Thermolysis Products Research Articles

Kinetic Enhancement of Sulfur Cathodes by N-Doped Porous Graphitic Carbon with Bound VN Nanocrystals.

The reaction kinetics of sulfur cathodes generally control the performance of lithium-sulfur (Li-S) batteries. Here, N-doped porous graphitic carbon with bound VN nanocrystals (3D VN@N-PGC), which is synthesized in one pot by heating a mixture of glucose as C source, urea as N source, and NH4 VO3 as V source, is reported to be an superior electrocatalytic cathode host for Li-S batteries. Notably, the VN nanocrystals, strongly bound to the N-PGC network, form via in situ reactions among the thermolytic products of starting materials. The dopant N atoms and bound VN nanocrystals exhibit synergistic electrocatalytic effects to promote the cathode reactions of the Li-S cells. The observed enhancements are supported by density functional theory simulations and by the observation of electrocatalytic N- and V-intermediate species, via X-ray absorption near-edge structure spectroscopy. Li-S cells assembled using 3D VN@N-PGC as cathode host exhibit superior performance in terms of specific capacity (1442mA h g-1 at 0.1 C), rate capability (641mA h g-1 at 4 C), and cycle life (466mA h g-1 after 1700 cycles at 2 C, corresponding to a capacity decay of 0.020% per cycle). The one-pot methodology is facile and scalable and offers a new approach for synthesis of various metal nitride-containing materials for other electrocatalytic applications.

Technical Carbon from the Products of Thermolysis of Discarded Tires

Based on studies of the process of steam thermolysis of discarded tires, the possibility of obtaining a high-grade technical carbon and of other ingredients from thermolysis products for the production of rubber has been substantiated. The efficiency of using composite mixtures of liquid and solid products of the thermolysis of tires as a raw material for obtaining technical carbon is shown.

Formation of Petroleum Hydrocarbons from Prokaryote Biomass: 3. Formation of Petroleum Biomarker Hydrocarbons from Biomass of Shewanella putrefaciens Bacteria and Asphaltenes Isolated from Crude Oil

The distribution of saturated biomarker hydrocarbons (n-alkanes, isoprenanes, steranes, terpanes) in extracts of the soluble part and thermolysis products of the insoluble part of biomass of the Shewanella putrefaciens bacteria isolated from crude oil of the Dagang field and in the products of thermolysis of asphaltenes from the same oil have been studied by gas chromatography–mass spectrometry. The homologous series of C10–C36 n-alkanes and C11–C20 isoprenanes and squalene have been found among aliphatic hydrocarbons (HCs) in the extracts and the thermolysis products of the insoluble part. Various n-alkanes predominate in the extracts collected at different times, while the value of the pristane/phytane genetic index corresponds to marine organic matter (OM) in all the cases. Petroleum steranes and terpanes are found among cyclic biomarker hydrocarbons, the distribution of which in the thermolysis products of the insoluble part of the biomass is close to the petroleum distribution. The relative concentration of n-alkanes in the products of thermolysis of asphaltenes prevails over the relative concentration of isoprenanes. It has been assumed that the Shewanella putrefaciens biomass made a certain contribution to the formation of the biomarker hydrocarbons of the Dagang oil.

Precursors for the Synthesis of Carbon Materials from Coal Pitch

The functional and group composition and structure of β and α2 fractions of medium-temperature coal pitch fraction (in powder form) are investigated by methods such as elemental analysis, electron microscopy, IR spectroscopy, ESR, X-ray diffraction analysis, derivatographic analysis, and chromatography and mass spectrometry. The morphology and structure of the coke residues from the thermal destruction of the pitch’s α2 fraction are studied at different stages of thermolysis. It is found that the polycyclic aromatic hydrocarbons in the volatile thermolytic products of the coal pitch are generated on decomposition of the β fraction. The data obtained by different methods are relatively consistent and more completely characterize the functional and group composition and structure of the β and α2 fractions of medium-temperature coal pitch. On that basis, new methods are proposed for the use of individual pitch fractions as precursors for the synthesis of carbon materials or selective sorbents.

Термическое разложение двойных комплексных соединений 3d-металлов.

