Thermolysis Products Research Articles

Hydrogen bond self-assembly strategy to preparation Zeolite@BM for enhancing the fire retardancy of EP

The inflammability of EP limits its wide application, and it is important to enhance its fire safety with appropriate flame retardants. In this study, a novel Zeolite@BM flame retardant was constructed based on the self-assembly of boric acid and melamine on the surface of zeolite. Synthetic Zeolite@BM incorporated into EP to strengthen its flame retardance. The incorporation of 10 wt% Zeolite@BM dramatically raised the flame retardation of EP. The LOI of EP climbed from 24.7 % to 27.4 %, reaching the V-0 level. Moreover, the PHRR, THR and TSP dropped significantly by 55.01 %, 29.14 % and 49.96 %, respectively. Zeolite@BM promotes char formation, minimizing thermolytic products emissions and significantly raising the fire retardance of EP. Therefore, Zeolite@BM endows EP with good flame retardancy, low smoke emission and heat release, providing a practicable and efficient strategy for using EP under high flame retardancy requirements.

Thermodynamics and kinetics of evaporation and thermal decomposition of 1-ethyl- and 1-butyl-3-methylimidazolium methanesulfonate ionic liquids: Experimental and computational study

Knudsen cell mass spectrometry was used to study the evaporation of two ionic liquids, 1-ethyl-3-methylimidazolium methanesulfonate ([EtMIm][MS], MS = CH3SO3) and 1-butyl-3-methylimidazolium methanesulfonate ([BuMIm][MS]), accompanied by thermal decomposition (thermolysis). The independent occurrence of evaporation and thermolysis reactions made it possible to determine their thermodynamic and kinetic characteristics under identical experimental conditions. The saturated vapor pressures were measured and the standard enthalpies of vaporization of [EtMIm][MS](l) and [BuMIm][MS](l) were obtained. The standard thermodynamic functions of formation in the liquid and gaseous states at 298.15 K were estimated from the available experimental data and the results of quantum chemical calculations. The gaseous decomposition products of ionic liquids were identified and the pressures of the thermolysis products of [EtMIm][MS](l) were determined. According to the experimental data and quantum chemical calculations, the thermolysis of [EtMIm][MS](l) occurs through heterogeneous reactions far from the equilibrium state. The kinetics of the reactions is described in two ways. When the degree of sample conversion is used as a variable, the constant reaction rates at the initial stage of thermolysis correspond to a pseudo-zero order reaction with a monotonic increase in the degree of conversion. In the proposed alternative approach, the reaction rates are estimated from the fluxes of thermolysis products and are expressed in terms of ionic liquid concentration.

Synthesis of copper-containing metal–polymer nanocomposites and their use as a humidity sensor

Recently, the synthesis of new gas-sensitive materials for use in resistive humidity sensors has attracted considerable interest. In the study, copper-containing metal–polymer nanocomposites were obtained by thermolysis of copper fumarate (I) and its complexes with 2,2′-dipyridyl (II) and 1,10-phenanthroline (III). The nanocomposites were characterized by Fourier transform infrared (FTIR) spectroscopy, elemental analysis, energy-dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The most common particle sizes of the thermolysis products of compounds I, II, and III were 18.7, 8.3, and 20.7 nm, respectively. The manufactured sensor samples exhibited good sensitivity to the relative humidity (RH) of air: 2.48%/%RH, 3.77%/%RH, and 3.11%/%RH for the thermolysis products of compounds I, II, and III, respectively. Because of the high porosity and moisture absorption of the film, the maximum sensitivity was approximately 0.005 MΩ/%RH, which indicates fairly effective behavior of the film with respect to humidity. The response and recovery times were 23.7, and 37.3 s; 24.7, and 35.8 s; 32.4, and 58.4 s, respectively. The experiment had 88%–97% reproducibility. The fabricated sensors have great potential as humidity-sensing elements for humidity monitoring.

