TG DTG Research Articles

Pyrolysis characteristics of oil shale semi-coke and its extracted bitumen

Fushun oil shale semi-coke and its extracted bitumen were prepared for analyzing their pyrolysis characteristics by TG–DTG, TG–FTIR, and Py–GC/MS. Semi-coke was the residue of oil shale pyrolyzed to 450 °C, and extracted bitumen was the organic matter extracted from semi-coke with [Bmim]Cl/NMP mixed solvents. Gaussian fitting method was used to analyze the proportions of bond cleavage reactions occured during the pyrolysis to 700 °C at a heating rate of 20 °C/min. Results showed that 3–4 kinds of bond cleavages were mainly involved. The outstanding pyrolysis behaviors were contributed by the cleavages of CalCal and weak bonds (including volatilization). The kinetic parameters based on Coats–Redfern method were calculated from the points for each pyrolysis stage and bond cleavage reaction. The evolution processes of typical gaseous products and distributions of flash pyrolysis products were displayed in detail, exhibiting the prominent roles of aliphatic compounds, CH4, and CO2. Moreover, the releases of the typical gaseous products for semi-coke tended to occur at higher temperatures.

Thermal Behavior of Some Indian Coals: Inferences from Simultaneous Thermogravimetry–Calorimetry and Rock–Eval

In this work, thermal behaviors of ten coal samples (across different thermal maturity levels) collected from five different open cast mines in the Jharia and Raniganj basins, India, were examined using differential scanning calorimeter (DSC), thermogravimetry (TG–DTG), Rock–Eval, and organo-petrographic techniques. Rank played a critical factor in controlling their thermal behavior, and with increasing coal rank the combustion parameters shifted towards higher temperatures. The oil-window mature non-coking coals were marked by least ignition and burnout temperatures, least DSC Tpeak, DTG Tpeak, and maximum reactivity. In contrast, the coking-coal samples of peak-oil window and condensate wet–gas window stages of maturity, because of their higher thermal maturity level and lower reactivity, required higher temperatures for combustion. Among the peak-oil window mature coking coals, one sample (C4) showed distinct lower combustion parameters relative to others, although vitrinite reflectance (Ro; %) and Rock–Eval pyrolysis Tmax showed similar results as the other coals. This sample was marked by higher reactive maceral content. Highest combustion parameters and least reactivity were shown by the Jhama sample (baked coal), followed by the condensate wet–gas window mature coking coals. The Rock–Eval S4 Tpeak clearly resolved the coal samples with distinct maturities and complemented the results from TG–DTG–DSC thermograms. Our results indicate that Rock–Eval S4Tpeak can be used to decipher convincingly the thermal maturity level of coals.

Mechanical properties and thermal characteristics of different-density phenolic foams

Phenolic foam (PF) has excellent performance in fire resistance, thermal insulation and other fields. It has the advantages of lightweight, flame retardant, no dropping and low level of toxic gas emission during combustion. In order to learn the relationships between density and properties, PF samples with density of 40, 50 and 60 kg · m−3 were obtained by adjusting the amount of blowing agent. Their micro-characteristics were analyzed with Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) experiments. Mechanical properties were measured with universal extending machine. Thermal properties and stability were tested by laser thermal conductivity analyzer and thermogravimetry analysis (TG), respectively. FT-IR spectra of samples demonstrate that chemical structure will not be affected by the ratio of foaming agent. Higher density comes with better sealing property of the cell holes and leads to better compressive strength. Changing PF density with foaming agent dosage could affect insulation effect, and the sample with density of 60 kg · m−3 showed poor performance compared with the other foams. TG–DTG curves of the PF samples are similar. Evaporation of water, volatilization of phenols and aldehydes, and pyrolysis of surfactant and curing agents are the main reason for the mass loss. Residues of samples increased with the increase in density at 900 °C. Results of this study can clarify that changing the density of PF with amount of foaming agent will not affect its chemical properties, but the ratio has impact on its physical properties.

