Department of Materials Science and Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
Nat Chem. 2009 Dec;1(9):722-8. doi: 10.1038/nchem.433. Epub 2009 Nov 8.
Tungstated zirconia is a robust solid acid catalyst for light alkane (C(4)-C(8)) isomerization. Several structural models for catalytically active sites have been proposed, but the topic remains controversial, partly because of the absence of direct structural imaging information on the various supported WO(x) species. High-angle annular dark-field imaging of WO(3)/ZrO(2) catalysts in an aberration-corrected analytical electron microscope allows, for the first time, direct imaging of the various species present. Comparison of the relative distribution of these WO(x) species in materials showing low and high catalytic activities has allowed the deduction of the likely identity of the catalytic active site--namely, subnanometre Zr-WO(x) clusters. This information has subsequently been used in the design of new catalysts, in which the activity of a poor catalyst has been increased by two orders of magnitude using a synthesis procedure that deliberately increases the number density of catalytically relevant active species.
氧化钨稳定氧化锆是一种用于低碳烷烃（C(4)-C(8)）异构化的强固体酸催化剂。已经提出了几种催化活性位的结构模型，但这一主题仍然存在争议，部分原因是缺乏对各种负载 WO(x)物种的直接结构成像信息。在具有像差校正功能的分析电子显微镜中，对 WO(3)/ZrO(2)催化剂进行高角度环形暗场成像，首次能够直接对各种存在的物种进行成像。比较在具有低和高催化活性的材料中这些 WO(x)物种的相对分布，就可以推断出催化活性位的可能特征，即亚纳米级 Zr-WO(x)簇。这些信息随后被用于设计新型催化剂，其中通过使用一种合成程序，即故意增加催化相关活性物种的数密度，提高了一种较差催化剂的活性，使其活性提高了两个数量级。