Thermal instability of 1-butyl-3-methylimidazolium chloride ionic liquid

The evaporation and thermal decomposition (thermolysis) of 1-butyl-3-methylimidazolium chloride ionic liquid, [BuMIm][Cl](l), were studied in the temperature range of 373–463 K by thermogravimetry–mass spectrometry (TG–MS) and Knudsen cell mass spectrometry (KCMS) methods. The saturated vapor pressures and the enthalpy of vaporization of [BuMIm][Cl](l) were determined within 373–398 K, where the thermolysis of this ionic liquid occurs via the SN2 mechanism at a low rate. With increasing temperature, the thermolysis becomes more extensive, which is accompanied by the C2-methylation of [BuMIm][Cl](l). The resulting ion pairs [BuMMIm+][Cl-] are thermally unstable and decomposed. A decrease in the vapor pressure of the ion pairs [BuMIm+][Cl-] at a constant temperature takes place due to side reactions, resulting in the suppression of the evaporation. Complex ionic compounds were found in the thermolysis/evaporation residues using atmospheric pressure chemical ionization (APCI) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) methods. The priority and possible pathways of reactions involving ion pairs and the thermolysis products were established by quantum chemical calculations.

Synthesis of nickel-containing metal-polymer nanocomposites and their use as a humidity sensor

In recent years, the synthesis of new gas-sensitive materials for resistive humidity sensors has attracted significant interest. In the present paper, nickel-containing metal-polymer nanocomposites were obtained by thermolysis of nickel itaconate (I) and its complexes with 2,2′-dipyridyl (II), 1,10-phenanthroline (III) and 4′-phenyl-2,2′:6′,2''-terpyridine (IV). The formed nanocomposites were characterized by FTIR, elemental analysis, EDX, SEM, TEM and XRD studies. The most common particle sizes are 28, 12.8, 10.7 and 12.3 nm for the thermolysis products of compounds I–IV respectively. The manufactured sensor samples have good sensitivity to air relative humidity (RH) of 3.24 %/%RH, 4.72 %/%RH, 2.18 %/%RH and 4.37 %/%RH for thermolysis products of compounds I–IV with the polymer binder polyacrylamide, respectively. The average initial resistance of the sensors is 4.54, 15.33, 20.8 and 35.75 MΩ, respectively. Due to the high porosity and moisture absorption of the film, the maximum sensitivity was about 0.003 MΩ/%RH, which indicates a fairly effective behavior of the film with respect to humidity. The response times were 27, 25, 33, 30 s, and the recovery time 47, 44, 51, 49 s, respectively, and repeating the experiment resulted in 87–92 % reproducible results. The fabricated sensors have great potential for use as a humidity sensing element in sensors that can be used for humidity monitoring.

Structure and thermal properties of acrylic copolymer gels: effect of composition and cross-linking method

Two approaches to the synthesis of hydrogels based on polyacrylamide (pAAm) with copolymers were compared in the paper—traditional chemical cross-linking and physical cross-linking with montmorillonite (MMT). The main aim of the work was to find an adequate replacement of the chemical toxic cross-linking agent MBAAm (N,N'-methylene-bis-acrylamide) by using non-toxic—natural clay MMT for synthesis of pAAm gels, which are planned to be used as soil conditioners. A series of hydrogels based on acrylic monomers (acrylamide (AAm), acrylonitrile (AN), acrylic acid (AA)) physically cross–linked by MMT and chemically cross-linked were synthesized. For the synthesized gels, the influence of the synthesis method on the formation of the structure and the mechanism of thermal destruction in the presence of air was analyzed using a set of physicochemical methods: FTIR, XRD, SEM, DSC and TG/DTG. According to FTIR and XRD data, pAAm-MMT and pAAm-AN-MMT samples formed an intercalated/exfoliated structure, whereas pAAm-AA-MMT had an intercalated structure. The endothermic reaction of decomposition of xerogels based on acrylic polymers with and without MMT was observed using DSC and derivative thermogravimetry analyses, coupled with measurement of FTIR spectra of volatile products of thermolysis. All studied composites were relatively thermoresistant, which had three distinct regions of phase transitions and their thermal decomposition occurred at a temperature range 310–465 °C.Graphical

