S.V. Baranova

Mesoporous aluminosilicates as components of gas oil cracking and higher-alkane hydroisomerization catalysts

Mesoporous aluminosilicates with a Si/Al ratio of 5 to 20, a pore diameter of 30 to 84 Å, and a specific surface area up to 1030 cm3/g have been prepared using hexadecylamine and Pluronic P123 as templates. These materials exhibit high activity in the cracking of hydrotreated vacuum gas oil. Bifunctional catalysts derived on their basis have high selectivity in the hydroisomerization of hexadecane.

Hydrogenation of aromatic compounds in the presence of dibenzothiophene over bimetallic catalysts containing mesoporous aluminosilicates

The hydrogenation of a mixture of naphthalene, tetralin, and toluene (a solution in n-heptane) in the presence of dibenzothiophene (150 and 400 ppm on a sulfur basis) over Pt-Pd catalysts containing Al-HMS mesoporous aluminosilicates has been studied. The catalyst supports contained 35 wt % Al-HMS and 65 wt % γ-Al2O3. The Pt and Pd loadings in the catalysts were 0.2 and 0.8 wt %, respectively. The process was carried out at 200–240°C, a pressure of 30 atm, and a weight hourly space velocity of 1.7 h−1. It has been found that the catalyst based on Al-HMS with Si/Al = 10 exhibits the highest activity. Thus, in the hydrogenation of a model mixture containing 150 and 400 ppm of sulfur, the conversion of toluene at 240°C was 22.2 and 10.9 wt %, respectively. In the presence of this catalyst, the concentration of aromatic hydrocarbons in the hydrotreated diesel fraction decreased from 28.4 to 6.8 wt %, and the sulfur content decreased from 45 to 5 ppm.

Hydrogen peroxide oxidative desulfurization of model diesel mixtures using azacrown ethers

Hydrogen peroxide oxidative desulfurization of model diesel fuel mixtures in the presence of azacrown ethers and their complexes with niobium pentachloride at 40–80°C has been studied. It has been found that the use of complexes of azacrown ethers with NbCl5 leads to a decrease in the total sulfur content in the model mixtures to 13% of the initial amount. The structure of the azacrown ether used has little effect on the extent of desulfurization of the model mixture.

Hydrogenation of aromatic hydrocarbons in the presence of dibenzothiophene over platinum-palladium catalysts based on Al-SBA-15 aluminosilicates

The hydrogenation of a 2-methylnaphthalene solution in n-heptane in the presence of dibenzothiophene (400 ppm in terms of sulfur) over Pt-Pd catalysts containing Al-SBA-15 mesoporous aluminosilicates has been studied. Supports for the catalysts contained 35 wt % Al-SBA-15 and 65 wt % γ-Al2O3. The Pt and Pd contents of the catalysts was 0.25 and 1.0 wt %, respectively. Experiments with the model feedstock were conducted in an autoclave at 240–260°C, an initial hydrogen pressure of 30 atm, and a substrate/metal weight ratio of 30. It has been found that a catalyst based on Al-SBA-15 with Si/Al = 5 exhibits the highest activity under poisoning with 400 ppm sulfur. Thus, the conversion of 2-methylnaphthalene at 260°C after 3 h was 85% with the selectivity for methyltetralins of 97%. The dearomatization of a hydrotreated diesel fraction with 45 ppm sulfur at 260°C at a pressure of 30 atm and a space velocity of 2.4 h−1 has made it possible to decrease the total aromatic content, in particular reduce the concentration of polycyclic aromatic compounds to a level of less than 1 wt %.

Hydroisomerization of n-dodecane on bifunctional catalysts containing mesoporous aluminosilicates

The hydroisomerization of n-dodecane on bifunctional catalysts with mesostructured aluminosilicates as an active component has been studied. Aluminosilicates with an Si/Al atomic ratio of 5 to 48 have been prepared using hexadecylamine as a template. Catalyst supports contained 35 wt % mesoporous material and 65 wt % γ-Al2O3. The platinum loading of the catalysts was 0.5% of the support mass. It has been found that the catalysts based on mesoporous aluminosilicates with an Si/Al ratio of 10 and 22 exhibit the highest selectivity. In their presence, the conversion reaches 43–46 wt % with the selectivity for iso-C12H26 of more than 90%.

Properties of mesoporous aluminosilicates prepared with nonionic surfactants

Mesoporous aluminosilicates with specific surface area up to 1030 m2/g and pore diameters from 33 to 43 Å were obtained using hexadecylamine and block copolymers of polyethylene and polypropylene oxides as structural directing agents. The synthesized materials were tested in catalytic cracking of hydrotreated vacuum gas oil at 500°C.