Thermogravimetry Mass Spectrometry Research Articles

Effect of Cubic Crystal Morphology on Thermal Characteristics and Mechanical Sensitivity of PYX

To investigate the influence of the cubic crystal morphology on the thermal properties and sensitivity of 2,6-bis(picrylamino)-3,5-dinitropyridine (PYX), cubic PYX (CPYX) crystals were prepared using the antisolvent method. Scanning electron microscopy (SEM), laser particle size analysis, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the morphology, particle size and structure of the prepared products. The thermal behavior, thermal decomposition kinetics, thermal safety parameters and thermal decomposition mechanism of CPYX were investigated by differential scanning calorimetry–thermogravimetry–mass spectrometry–Fourier transform infrared spectrometry (DSC-TG-MS-FT-IR) and in situ FT-IR experiments. Meanwhile, the mechanical sensitivity of CPYX was determined by means of the explosion probability method. The results showed that the product had a smooth cubic morphology and small crystal aspect ratio with an average particle size (d50) of 10.65 μm, but it had no distinct differences from the crystal structure of raw PYX (RPYX). The thermal decomposition peak temperature, the self-accelerating decomposition temperature and the critical temperature of the thermal explosion of CPYX increased by 7.2 °C, 6.1 °C and 10.4 °C, respectively, compared to RPYX. Similarly, the apparent activation energy increased by 15%. Besides these, the impact sensitivity and friction sensitivity of CPYX decreased by 36% and 20%, respectively, compared to RPYX. The decomposition process of CPYX contains two stages. The first stage involves the breakage of N-H bonds and -NO2 groups with the release of CO2, N2O, NO, HCN and H2O, followed by the thermal decomposition of the resulting intermediate and the release of CO2, N2O and HCN in the second stage.

Gasification study of Meulaboh coal under limited synthetic air and carbon dioxide environments

Gasification characteristics of Meulaboh coal have been investigated using chemical, petrographical, and thermogravimetry–mass spectrometry (TG-MS) approaches. The coal is classified as sub-bituminous C and dominated by huminite maceral (77% vol.). Based on proximate analysis, the coal comprises 12.56% moisture, 17.36% ash, 38.92% volatile matter, and 31.16% fixed carbon (adb). The coal is low in rank and dominated by reactive maceral. Thus, it is suitable for gasification study. TG-MS measurement revealed that the main pyrolysis product consists of H2O, CO2, and CH4, which generated significantly in slow and fast pyrolysis stages (180-294°C and 194-529°C, respectively). Gasification was performed using limited synthetic air and CO2 environments. TG and DTG thermograms show that gasification using CO2 resulted a higher mass loss rate than that using limited synthetic air. Moreover, gasification in a limited air atmosphere produced higher contents of H2O and CO2, while gasification in a CO2 atmosphere produced primarily CO.

Characterization of Pyrolytic Tars Derived from Different Biomasses

The pyrolysis of three different biomasses, rice husk (RH), zoita wood sawdust (ZW) and pine wood sawdust (PW), was studied at 500 °C in a multipurpose unit at the bench scale to determine the yields of the different products and the compositions and properties of the liquid products, with particular emphasis given to the alquitranous fractions (tars). It was possible to link the characteristics of the tars with the compositions of the raw biomasses and verify their potential in various applications. The analytical techniques employed in the characterization of biomasses included lignin, celulose and hemicellulose analysis, ultimate and proximate analysis and thermogravimetry–mass spectrometry analysis (TG-MS). Elemental analysis, gas chromatography–mass spectrometry (GC-MS), nuclear magnetic resonance spectroscopy (1H NMR), Fourier transform infrared spectroscopy (FTIR) and size exclusion chromatography (SEC) were used to characterize the tars. The tar yields were 1.8, 7.4 and 4.0 %wt. in the cases of RH, ZW and PW, respectively. The tars showed higher carbon content, between 60.3 and 62.2 %wt., and lower oxygen content, between 28.8 and 31.6 %wt., than the corresponding raw biomasses. The main components of the tars had aromatic bases, with phenols representing more than 50%. Tar RH included more guaiacols, while Tars ZW and PW included more phenols and alkylated phenols.