Thermal desorption – gas chromatography – mass spectrometry (TD-GC-MS) analysis of PFAS used in food contact materials

Per- and polyfluoroalkyl substances (PFAS) are used in food contact materials (FCMs), e.g. as production aids in the fabrication of PTFE based coatings for kitchenware or as additives in paper and board. Growing concerns about the environment and health related to PFAS have led to an increasing interest in monitoring PFAS levels in FCMs as well as their migration into food. In this study, method development for the analysis of PFAS by thermal desorption – gas chromatography – mass spectrometry (TD-GC-MS) was done. In addition to fluorotelomer alcohols (FTOHs), which are the only PFAS commonly analysed by GC-MS, it was proven that perfluorocarboxylic acids (PFCAs) and per- and polyfluoroether carboxylic acids (PFECAs) as well as their thermolysis products, perfluoroethers (PFEs) and perfluoroalkenes, can be analysed by GC-MS without prior derivatization. Screening for PFCAs and FTOHs was possible by electron impact ionization (EI) using group specific SIM fragments. Confirmation of identity has been done by EI scans as well as chemical ionization (CI) SIM measurements. LODs (limits of detection) of PFCAs, FTOHs and PFECAs in the TD-GC-MS instrument were in the low pg range. Thermal degradation of PFCAs and PFECAs during TD-GC-MS measurement was investigated.

Catalytic Pyrolysis of Polypropylene for Cable Semiconductive Buffer Layers.

With the progress of the power grid system, the coverage area of cables is widening, and the problem of cable faults is gradually coming to affect people's daily lives. While the vast majority of cable faults are caused by the ablation of the cable buffer layer, polypropylene (PP), as a common cable buffer material, has pyrolysis properties that critically impact cable faults. Studying the semiconductive buffer layer of polypropylene (PP) and its pyrolysis properties allows us to obtain a clearer picture of the pyrolysis products formed during PP ablation. This understanding aids in the accurate diagnosis of cable faults and the identification of ablation events. In this study, the effects of temperature and catalyst (H-Zeolite Standard Oil Corporation Of New York (Socony) Mobil-Five (HZSM-5)) content on the PP thermolysis product distribution were studied by using an online tubular pyrolysis furnace-mass spectrometry (MS) experimental platform. The results showed that PP/40% HZSM-5 presented the highest thermolytic efficiency and relative yield of the main products at 400 °C.

The Influence of Freezing-thawing on the Properties of Sludge from Water Treatment Facilities and the Prospects for its Disposal

It has been shown that the freezing-thawing method allows a sharp increase in the water-yielding capacity of water treatment sludge (WTS sludge) and leads to an increase in the median particle size of the dispersed phase of sludge. The distribution of bound water types in WTP sludge was studied using thermogravimetry (TG), differential thermal thermogravimetry (DTG), differential scanning calorimetry (DSC) and mass spectrometry of gaseous thermolysis products (MS). It has been established that the release of water and carbon dioxide is completely completed at a temperature of 600°C. The specific surface area of the solid phase of WTP sludge before and after freezing-thawing was determined. The pore size distribution was studied. The BET isotherm of WTP sludge corresponds to mesoporous sorbents.