The paper is devoted to the study of thermolysis of double complex compounds (DCС) of metalsin the I transition series. 30 DCСwith various combinations of metal-central atoms (Co-Fe, Cu-Fe, Ni-Fe Cr-Fe, Cr-Co,) and ligands (ammonia, urea (ur), ethylenediamine (en), 1,3-diaminopropane (tn), cyanide, oxalate and nitrite anions) were synthesized and characterized. A complete study of the thermal proper-ties of these DCCs in three atmospheres was carried out: oxidizing (air), inert (Ar, N2, partly He) and re-ducing (H2), in the temperature range of 20–1000°Cand at constant heating rate of 10°C/min. The solid and gaseous thermolysis products were studied. In the air solid thermolysis products are represented by mixtures of central ions oxides or mixed oxides of the MIMII2O4type. The main gaseous products of thermolysis underthe temperature below 300°Cinclude NH3, HNCO (for urea DCС) and HCN (for cya-nocomplexes), and above 300°C —СО2. In addition, undecomposed ligands, CO, nitrogen oxides and probably nitrogen are presented in the gas phase. Thermolysis of the studied DCCgoesin the most com-plex way in inert atmospheres. Solid thermolysis products are heterogeneous mixtures of metals (Cu, Fe), solid solutions of CoxFe1-x, Ni3Fe intermetallic compounds, oxides, carbides and nitrides of central ions and amorphous carbon; the content of the latter reaches 58% of the initial content in the complex. The gaseous products of thermolysis include the same compounds, except for CO2, as in the atmosphere of air, but also in different ratios. In an H2atmosphere, all studied DCCs, except Cr-containing ones, are re-duced to the sum of central ions —Cu + Fe or solid solutions Co-Fe and Ni-Fe, practically free of carbon. Gaseous products are the same as in an inert atmosphere, butan increased yield of NH3and a reduced yield of CO2and/or HCN speak in favor of partial hydrogenation of the ligands to hydrocarbons. A review of the catalytic properties of solid products of DCC thermolysis (~170 samples) showed that about 1/3 of themare active in model reactions (catalytic decomposition of hydrogen peroxide, thermal decomposi-tion of ammonium perchlorate).

Crystal Structures, Hirshfeld Surfaces, and Thermal Study of Isostructural Polymeric Ladders of La(III) and Sm(III) Coordination Compounds with 4,4'-Bipyridine and Dibromoacetates.

Two novel mixed ligand complexes with general formula [M2(4,4′-bpy)1.5(CBr2HCOO)6(H2O)2]n (where 4,4′-bpy = 4,4′-bipyridine) were synthesized. Thermal analysis was used to describe a solid intermediate and final products of thermolysis. A coupled TG-MS system was used to monitor principal volatile fragments evolved during pyrolysis. Crystal structures of the complexes were determined. Cationic dinuclear M2 (M(III) = La, Sm) coordination cores were obtained. Both crystal structures are isostructural. Single crystal X-ray diffraction analysis revealed that investigated structures of 1D coordination polymers assembled in ladder-like systems. The central atom replacement resulted in unit cell identity parameter П = 0.0091. Additionally, the isostructurality of the reported La(III) and Sm(III) complexes was revealed using Hirshfeld Surface analysis supported by Enrichment Ratio calculations.

Precursor technology for the production of white and color phosphors based on Al2O3:Ln (Ln=Eu3+, Tb3+ or Eu3+/Tb3+)

Al1-xLnx(OH)(HCOO)2 (Ln ​= ​Eu3+, Tb3+ or Eu3+/Tb3+) precursors were synthesized and used as starting reagents for the preparation of white and color luminescent materials. The X-ray powder diffraction data, Infrared, Raman spectra and thermal analysis of precursors are discussed in detail. Vibrational spectroscopy corroborates the X-ray diffraction results, Al1-xLnx(OH)(HCOO)2 crystallize in the monoclinic system. Thermolysis of Al1-xLnx(OH)(HCOO)2 precursors in helium atmosphere and in air at temperatures below 700°С allows one to obtain poorly crystallized Al2O3:Ln samples. The temperature required for the synthesis of γ-(Al1-xLnx)2O3 solid solutions is equal to 900°С. Complete characterization of the products of thermolysis of precursors was performed using X-ray powder diffraction, 27Al MAS NMR, optical absorption and luminescence. The presence of europium and terbium ions in the aluminum oxide leads to the stability of the γ-phase, i.e. inhibits the formation of α-Al2O3. The europium and terbium codoped Al2O3 prepared by thermolysis of precursors in helium atmosphere and in air exhibits luminescence close to white light under UV excitation. The optimal concentration of dopants, Eu3+ and Tb3+ ions, in the γ-Al2O3 hosts with white-blue emission makes it possible to improve the CIE color coordinates and obtain white luminescence.