Pyrolysis behavior of low-rank coal in an H2-containing atmosphere and combustion properties of the prepared chars

The H2 atmosphere exerts an important influence on both the pyrolysis behavior of low-rank coal and the efficient application of the resultant char. Thermogravimetry-mass spectrometry in conjunction with the Fourier transform infrared was applied to examine the pyrolytic properties of low-rank coal in an H2-containing atmosphere. The coal chars’ carbon chemical structure, surface morphology, pore structure, and combustion reactivity were subjected to characterization by Raman spectroscopy, scanning electron microscopy, CO2 adsorption, and thermal analysis, respectively. The results indicate that the H2-atmosphere enhanced the volatiles release during the pyrolysis stage of low-rank coal. H2-containing atmosphere accelerated the synthesis of H2O through the transformation of the hydroxyl group in coal during coal pyrolysis; the H2 and CH4 production was increased through the chemical interaction of active hydrogen group with aromatic or aliphatic C–H groups; CO2 and CO evolution reduced owing to the dissociation inhibition of carbonyl groups and functional groups containing oxygen. H2-containing atmosphere enhanced the order of carbon structure (as the proportion (20–60%) of H2 contained in the pyrolysis atmosphere increases, the IG/IAll (12.72, 13.14, and 14.03%, respectively) of char-H2 increased), which was not conducive to the pore structure (the specific surface area are 373.7, 364.6, and 357.9 m2·g−1, respectively) development of char-H2. Lower volatile content as well as ordered carbon structure reduced the combustion reactivity of chars-H2 (S are 2.27 and 2.04, respectively). Similarly, lesser development of pore structure also reduced the combustion reactivity of chars-H2 (S is 1.81). Char-H2 (pyrolysis atmosphere with H2 ratio of 20, 40%) meets the grindability index requirements of blast furnace coal injection and char-H2 (pyrolysis atmosphere with H2 ratio of 60%) meets the strength requirements of ferroalloy smelting.

Prediction of Hydrogel Degradation Time Based on Central Composite Design

Prediction of Hydrogel Degradation Time Based on Central Composite Design

Correlation of Efficient Dispersion and Catalytic Performance of Nanocombustion Catalysts in Energetic Materials: A Case Study of the Nanocopper Oxide Catalyst with Superfine Ammonium Perchlorate.

Obviously, the dispersion of nanocatalytic materials has significant influence on their catalytic performance. In this study, an evaluation method for the dispersion of nanomaterials was established according to the different solid UV absorptions of different substances by taking the dispersion of nanocopper oxide (nano-CuO) in superfine ammonium perchlorate (AP) as an example. The nano-CuO/superfine AP composites with different nano-CuO dispersions can be obtained by changing the process parameters, such as varying the grinding method, the grinding strength, and the grinding time. Three replicate experiments were carried out for different composites to derive the average values of absorbance at 212 nm, and the dispersion of nano-CuO in superfine AP was calculated using the difference equation, as the solid UV curves at 210-214 nm were almost identical for each sample, especially at 212 nm. The properties of different samples were tested by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), differential scanning calorimetry (DSC), and thermogravimetry-mass spectrometry (TG-MS). The results show that the particle size and structure of superfine AP in the composites prepared by different methods were not changed. The XRD and IR techniques in this study were unable to characterize the dispersion of nano-CuO in the composites due to its low content. The dispersion of nano-CuO in the nano-CuO/superfine AP composites was significantly enhanced with the increase of grinding strength and grinding time, and the dispersion of nano-CuO was positively correlated with its catalytic performance, which means that the thermal decomposition performance of different composites improved with the increasing dispersion of nano-CuO. Highly dispersed nano-CuO exhibited a significant catalytic effect on superfine AP in TG-MS. The above conclusions demonstrate the accuracy of the difference equation for evaluating the dispersion of nanomaterials based on solid UV curves, which is expected to be used extensively in evaluating the dispersion of nanocatalytic materials in energetic materials.

