Microwave-assisted synthesis, characterization and modeling of cpo-27-mg metal-organic framework for drug delivery

The coordination polymer CPO-27-Mg was rapidly synthesized under microwave irra-diation. This material exhibits a sufficiently high drug loading towards aspirin (~8% wt.) and paracetamol (~14% wt.). The binding of these two molecules with the inner surface of the metal-organic framework was studied employing the Gaussian and Plane Wave approach of the Density Functional Theory. The structure of CPO-27-Mg persists after the adsorption of aspirin or paracetamol and their desorption energies, being quite high, decrease under solvent conditions. © 2021 by the authors. Li-censee MDPI, Basel, Switzerland

A Brief Review of Carbon Dioxide Hydrogenation to Methanol Over Copper and Iron Based Catalysts

Climate change and global warming have become a challenging issue affecting not only humanity but also flora and fauna due to an intense increase of CO2 emission in the atmosphere which has gradually led to amplification in the average global temperature. Hence, a number of mechanisms have been promoted to diminish the atmospheric commutation of carbon dioxide. One of the well-known techniques is Carbon Capture and Storage (CCS) which mechanism is based on capture and storage vast quantities of CO2, as well as Carbon Capture and Utilization (CCU) which mechanism is based on CO2 conversion to liquid fuels (e.g. methanol, hydrocarbons, dimethyl carbonate, propylene, dimethyl ether, ethylene, etc.). Particularly, methanol (CH3OH) is a key feedstock for industrial chemicals, which further can be converted into high molecular alternative liquid fuels. In this regard, hydrogenation of CO2 is one of the promising, effectual and economic techniques for utilization of CO2 emission. Nevertheless, the reduction/activation of CO2 into useful liquid products is a scientifically challenging issue due to the complexities associated with its high stability. Thus, various catalysts have been applied to reduce the activation energy of the hydrogenation process and transform CO2 into value-added products. Thereby, this review article highlights the progress and the recent advances of research investigation in Cu and Fe-based catalytic conversion of CO2, reaction mechanisms, catalytic reactivity, and influence of operating parameters on product efficiency

Catalysis by Hybrid Nanomaterials

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IR-Spectroscopic Study of Complex Formation of Nitrogen Oxides (NO, N₂O) with Cationic Forms of Zeolites and the Reactivity of Adsorbed Species in CO and CH₄ Oxidation

The formation of complexes and disproportionation of nitrogen oxides (NO, N2O) on cationic forms of LTA, FAU, and MOR zeolites was investigated by diffuse-reflectance IR spectroscopy. N2O is adsorbed on the samples under study in the molecular form and the frequencies of the first overtone of the stretching vibrations ν10–2 and the combination bands of the stretching vibrations with other vibrational modes for N2O complexes with cationic sites in zeolites (ν30–1 + ν10–1, ν10–1 + δ0–2) are more significantly influenced by the nature of the zeolite. The presence of several IR bands in the region of 2400–2600 cm−1 (the ν10–1 + δ0–2 transitions) for different zeolite types was explained by the availability of different localization sites for cations in these zeolites. The frequencies in this region also depend on the nature of the cation (its charge and radius). The data can be explained by the specific geometry of the N2O complex formed, presumably two-point adsorption of N2O on a cation and a neighboring oxygen atom of the framework. Adsorption of CO or CH4 on the samples with preliminarily adsorbed N2O at 20–180 °C does not result in any oxidation of these molecules. NO+ and N2O3 species formed by disproportionation of NO are capable of oxidizing CO and CH4 molecules to CO2, whereas NOx is reduced simultaneously to N2 or N2O. The peculiarities in the behavior of cationic forms of different zeolites with respect to adsorbed nitrogen oxides determined by different density and localization of cations have been established

Microwave-Assisted Conversion of Carbohydrates

Catalytic conversion of carbohydrates into value-added products and platform chemicals became a trend in recent years. Microwave activation used in the processes of carbohydrate conversion coupled with the proper choice of catalysts makes it possible to enhance dramatically the efficiency and sometimes the selectivity of catalysts. This mini-review presents a brief literature survey related to state-of-the-art methods developed recently by the world research community to solve the problem of rational conversion of carbohydrates, mostly produced from natural resources and wastes (forestry and agriculture wastes) including production of hydrogen, synthesis gas, furanics, and alcohols. The focus is made on microwave technologies used for processing carbohydrates. Of particular interest is the use of heterogeneous catalysts and hybrid materials in processing carbohydrates

