Aleksey Vasiliev

Low pressure catalytic co-conversion of biogenic waste (rapeseed cake) and vegetable oil

Zeolite catalysts of three types (H-ZSM-5, Fe-ZSM-5 and H-Beta) were tested in the catalytic co-conversion of rapeseed cake and safflower oil into bio-fuel. This low pressure process was carried out at the temperatures of 350 and 400 degrees Celsius. The yields and compositions of the product mixtures depended on the catalyst nature and the process temperatures. The produced organic phases consisted mainly of hydrocarbons, fatty acids and nitriles. This mixture possessed improved characteristics (e.g. heating value, water content, density, viscosity, pH) compared with the bio-oils, making possible its application as a bio-fuel. The most effective catalyst, providing the highest yield of organic liquid phase, was the highly acidic/wide-pore H-Beta zeolite. The products obtained on this catalyst demonstrated the highest degree of deoxygenation and the higher HHV (Higher Heating Value). The aqueous liquid phase contained water-soluble carboxylic acids, phenols and heterocyclic compounds.

Immobilization of heavy metals on pillared montmorillonite with a grafted chelate ligand

The objective of this work was the development of an efficient adsorbent for irreversible immobilization of heavy metals in contaminated soils. The adsorbent was prepared by pillaring of montmorillonite with silica followed by grafting of a chelate ligand on its surface. Obtained adsorbent was mesoporous with high content of adsorption sites. Its structure was studied by BET adsorption of N2, dynamic light scattering, and scanning electron microscopy. The adsorption capacity of the organoclay was measured by its mixing with contaminated kaolin and soil samples and by analysis of heavy metal contents in leachate. Deionized water and 50% acetic acid were used for leaching of metals from the samples. As it was demonstrated by the experiments, the adsorbent was efficient in immobilization of heavy metals not only in neutral aqueous media but also in the presence of weak acid. As a result, the adsorbent can be used for reduction of heavy metal leaching from contaminated sites.

Synthesis of mesoporous silica gels with embedded heteropolyacids

Silica gels containing embedded heteropolyacids were synthesized in acidic media by co-condensation of tetraethoxysilane with phosphotungstic or phosphomolybdic acids using the sol-gel technique. Surfactants dodecylamine, sodium dodecylsulfate, trimethylstearylammonium chloride, and Pluronic P123 were used as templates. The effect of the synthesis conditions on their structure and morphology was studied. All materials were mesoporous but contained micropores in their structures. Presence of bands of Keggin structures in fourier transform infrared spectroscopy spectra along with absence of X-ray diffraction patterns of crystalline heteropolyacids confirmed their fine incorporation into silica network. Particle sizes of modified materials were 500–1100 nm except for the W-containing sample obtained with trimethylstearylammonium chloride, which was significantly lower. This unusual effect was attributed to stabilization of primary silica nanoparticles by interactions between the surfactant and heteropolyacid. High ratio heteropolyacid/tetraethoxysilane resulted in partial loss of porosity. Obtained results might be used for optimization of synthesis of effective catalysts and adsorbents containing heteropolyacids in mesoporous structure.Graphical Abstract

Mesoporous Silsesquioxanes with High Contents of Surface Amine Groups

The objective of this work is the synthesis of highly functionalized hybrid organic/inorganic materials by the polycondensation of bis[3-(trimethoxysilyl) propyl]amine in the presence of surfactants. High contents of amine groups were achieved by carrying out the syntheses without an inorganic cross-linker. The silsesquioxanes obtained had a mesoporous structure. The stability of their porous system in the absence of an inorganic cross-linker was enhanced by the precursor’s bridged structure. The material structures were studied by FT-IR spectroscopy, Porosimetry, X-Ray Diffraction and Small Angle X-Ray Scattering methods. A material prepared in the presence of dodecylamine as a template had a higher surface area and narrower pore size distribution while the use of sodium dodecyl sulfate resulted in the formation of mesopores with a wide size distribution. Surface amine groups in silsesquioxanes were accessible for adsorption of small molecules of acidic nature.

Modification of Silica Gel by Heteropolyacids

Silica gels containing incorporated heteropolyacids (HPAs) were synthesized in acidic media by co-condensation of tetraethoxysilane (TEOS) with phosphotungstic or phosphomolybdic acids using the sol-gel technique. The effect of the synthesis conditions on their structure and morphology was studied. Yields of modified materials were somewhat lower compared to non-modified silica gels. All materials were mesoporous but contained micropores in their structures. Presence of bands of Keggin’s structures in FT-IR spectra along with absence of XRD patterns of crystalline HPAs confirmed their fine incorporation into silica network. Particle sizes of modified materials were 500-1100 nm except for the W-containing sample obtained with trimethylstearylammonium chloride, which was significantly lower. This unusual effect was attributed to stabilization of primary silica nanoparticles by interactions between the surfactant and HPA. High ratio HPA/TEOS resulted in partial loss of porosity. Obtained results might be used for optimization of synthesis of effective catalysts and adsorbents containing HPAs in mesoporous structure.

Bridged mesoporous silsesquioxanes as potential CO2 adsorbents

Mesoporous amino-functionalized adsorbents for post-combustion CO2 capture were synthesized by grafting and sol–gel methods. The silsesquioxane obtained by polycondensation of bis[3-(trimethoxysilyl)-propyl]amine without a cross-linker had the highest amount of surface amino groups. Their content was 8.4 times higher than in the grafted material prepared with the same precursor. All obtained materials were tested in CO2 reversible adsorption from a gas stream. The bridged silsesquioxane adsorbent had the adsorption capacity 4.7 times higher than the grafted sample obtained from the same precursor. Porosity study of this material revealed wide pore size distribution with notable fraction of macropores. The nature of adsorbed species was determined from the FTIR spectrum after adsorption. It was found that CO2 formed carbamate and bicarbonate species on the surface.Graphical Abstract