Mechanism of the Suppression of Sulfur Oxides in the Oxidative Thermolysis Products of Coals upon Their Combustion in a Mixture with Dispersed Wood

Mechanism of the Suppression of Sulfur Oxides in the Oxidative Thermolysis Products of Coals upon Their Combustion in a Mixture with Dispersed Wood

Thermal decomposition of Prussian blue analogues in various gaseous media

Prussian blue analogues with formulae Ni3[Co(CN)6]2·16H2O(I), Cu3[Co(CN)6]2·17H2O(II), Ni3[Fe(CN)6]2·15H2O(III) and Cu3[Fe(CN)6]2·13H2O(IV) have been synthesized. The thermal decomposition of all complexes in oxidizing (air), reducing (hydrogen) and inert (argon) atmospheres was studied in the temperature range from 20 to 1000 °C. TG–DSC curves were obtained; analysis of solid thermolysis products was performed. It was established that the decomposition process of all the studied compounds in air ends up to 450–500 °C, and mass loss continues up to 1000 °C in argon. Solid products of thermolysis are oxides of central ions (NiO, CuO, Co3O4, Fe3O4) in air; mixtures of metals or Ni3Fe (III) in argon; Ni and Co (I) and Ni3Fe + Fe(III), and mixtures of Cu + Co (II) and Cu + Fe(IV) in hydrogen. Hexacyanocobaltates are reduced at lower temperatures and more fully than hexacyanoferrates under the same conditions.

Features of the Thermolysis of Li, Na, and Cd Maleates

Processes of the multi-stage decomposition of maleic acid and Li, Na, and Cd maleates in an inert atmosphere are studied via thermal analysis with synchronous analysis of the composition of the released gases. Reaction mechanisms are proposed according to the data on the mass loss stages determined via thermal analysis, gaseous products, and the final solid decomposition products. It is shown that when heated to 700°C, Li and Na carbonates incorporated into the porous carbon matrix are the final products. Above 350°C, cadmium is reduced from oxide to metal and evaporates to form a porous carbon residue as the only product of thermolysis. All carbon products are X-ray amorphous. Maleic acid decomposes completely into gaseous products in the range of 133–239°C. The maleate ion is more stable in the structure of lithium maleate than in free maleic acid, and Na and Cd cations reduce its stability.

Directed Synthesis of Ultradisperse Individual and Bimetallic Zirconium and Hafnium Oxides by Supercritical Antisolvent Precipitation

A method for the synthesis of mono- and bimetallic zirconium and/or hafnium oxides by supercritical antisolvent precipitation has been developed. The oxides have been obtained using a laboratory dispersing system, alkoxides (zirconium propoxide, hafnium butoxide) and zirconium acetylacetonate have been used as precursors. A white powder of amorphous phase with composition MO2 · mH2O · nCxHyOz (M = Zr, Hf) has been obtained in all experiments. Differential thermal and X-ray powder diffraction analysis have been used to study the obtained phases and their thermolysis products (mono- and bimetallic zirconium and/or hafnium dioxides). Particle size and their morphology have been studied by optical and electron microscopy and dynamic light scattering. It has been shown that the particles of prepared oxides have spherical shape, while their size is dependent on the molar ratio of initial solution components. According to electron microscopy data, annealed samples have smaller particle size as compared with the initial samples.

Thermolysis of Asphaltenes of Timan–Pechora Heavy Oils

The hydrocarbon composition of the thermolysis products of asphaltenes from biodegraded oils of the Labagan and Usa oilfields and non-biodegraded oil of the Salyukinskoe oilfield of the Timan–Pechora sedimentary basin has been studied. The IR spectra of the asphaltenes are identical, indicating their similar structural group composition. The thermolysis of the asphaltenes has been carried out in an argon flow successively at 300 and 350°C. It has been shown that desorption of saturated and aromatic components from the pores of the asphaltenes predominantly occurs at 300°C. For the initial biodegraded oils and the oil that did not undergo biochemical oxidation, a number of geochemical parameters calculated in terms of acyclic hydrocarbons (HCs) and polycyclic biomarkers turns out to be similar to those obtained for the thermolysis products of the asphaltenes heated at 350°C. The values of the methylphenanthrene index are similar for the thermolysis products of asphaltenes and the parent oils. This similarity, in turn, allows the genetic identification of oils and evaluation of their catagenetic maturity by asphaltene thermolysis products in the case when biomarkers of the aliphatic fraction are lost during biodegradation. An analysis of the supermolecular structure of the asphaltenes of the oils under study has shown a general trend of its change by heating at 350°C, which consists in a sharp decrease in the particle size and loosening of the particle packing due to the appearance of pronounced porosity.

