This review provides an analysis of recent scientific and engineering literature on chemical methods for CO2 processing using heterogeneous catalysts. The following major uses of carbon dioxide are discussed: exhaustive hydrogenation; synthesis of hydrocarbons including light olefins; synthesis of oxygenates; and production of cyclic carbonates. Furthermore, the paper highlights the main design approaches for CO2 conversion catalysts and formulates priorities for decarbonization using heterogeneous catalytic reactions .

Carbon materials were formed by the hydrothermal carbonization of cellulose, which were used as support for carbon dioxide hydrogenation catalysts (Fe/C and Fe-Mn/C). In the presence of these catalytic systems, CO2 conversion reached 50%. It is shown that the manganese introduction into the Fe-containing catalytic system significantly affects the distribution of gaseous С1-С4 products and liquid С5+ hydrocarbons. Promotion leads to the suppression of methane formation and an increase in the proportion of C2-C4 light olefins in gaseous products, as well as to intensification of secondary processes with the formation of a significant amount of iso-structures in liquid products. The different distribution of С1-С6 alcohols in the oxygen-containing products on the Fe/C and Fe-Mn/C catalysts indicates the manganese effect on the routes of their formation.

The use of commercial magnetite-type iron ore and of ferriferous quartzite type ore as catalysts for low-temperature Fischer–Tropsch synthesis is described. According to the results of chemical analysis, the ores mainly contained iron magnetite, carbon, and also baddeleyite (ZrO2 + HfO2) and hatchettolite (Ta2O5 + Nb2O5 + U3O8). The ore samples with the highest iron content (48–59%) and the lowest sulfur content (0.1% and less) showed activity in the Fischer–Tropsch synthesis without additional modification in the commercial form. The yield of liquid products in the synthesis performed on the most active samples of ore catalysts exceeded 100 g m–3 at the СО conversion of approximately 60%. The ore activity in the Fischer–Tropsch synthesis may be associated with the fact that these natural mineral formations contain oxides exerting a promoting effect when using the ores as catalysts.

Cu-Co-containing cellulose-based carbon composite materials (Cu-Co/Cel) were formed by a matrix isolation method. Using X-ray diffraction (XRD), transmission electron microscopy (TEM), infrared-Fourier spectroscopy (IR-Fourier spectroscopy), and non-isothermal research methods, the physicochemical properties of the composites were established. The catalysts are nanosized particles distributed in a carbon matrix, containing fragments of a system of conjugated bonds (C=C-C=C) of various lengths. Cu-Co/Cel catalysts are active in the synthesis of alcohols from CO and H-2, demonstrating high CO conversion (68%) and specific activity (17 mol CO g(Me)(-1) s(-1)). Differences in the mechanism of alcohol formation from CO and H-2 on cellulose-based composites and an oxide support (comparison catalyst) were shown by analyzing the distribution of synthesis products.

Currently, the processes of obtaining synthetic liquid hydrocarbons and oxygenates are very relevant. Fischer-Tropsch synthesis (FTS) is the most important step in these processes. The products of thermal destruction in argon of the mixture [Co(NH3)6][Fe(CN)6] and Al(OH)3 were used as catalysts for CO hydrogenation. The resulting compositions were studied using powder X-ray diffraction, IR spectroscopy, elemental analysis, SEM micrographs. The specific surface area, pore and particle size distributions were determined. It was determined that the DCS-based catalysts were active in the high-temperature Fischer-Tropsch synthesis. The effect of aluminum in the catalyst composition on the distribution of reaction products was revealed.

Copper-containing catalytic slurries with different concentrations of active metal precursor solutions are synthesized by drop thermolysis in situ in the hydrocarbon medium of a slurry reactor. According to dynamic light scattering, the particle size of the catalytic slurry dispersion phase is 3–4.5 nm and it remains almost unchanged during the synthesis. Using FTIR spectroscopy it is shown that the structure of precursors of slurry active species depends on the concentration of solution, which may influence the phase composition of catalytically active fragments of the surface during the reduction and synthesis of alcohols. It is demonstrated that alcohols may be synthesized from CO and H 2 in the slurry reactor in the presence of the formed nanosized slurries. It is revealed that the composition of alcohol phase products differs significantly with target product selectivity being comparable: at a low concentration of precursor solution a marked amount of methanol is contained in the mixture (up to 66%), while an increase in the concentration of precursor solution causes a rise in the proportion of higher molecular weight alcohols to 88%.

The possibility, in principle, of high-temperature three-phase Fischer-Tropsch synthesis, which is implemented in the presence of iron-containing catalytic dispersions in a bubble column reactor, is demonstrated. The catalytic system is activated in situ in a CO stream. It is proved that the particle size of the iron-containing dispersion used as the catalyst for this process depends on the precursor solution injection technique and in no case does it exceed 50 nm. It is shown that the described three-phase high-temperature Fischer-Tropsch synthesis method makes it possible to achieve high process parameters, such as target products yield up to 138 g/m(3) with 90% selectivity of products formation. The properties of the developed catalyst enable it to perform for a prolonged period with high conversions without impairment of process selectivity.

