High-Visible-Light Photoactivity of Plasma-Promoted Vanadium Clusters on Nanozeolites for Partial Photooxidation of Methanol

Cold VCl₃–plasma is employed for the preparation of highly dispersed vanadium oxide clusters on nanosized zeolite. Different types of zeolites, such as EMT, FAU (z.X), and Beta, are used. The activity of the prepared catalysts is studied in the selective photooxidation of methanol under polychromatic visible and UV irradiations. The physicochemical properties and catalytic performance of plasma-treated zeolite Beta (P-V₂O₅@Beta) catalyst is compared with zeolite Beta (V₂O₅@Beta) and amorphous silica (V₂O₅@SiO₂) impregnated vanadium oxide catalysts. Pure V₂O₅ is used as a reference material. The set of catalytic data shows that plasma-prepared zeolite Beta based catalyst displays the highest activity. Complementary characterization techniques including XRD, N₂-sorption, FTIR, ionic exchange, pyridine adsorption, Raman, NMR, TPR, and EDX-TEM are used to study the impact of the preparation approach on the physicochemical properties and catalytic performance of photocatalysts

Recrystallization on Alkaline Treated Zeolites in the Presence of Pore-Directing Agents

In previous works aiming at understanding the mesoporous network after alkaline treatment in the presence of organic additives, conventional bulk characterization techniques led to the conclusion that the dissolved zeolite does not undergo any kind of recrystallization [Verboekend, D., Cryst. Growth. Des. 2013, 13, 5025−5035]. Here for the first time, we demonstrate using the data obtained from ¹H and ¹²⁹Xe NMR spectroscopy that such recrystallization does occur, which leads to the formation of a very thin coating of the mesopore walls. This demonstration is done on a beta (BEA) zeolite treated in the presence of TPA⁺ in an alkaline solution. The formation of a small amount of nanosized crystals or embryonic phases of silicalite-1 (MFI) zeolite is evidenced, as well as their homogeneous dispersion on the mesoporous surface of the beta zeolite. We think that these results may explain why a homogeneous mesopore size distribution is obtained, when organic pore-directing agents are used in the zeolite hierarchization process performed in an alkaline medium

Insight in the Alginate Pd-IonogelsApplication to the Tsuji–Trost Reaction

A new class of catalytic ionogels based on the entrapment of an ionic liquid phase within a sodium alginate matrix was applied to the Pd-catalyzed allylic substitution reaction. High activity and promising recyclability were obtained in C–N bond formation. Scanning electron microscopy, scanning transmission electron microscopy, and solid-state NMR studies provided a better insight into the catalytic behavior, and the stability of the catalytic ionogels was studied through a recycling process