Heterophase synthesis of rare-earth zirconates

This study focuses on developing a heterophase process for synthesizing rare-earth zirconates, specifically R2Zr2O7 /R2O3·2ZrO2 (R = La, Sm, Gd, Dy). We investigated the sorption properties of low-hydrated zirconium hydroxide, a precursor for complex-oxide phases, towards rare-earth elements' ions (La, Sm, Gd, Dy). The results indicate that sorption by low-hydrated zirconium hydroxide is a multifaceted process, involving the incorporation of rare-earth cations into the pores of low-hydrated hydroxide and ion exchange. The paper details the synthesis of R2Zr2O7 /R2O3·2ZrO2 (R = La, Sm, Gd, Dy), considering both «light» and «heavy» elements. The process process involves the interaction between Zr(OH)3÷1O0.5÷1.5·(1.6÷2.6)H2O, low-hydrated zirconium hydroxide, and an aqueous solution of rare-earth acetate (С(La3+) = 0.155 mol/l, С(Sm3+) = 0.136 mol/l, С(Gd3+) = 0.141 mol/l, С(Dy3+) = 0.120 mol/l) followed by heat treatment. The resulting phases and their thermolysis products were analyzed using differential thermal analysis and X-ray phase analysis. Single-phase rare-earth zirconates R2Zr2O7 (R = La, Sm, Gd) and the Dy2O3·2ZrO2 solid solution were only obtained at 800 °С. The lattice parameters are calculated for each phase. Lanthanum, samarium, and gadolinium zirconates exibited a cubic pyrochlore structure (Fd3–m), while dysprosium displayed a fluorite structure (Fm3–m). The average particle size of all zirconates was 1.14 ± 0.02 μm.

Synthesis and Reactivity of Tricoordinate Organoberyllium Azides.

A series of terminal mono- and disubstituted beryllium azides of the form [(CAAC)Be(N3)R] (R=CAACH, Dur; CAACH/CAAC=1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-yl/idene, Dur=2,3,5,6-tetramethylphenyl) and [L2Be(N3)2] (L=CAACNH=1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-imine, IiPrMe=1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene), respectively, were synthesized and characterized by NMR spectroscopy and X-ray crystallography. Thermolysis and photolysis products of these first examples of tricoordinate azidoberyllium complexes evidence extensive ligand scrambling and the formal insertion of nitrenes into the CAAC-Be bond, generating cyclic alkyl(amino)imine (CAAI) ligands. Furthermore, the reaction with a small N-heterocyclic carbene (NHC) leads to unexpected CAAC-NHC ligand exchange, while the reaction with pentaphenylborole yields the first γ-azide adduct of a borole, long postulated to be the first step in the synthesis of 1,2-azaborinines from boroles and azides.

STUDY OF THE THERMAL PROPERTIES OF SILVER(I) COORDINATION COMPOUNDS WITH 1,2,4-TRIAZOLES

In this work, using the differential thermal method, the thermal properties of silver (I) complexes with 1,2,4-triazole (1,2,4-triazolethiol) were studied. Based on the studies carried out, intermediate and final products of thermolysis of these complexes were determined, reactions of their thermal decomposition, thermal dehydration processes, and the sequential removal of acid and organic ligands from their composition were proposed. It was revealed that the onset of dehydration temperature depends on the nature of the resulting complex and the method of addition of the water molecule.

Dynamics of carbon framework of coal tar pitch with carbon additives in the thermolysis process

This paper studies the transformation of the carbon framework of coal tar pitch in the process of thermolysis in the presence of carbon additives of different structures. It is established that as a result of the application of all investigated carbon additives, the content of volatile products released as a result of the thermolysis of the ash, including carcinogenic compounds, decreases, which contributes to the increase of the coke residue yield. The highest yield of coke residue was found when using nanostructured carbon materials as an additive, but the structure of the resulting carbon material is more disordered than in the case of individual pitch. It is shown that the use of such additives promotes the formation of graphite-like structures in the process of thermolysis of pitch and to a greater extent than amorphous carbon additives, reduces the amount of carcinogenic volatile products of coal tar pitch thermolysis.

Comprehensive studies of coal tar pitch components

By methods of electron microscopy, adsorption porometry, NMR, IR- EPR spectroscopy, X-ray diffractometry, thermal analysis, chromatography-mass spectrometry the composition, structure and particle morphology of β- and α2-fraction powders of medium-temperature coal ash were investigated. The morphology and structure of coke residues depending on the heating temperature were investigated. Polyaromatic hydrocarbons in the composition of volatile products of coal ash thermolysis were found to be formed mainly by the decomposition of components of β-fraction. The results obtained are of interest from the point of view of the feasibility of using the isolated fractions of coal ash as precursors for the production of functional carbon materials.

