Determination of Acidity Functions of Liquid Acids by C-13 NMR and Development of a Theoretically Justified Calibration of Solid Acidity

摘要CTS-9528412是早期开发的测定真实催化剂Hammett酸度函数的核磁共振波谱方法的扩展。主要目的是将该方法应用于固体“酸”，这类材料不适用于Hammett酸度概念。定义了一个名为“相对质子化能力”的参数，并将其用于酸的“强度”比较；它由化学计量比的指示剂与酸中心或分子的质子化来确定。既研究了传统的固体酸，也研究了固体表面处理形成的材料，包括杂多金属酸盐、硫酸金属氧化物和沸石。为了扩大可测量的酸度范围，研究了氟代烯烃和芳香烃作为可能的指示剂。从-80℃到200℃研究了质子化对温度的依赖关系。酸强度与催化活性有关，如烯烃或烷烃的异构化。固体酸在工业过程中的使用频率越来越高，因为它们具有明显的环境优势。然而，还没有足够的客观方法来衡量它们的酸强度。此外，关于固体中的酸度应该如何定义也存在争议。这些问题在这个项目中得到了解决。该项目由化学和运输系统司以及化学司共同支持。***

ABSTRACT CTS-9528412 This is an extension of the earlier development of a nuclear magnetic resonance (NMR) spectroscopic method for determining Hammett acidity functions for real catalysts. The main thrust is the application of the method to solid "acids", a class of materials to which the Hammett acidity concept does not apply. A parameter named "relative protonating ability" is defined and used for acid "strength" comparisons; it is determined by protonation of indicators at stoichiometric ratios to the acid sites or molecules. Both traditional solid acids as well as materials formed by surface treatment of solids are studied, including heteropolymetallates, sulfated metal oxides, and zeolites. To expand the measureable acidity range, fluorinated alkenones and aromatic hydrocarbons are studied as possible indicators. The dependence of protonation on temperature is studied from -80( C to 200( C. The acid strengths are correlated with catalytic activity for well-studied reactions such as isomerizations of olefins or paraffins. Solid acids are being used with increasing frequency in industrial processes because of their perceived environmental advantages. However, adequate objective measures of their acid strength are not available. In addition, there is controversy about how acidity in solids should be defined. These issues are addressed in this project. This project is supported jointly by the Divisions of Chemical and Transport Systems and of Chemistry. ***