceptible to sintering-especially under reducing conditions. Embedding the metals in supports such as organic polymers, metal oxides, and zeolites confers stability on the metals but at the cost of catalytic activity associated with the lack of accessibility of metal bonding sites to reactants. An approach to stabilizing noble metal catalysts while maintaining their accessibility involves anchoring them in molecular-scale nests that are in or on supports. The nests include zeolite pore mouths, zeolite surface cups (half-cages), raft-like islands of oxophilic metals bonded to metal oxide supports, clusters of non-noble metals (e.g., hosting noble metals as single-atom alloys), and nanoscale metal oxide islands that selectively bond to the catalytic metals, isolating them from the support. These examples illustrate a trend toward precision in the synthesis of solid catalysts, and the latter two classes of nested catalysts offer realistic prospects for economical large-scale application.
在技术领域中重要的负载型催化剂主要包括原子分散的金属和金属簇。当金属为贵金属时，它们通常不稳定——易受烧结影响——尤其是在还原条件下。将金属嵌入有机聚合物、金属氧化物和沸石等载体中可赋予金属稳定性，但代价是与金属键合位点难以接触反应物相关的催化活性降低。一种在保持贵金属催化剂可及性的同时使其稳定的方法是将它们锚定在载体内部或表面的分子尺度的“巢穴”中。这些“巢穴”包括沸石孔口、沸石表面杯状结构（半笼）、与金属氧化物载体键合的亲氧金属的筏状岛、非贵金属簇（例如作为单原子合金容纳贵金属）以及选择性地与催化金属键合从而将它们与载体隔离的纳米级金属氧化物岛。这些例子说明了固体催化剂合成中精确性的趋势，后两类嵌套催化剂为经济的大规模应用提供了现实前景。
