Application of Inverse Gas Chromatography (IGC) for inner surface characterization on porous glass and zeolite catalysts

为了阐明催化过程和提高工艺效率，多孔催化剂的表征是至关重要的。作为接触角测量的替代方法，逆气相色谱法（IGC）是一种灵敏的气相方法，用于研究颗粒、颗粒或纤维的表面性质。在表征良好的探针分子的帮助下，IGC能够检测到基本相同材料的微小差异。因此，IGC常用于药物、矿物、聚合物和复合材料的表征。然而，对微孔和介孔催化剂或催化剂载体的研究数量有限，尽管几种探针分子的性质很适合用于多孔材料内表面的研究。IGC方法能够确定大量的物理化学性质，例如表面能（色散和极性）、表面的酸/碱/极性官能团、吸附焓/熵、吸附等温线和BET表面积。IGC将对介孔玻璃（PG）、小孔、中孔和大孔沸石进行研究，以考察通过接枝不同硅烷进行附加表面改性的影响。这些材料具有明确的表面特性和孔隙结构。对于潜在的催化，药物传递和传感器应用，广泛的表征是必要的。IGC研究将获得表面能的色散量γ_s^d和吸附自由焓〖ΔG〗_ads^sp等表面性质，以估计吸附位点与不同吸附剂之间的相互作用强度。此外，确定了符合非线性VAN OSS方法的表面的酸/碱特征（γ_s^+/γ_s^-），利用单极和两性探针分子和加权最小二乘法计算了比表面能。此外，吸附的DFT计算将被应用于获得关于非极性和极性吸附剂在无硅醇和含硅醇的二氧化硅表面上的排列和吸附强度的信息。针对小孔、中孔和大孔沸石的催化应用，将对丁醇进行气相脱水，考察其孔结构对催化活性、选择性和长期稳定性的影响。硅烷液相接枝对材料亲水性/疏水性和酸度的影响将与IGC测量结果（表面能，根据GUTMANN方法的酸度/碱度参数（KA/KB））进行比较。

For elucidating catalytic processes and enhancing process efficiency, the characterization of porous catalysts is crucial. As an alternative for contact angle measurements, the inverse gas chromatography (IGC) is a sensitive gas phase method to investigate surface properties of particles, granulates or fibers. With the assistance of well-characterized probe molecules, the IGC is able to detect even small differences of largely identical materials. Thus, the IGC is often applied for characterization of drugs, minerals, polymers and composites. However, there is only a limited number of studies on micro- and mesoporous catalysts or catalyst supports, regardless of the well suited properties of several probe molecule for the investigation of the inner surface of porous materials. The IGC method is able to determine a large number of physico-chemical properties, for example, surface energies (dispersive and polar), acid/base/polar functionality of surfaces, adsorption enthalpy/entropy, sorption isotherms and BET surface areas.Mesoporous glasses (PG), small-, medium- and large-pore zeolites will be investigated by the IGC to examine the influence of an additional surface modification by grafting with different silanes. These materials are characterized by well-defined surface properties and pore structures. For potential catalytic, drug delivery and sensor applications an extensive characterization is necessary. IGC studies will be performed to obtain surface properties like the dispersive amount of the surface energy γ_s^d and the free enthalpy of adsorption 〖ΔG〗_ads^sp to estimate the strength of the interactions between adsorption sites and different adsorptives. Furthermore, the acid/base characteristics (γ_s^+/γ_s^-) of the surface accord¬ing to the nonlinear VAN OSS approach are determined to calculate the specific surface energy using both monopolar and amphoteric probe molecules and a weighted least-square method. In addition, DFT calculations on adsorption will be applied to obtain information regarding the arrangement and adsorption strength of nonpolar and polar adsorptives on a silanol-free and silanol-containing silica surface.Regarding the catalytic application of small-, medium- and large-pore zeolites, gas phase dehydration on butanol will be accomplished to investigate the influence of the pore structure on catalytic activity, selectivity and long-term stability. The effects of a liquid phase grafting with silanes on the materials hydrophilicity/hydrophobicity and acidity will be compared with the results of the IGC measurements (surface energy, acidity/basicity parameter (KA/KB) according to the GUTMANN approach).