Experimental investigation on spontaneous combustion of coal affected by exothermic reaction of polyurethane in underground coal mines

Organic elastomers such as polyurethane are widely used as a filling material in underground coal mines. However, the risk of fire hazard in coal seams is increased due to the flammability of polyurethane. Laboratory tests illustrate that in a thermostatic reactor with initial temperature of 25 °C, the temperature during the production of polyurethane increases up to > 140 °C. Adiabatic oxidation experiments and TG–DTG analysis showed that the heating rate of the mixed samples of polyurethane and coal was higher than that of any single component in the initial oxidation stage. From the initial temperature to 100 °C, increasing the proportion of polyurethane was conducive to the acceleration of temperature rise. From 0.180 to 0.850 mm, the self-heating rate was inversely proportional to the particle size. At the initial stage, the low ventilation rate promoted the spontaneous combustion of mixed samples, but when the temperature is > 70 °C, an opposite trend was seen. Kinetic parameters suggested that the activation energy decreases with the introduction of polyurethane. According to the mathematical model, the variation of the spontaneous combustion period of coal and polyurethane was predicted.

Fabrication of biomimetic robust self-cleaning superhydrophobic wood with canna-leaf-like micro/nanostructure through morph-genetic method improved water-, UV-, and corrosion resistance properties

Morphology of the canna-leaf-like micro-nanostructures was prepared by the polydimethylsiloxane (PDMS) template secondary transfer replica technology on the surface of ash timber loaded with PVB/SiO2 coating inspired by the canna-leaf. The morphology, structure, chemical components, element variation and thermally stable property of the as-prepared biomimetic morphologies superhydrophobic wood (BMSW) was analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) thermogravimetric/differential thermogravimetric (TG–DTG). Results show that the micro/nano-biomimetic structures were successfully replicated on wood surfaces. By contrast, as-prepared BMSW not only exhibited self-cleaning superhydrophobic performance with a water contact angle (WCA) of 155° and the surface exhibits excellent self-cleaning ability with sliding angle of 6°, but also possess thermally stable properties, which outperforming original wood timber. In addition, as-prepared BMSW samples exhibited stable superhydrophobicity even after being immersed in various pH for 1 h, indicating the excellent anti-corrosion property of the as-prepared BMSW samples surface. Besides the superhydrophobic robust performance of the as-prepared BMSW samples under sand abrasion tests, but the contact angles lower than the as-prepared BMSW samples. Meanwhile, the as-prepared BMSW samples also presented superior water-resistant, UV resistant, and high-temperature-humidity-resistant properties.

Thermal behaviors and kinetic analysis of two natural kaolinite samples selected from Qingshuihe region in Inner Mongolia in China

The thermal characteristic behaviors of two kaolinite samples selected from Qingshuihe region in Inner Mongolia in China were studied through thermogravimetry, derivative thermogravimetry, and differential scanning calorimetry (TG–DTG–DSC), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy. The activation energies of dehydroxylation for the two kaolinite samples (determined as Kaol-1 and Kaol-2) were calculated based on KAS and FWO methods. The XRD results indicated that Kaol-1 and Kaol-2 both were determined as kaolinite, and a small amount of quartz, but the Kaol-2 presented many amorphous organic matters. The TG–DSC results displayed the adsorbed water desorption and dehydroxylation with the temperature increased from 200 to 1100 °C. The dehydroxylation is followed as the intensities decrease in the bands at 3690 cm−1, 3620 cm−1 and 914.0 cm−1 attributing to the stretching mode of inner surface hydroxyls, and which disappeared when the temperature reached at 600 °C. The endothermic peak temperature of dehydroxylation for Kaol-2 presented higher than that of Kaol-1, which may be attributed to present of amorphous organic matter and was in agreement with the XRD data. The maximum endothermic temperature of dehydroxylation increased both for Kaol-1 and Kaol-2 with the increase in heating rate, which was attributed to more sufficient decomposition as the decrease in heating rate. The thermal kinetic analysis indicated that the dehydroxylation reaction of Kaol-1 should be a single kinetic mechanism, but the E of Kaol-2 decreased as α increasing from 0.2 to 0.5 and then gradually increased with the increase of α. The average E of dehydroxylation for Kaol-2 both was lower than that of Kaol-1 based on Kissenger–Akahira–Sunose and Flynn–Wall–Ozawa methods, which was attributed to the relatively higher organic carbon content in Kaol-2.