How microplastics affect sludge pyrolysis behavior: Thermogravimetry-mass spectrum analysis and biochar characteristics

The concentration of microplastics (MPs) in sewage sludge (SS) ranged from 1600 to 56400 particles per kilogram of dried SS (MPs: dried SS = 0.14–5.09), so its effect on SS pyrolysis performance should not be negligible. This study attempted to investigate the effect of typical MPs, including polypropylene (PP), polyethylene (PE), and polyvinyl chloride (PVC), on the pyrolysis performance (pyrolysis characteristics and major gaseous product evolution) of SS and their biochar characteristics via thermogravimetry-mass spectrometry (TG-MS) and physicochemical property analysis of biochar. The results showed that the PVC MPs enhanced the pyrolysis of SS, while the PP and PE MPs had an inhibitory effect. The total amounts of gas products tended to decrease with all MPs addition. However, the proportions of combustible components (H2, CH4, and C2H2) increased. Among the biochar products, the presence of PVC MPs during the pyrolysis of SS resulted in a more porous, stable and aromatic biochar.

Exploration of the sulfur removal mechanism of diphenyl sulfone loaded on activated carbon during Fe-assisted pyrolysis

ABSTRACT Iron-assisted pyrolysis (Fe-assisted pyrolysis) is a high-efficiency technique to remove sulfur from low-rank coal. However, the sulfur removal mechanism of Fe-assisted pyrolysis did not compressively address. For filling this gap, this study explored the sulfur removal mechanism of diphenyl sulfone during Fe-assisted pyrolysis based on the factor optimization of desulfurization performance. The iron powder under the optimal conditions of Fe-assisted pyrolysis was characterized with X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS), showing that FeS and some FeS2 were formed on the surface of post-pyrolysis iron powder. Gas chromatography (GC) analysis manifested that the addition of iron powder in the pyrolysis process could considerably reduce the SO2 emission. GC and Fourier transform infrared spectrometer (FTIR) analyses demonstrated that there was C–S bond broken in the diphenyl sulfone structure during Fe-assisted pyrolysis. From the results of thermogravimetry-mass spectrometry (TG-MS), the addition of iron powder in the pyrolysis process could enhance the reaction rate and reduce the temperature required for the reaction. We believe that the results of the present study provided a theoretical basis for a profound understanding of the desulfurization mechanism of Fe-assisted pyrolysis.

Aroma Profile of Grapevine Chips after Roasting: A Comparative Study of Sorbara and Spergola Cultivars for More Sustainable Oenological Production

This study aimed to compare the aroma profiles of Sorbara and Spergola grapevine prunings roasted at different temperatures (120, 140, 160, 180, 200, and 240 °C). One potential application of grapevine prunings is their use as infusion chips to enhance and improve the aging processes of alcoholic beverages and vinegars. Aromatic compounds impart unique flavors and contribute to the complexity of the final products. Thermogravimetry–mass spectrometry coupled with evolved gas analysis (TGA-MS-EGA) was conducted to identify the thermal steps at which substantial changes occurred in the wood matrix. Solid-phase microextraction–gas chromatography–mass spectrometry (SPME-GC-MS) was used for the analysis of volatile compounds. Several key volatile compounds were identified, showing variations in their concentrations as a function of cultivar and roasting temperature. Furan derivatives, such as furfural, and phenolic compounds, such as guaiacol and vanillin, were the two main chemical classes of volatile compounds that predominantly defined the aroma of grapevine chips roasted above 180 °C. At lower roasting temperatures, some aldehydes, such as hexanal and terpenes, defined the aroma profiles of the samples. By repurposing waste materials, this application offers a pathway for environmentally conscious viticulture and sustainable practices within the food industry.

