M. V. Kulikova

Fischer-Tropsch process in a three-phase system over iron-cobalt catalyst nanoparticles in situ synthesized in a hydrocarbon medium

It has been shown that Fe-Co nanocatalysts in situ synthesized in a hydrocarbon medium with a Fe/Co weight ratio of 2–6 can mediate the Fischer-Tropsch synthesis in a three-phase system at a pressure of 20 atm, a temperature of 250–300°C, and a CO/H2 ratio of 1: 1. The introduction of CO leads to a significant increase in the total activity of the catalyst system (KCO reaches 85% at 300°C). However, gas evolution is enhanced and the highest yield of liquid products is as low as 74 g/m3 in this case. The introduction of K and Al into the Fe-Co catalysts and the optimization of the Fe/Co ratio make it possible to increase the yield of liquid products to 143 g/m3 (Fe/Co = 2.4) and achieve an efficiency of 337 g/(kg Me h). The Fe-Co nanocatalysts exhibit a high polymerizing activity (Schulz-Flory alpha is higher than 0.8). Hydrocarbons obtained over Fe-Co-K-Al catalysts contain more than 20% olefins. Their amount increases with the increasing Fe concentration in the sample. Oxygenates formed over these catalysts are composed of alcohols by over 90%, of which ethanol prevails (65–70%).

Fischer-Tropsch synthesis in a slurry reactor in the presence of nanosized cobalt catalysts synthesized in situ in a hydrocarbon medium

Fischer-Tropsch synthesis in a slurry reactor at a pressure of 20 atm and a temperature of 220–300°C in the presence of 100Co : 2Pd : (5–50)Al2O3 and 100Co : 2Pd : (20–50)ZrO2 (parts by weight) catalysts in situ synthesized in a hydrocarbon medium has been studied. The catalysts were prepared by the decomposition of cobalt salts and promoters in melted petroleum paraffin P-2 at 300°C and in situ reduced with hydrogen. It has been found that the nanocatalyst containing 20 parts by weight of ZrO2 exhibits the highest activity in the Fischer-Tropsch synthesis and provides the yield of liquid products of 70 g/m3 at a CO conversion of 80%.

Fischer-Tropsch synthesis in the presence∣ of cobalt-containing composite materials based on carbon

The Fischer-Tropsch synthesis in the presence of composite materials prepared by the IR pyrolysis of polyacrylonitrile (PAN) with cobalt salts immobilized on it was studied. The catalysts were small granules containing PAN carbonization products and to 80% cobalt metal particles of size 10–17 nm. The synthesis was performed in flow reactors with a fixed bed and a catalyst bed suspended in a liquid at 2–3 MPa and 200–310°C. It was established that the activity of the catalyst depends on the nature of the cobalt salt used, the temperature of IR pyrolysis, and the synthesis conditions. The catalyst prepared with the use of cobalt carbonate exhibited the greatest activity. The yield of liquid hydrocarbons on it reached ∼70 g/m3 at ∼60% selectivity. It was found that the test composite materials were characterized by an extremely high productivity of 2–5 kg (kg Co)−1 h−1.

Fischer–Tropsch synthesis in the presence of nanosized iron-polymer catalysts in a fixed-bed reactor

Nanocomposite materials based on poly(vinyl alcohol), cellulose, polystyrene, and styrene–divinylbenzene copolymer are synthesized by IR pyrolysis, and their structures are studied by FTIR spectroscopy and X-ray powder diffraction. It is found that the composites show catalytic activity in Fischer–Tropsch synthesis. An explanation is provided for the high catalytic activity of the test systems.