Preparation of Chitosan/NiFe-Layered Double Hydroxides Composites and Its Fenton-Like Catalytic Oxidation of Phenolic Compounds

In this study, chitosan-based Ni–Fe hydrotalcite composites (CS/NiFe-LDHs) and Ni–Fe hydrotalcite (NiFe-LDHs) were prepared by low-saturation coprecipitation method to investigate their oxidation and catalytic properties for phenolic compounds. The materials were characterized by TEM, XRD, FTIR, SEM, and TG–DTG, which proved that chitosan (CS) was successfully introduced into hydrotalcite forming CS/LDHs, which still had the structural characteristics of hydrotalcite. The oxidation effect and catalytic oxidation effect of CS/NiFe-LDHs on phenolic compounds were investigated. The results showed that under the optimal conditions, the oxidation efficiency on phenolic compounds (BPA, 2,4-DCP, and phenol) was 62.25%, 70.02%, and 42.13%, respectively, and the removal efficiency was 94.8%, 93.71%, and 98.98% by heterogeneous Fenton-like catalytic oxidation. CS/NiFe-LDHs as a catalyst has a good removal effect on phenolic compounds, and no sludge is produced, the range of pH value is broadened in the reaction (3–12). It can be easily recycled for five subsequent runs and has a good application prospect.

Thermoanalytical tests (TG\u2013DTG\u2013DSC, Py-GC/MS) of foundry binders on the example of polymer composition of poly(acrylic acid)\u2013sodium carboxymethylcellulose

The results of thermal analysis (TG–DTG–DSC) of a foundry binder from the BioCo group in the form of a polymer composition of poly(acrylic acid)–sodium carboxymethylcellulose (PAA/CMC-Na) are presented in this article. The range of temperature of degradation has been determined. It was found that as the temperature rises, physical and chemical changes take place in the binder as a result of evaporation of solvent water, release of constitutional water, intermolecular dehydration reactions and decomposition of polymer chains with the formation of gaseous decomposition products. Pyrolysis gas chromatography mass spectrometry method (Py-GC/MS) was used to identify PAA/CMC-Na binder degradation products in a predetermined temperature range based on the previously performed thermal analysis of TG–DTG–DSC. Py-GC/MS tests were also carried out to determine the emission level of gaseous products of the polymeric binder in the context of the processes occurring in the moulding (foundry) sand, in conditions of its contact with liquid metal. In addition, Py-GC/MS tests were carried out for two commonly used foundry binders based on alkaline phenolic resin cured with esters and based on urea-formaldehyde resin with furfuryl alcohol cured with sulphonic acids. The obtained Py-GC/MS results for commercial binders were referred to the results obtained for the new PAA/CMC-Na binder. It was found that the new polymer binder is characterized by the lowest emission level of gaseous products.

The gaseous products characterization of the pyrolysis process of various agricultural residues using TGA–DSC–MS techniques

Slow pyrolysis characteristics of agricultural residue feedstocks (corn brakes, wheat straw, and hazelnut shell) were investigated by simultaneous thermal analysis (STA–TG–DTG–DSC), coupled with mass spectrometry (MS). Thermal decomposition of agricultural residues was divided into three stages, corresponding to removal of water, devolatilization, and formation of bio-char. It was found that differences in thermal behavior of samples are due to differences in their composition. The MS results showed that H2, CH4, H2O, CO2 (C3H8), CO, and C2H6 were the main gaseous products released during pyrolysis. It was shown that hazelnut shells could be a good combustion fuel, since during its pyrolysis at high temperature, more gaseous products compared to other systems are very favored. For hazelnut shell pyrolysis, the CO2 can be used on the large scale for the production of CO-rich syngas.

Using Nanoimprint Lithography to Create Robust, Buoyant, Superhydrophobic PVB/SiO2 Coatings on wood Surfaces Inspired by Red roses petal

Robust, buoyant, superhydrophobic PVB/SiO2 coatings were successfully formed on wood surface through a one-step solvothermal method and a nanoimprint lithography method. The as-prepared PVB/SiO2/wood specimens were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), thermogravimetric/differential thermogravimetric (TG–DTG) analyses. The superhydrophobic property and abrasion resistance of rose-petal-like wood were measured and assessed by water contact angle (WCA) and sand abrasion tests. The results show that PVB/SiO2/wood not only exhibited a robust superhydrophobic performance with a WCA of 160° but also had excellent durability and thermostability during the sand abrasion tests and against corrosive liquids. Additionally, the as-prepared PVB/SiO2/wood specimens show high buoyancy.

