An efficient synthetic method for the preparation of multisubstituted furans, thiophenes, and pyrroles using ynolates was developed. This novel formal [4 + 1] annulation by C2-C3 and C3-C4 bond formations includes cycloaddition, cyclization, decarboxylation, and dehydration as key steps.
Crystalline
trigonal Mo3VO
x
(Tri-MoVO)
catalyst is constructed of {Mo6O21}6– pentagonal units and octahedral {MO6} units that form
hexagonal and heptagonal channels in the crystal
structure. Tri-MoVO is an extremely active catalyst for selective
oxidation of acrolein (ACR) to form acrylic acid (AA), with the local
structure around the heptagonal channel responsible for the catalysis.
Here, promoter elements that are widely used in industrial Mo–V-based
mixed oxide catalysts (W and Cu) were introduced without altering
the crystal structure of Tri-MoVO. W was located at the pentagonal
unit sites by replacing Mo, and Cu was located in the interstitial
spaces of lattice oxygens in the corner of the heptagonal channel
micropore, forming a sophisticated crystal structure involving the
four constituent elements. Introduction of W improved the ACR conversion
without altering AA selectivity even when the water pressure in the
reaction gas was decreased, owing to the promotion of the dissociative
adsorption of water. The introduction of Cu resulted in improvement
of the AA selectivity from ca. 93–94% to ca. 97%. Based on
the structural and elemental similarities between Tri-MoVWCuO and
industrially utilized Mo–V-based mixed oxide catalysts synthesized
according to the patented procedure, we concluded that Tri-MoVWCuO
is the true catalytically active structure for selective oxidation
of ACR.
A simple, convenient, reusable, and inexpensive air-and water-purification unit including a one-end sealed porous amorphous-silica (a-silica) tube coated with TiO2 photocatalyst layers has been developed. The porous a-silica layers were formed through outside vapor deposition (OVD). TiO2 photocatalyst layers were formed through impregnation and calcination onto a-silica layers. The resulting porous TiO2-impregnated a-silica tubes were evaluated for air-purification capacity using an acetaldehyde gas decomposition test. The tube (8.5 mm e.d. × 150 mm) demonstrated a 93% removal rate for high concentrations (ca. 300 ppm) of acetaldehyde gas at a single-pass condition with a 250 mL/min flow rate under UV irradiation. The tube also demonstrated a water purification capacity at a rate 2.0 times higher than a-silica tube without TiO2 impregnation. Therefore, the tubes have a great potential for developing compact and in-line VOC removal and water-purification units.
OPEN ACCESSCatalysts 2015, 5 1499
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.