Recycling of molybdenum in iron-potassium catalysts for dehydrogenation of isoamylenes

© 2015 Pleiades Publishing, Ltd. Method is found and substantiated for recovery of molybdenum from a spent iron-potassium catalyst for dehydrogenation of isoamylenes to isoprene. The effect of various factors (nature and concentration of the extracting agent, temperature and duration of the extraction process, and ratio between the liquid and solid phases) on the selectivity of recovery and the yield of molybdenum was studied. It is shown that molybdenum can be recycled in manufacture of iron-potassium catalysts for dehydrogenation of isoamylenes to isoprene

Preparation of cerium oxalate from spent iron-potassium catalyst for dehydrogenation of isoamylenes into isoprene

© 2015 Pleiades Publishing, Ltd. The cerium recovery in the oxalate form from spent iron-potassium catalyst for dehydrogenation of isoamylenes into isoprene was studied. The optimum conditions allowing preparation of the pure product with high degree of recovery were found. It was proved by X-ray diffraction, thermal gravimetric analysis, differential scanning calorimetry, and X-ray fluorescence analysis that the product obtained by the precipitation was cerium oxalate decahydrate containing no less than 98 wt % main substance

Pilot tests of a catalyst for the selective hydrogenation of acetylene

Pilot tests of SGA-2M promoted Pd/Al2O3 catalyst in the selective hydrogenation of acetylene are performed on an industrial ethane-ethylene fraction in a system of two serially arranged adiabatic flow reactors. The optimum process conditions under which the conversion of acetylene reaches 100% at a selectivity of 68.2% with respect to ethylene are determined: system pressure, 21 atm; hydrocarbon feedstock hourly space velocity (HSV), 1500 h-1, carbon monoxide concentration, 7 ppm; H2: C 2H2 molar ratio at the first and second hydrogenation stages, 1.0: 1.0 and 1.4: 1.0; inlet temperature of the first and second reactors, 40 and 55 C, respectively. The interregeneration service life of the SGA-2M catalyst under optimum conditions is estimated at 12 months. SGA-2M catalysts can be recommended for purifying ethane-ethylene fractions containing up to 2 vol % of acetylene. © 2013 Pleiades Publishing, Ltd

Effect of promotion with cobalt or zinc on the hydrogenating and oligomerizing activities of the Pd/Al2O3 catalyst in the hydrogenation of the BTX fraction

The promoter nature and content effects on the catalytic activity and stability of Pd-Co/δ-Al2O3 and Pd-Zn/δ-Al 2O3 bimetallic catalysts in the hydrogenation of dienic and vinyl aromatic hydrocarbons in the BTX fraction have been investigated by IR spectroscopy and temperature-programmed reduction. The Pd: Co (Zn) molar ratio in the catalysts prepared is 1.0: 0.5, 1.0: 1.0, or 1.0: 1.5, and their Pd content is 0.5 wt %. The support is δ-Al2O3 doped with sodium (0.5 wt %). Promotion of the palladium catalyst with zinc and cobalt causes the disappearance of cationic palladium species, thereby reducing the oligomerizing capacity of the active component, and, as was demonstrated by 100-h-long catalytic tests, enhances the stability of the catalyst. The Pd-Co/δ-Al2O3(Na) catalyst with Pd: Co = 1.0: 1.0 mol/mol is recommended for the hydrogenation of the BTX fraction under industrial conditions. The expected service life of this catalyst between regenerations is 16 months. © 2013 Pleiades Publishing, Ltd

Effect of chemical modification on oligomerization capacity of alumina support for Pd-Al 2O 3 catalyst

Effect of modification with an alkali metal on the acid properties of alumina supports and on the oligomerization capacity and working stability of Pd-Al 2O 3 catalysts was studied. © Pleiades Publishing, Ltd., 2011

DEVELOPMENT OF A NEURAL NETWORK ALGORITHM FOR FINDING OPTIMAL STRATEGIES FOR THE QUANTUM HEX GAME

Based on the AlphaGo Zero training algorithm, we developed a reinforcement learning algorithm to train an agent to play quantum games with the possibility of collapsing a position on the board. Using this algorithm, the created neural network agent was trained to play the game Quantum Hex