Efficient synthesis of high silica SSZ-13 zeolite via a steam-assisted crystallization process

High silica SSZ-13 zeolite was synthesized by an efficient and green steam-assisted crystallization (SAC) method under a low alkalinity and low organic templates amount system. The as-prepared samples were characterized by XRD, SEM, N2 adsorption–desorption, TG–DTG and NH3-TPD. The results showed that the SAC method can not only remarkably improve zeolite yield but also enhance the crystallization rate of SSZ-13 zeolite compare to conventional hydrothermal route. Meanwhile, it was also found that the various content of the organic structure directing agent (N,N,N-trimethyladamantammonium hydroxide, TMAdaOH) in the dry gel can adjust flexibly the crystal size, morphology and acidity of samples. The zeolite samples with smaller particles and more strong acidity amount were more likely obtained under the higher TMAdaOH/SiO2 ratio (0.2) condition. In addition, the catalytic evaluation in methanol-to-olefins (MTO) reaction showed that the high silica SSZ-13 catalysts synthesized by SAC method exhibited longer lifetime and comparative selectivity to ethylene and propene than those of the SSZ-13s obtained by conventional hydrothermal route. Thus, the SAC route is believed to be a competitive strategy to synthesize high silica SSZ-13 zeolites with improved MTO catalytic performance.

Thermal behaviors of a porous calcium silicate material prepared from coal-bearing strata kaolinite

The thermal behaviors of a porous calcium silicate (PCS) material prepared from coal-bearing strata kaolinite were investigated by thermogravimetry and derivative thermogravimetry (TG–DTG), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, and Brunauer–Emmett–Teller method. The XRD results showed that the PCS was determined as calcium silicate hydrates (C–S–H) and a small amount of CaCO3, which transformed to an orderly crystal structure of wollastonite approximately at 700 °C. The TG–DTG results indicated that the dehydration was observed until 300 °C and the dehydroxylation presented at 728 °C. The PCS exhibited a large number of pores with a fibrous flake network structure, which disappeared at 800 °C. The BET data showed that the specific surface area of material decreased as the temperature increased. The high-temperature phase transformation of PCS underwent the following transformation: active calcium silicate → dehydrated calcium silicate → dehydroxylated calcium silicate → wollastonite.

Comparative study on the thermal behavior of structural concretes of sodium-cooled fast reactor

Thermal behaviors of two different siliceous concretes used in a sodium-cooled fast reactor were comparatively investigated in a temperature range from room temperature to 1900 K for obtaining fundamental information required for establishing a plant simulation system for safety assessment under a postulated accidental condition. Silica crystals and Portland cement were identified as the major component of the aggregate and cement portions of the concrete samples, respectively. The thermal decomposition of the cement portion exhibited partially overlapping multistep reaction comprising the thermal dehydration, thermal decomposition processes of Ca(OH)2 and carbonate compounds including CaCO3. TG–DTG curves recorded for the multistep thermal decomposition process of the cement portion were analyzed using the kinetic deconvolution analysis, and the contributions and kinetic parameters of each reaction step were determined. The kinetics of comparable reaction steps between two samples were practically identical, while the difference between the samples was found in the content ratio of Ca(OH)2/CaCO3. The melting behavior of the siliceous concretes was revealed by the complementary interpretation of TG–DTA curves and the morphological observation of the sample heated to different temperatures. The softening and melting behaviors of the siliceous concretes initially occurred in the thermal decomposition product of the cement portion at a temperature range of 1400–1600 K. The subsequent melting behavior of the aggregate portion that occurs at a higher temperature was different between the samples, owing to the different compositions of the aggregates and the possible interaction of the aggregate with the molten cement portion.

Co-oxidation effects and mechanisms between sludge and alcohols (methanol, ethanol and isopropanol) in supercritical water

Sludge is a by-product of wastewater treatment process with high organic and nitrogen contents. Supercritical water oxidation (SCWO) rates of refractory species in sludge might be accelerated by reactive alcohols, which is referred to as a co-oxidation phenomenon. In this work, influences of three typical reactive alcohols (methanol, ethanol and isopropanol) on TOC and of NH3–N removal rates of sludge by SCWO were analyzed and their co-oxidation products were characterized by GC–MS, FT–IR, EDS and TG–DTG methods. Additionally, to capture the nature of co-oxidation, HO2 and OH radicals released by alcohols were theoretically compared with detailed chemical kinetics models using the Chemkin Software. The results show that methanol, ethanol and isopropanol all exhibited co-oxidation accelerated effects on TOC and NH3–N removal rates of sludge. One reason was that alcohols provided reactive HO2 and OH radicals. The other reason was that adding alcohols not only prevented forming recalcitrant products (non-nitrogen and nitrogen aromatic compounds) but also encouraged producing reactive products (non-nitrogen open chain compounds). Ethanol offered the best co-oxidation promotion effects on the removal of TOC and NH3–N in the liquid products and also gave the lowest organic contents in the solid products, followed by isopropanol and methanol. This order was consistent with the difficulty of how the alcohols themselves could be oxidized in supercritical water since ethanol could support the highest amount of HO2 radicals for sludge in the shortest time.