Nitrous Oxide Adsorption and Decomposition on Zeolites and Zeolite-like Materials

Decomposition of N2O on modified zeolites, crystalline titanosilicalites, and related amorphous systems is studied by the catalytic and spectroscopic methods. Zinc-containing HZSM-5 zeolites and titanosilicalites with moderate Ti/Si ratios are shown to exhibit a better catalytic performance in N2O decomposition as compared with conventionally used Cu/HZSM-5 zeolites and amorphous Cu-containing catalysts. Dehydroxylation of the HZSM-5 zeolite by calcination at 1120 K results in an enhancement of the N2O conversion. The mechanism of the reaction and the role of coordinatively unsaturated cations and Lewis acid sites in N2O decomposition are discussed on the basis of the spectroscopic data

Effect of Cr on a Ni-Catalyst Supported on Sibunite in Bicyclohexyl Dehydrogenation in Hydrogen Storage Application

A comparison of the activity of mono- and bimetallic Ni-Cr/C catalysts deposited on a carbon carrier (sibunite) in the bicyclohexyl dehydrogenation reaction as a stage of hydrogen evolution in hydrogen storage systems is carried out. The interaction of Ni and Cr supported onto the carbon carrier—sibunite in bimetallic NiCr systems affects the change in the parameters of the crystal lattice of nickel, compared with the FCC lattice of Ni, as shown by the methods of XPS, TPR, XRD, high-resolution TEM and electron diffraction

Activity of Mono-, Bi-, and Trimetallic Catalysts Pt-Ni-Cr/C in the Bicyclohexyl Dehydrogenation Reaction

The influence of metals with different redox properties and a carbon carrier on the activity of mono-, bi- and trimetallic Pt-Ni-Cr/C catalysts has been studied in the bicyclohexyl dehydrogenation reaction as the hydrogen release stage in hydrogen storage. An increase in the conversion (X > 62%) of bicyclohexyl and selectivity for biphenyl (S > 84%) was observed on trimetallic catalysts Pt-Ni-Cr/C compared with the monometallic catalyst Rt/C (X > 55%; S > 68%). It has been established that the increase in the conversion of bicyclohexyl and selectivity for biphenyl in the dehydrogenation reaction on trimetallic catalysts is due to an increase in the activity of Pt nanoparticles in the vicinity of local Cr-Ni clusters of solid substitution solutions

Effect of Cr on a Ni-Catalyst Supported on Sibunite in Bicyclohexyl Dehydrogenation in Hydrogen Storage Application

A comparison of the activity of mono- and bimetallic Ni-Cr/C catalysts deposited on a carbon carrier (sibunite) in the bicyclohexyl dehydrogenation reaction as a stage of hydrogen evolution in hydrogen storage systems is carried out. The interaction of Ni and Cr supported onto the carbon carrier—sibunite in bimetallic NiCr systems affects the change in the parameters of the crystal lattice of nickel, compared with the FCC lattice of Ni, as shown by the methods of XPS, TPR, XRD, high-resolution TEM and electron diffraction

Kinetic Modeling of Hydrogen Production by Dehydrogenation of Polycyclic Naphthenes with Varying Degrees of Condensation

The kinetics of reactions of dehydrogenation of polycyclic naphthenes (cyclohexane, decalin, bicyclohexyl, ortho-, meta-, and para-isomers of perhydroterphenyl) is modeled on the basis of a formal comparison of kinetic equations of the 1st and 2nd orders based on real experimental data. It is shown that the reaction of the 1st order is predominating in the series of cyclohexane–bicyclohexyl–perhydroparatherphenyl. For all other substrates, the probability of describing the reaction in accordance with the equation of the 2nd order increases markedly, and for trans-decalin it becomes the predominant form of describing the kinetics of the reaction