The influence of the structural and electronic characteristics of palladium on the activity and selectivity of Pd/Al 2O 3 and Pd-Co/Al 2O 3 catalysts for the hydrogenation of acetylene hydrocarbons

The influence of the structural and electronic characteristics of nonpromoted and cobalt-promoted Pd catalysts on their adsorption and catalytic properties is studied. It is shown that the conversion of vinylacetylene depends on the dispersion of palladium for both types of catalysts synthesized from acetate and acetylacetonate complexes. The palladium acetylacetonate catalysts have a higher palladium dispersion than the samples obtained from acetate complex solutions, thus leading to a higher conversion of vinylacetylene. It is established that the selectivity of vinylacetylene conversion into 1,3-butadiene on palladium acetate and acetylacetonate catalysts depends on the state of the 3d orbitals of surface Pd atoms. The palladium acetate catalysts are characterized by a higher electron density on the 3d orbital in comparison with the acetylacetonate samples, thus producing higher selectivities of vinylacetylene conversion into 1,3-butadiene. The introduction of cobalt into Pd/δ-Al 2O 3 catalyst synthesized from acetylacetonate complex leads to the formation of bimetallic Pd-Co particles, in which Pd atoms have higher electron density than those in the nonpromoted Pd/δ-Al 2O 3 catalyst, due probably to the donation of electron density from promoter atoms, with a resulting decline in the adsorption ability of bimetallic particles with regard to 1,3-butadiene and hydrogen. As a consequence, the selectivity of vinylacetylene conversion into 1,3-butadiene increases. Requirements for the size, dispersion, and electronic characteristics of the active component in the catalysts for the selective hydrogenation of vinylacetylene are formulated, and two techniques for their synthesis are proposed. © 2011 Pleiades Publishing, Ltd

Selection of the optimum composition of an alumina support of Pd/Al 2O3 catalysts for pyrolysis gasoline hydrogenation

To optimize the chemical composition of catalysts for the selective hydrogenation of diene and vinyl aromatic hydrocarbons in pyrolysis gasoline, we study the effect of the acid-base and textural characteristics of a support modified with additives of sodium compounds on the activity and stability of the catalysts in reactions of hydrogenation and oligomerization of unsaturated compounds. It is shown that the rate of formation of oligomeric compounds depends on the number of Lewis (Q CO > 34 kJ/mol) and Brönsted sites (νOH = 3688 cm-1). An increase in their total amount on the catalyst surface leads to an increase in the rate of formation of oligomeric hydrocarbons. The amount of surface condensation products is determined by the concentration of strong aprotic sites with Q CO > 35 kJ/mol. Alumina support samples with a high surface concentration of medium-strong Lewis sites, wedge-shaped or conical pores, and the preferential distribution of porometric volume in pores with a diameter of 5-15 nm are characterized by a significant ability to oligomerize unsaturated compounds. Catalysts that contain 0.5 wt % Na exhibit the lowest oligomerization ability and a high stabile activity in reactions of hydrogenation of diene and vinyl aromatic hydrocarbons in pyrolysis gasoline. For the selective hydrogenation of diene and vinyl aromatic hydrocarbons in pyrolysis gasoline, we recommend a catalyst with 0.5 wt % Pd supported from palladium acetylacetonate on δ-Al2O3 modified with 0.5 wt % sodium; it is characterized by the absence of wedge-shaped or conical pores, the preferential (60.7%) distribution of porometric volume in a range of d p > 15 nm, and a low aprotic acidity (L = 3.1 μmol/g), which contributes to the decrease in the amount of resulting condensation products (V = 3.6 μg/(gcat h)) and a high stable activity (DN = 0.68 g J2/100 g) in reactions of hydrogenation of unsaturated compounds. © 2010 Pleiades Publishing, Ltd

Preparation of cerium oxalate from spent iron-potassium catalyst for dehydrogenation of isoamylenes into isoprene

© 2015 Pleiades Publishing, Ltd. The cerium recovery in the oxalate form from spent iron-potassium catalyst for dehydrogenation of isoamylenes into isoprene was studied. The optimum conditions allowing preparation of the pure product with high degree of recovery were found. It was proved by X-ray diffraction, thermal gravimetric analysis, differential scanning calorimetry, and X-ray fluorescence analysis that the product obtained by the precipitation was cerium oxalate decahydrate containing no less than 98 wt % main substance