Reactivity Alteration of Granulated Blast Furnace Slag by Mechanical Activation for High Volume Usage in Portland Slag Cement

Augmenting granulated blast furnace slag (GBFS) content in Portland Slag Cement (PSC) beyond the conventional limit of 70% is the stimulus for this study. Such enhancement other than bringing down the carbon footprint of cement conserves natural resources. However, beyond 70% slag incorporation, early strength gain of PSC is meagre because of its low reactivity. This study explores mechanical activation (MA) of GBFS to alter its reactivity, and thereby raising the possibility of increased slag incorporation in PSC. MA of slag is carried in an eccentric vibration mill. Formulations with different MA slag contents and clinker are studied in terms of heat of hydration (using isothermal conduction calorimetry) and compressive strength (CS). CS of clinker–slag formulations augmented with the extent of MA. Hydration behaviour of these blends i.e. increased heat evolution, accelerated reactions etc. is in agreement with CS values. X-ray diffraction and TG–DTG employed as complimentary tools to comprehend the hydration process corroborate with CS results, and hydration characteristics. Thus, MA can be used to enhance the hydration characteristics (reactivity) of GBFS, and henceforth its content in PSC. Sufficiently activated slag incorporation even up to 90% yields comparable strength than commercial PSC at all ages of curing.

Hyper-branched structure-an active carrier for copolymer with surface activity, anti-polyelectrolyte effect and hydrophobic association in enhanced oil recovery.

Herein, a hyper-branched polymer h-PMAD with, simultaneously, surface activity, an anti-polyelectrolyte effect and a hydrophobic association was prepared via aqueous solution free radical polymerization, and characterized by IR, NMR, TG–DTG and SEM. The polymer h-PMAD provided excellent comprehensive properties in terms of surface activity, thickening, water solubility, rheology and aging, which were compared with studies of HPAM and the homologous linear polymer PMAD. Specifically, the IFT value was 55.40 mN m−1, 789.24 mPa s apparent viscosity with a dissolution time of 72 min, 97.72, 90.77 and 105.81 mPa s with Na+, Ca2+ and Mg2+ of 20 000, 2000 and 2000 mg L−1, respectively. Meanwhile, the non-Newtonian shear thinning behavior had a 96.33% viscosity retention while the shear rate went from 170 s−1 to 510 s−1 and then returned to 170 s−1 again and 0.12 Hz curve, with an intersection frequency of G′ and G′′. Also, it had 33.51% and 50.96% viscosity retention in formation and deionized water at 100 °C and a low viscosity loss in formation water at 80 °C over 4 weeks. Moreover, the h-PMAD had an EOR of 11.61%, was obviously higher than PMAD with 8.19% and HPAM with 5.88%. Most importantly, the better EOR of h-PMAD over that of PMAD testified that the hyper-branched structure provided an active carrier for copolymers with functionalized monomers to exert greater effects in displacement systems, which is of an extraordinary meaning.

Thermal behavior and thermokinetic of double-base propellant catalyzed with magnesium oxide nanoparticles

Catalytic effect of magnesium oxide nanoparticles (nano-MgO) on the thermal behavior and decomposition reaction kinetic of the double-base propellant formulation was investigated in order to model the thermal degradation process. Thermal analysis studies were performed by various techniques, i.e., simultaneous thermogravimetry–differential thermogravimetry (TG–DTG) and differential scanning calorimetry (DSC). The results showed that magnesium oxide nanoparticles significantly change thermal pattern of the studied propellant. Non-isothermal DSC data were used to predict the thermokinetic parameters such as activation energy, frequency factor, the critical ignition temperature of thermal explosion, the self-accelerating decomposition temperature and thermodynamic parameters of the studied propellant via two well-known integral methods (i.e., Coats–Redfern and Flynn–Wall–Ozawa) and also two differential methods (i.e., Kissinger and Starink). The resulted data showed that nano-MgO could change the thermal decomposition mechanism function and the corresponding kinetic equation to thermal degradation of the propellant sample.