Fischer–Tropsch synthesis in the presence of ultrafine iron-containing catalysts derived from reverse microemulsions

It is shown that active catalysts for Fischer–Tropsch synthesis with a controlled size of the particles of the dispersed phase may be formed on the basis of reverse microemulsions in a slurry reactor. After optimization of the composition of the reverse microemulsion (iron nitrate nonahydrate as a precursor of the active metal and SPAN-80 as a surfactant, 5 wt %), the size of the microemulsion droplets decreases to 130 nm. The chosen method for the synthesis of catalytic systems makes it possible to introduce promoters without any marked enlargement of the dispersed phase (130–160 nm). High-temperature Fischer–Tropsch synthesis is performed in a slurry reactor using catalysts prepared from reverse iron-containing microemulsions. The tested iron-containing catalytic systems feature high selectivity (up 73 wt %) in the formation of gasoline fractions (the C5–C10 fraction) that contain an abnormally high (up to 77 wt %) level of unsaturated hydrocarbons.

Catalytic and magnetic properties of nanocomposites based on iron-containing polymer microspheres in Fischer-Tropsch synthesis

It has been found that the composite material synthesized on the basis of iron-containing polymer microspheres exhibits high catalytic activity in the Fischer-Tropsch process. The structure of the original molded copolymer and the synthesized nanocomposite has been studied by FTIR spectroscopy. The magnetic properties of the material have been examined by in situ magnetometry.

Formation of alcohols on nanosized iron catalysts under Fischer-Tropsch synthesis conditions

Regularities of the alcohol formation in a three-phase system in the presence of the nanosized 100Fe: 8Al2O3: 3K2O (parts by weight) iron catalyst under the Fischer-Tropsch synthesis conditions have been determined. It has been found that the molecular-weight distribution of alcohols does not follow the Anderson-Schulz-Flory law. The principal product is ethanol; its proportion in the mixture can be as high as 78 wt %. It has been supposed that the formation of alcohols can follow the mechanism including the CO insertion in the metal-carbon bond. It has been shown that the highest ethanol yield (78 wt %) is obtained using 20 atm, 300°C, and H2/CO = 2.5 (mol/mol), an iron-containing catalyst charge in the reactor of 2 wt %.

Catalytic and physicochemical properties of Fe-polymer nanocatalysts of Fischer–Tropsch synthesis: Dynamic light scattering and FTIR spectroscopy study

Catalytic and structural properties of ultrafine, including nanosized, Fe-polymer catalysts of Fischer–Tropsch synthesis have been studied. The use of dynamic light scattering and ATR FTIR spectroscopy has made it possible to analyze structural features of the polymer matrix surrounding an active metal-containing nanoparticle and to relate them to catalyst activity in Fischer–Tropsch synthesis.

Influence of dispersion medium composition on Fischer—Tropsch synthesis in three-phase system in the presence of iron-containing catalysts

The Fischer—Tropsch synthesis over iron-containing catalysts in a three-phase system with synthetic polymers of different compositions introduced into the dispersion medium has been studied. It has been found that these catalysts exhibit activity in the synthesis of liquid hydrocarbons from CO and H2. It has been revealed that the addition of synthetic polymers into the catalyst samples leads to the formation of smaller particles, the size of which depends on the employed polymer, and to an increase in the selectivity for the target product of the synthesis in the entire studied temperature range.

Fischer–Tropsch synthesis and hydrogenolysis of long-chain alkanes over cobalt-containing nanosized catalysts in a slurry reactor

Fischer–Tropsch synthesis in the presence of nanosized cobalt-containing catalysts suspended in a mixture of long-chain alkanes has been studied. It has been found that the molecular-mass distribution of the products differs substantially from the typical Anderson–Schulz–Flory distribution. The most evident cause of this phenomenon is the intense hydrogenolysis of long-chain alkanes of the liquid medium which occurs during catalyst activation; this process may proceed to a sufficient extent during Fischer–Tropsch synthesis. The molecular-mass distribution of hydrogenolysis products shows a number of specific features that differ appreciably from those for both classical hydrogenolysis (cracking) in the presence of zeolites and terminal methanolysis, which is frequently observed in the presence of group VIII metals. Problems encountered during the construction of models for the observed distribution are discussed.