Effective extraction of nickel and cobalt from sintered nickel alloy via reduction roasting and leaching

In this work, a carbothermic reduction technique is developed to improve the extraction of valuable metals from sintered nickel alloys by atmospheric acid leaching. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS) analyses indicate that NiO in the sintered nickel alloy and the NiO coated by Ni2O3 hinders further dissolution of nickel. Nickel oxides can be transformed into easily leached metallic nickel by carbothermic reduction. The reduction roasting was investigated and optimized by thermodynamic analysis, thermogravimetry-mass spectrometry, XRD, and response surface methodology (RSM). The results show that the leaching efficiencies of nickel and cobalt are respectively increased from 80.34% and 69.92% to 98.65% and 96.71% after the reduction roasting under the optimized conditions: 935 °C of temperature, 50 min of time, and 29.9% of carbon dosage. The leaching of nickel was optimized by single-factor test method and the optimum conditions have been established as: 150 g/L of H2SO4 concentration, 25% of H2O2 dosage, 10 mL/g of liquid–solid ratio, 400 rpm of stirring speed, 80 °C of temperature, and 80 min of time. The kinetic analysis of leaching process shows that the activation energies of nickel and cobalt leaching are 20.71 kJ/mol and 16.33 kJ/mol, respectively, indicating that the leaching process is an internal diffusion control process. This study provides a feasible and effective approach to extract nickel from sintered alloys.

Analysis of the catalytic pyrolysis of shale gas oil‐based drill cuttings via TG‐MS

AbstractBACKGROUNDShale gas oil‐based drill cuttings are receiving increasing attention because of their hazards and contamination. In this study, two catalysts (Fe2(SO4)3 and a synthesised catalyst) were used to study the pyrolysis products, possible reaction mechanisms, and kinetic characteristics via thermogravimetry‐mass spectrometry (TG‐MS) analysis.RESULTSThe results indicate that the synthesised catalyst, YAP‐3, exhibited an improved catalytic effect on the pyrolysis of drill cuttings with a good conversion rate. The reaction activation energy during the pyrolysis was reduced from 9.6 to 1.4 kJ/mol. In addition to hydrocarbons, the pyrolysis products contained nitrogen oxides and other compounds.CONCLUSIONA comparison of the peak temperature range and response intensity of the same substance with the same mass‐to‐charge ratio (m/z) showed that YAP‐3 significantly promoted the formation of pyrolysis products. This study provides theoretical support for the catalytic pyrolysis treatment of shale gas drill cuttings. © 2023 Society of Chemical Industry.

Alterations promoted by acid straightening and/or bleaching in hair microstructures.

Human hair is a biopolymer constituted mainly of keratin intermediate filaments, lipids, pigments and water. Cosmetic treatments usually interact with the hair at the molecular level, inducing changes in its components and modifying the physicochemical and mechanical properties of the fibers. Here, the effect of acid straightening on the morphology and ultrastructure of Caucasian hair was investigated by a group of complementary experimental methods: wide-, small- and ultra-small-angle X-ray scattering; high-resolution 3D X-ray microscopy; quasi-elastic neutron scattering and inelastic neutron scattering; thermogravimetry-mass spectrometry; and differential scanning calorimetry (DSC). X-ray diffraction patterns showed that acid straightening associated with a flat iron (∼180°C) changed the cortex of the fiber, shown by denaturation of the intermediate filaments (measured by DSC). The increase in the spacing of the lipid layers and the observation of the dehydration behavior of the fiber provided indications that water may be confined between these layers, while neutron spectroscopy showed alterations in the vibration mode of the CH2 groups of the lipids and an increase of the proton (H+) mobility in the hair structure. The latter may be associated with the extremely low pH of the formulation (pH ≃ 1). Additionally, this investigation showed that bleached hair (one-time bleached) is more damaged by the action of acid straightening than virgin hair, which was shown by a threefold increase in the percentage of total porosity of the tresses. The obtained results demonstrate that the investigation approach proposed here can provide very important thermodynamic and structural information on induced changes of hair structure, and certainly can be applied for the evaluation of the action mode and efficiency of cosmetic treatments.