The optimum loading on the iron-containing catalytic dispersion of the three-phase Fischer—Tropsch synthesis is 25 nL h−1 when using an autoclave reactor. The linear velocity of the synthesis gas corresponds to 0.003 cm s−1. Under these conditions, the following synthesis parameters were achieved: CO conversion of 80%, liquid hydrocarbon productivity 400 g kg Fe−1 h−1. Based on the data obtained, when modeling a column reactor for three-phase Fischer—Tropsch synthesis, the following unit dimensions were calculated: height 1.6 m, internal diameter 0.045 m.

The conversion of ethanol and fusel oils to a С3–С12 alkane–aromatic fraction with high activity and selectivity in the presence of the Pd–Zn/TsVM pilot catalyst has been demonstrated. It has been shown that the ethanol conversion to alkanes and aromatic hydrocarbons in the presence of this catalyst proceeds by various routes to give ethylene and diethyl ether as intermediate products providing a 90–95% yield on the converted ethanol carbon basis for the target С3–С12 fraction containing up to 40% of branched alkanes.

A method for the production of a С 3 –С 11 alkane–aromatic hydrocarbon (HC) fraction by the coconversion of a mixture of alcohols simulating biomass fermentation products and vegetable oil without using molecular hydrogen has been developed. A characteristic feature of this method is the occurrence of coupled alcohol aromatization reactions evolving hydrogen consumed for the hydrogenation of unsaturated HC moieties formed from fatty acid triglycerides in the presence of a pilot sample of the Pd–Zn/TsVM/Al 2 O 3 catalyst. It has been found that the optimum amount of vegetable oil in the feed mixture is 25–50 vol %; this amount provides the target fraction yield of up to 95% on a fed carbon basis.

Methods for the formation of stable iron-containing suspensions that exhibit activity in the conversion of synthesis gas to C5+ hydrocarbons by the Fischer-Tropsch method are proposed. By XRD and DLS methods it was determined that the formation of the Fe2O3 phase with a bimodal particle size distribution of 50 and 295 nm results in the formation of a suspension by the drop thermolysis method − the gradual introduction of the active metal precursor solution into the dispersion medium (mixture of hydrocarbons C19H40-C32H66). Pulsed introduction of the active metal precursor solution (flash-pyrolysis) into the reactor zone leads to the formation of the Fe3O4 phase with a particle size of 91 and 460 nm. By TEM and AFM methods it was established that, regardless of the slurry forming method, large active phase particles are agglomerates of a finer fraction of particles with an average size of 42 nm. The obtained suspensions demonstrated high activity in the Fischer-Tropsch synthesis under the slurry-reactor conditions, however, the degree of CO conversion is slightly higher in the case of the catalytic suspension prepared by the drop thermolysis method. It is shown that the method of forming the suspension significantly affects the fractional composition of the resulting reaction products. In the presence of a suspension obtained by drop thermolysis, the yield of liquid hydrocarbons reaches 130 g/m3, while a high content of C19+ hydrocarbons is observed. The system formed by the method of flash-pyrolysis makes it possible to obtain mainly the gasoline (C5-C10) and diesel (C11-C18) hydrocarbon fractions. It should be noted that the products of the reaction have a high content of unsaturated hydrocarbons, which reaches 55%. Thus, the composition of the final products of FTS can be controlled by the choice of the catalytic suspension prepared method. For citation: Kulikova M.V., Dement’eva O.S., Chudakova M.V., Ivantsov M.I. Influence of preparing nanoscale suspensions method on its physico-chemical and catalytic properties under the conditions of Fischer-Tropsch synthesis. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 9-10. P. 70-75

It is shown that the effective synthesis of methanol may be performed in the presence of ultrafine catalyst systems formed by drop thermolysis in situ in a slurry reactor. Using the X-ray powder diffraction and FTIR spectroscopy data on the evolution of Cu–Zn–Al-containing catalyst dispersion during activation and catalysis, possible reasons for ultrafine catalyst deactivation are considered.

The physicochemical and catalytic properties of pyrolyzed cellulose-based Cu–Co solid dispersed composite catalysts synthesized by matrix isolation under the action of IR radiation have been studied. It has been shown that alcohols can be produced from CO and H 2 in the presence of the synthesized composite catalysts comprising Cu–Co solid dispersed phase nanoparticles. The effect of synthesis conditions on the structure of the composite catalysts and their activity in synthesis gas conversion to alcohols has been studied by X-ray diffraction analysis, ATR-FTIR spectroscopy, and in situ magnetometry.