3 research outputs found
High-Visible-Light Photoactivity of Plasma-Promoted Vanadium Clusters on Nanozeolites for Partial Photooxidation of Methanol
Cold VCl<sub>3</sub>âplasma
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-V<sub>2</sub>O<sub>5</sub>@Beta) catalyst is compared
with zeolite Beta (V<sub>2</sub>O<sub>5</sub>@Beta) and amorphous
silica (V<sub>2</sub>O<sub>5</sub>@SiO<sub>2</sub>) impregnated vanadium
oxide catalysts. Pure V<sub>2</sub>O<sub>5</sub> 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, N<sub>2</sub>-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, 5025â5035]. Here for the first time, we demonstrate
using the data obtained from <sup>1</sup>H and <sup>129</sup>Xe 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<sup>+</sup> 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-IonogelsîžApplication to the TsujiâTrost 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 CâN 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