Thermal characterization of leathers tanned by metal salts and vegetable tannins

In this work, the thermal properties of vegetable (mimosa), metal salt (chromium) and mixed (chromium-mimosa and aluminum-myrobalan) tanned bovine leathers were studied to understand the thermal decomposition processes with the aim of possible utilization of various leather wastes by thermal conversion. Thermogravimetry/mass spectrometry (TG/MS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) measurements were carried out to compare the thermal behavior and reveal interactions between the leather and various tannins. Bovine parchment was used as an untanned reference material. The tanning agent ratios were estimated by determination of ash, nitrogen and protein contents of the samples. It was found that ash yield is a good indicator for the inorganic content, while the protein content is inversely proportional to the total tannin content in leathers. The thermal decomposition of the samples as a function of the temperature was performed using TG/MS. The differences between the samples are clearly recognizable on the thermogravimetric curves and the mass spectrometric evolution profiles of the products. Among the tanning agents, chromium had the largest impact on the thermal decomposition process. Therefore, additional TG/MS experiments were carried out on chromium-treated parchment samples and the catalytic effect of chromium was demonstrated on the evolution curves of several products. It was established that hydrolysis of the amide bonds of the polypeptide chain was retarded resulting in less ammonia formation, and higher yield of water. On the other hand, higher amounts of hydrogen cyanide and other nitriles were released in the presence of chromium sulfate. The decomposing chromium sulfate released oxygen beside sulfur dioxide, which dehydrogenated certain amino acid residues leading to the enhanced formation of nitriles and water. The volatile compounds of the decomposition were determined by Py-GC/MS at 400 and 600 °C. The diketopiperazines (DKPs) dominated the pyrograms at both temperatures, but the ratio of gaseous and other products of smaller molecular mass was increased at higher pyrolysis temperature and in the presence of metal tanning agents. The chromium-treated parchment samples were also studied by Py-GC/MS. The relationship between the chromium content and the formation of certain decomposition products has been confirmed. Principal component analysis (PCA) was performed using the Py-GC/MS data of leathers and parchment. The PCA results show clear separation between the chromium-tanned, vegetable-tanned and mix-tanned leathers as well as parchment.

Cotton-Based Activated Carbon Fiber with High Specific Surface Area Prepared by Low-Temperature Hydrothermal Carbonization with Urea Enhancement

The traditional preparation method of activated carbon fiber is high-temperature carbonization and activation. In this experiment, cotton-based activated carbon fiber was prepared by urea-enhanced low-temperature hydrothermal carbonization and activation method. A specific surface area of 2304.8 m2/g of activated carbon fiber prepared by low-temperature hydrothermal carbonization with urea enhancement was the maximum reported using biomass as a raw material, which was higher than that of activated carbon fibers prepared by other biomass raw materials. X-ray photoelectron spectroscopy and elemental analysis studies have shown that the form of N transformed and decomposed during the high-temperature process, leading to the separation of C–N. Thermogravimetry mass spectrometry characterization analysis found that K2CO3 of low-temperature hydrothermal-assisted KOH activation may fully react with the N-containing group produced during the carbonization process to generate NH3, which lead to the formation of more pore structures in the carbon materials. The adsorption capacity of activated carbon fiber activated by hydrothermal-assisted KOH for iodine could reach up to 2254.8 mg/g. This process provides a new idea for the preparation of high-performance activated carbon fibers.

