Carbon dioxide was shown to identify surface basic properties of nitrogen-substituted microporous and mesoporous silicas, in addition to conventional basic oxides, by a detailed study using isotherm and heat of adsorption measurements as well as by infrared spectroscopy. A hydrogen-bonded weak interaction was primarily observed between CO₂ and silanol (Si–OH) and silamine (Si–NH–Si) groups. The heat of adsorption of CO₂ demonstrated that the latter adspecies were formed preferentially over the former, although a much higher amount of linear CO₂ adspecies were found on SBA-15 mesoporous silica because of the presence of a large quantity of silanol groups on its surface. Carbamate-type chemisorbed adspecies were not detected on silamino sites, whereas carbonate-type adspecies were formed on alkali ion-exchanged zeolites and also residual sodium ions on the surface of silicalite-1. CO₂ was shown to be a successful probe molecule for identifying weakly interactive hydrogen-bonding sites, and it has potential as a surface probe for strongly interactive nucleophilic sites derived from alkaline ions or a methylated silamino group, Si–N(CH₃)–Si.

中文翻译：

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使用CO ₂作为探针分子的氮取代微孔和中孔硅酸盐骨架的基本位点的确定

通过使用等温线和吸附热测量以及红外光谱的详细研究表明，除常规的碱性氧化物外，二氧化碳还可以确定氮取代的微孔和中孔二氧化硅的表面碱性。主要观察到在CO ₂与硅烷醇（Si–OH）和硅烷胺（Si–NH–Si）基团之间存在氢键键合的弱相互作用。吸附CO ₂的热量表明，尽管后者的线性CO ₂含量高得多，但后者的形成要优先于前者。由于SBA-15中孔二氧化硅表面存在大量硅烷醇基团，因此在SBA-15中孔二氧化硅中发现了相应的种类。在硅氨基位点未检测到氨基甲酸酯型化学吸附态，而在碱性离子交换的沸石上以及在silicalite-1表面残留的钠离子上形成了碳酸盐型态。事实证明，CO ₂是识别弱相互作用氢键位点的成功探针分子，它有可能作为表面探针来探测源自碱性离子或甲基化硅氨基基团Si–N（CH ₃）–的强相互作用亲核位点。硅。