Elucidation of the basicity dependence of 1-butene isomerization on MgO/Mg(OH)2 catalysts

A Study of Al2O3/MgO Composite Films Deposited by FCVA for Thin-Film Encapsulation

Al₂O₃ and MgO composite (Al₂O₃/MgO) films were rapidly deposited at low temperatures using filtered cathode vacuum arc (FCVA) technology, aiming to achieve good barrier properties for flexible organic light emitting diodes (OLED) thin-film encapsulation (TFE). As the thickness of the MgO layer decreases, the degree of crystallinity decreases gradually. The 3:2 Al₂O₃:MgO layer alternation type has the best water vapor shielding performance, and the water vapor transmittance (WVTR) is 3.26 × 10^-4 g·m^-2·day^-1 at 85 °C and 85% R.H, which is about 1/3 of that of a single layer of Al₂O₃ film. Under the action of ion deposition, too many layers will cause internal defects in the film, resulting in decreased shielding ability. The surface roughness of the composite film is very low, which is about 0.3-0.5 nm depending on its structure. In addition, the visible light transmittance of the composite film is lower than that of a single film and increases with the increase in the number of layers.

Yttria-Stabilized Zirconia of Balanced Acid-Base Pair for Selective Dehydration of 4-Methyl-2-pentanol to 4-Methyl-1-pentene

The selective transformation of secondary alcohols to alpha-olefins is a challenging task in heterogeneous catalysis, as is the case of 4-methyl-2-pentanol (4M2Pol) conversion to 4-methyl-1-pentene (4M1P). Herein, the co-precipitated yttria-stabilized zirconia (YSZ) catalysts exhibit superior performance to both bare and Y-impregnated ZrO2 in selective 4M2Pol dehydration. In order to track the activity origin of YSZ, temperature-programmed desorption experiments using NH3 and CO2 are performed along with X-ray photoelectron spectroscopy. The conversion of 4M2Pol (max. 85%) is proportional to weak acidity and inverse to medium basicity. In contrast, the selectivity of 4M1P increases to 80% as the ratio of weak acidity to medium basicity is close to and exceeds the unity. These indications corroborate that the balanced acid–base pair of YSZ leads to the selective formation of 4M1P from 4M2Pol, which is caused by strong interaction between zirconia and yttria in the YSZ. Additionally, the dehydration activity over YSZ of 4 mol% yttrium is sustained at 450 °C for 50 h. Therefore, the YSZ, which is often used for electrocatalysis, is believed to be a promising catalyst in the dehydration of 4M2Pol and, further, secondary alcohols.

Solid-State Molecular Organometallic Catalysis in Gas/Solid Flow (Flow-SMOM) as Demonstrated by Efficient Room Temperature and Pressure 1-Butene Isomerization

The use of solid–state molecular organometallic chemistry (SMOM–chem) to promote the efficient double bond isomerization of 1-butene to 2-butenes under flow–reactor conditions is reported. Single crystalline catalysts based upon the σ-alkane complexes [Rh(R₂PCH₂CH₂PR₂)(η²η²-NBA)][BAr^F₄] (R = Cy, ^tBu; NBA = norbornane; Ar^F = 3,5-(CF₃)₂C₆H₃) are prepared by hydrogenation of a norbornadiene precursor. For the ^tBu-substituted system this results in the loss of long-range order, which can be re-established by addition of 1-butene to the material to form a mixture of [Rh(^tBu₂PCH₂CH₂P^tBu₂)(cis-2-butene)][BAr^F₄] and [Rh(^tBu₂PCH₂CH₂P^tBu₂)(1-butene)][BAr^F₄], in an order/disorder/order phase change. Deployment under flow-reactor conditions results in very different on-stream stabilities. With R = Cy rapid deactivation (3 h) to the butadiene complex occurs, [Rh(Cy₂PCH₂CH₂PCy₂)(butadiene)][BAr^F₄], which can be reactivated by simple addition of H₂. While the equivalent butadiene complex does not form with R = ^tBu at 298 K and on-stream conversion is retained up to 90 h, deactivation is suggested to occur via loss of crystallinity of the SMOM catalyst. Both systems operate under the industrially relevant conditions of an isobutene co-feed. cis:trans selectivites for 2-butene are biased in favor of cis for the ^tBu system and are more leveled for Cy.

Insight into the optical, color, photoluminescence properties, and photocatalytic activity of the N–O and C–O functional groups decorating spinel type magnesium aluminate

MgAl₂O₄ with a spinel structure was successfully synthesized using a gamma-ray irradiation assisted polyacrylamide gel method.

One-step synthesis, electronic structure, and photocatalytic activity of earth-abundant visible-light-driven FeAl2O4

The development of inexpensive visible-light-driven photocatalysts is an important prerequisite for realizing the industrial application of photocatalysis technology. In this paper, an earth-abundant FeAl₂O₄ photocatalyst is prepared via facile solution combustion synthesis. Density functional theory and the scanning Kelvin probe technique are employed to ascertain the positions of the energy bands and the Fermi level. Phenol is taken as a model pollutant to evaluate the photocatalytic activity of FeAl₂O₄. The scavenger experiment results, ˙OH-trapping fluorescence technique, and electron spin resonance measurements confirm that the superoxide anion radical is the main active species generated in the photocatalytic process, which also further corroborates the proposed electronic structure of FeAl₂O₄. The degradation experiments and O₂ temperature programmed desorption results over various samples verify that the crystallinity degree is a more important factor than the oxygen adsorption ability in determining photocatalytic activity.

Development of basicity in mesoporous silicas and metallosilicates

We report herein an experimental study on the development of basicity on mesoporous silicas and metallosilicates (Nb- and Ce-) on SBA-15 and MCF porous structures.

Synergetic effect of ruthenium and basicity sites in the Ru–MgAl catalyst for hydrogen-free production of conjugated linoleic acids

A series of Ru–MgAl composite oxide catalysts prepared by calcining the ruthenium grafted hydrotalcite-like precursor at various temperatures were used in the hydrogen-free production of conjugated linoleic acid.

A novel synthetic route for magnesium aluminate (MgAl2O4) nanoparticles using sol-gel auto combustion method and their photocatalytic properties

In this paper a novel and inexpensive route for the preparation of spinel magnesium aluminate nanoparticles (MgAl2O4) is proposed. Magnesium aluminate photocatalyst was synthesized via sol-gel auto combustion method using oxalic acid, urea, and citric acid fuels at 350°C. Subsequently, the burnt samples were calcined at different temperatures. The pure spinel MgAl2O4 with average crystallite size 27.7, 14.6 and 15.65nm was obtained at 800°C calcinations using the aforementioned fuels, respectively. The obtained samples were characterized by powder X-ray diffraction, Fourier transform infrared, UV-Vis spectroscopy, transmission electron microscope, scanning electron microscope. The photo catalytic activity of MgAl2O4 product was studied by performing the decomposition of Reactive Red Me 4BL dye under UV illumination or sunlight irradiation. The dye considerably photocatalytically degraded by 90.0% and 95.45% under UV and sunlight irradiation, respectively, within ca. 5h with pseudo first order rate constants of 5.85×10(-3) and 8.38×10(-3)min(-1), respectively.