Structure phase engineering strategy through acetic acid coupling to boost hydrogen evolution reaction performance of 2H phase MoS2 at wide pH range

The semiconductor phase molybdenum disulfide (2H-MoS2) with poor hydrogen evolution reaction (HER) performance restricts the further improvement of hydrogen production. Herein, an acetic acid coupled structure phase engineering (SPE) strategy is developed to synthesize a homogeneous and orderly cobalt molybdenum composite structure. The resulting CoS2/MoS2 complexes reveal excellent HER activity with a low overpotential of 80, 95, and 135 mV at 10 mA cm−2 in 0.5 M H2SO4, 1 M KOH, and 1 M PBS. Fourier transform infrared spectroscopy (FT-IR) and thermogravimetry mass spectrometry (TGA-MS) results illustrate that acetic acid is successfully coupled at the interface between CoS2 and MoS2. Results from density functional theory demonstrate that the π-π conjunction formed by acetic acid coupling can work as a bridge to help electrons transfer from cobalt to molybdenum. More importantly, the method can be extended to the synthesis of other composite materials with the similar structure.

Effects of hafnium sources and hafnium content on the structures and properties of SiBNC–Hf ceramic precursors

AbstractThe synthesis of SiBNC–M (M is metal element) multinary ceramic precursors has mainly been through chemical modification of the SiBNC ceramic precursors with the introduction of the metal element/compound. This misses the simplicity, efficiency, and combined benefits of single reactor synthesis routes. We herein adopt a one‐pot method to synthesize SiBNC–Hf ceramic precursors (PBSHZ) from different Hf sources, and with varying Hf content. The starting materials include hafnium tetrachloride, hafnium dichloride, trichlorosilane, hexamethyldisilazane, and boron trichloride. Fourier transform infrared spectroscopy (FT‐IR), nuclear magnetic resonance (NMR), X‐ray photoelectron spectroscopy (XPS), and thermogravimetric analysis are employed to characterize the structures and properties of the PBSHZ. The results reveal the successful incorporation of Hf into the precursors. Compared to the hafnium tetrachloride source, the precursor synthesized from hafnium dichloride yields more ceramics and shows better solubility, due to fewer Hf–Cl bonds available for reaction. Meanwhile, there is a positive correlation between the rise in the Hf content of PBSHZ and the ceramic yield. However, the solubility and processability of the precursors decline, due to the multiplication of the cross‐linking degree in the molecular structure. Further FT‐IR, NMR, XPS, and thermogravimetry–mass spectrometry (TG–MS) analysis indicate a full polymer‐to‐ceramic transformation at 1000°C pyrolysis temperature. At this point, the SiBNC–Hf ceramics mainly consist of an Si–B–N skeleton, HfN, and free carbon.

Thermal studies of novel heat-resistant 3,6-dinitropyrazolo[4,3-c]pyrazole-based energetic materials

1,4-Bis(2′,4′,6′-trinitrophenyl)−3,6-dinitro[4,3-c]pyrazole (DTNBDNP) is a newly developed heat-resistant explosive exhibiting superior properties to most traditional heat-resistant energetic materials with a significantly high thermal decomposition temperature of 410 °C. Detailed thermal behaviors and nonisothermal decomposition kinetics of DTNBDNP and 1,4-bis(2′,4′-dinitrophenyl)−3,6-dinitro[4,3-c]pyrazole (DDNBDNP) were investigated using a differential scanning calorimeter (DSC), and the thermal safety was evaluated by different criteria, including the self-accelerating decomposition temperature and critical temperature of thermal explosion. Their thermodynamic functions were also obtained based on the specific heat capacity data determined using a micro-DSC method. Further studies on the thermal decomposition mechanism were carried out through condensed-phase thermolysis/Fourier transform infrared (in situ FTIR) spectroscopy and the combination of differential scanning calorimetry–thermogravimetry–mass spectrometry–Fourier transform infrared spectroscopy (DSC–TG–MS–FTIR) techniques. The experimental results prove that the decomposition of DTNBDNP and DDNBDNP is most likely to begin with a ring-opening reaction of the fused-heterocycle backbone. In addition, the main gaseous products, including NO, CO2, N2O, and NO2, are released from the decomposition of DTNBDNP and DDNBDNP.