Synthesis and characterization of molybdenum complex supported on magnetic and non-magnetic supports: comparing their catalytic activity, selectivity, and reusability

A molybdenum complex was immobilized on Schiff-base-modified magnetic and non-magnetic particles by covalent linkage. The characterizations of the obtained materials were carried out by means of TG–DTG, SEM, TEM, VSM, XPS, IR, and Raman microprobe techniques. All of them exhibited efficient activities in the oxidation of sulfides to sulfoxides by urea hydrogen peroxide oxidant. The advantages and disadvantages of these catalysts are discussed in detail. Molybdenum complex immobilized on silica bead can be recycled and recovered by simple filtration, but it demonstrated low activity in catalytic oxidation reaction. Immobilization on nano-SiO2 leads to the formation of nanocatalyst having high catalytic activity but inefficient reusability. The best results were obtained with nano-Fe3O4 magnetic support. The immobilized molybdenum complex on silica-coated magnetic nanoparticles can easily be recovered from the reaction system using an external magnet and reused several times with high yields.

Impact of rock fabric, thermal behavior, and carbonate decomposition kinetics on quicklime industrial production and slaking reactivity

This paper deals with thermal analyses, burning trials and reactivity tests on 15 carbonate rocks, i.e., pure and impure carbonates, mud-supported and grain-supported limestones, crystalline marbles, and dolomites, used for the production of different lime products in industrial vertical shaft kilns worldwide. In particular, thermogravimetric and differential thermogravimetric analysis (TG–DTG) on massive (80–120 g) fine-grained (< 3.35 mm) samples allowed the extrapolation of the Arrhenius kinetic parameters, i.e., the (apparent) activation energy (Ea) and the pre-exponential or frequency factor (A). Other calcination parameters, i.e., the duration time, starting and ending calcination times and temperatures, and peaks of maximum calcination rate were also extrapolated in order to enhance their relationships with quicklime reactivity. Moreover, thermal analyses (TG–DTG–DTA) were repeated on powders (90 mg) using a more accurate analyzer to compare results. The study is completed by a thorough chemical–physical and mineralogical–petrographic characterization of carbonate rocks and derived burnt products. Results pointed out that medium-to-coarse crystalline materials, i.e., grain-supported limestones, diagenetic dolomites, and granoblastic marbles presented the highest activation energy, burnability and slaking reactivity. Conversely, microcrystalline carbonates with the highest micrite-to-sparite ratio, i.e., mud-supported limestones, and impure carbonates, enriched in quartz, clay minerals, and other subordinated non-carbonate impurities, presented the lowest activation energy, burnability, and slaking reactivity. This study also investigated the effect of BET-specific surface area and real density, depending on specific sintering tendency, on quicklime reactivity. Results from this multidisciplinary research activity put further constraints on carbonate rocks calcination kinetics and their suitability in the lime industry.

Carbon Dioxide Hydrogenation under Subcritical and Supercritical Conditions in the Presence of 15% Fe/SiO2 Catalyst

Results are presented from a comparative study of CO2 hydrogenation under gas-phase and supercritical conditions for CO2 in the presence of 15% Fe/SiO2 catalyst. The reaction is studied in the temperature range of 300–500°C at atmospheric pressure under gas-phase conditions and at a pressure of 95 atm under supercritical conditions at an Н2 : СО2 molar ratio of 2 : 1. It is found that the process proceeding under supercritical conditions lowers CO selectivity from 90–95 to 30–50% over the range of temperatures and raises (up to 60%) the hydrocarbon selectivity. In contrast to gas-phase hydrogenation, the formation of alcohols is observed in the reaction under supercritical conditions. Using a combination of thermogravimetry, differential thermogravimetry, and differential thermal analysis (TG–DTG–DTA), it is shown that the process proceeding under supercritical conditions results in a 2.2-fold drop in the amount of carbon-like deposits on the catalyst surface. X-ray diffraction analysis shows that under gas-phase process conditions, graphite-like structures form on the catalyst surface; this effect is not observed under supercritical conditions. The developed catalyst and the process for CO2 hydrogenation can be recommended for the further modification and improvement of the properties of a catalyst based on iron nanoparticles that is much (10–100 times) cheaper than the previously reported CO2 hydrogenation catalysts.