V. I. Bogdan

Selective oxidation of aromatic compounds on zeolites using N2O as a mild oxidant: A new approach to design active sites

Abstract Dehydroxylated ZSM-5 type zeolites are used for selective oxidation of aromatic compounds, including benzene, chlorobenzene, styrene, difluorobenzenes, phenol, alkylbenzenes into corresponding phenols and diphenols using nitrous oxide as a mild oxidant. In the case of benzene, the yield of phenol reaches 70–80%. Extremely high selectivity (∼98–100%) in the case of benzene and ∼85% in the case of difluorobenzenes and high regioselectivities are observed on the dehydroxylated HZSM-5 zeolite. The active sites are shown to be the strong Lewis acid–base pair sites formed upon dehydroxylation of the zeolites. The reaction mechanism that is alternative to the proposed iron-mediated mechanism is discussed.

Platinum-containing catalyst supported on a metal-organic framework structure in the selective oxidation of benzyl alcohol derivatives into aldehydes

The platinum catalyst supported on the metal-organic framework structure MOF-5 is usable in the selective oxidation of vanillyl and piperonyl alcohols into the corresponding aldehydes.

The influence of the dispersion of metals on the activity of Pt/C and Pd/C catalysts in the dehydrogenation of perhydroterphenyl

The activity of Pt/C and Pd/C catalysts in the dehydrogenation of perhydroterphenyl was studied at conversions lower than 30% depending on the dispersion of platinum and palladium metals, which was estimated by two independent methods (adsorption of CO and X-ray diffraction).

Comparing the activities of catalysts in perhydro- m -terphenyl dehydrogenation

The activities of various catalysts based on Pt, Pd, Cr, and Ni in perhydro-m-terphenyl dehydrogenation have been compared in order to develop new catalytic composites based on organic compounds for hydrogen storage. Catalytic tests have been carried out at 300–320°C in a flow reactor with an inner diameter of 10 mm. The largest amount of hydrogen released as a result of perhydro-m-terphenyl dehydrogenation to m-terphenyl is observed with the (3% Pt)/Sibunit catalyst at 320°C. The maximum selectivity toward complete dehydrogenation is 95% in this case.

Biodiesel fuel production from lipids of filamentous fungi

The main stages in the production of biodiesel fuel from lipids of filamentous fungi belonging to the order Mucorales are described. Fungi of the family Cunninghamellaceae have been screened; the lipogenic activity of the examined strains has been assessed; and a producer generating up to 50% of lipids, represented by triacylglycerols, has been found. The substitution effect of a source of carbon and nitrogen with less expensive components (in particular, various industrial wastes) has been studied, as well as their influence on the quantity and major characteristics of the final product. An ecologically friendly method for extracting lipids from fungal mycelia, utilizing supercritical technologies, has been used. A correlation between the lipid content in the spore inoculum and the maximal lipid content in biomass has been discovered; this correlation is proposed for optimizing the biotechnology and increasing the yield of final products.

Using ceramic membranes for the separation of hydrogen produced by dehydrogenation of perhydro- m -terphenyl

The efficiency of a variety of ceramic membranes for the purification of hydrogen obtained by dehydrogenation of perhydro-m-terphenyl in a catalytic flow reactor from vapors of initial hydrocarbons and dehydrogenation products is investigated.

Alkylation of isobutane with C 4 olefins under conventional and supercritical conditions

The solid acid alkylation of isobutane with butylenes on the ultrastable zeolite Y is studied in the temperature range from 120 to 150°C and in a pressure range of 20–120 atm. The catalyst service life becomes longer on passing from the conventional (liquid- and gas-phase) conditions of alkylation to supercritical conditions. The maximum period of complete butylene conversion at 150°C and 120 atm is 3.5 h. The composition of the reaction products is determined by the phase state of the reaction mixture, the reaction time, and the conversion of the C4 olefins. When the alkylation is carried out under supercritical conditions, the C8 hydrocarbon selectivity varies between 30 and 40%. Thermoanalytical data suggest that the surface of the spent catalyst contains carbon deposits indicating the formation of oligomeric and cyclic structures.

Effect of the structure of the ortho, meta, and para isomers of perhydroterphenyl on their reactivity in heterogeneous catalytic dehydrogenation

The kinetics of the dehydrogenation of the individual ortho, meta, and para isomers of perhydroterphenyl and their mixtures over a (3 wt % Pt)/C catalyst has been investigated in a flow reactor at 280–340°C. The rate of the isomerization of the stereoisomers of the initial substrate (perhydroterphenyl) and terphenyl dehydrogenation products has an effect on the hydrogen release kinetics. The highest reactivity in isomerization is shown by the ortho isomer. The largest amount of hydrogen (7.0 wt %) is released in the dehy-drogenation of perhydro-meta-terphenyl and perhydro-para-terphenyl, whose conversion at 320°C is 96%.

Gas-phase and supercritical n-pentane isomerization on H-mordenite

The skeletal isomerization of supercritical n-pentane on the H form of mordenite under flow conditions was studied for the first time. It was found that the conversion of supercritical n-pentane was 30–35% at 90% selectivity for isopentane at 260°C, 130 atm, and a liquid hourly space velocity of 30 h−1. The catalyst was deactivated as the temperature was increased above 280°C. According to differential thermal analysis data, the deactivation was related to the deposition of condensation products on the surface. The resistance of the H form of the zeolite to poisoning in n-pentane isomerization in a gas phase at 1–8 atm was lower than that under supercritical conditions. It was found that H-mordenite deactivated under gas-phase reaction conditions at 260°C and 8 atm can be regenerated by passing to supercritical isomerization conditions (260°C and 130 atm).

Transformation of aqueous solutions of glucose over the Pt/C catalyst

The transformations of glucose over the Pt/C catalyst in a flow reactor in the temperature range 140–200°C at a pressure of 5.0 MPa have been studied. The main routes of glucose conversion in an aqueous phase in the presence of hydrogen, helium, or air have been considered. A product formation scheme depending on the reaction parameters has been proposed. At 140°C, glucose hydrogenation into sorbitol occurs with a selectivity of 77%. In an oxidizing atmosphere, glucose transforms into gluconic acid (with 73% selectivity at 140°C); here, the formation of sorbitol and mannitol (with a selectivity of 5–7% at 180–200°C) is also possible. Glucose transformation by-products, such as C3–C5 polyatomic alcohols, ketones, acids, and furfural derivatives, have been identified. The degree of glucose reforming in the aqueous solution with the formation of the gaseous products H2 and CO2 is no higher than 10% at 200°C.