ДОСЛІДЖЕННЯ ВОГНЕСТІЙКОСТІ ПОКРИТТЯ РЕАКТИВНОГО ТИПУ В УМОВАХ ВУГЛЕВОДНЕВОЇ ПОЖЕЖІ

The purpose of the study is to compare the efficiency of reactive fire protection coatings in modelling scenarios of standard and hydrocarbon fires. Methodology. Fire tests were carried out in a small-scale furnace, as regulated by DSTU EN 16623:2015. The linear coefficient of swelling K was determined in accordance with DSTU-N P B V.1.1-29:2010, and the strength of the char layer was measured using a ST-2 structurometer. The chemical structure of the thermolysis products of the fireproof coatings was studied by IR spectroscopy. Results. The study proposes an experimental protocol for assessing the strength of swollen coatings on steel plates under the influence of a standard and hydrocarbon fire. The evaluation method is based on monitoring the physical integrity and mechanical stability of the char-insulating layer formed from the reactive coating under high temperatures. It has been found that the reactive-type coating under the influence of a standard and hydrocarbon fire forms heat-protective char layers, the degree of swelling, mechanical strength and adhesion of which to the metal plate are proportional and differ on average by up to 10 %. It has been concluded that the studied coating Ammokote MW-120 can be used for fire protection of steel structures operated under potential conditions of hydrocarbon fire. Scientific novelty. The study proposes a simple and reliable method for assessing the possibility of using reactive-type coatings for fire protection of metal structures intended for use and certified for standard fire conditions in hydrocarbon fires. Pactical significance is to expand the scope of application of Ammokote MW-120 coating for fire protection of steel structures under the influence of standard and hydrocarbon fires. Keywords: fire protection of steel structures, hydrocarbon fire, intumescent coating, swelling coefficient.

Possible application of bicyclic sesquiterpanes to evaluate the thermal maturity of oils. A study of Kamchatka and Chukotka oils from Cenozoic deposits, Russia

The distribution of bicyclic sesquiterpanes in crude oils was studied to assess the applicability of the sesquiterpane ratios as maturity parameters. GC–MS analysis was conducted on ten oil samples that were generated in Miocene-Paleogene deposits located within the Kamchatka Peninsula and southeast Chukotka, the Russian Far East. During catagenesis, there is a shift in the distribution of sesquiterpanes with increasing thermal maturity, e.g., a decrease of the relative content of C16 homodrimanes towards an increase of C15 drimanes and C14 sesquiterpanes. New maturity indices, based on sesquiterpanes, correlate well with commonly used maturity indicators, such as a methylphenanthrene index (MPI-1) and a methyldibenzothiophene ratio (MDR) (the R2 value greater than 0.746). Since C14 sesquiterpanes can arise as a product of thermolysis of higher homologues or may be derived from other organic sources, it is not included in one of the new indices.

Comparison of the Hydrocarbon Distribution in Thermolysis Products of Asphaltenes, Resins, and Acids Isolated from Weakly Transformed Crude Oil from the Anastasievsko-Troitskoe Oil Field (Horizon IV)

Regular trends in the distribution of hydrocarbon biomarkers (n-alkanes, isoprenanes, steranes, and terpanes) and hydrocarbons of the adamantane series in low-maturity crude oil from the Anastasievsko-Troitskoe oil field (horizon IV) and in products formed by thermolysis of asphaltenes, resins, and acids from this oil were studied by gas chromatography–mass spectrometry. Thermolysis of high-molecular-mass oil precursors yields the same hydrocarbons (HCs) as those present in the initial oil, and also protoadamantanes (precursors of adamantanes). HCs of the adamantane series are not formed, and their presence in this crude oil is due to their supply from other oil source strata. The experiments show that the n-alkanes present in the initial oil in small amounts are released under more severe conditions.