Molybdenum(VI) oxide: New methods of synthesis and properties

Objectives. The present study aims to develop new methods for the synthesis of molybdenum(VI) oxide, which is a precursor for the synthesis of functional materials, as well as to investigate the physicochemical properties of the resulting oxide phases. Methods. The synthesized phases and the products of their thermolysis were studied by differential thermal analysis, IR spectroscopy, X-ray diffraction analysis, and granulometry. Results. Three methods for the synthesis of molybdenum(VI) oxide were developed, and the physicochemical properties of the oxide phases obtained were studied. The first method consisted in the reaction of molybdenum pentachloride with a 6.0–9.5 mol/L ammonia solution, the second one was the reaction of niobium pentachloride with a sulfuric acid solution, and the third method involved the reaction of ammonium molybdate with nitric acid, affording brown molybdenum(V) MoO(OH)3 hydroxide, a bright blue precipitate of molybdenum blue MoO2.75, and white hydrated oxide MoO3·H2O, respectively. Conclusions. A series of thermal and X-ray diffraction analysis demonstrated that in all cases the samples were amorphous phases. Heat treatment at 580 °C of the synthesized phases led to the formation of a rhombic modification of molybdenum trioxide. The lattice parameters and X-ray density were calculated for all thermolysis products. The effect of heat treatment on the particle size of the synthesized samples and their thermolysis products was studied. Particle size analysis demonstrated that particles of different diameters were formed depending on the synthetic method. The smallest particle size (0.3–0.6 µm) was found in molybdenum trioxide, a product of the thermolysis of the sample obtained by the reaction of molybdenum pentachloride with a concentrated ammonium solution.

Synthesis of Zinc-Doped Lithium Tantalate Charge in the Technology of Novel Crystalline Functional Materials

A procedure was developed for preparing lithium tantalate (LiTaO3) charge homogeneously doped with lithium from high-purity tantalum-containing solutions, based on heat treatment of lithium-, tantalum-, and zinc-containing citrate precursors. The thermolysis products were studied by thermal analysis, X-ray diffraction, and IR absorption spectroscopy. The optimum synthesis conditions and zinc concentration to obtain a single-phase LiTaO3:Zn charge were determined. Comparison with the properties of an isomorphic compound LiNbO3 (LiNbO3:Zn) demonstrated the advantages of the synthesis procedure developed and practically important properties such as high optical stability of LiTaO3:Zn crystals and low coercive field, acquired by lithium tantalate upon doping with zinc. Samples of LiTaO3:Zn charge of various compositions, suitable both for the technology of LiTaO3:Zn crystals and for the preparation of piezoelectric ceramics based on zinc-doped lithium tantalate, were prepared by the developed procedure.

Thermolytic Conversion of Copper (II) Based Coordination Polymer into Copper Oxide–Carbon Nanocomposite for Selective Removal of Cd (II) from Aqueous Solution

In this work, we report the synthesis of a Cu (II) based metal–organic frameworks (HKUST-1) by mechanochemical method and metal-oxide–carbon nanocomposite (CuO@C) as thermolysis products. The prepared HKUST-1 and composite were characterized by elemental CHNS/O microanalysis, scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM–EDX), transmission electron microscopy (TEM), ultraviolet–visible spectroscopy (UV–vis), thermogravimetric analyses (TGA), fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD) and Brunauer–Emmett–Teller (BET) analysis. The TEM analysis, confirmed the CuO nanoparticles in the porous carbon matrix. The synthesized compounds were further investigated for adsorption of Cd (II) from aqueous solution. The composite exhibited a high cadmium uptake of 132.6 mg g−1 compared to the parent HKUST-1, and fast kinetics with a kinetic rate constant k2 of 0.031 g mg−1 min−1, which is greater than some existing adsorbents for cadmium adsorption from aqueous solution under similar condition. The cadmium adsorption on CuO@C composite showed pH, temperature and time dependence to the prepared HKUST-1, as well as greater surface area and pore volume. The CuO@C composite can be readily recycled and regenerated without significant loss of the cadmium adsorption capacity.

