Solid acid catalysts are used extensively in various advanced chemical and petrochemical processes. Their catalytic performance (namely, activity, selectivity, and reaction pathway) mostly depends on their acid properties, such as type (Brønsted versus Lewis), location, concentration, and strength, as well as the spatial correlations of their acid sites. Among the diverse methods available for acidity characterization, solid-state nuclear magnetic resonance (SSNMR) techniques have been recognized as the most valuable and reliable tool, especially in conjunction with suitable probe molecules that possess observable nuclei with desirable properties. Taking ³¹P probe molecules as an example, both trimethylphosphine (TMP) and trimethylphosphine oxide (TMPO) adsorb preferentially to the acid sites on solid catalysts and thus are capable of providing qualitative and quantitative information for both Brønsted and Lewis acid sites. This protocol describes procedures for (i) the pretreatment of typical solid acid catalysts, (ii) adoption and adsorption of various ³¹P probe molecules, (iii) considerations for one- and two-dimensional (1D and 2D, respectively) NMR acquisition, (iv) relevant data analysis and spectral assignment, and (v) methodology for NMR mapping with the assistance of theoretical calculations. Users familiar with SSNMR experiments can complete ³¹P–¹H heteronuclear correlation (HETCOR), ³¹P–³¹P proton–driven spin diffusion (PDSD), and double-quantum (DQ) homonuclear correlation with this protocol within 2–3 d, depending on the complexity and the accessible acid sites of the solid acid samples.

固体酸催化剂广泛用于各种先进的化学和石化工艺中。它们的催化性能（即活性，选择性和反应途径）主要取决于它们的酸性质，例如类型（布朗斯台德与路易斯），位置，浓度和强度以及其酸位的空间相关性。在可用于酸度表征的各种方法中，固态核磁共振（SSNMR）技术已被认为是最有价值和最可靠的工具，尤其是与拥有可观察核且具有所需特性的合适探针分子结合使用时。服用³¹以P探针分子为例，三甲基膦（TMP）和三甲基氧化膦（TMPO）都优先吸附到固体催化剂上的酸性位置，因此能够提供布朗斯台德和路易斯酸性位置的定性和定量信息。该协议描述了以下步骤：（i）预处理典型的固体酸催化剂，（ii）采用和吸附各种³¹ P探针分子，（iii）考虑一维和二维（分别为1D和2D）NMR采集， （iv）相关数据分析和光谱分配，以及（v）借助理论计算进行NMR绘图的方法。熟悉SSNMR实验的用户可以完成³¹ P– ¹ H异核相关（HETCOR），³¹P– ³¹ P质子驱动的自旋扩散（PDSD）和双量子（DQ）同核相关性在2-3 d内取决于此规程，具体取决于固体酸样品的复杂性和可接近的酸位。