Double pseudo-polymeric complexes of [Au(S2CNR2)2][TlCl4], R2 = (CH2)5, (CH2)6: preparation, structural organization, and thermal behavior (low-temperature reduction and crystallization of gold)

The capability of thallium(I) alkylenedithiocarbamates to bind gold(III) from solutions in 2 M HCl was studied. Double complexes of [Au{S2CN(CH2)5}2][TlCl4] and [Au{S2CN(CH2)6}2][TlCl4] were preparatively isolated as individual forms of gold(III) binding into the solid phase. In the crystalline state, the ionic structural units of the complexes are combined together due to the secondary Au···S, Tl···S and S···Cl bonds that results in complicated supramolecular architectures. Thermal behavior of compounds was studied using the simultaneous thermal analysis technique; both reduced elemental gold and thallium(I) chloride were identified as the final thermolysis products.

Preparation of Reactive Indicator Papers Based on Silver-Containing Nanocomposites for the Analysis of Chloride Ions.

In recent decades, metal-containing nanocomposites have attracted considerable attention from researchers. In this work, for the first time, a detailed analysis of the preparation of reactive indicator papers (RIPs) based on silver-containing nanocomposites derived from silver fumarate was carried out. Thermolysis products are silver-containing nanocomposites containing silver nanoparticles uniformly distributed in a stabilizing carbon matrix. The study of the optical properties of silver-containing nanocomposites made it possible to outline the prospects for their application in chemical analysis. RIPs were made by impregnating a cellulose carrier with synthesized silver fumarate-derived nanocomposites, which change their color when interacting with chlorine vapor. This made it possible to propose a method for the determination of chloride ions with preliminary oxidation to molecular chlorine, which is then separated from the solution by gas extraction. The subsequent detection of the active zone of RIPs using colorimetry makes it possible to identify mathematical dependences of color coordinates on the concentration of chloride ions. The red (R) color coordinate in the RGB (red-green-blue) system was chosen as the most sensitive and promising analytical signal. Calibration plots of exponential and linear form and their equations are presented. The limit of detection is 0.036 mg/L, the limits of quantification are 0.15-2.4 mg/L, and the time of a single determination is 25 min. The prospects of the developed technique have been successfully shown in the example of the analysis of the natural waters of the Don River, pharmaceuticals, and food products.

Short flow and green process for the production of V2O3 powder via ammonia reduction method

BackgroundThe NH3, a clean reductant, generated by the thermolysis of NH4VO3, is not effectively utilized in the conventional process of vanadium metallurgy. Additionally, the preparation process of V2O3 is both long and costly. Ammonia recovery is essential to prevent environmental issues resulting from ammonia release. By direct thermolysis of NH4VO3 and effectively utilizing of active NH3, it is possible to achieve the short flow and green process for the production of V2O3. MethodIn an open NH3 atmosphere, one end of the flange was connected to the liquid ammonia gas cylinder, while the other end was connected to the tail gas absorber. Furthermore, in a closed NH3 atmosphere, both ends of the tube furnace were sealed with flanges, and the initial atmosphere in the tube was pre-injection NH3. The products of NH4VO3 thermolysis were characterized using various techniques, including XRD, FT-IR, ICP-OES, SEM, XPS, and TG. Significant findingThe thermolysis process of NH4VO3 with pre-injection of NH3 under the sealed condition was a simulation of the continuous production process of V2O3 using a rotary kiln in industrial production. The rational utilization of ammonia resulted in the reduce of energy consumption, extra reductant consumption, and significant NH3 emissions compared to the traditional V2O3 production process. It was observed that V2O3 was easily obtained through the thermolysis of NH4VO3 with pre-injection of NH3 under the sealed condition at 600 °C for 3 h, using a dosage of NH4VO3 ranging from 2 g to 10 g. During this process, the NH4VO3 went through the phase transition as follows: NH4VO3→NH4V3O8→(NH4)0.38V2O5→V6O13→VO2→V4O7→V3O5→V2O3, and the relevant characterization of products showed that the V2O3 obtained was qualified. These experimental results were of great significance to the industrial practice of vanadium metallurgy. Based on these results, short flow and green process of V2O3 could be achieved in industry by partially improving the calcination process of NH4VO3 in large-scale rotary kilns.