Solid acids, surface acidity and heterogeneous acid catalysis

MWW and MFI Frameworks as Model Layered Zeolites: Structures, Transformations, Properties, and Activity

“…Probing Lewis Acidity in 2D Zeolites. Lewis acid sites in zeolites are classified into three types: 288 (i) coordinatively unsaturated extra-framework or "frameworkassociated" Al atoms; (ii) metal cations at ion-exchange positions; and (iii) intrinsic centers related to framework tetravalent elements (Ti, Sn, Zr, and others).…”

Tuning the Cu/SiO2 wettability features for bio-derived platform molecules valorization

“…Utilizing different probes with diverse size is often used as a method to assess accessibility of the acid sites. [66][67][68][69] The information gained from the surface features such as morphology, wettability and acidity lead us to hypothesize a viable explanation of the critical aspects involved in the increased selectivity in the hydrogenation of GVL to 1,4-PDO. Wettability is a key factor in driving the removal of the diol product from the catalytic active sites.…”

Role of Brønsted Surface Acid Sites of B2O3–Al2O3 Catalyst Supports in Perylene Radical Cation Formation Studied by Probe EPR with TEMPO Radicals

“…An important characteristic of these catalysts is the concentration and ratio of two different acid sites, i.e., Brønsted (BAS) and Lewis acid sites (LAS), which determine the yields and selectivity of the target and byproduct formation in catalytic reactions. Also, the problems of developing simple and experimentally convenient methods and approaches for studying the acid properties of catalysts under conditions close to their real application are still relevant today . One of such methods can be EPR spectroscopy of probe molecules, in particular, the application of stable nitroxyl radicals, which form specific complexes with acid sites. − …”

“…Also, the problems of developing simple and experimentally convenient methods and approaches for studying the acid properties of catalysts under conditions close to their real application are still relevant today. 7 One of such methods can be EPR spectroscopy of probe molecules, in particular, the application of stable nitroxyl radicals, which form specific complexes with acid sites. 8−11 In a series of studies, we have previously determined the qualitative regularities of changes in the acid properties of catalysts and supports based on borate- 12,13 and tungstatemodified alumina.…”