Theoretical and infrared spectroscopy study of the structure of copper(II) poly-5-vinyltetrazolate and the products of its thermolysis

The structure of copper(II) poly-5-vinyltetrazolate and the products of its thermolysis has been studied by means of density functional theory and infrared spectroscopy. Copper(II) poly-5-vinyltetrazolate has been obtained and subsequently subjected to thermolysis. Infrared spectra of copper(II) poly-5-vinyltetrazolate and the products of its thermolysis have been recorded. The possible ways of coordination of copper(II) ions with tetrazole-containing ligands were established by analyzing the calculated molecular electrostatic potential distribution and comparing the calculated IR-spectra of the model structures to the experimental ones. It has been shown that the best agreement between the calculated and experimental data is observed for the model with three-coordinated copper(II) ions, which includes both the tetrazole-containing ligands coordinating two copper(II) ions through N(1)- and N(3)-atoms of the tetrazole ring, and the tetrazolecontaining ligands coordinating one copper(II) ion through either the N(2)- or the N(3)-atom. Recently we have shown that the product of thermolysis of copper(II) poly-5-vinyltetrazolate exhibits high catalytic activity in homocoupling of phenylacetylene and Huisgen [3 + 2]-cycloaddition. To establish the structure of the products of thermolysis of copper(II) poly-5-vinyltetrazolate, seven possible products have been proposed based on the analysis of the structure of copper(II) poly-5-vinyltetrazolate and the experimental IR-spectrum. IR-spectra of all proposed products have been calculated and the results of the calculations have been compared with the experimental IR-spectrum of copper(II) poly-5-vinyltetrazolate thermolysis product. It has been shown that the main product of thermolysis is cis-polycyanoacetylene.

Coordination polymers based ontrans, trans-muconic acid: synthesis, structure, adsorption and thermal properties

AbstractMetal-organic frameworks (MOFs) are promising sacrificial templates for synthesis of carbon functional materials with a relatively high concentration of stabilized metallic species. In this work coordination polymers based ontrans,trans-muconic acid and transition metals (Cu, Zn, Ni, Co) were prepared and selected as the precursors for supramolecular organization of nanocomposites. The coordination polymers and metal-containing thermolysis products obtained were characterized using a number of analytical techniques including powder X-ray diffraction, elemental analysis, thermal gravimetric analysis, scanning electron microscopy and volumetric nitrogen adsorption/desorption. This study extends the application of coordination polymers as precursors for designing of carbon materials incorporating metal nanoparticles. It is shown that appropriate choice of metal-organic precursors in solid-phase thermolysis allowed to get materials with determined morphologies.

Effect of irradiation on the oxidation kinetics of TODGA-based extraction mixtures at atmospheric pressure

The gas evolution from mixtures consisting of 0.2 M solution of N,N,N′,N′-tetra-n-octyldiglycolamide (TODGA) in n-alcohol (n-decanol or n-nonanol) with Isopar-M diluent was investigated during thermal oxidation. The effect of ionizing radiation on their thermal stability has been studied. It has been determined that the volume of gaseous thermolysis products increases by 260% in the case of n-nonanol and 80% in the case of n-decanol compared to non-irradiated solutions. It has been shown that the gas evolution rate and gas volume increase when the irradiated mixture saturated with nitric acid is heated. However, there are no prerequisites for the development of autocatalytic oxidation.

Thermal Transformations of Petroleum Residue Components in the Presence of Power-Plant Flyash Ferrospheres and Sunflower Oil

The thermal transformations of components of the residue (boiling point above 350°C) of Zuunbayan heavy, high-wax oil (Mongolia) in the presence of cogeneration plant flyash ferrospheres and sunflower oil have been studied. The use of the additives made it possible to obtain additional amounts of distillate fractions (IBP–360°C). The physicochemical characteristics and composition of the products have been determined. The structural-group characteristics of the resin–asphaltene components of the feed petroleum residue and the products of its thermal conversion in the presence of sunflower oil and flyash ferrospheres have been compared. The presence of sunflower oil and ferrospheres leads to a decrease in the molecular weight of the resins and asphaltenes isolated from thermolysis products. The number of naphthenic and paraffinic carbon atoms in resin and asphaltene molecules decreases, and the proportion of aromatic atoms markedly increases.

Sol–Gel Synthesis of a Zn-Doped Lithium Tantalate Growth Charge

We have developed a method for the synthesis of a zinc-doped lithium tantalate (LiTaO3) growth charge using high-purity tantalum-containing solutions, which is based on the heat treatment of lithium-, tantalum-, and zinc-containing citrate precursors. The thermolysis products have been characterized by thermal analysis, X-ray diffraction, and infrared absorption spectroscopy. We have optimized synthesis conditions and zinc concentration for obtaining a single-phase LiTaO3〈Zn〉 growth charge. Using the proposed process, we have obtained LiTaO3〈Zn〉 materials with tailored dopant concentrations, which can be used in both LiTaO3〈Zn〉 crystal growth and the preparation of doped lithium tantalate-based functional ceramics.