Study on the multiple roles of CaO on nitrogen evolution mechanism of protein inside sewage sludge pyrolysis

The aim of this study was to clarify the multiple influence mechanisms through which Ca influences the emission of NOx precursors (NH3 and HCN) during sewage sludge pyrolysis and to establish a scientific correlation between the mechanisms and temperatures. In this study, the effects of CaO on pyrolysis kinetics and NOx precursor emission temperature of deashed sludge were estimated using Thermogravimetry-mass spectrometry. Based on this, the NH3 and HCN evolution pathways were investigated at these nitrogen emission temperatures by employing sludge protein model compounds in a self-designed all-quartz pyrolysis system. Results showed that the addition of CaO reduced the activation energy of sludge pyrolysis by approximately 0–40 kJ/mol. CaO promoted the retention of nitrogen in char and the conversion of nitrogen into gas phase while hampering its migration to tar. The Ca-fixed nitrogen in char reacted with NH3/HCN to form CaCxNy, such as CaCN2 and CaN2. Notably, results revealed the overwhelming effects of temperature on nitrogen evolution. Specifically, CaO was found to affect only the dominant reaction at the target temperature. At lower temperatures (255–350 °C), CaO promoted the conversion of protein-N to NH3 and inhibited nitrile-N decomposition to HCN in char. In contrast, at comparatively higher temperatures (490–750 °C), CaO inhibited the production of NH3 by promoting the hydrogenation of heterocyclic-N in char and the dimerization of amino acid molecules in tar, while CaO increased HCN release by promoting the dehydrogenation of amine-N in tar and ring opening of heterocyclic-N to form nitrile-N and subsequently HCN. These results would guide NOx control for obtaining energy from nitrogen-rich solid waste for industrial applications and the targeted regulation of NH3 (carbon-free hydrogen-rich fuels) utilization.

Predicting Pyrolysis of a Wide Variety of Petroleum Coke Using an Independent Parallel Reaction Model and a Backpropagation Neural Network

In this work, the pyrolysis behavior and gaseous products of petroleum coke were investigated by nonisothermal thermogravimetric analysis (TGA) and thermogravimetry-mass spectrometry (TG-MS). Then, the pyrolysis kinetics of six kinds of petroleum coke (Fushun (FS), Fuyu (FY), Wuhan (WH), Zhenhai (ZH), Qilu (QL), and Shijiazhuang (SJZ)) were determined by an independent parallel reaction (IPR) model, and the kinetic parameters (activation energy and preexponential factor) were obtained. In addition, an efficient backpropagation neural network (BPNN) was developed to predict the thermal data of six kinds of petroleum coke. The BPNN-predicted thermal data were used to calculate the kinetic parameters based on the IPR model, and the results were compared with the ones calculated using experimental data. The results showed that the pyrolysis process of six kinds of petroleum coke was divided into three stages, of which stage II (250-900 °C) had the significant mass loss, corresponding to the devolatilization of petroleum coke. MS fragmented ion intensity analysis indicated that the main pyrolysis products were methane CH x (m/z = 13, 14, 15, and 16), aliphatic hydrocarbon C3H5, H2, CO, CO2, and H2O. The thermal data predicted by the IPR, BPNN, and BPNN-IPR (BPNN combined with IPR) models were in good agreement with the experimental data. Most importantly, it was concluded that the BPNN-predicted data can be further applied to calculate the kinetic parameters using the IPR kinetic model.

Enhanced catalytic activity and ignition characteristics of three-dimensional ordered macroporous FeCo2O4 through controlled synthesis

To improve the combustion performance of solid propellants relies on efficient combustion catalyst with large specific surface area and high density of active sites. In this work, three-dimensional ordered macroporous FeCo2O4 (3DOM-FeCo2O4) with four different pore diameters was successfully prepared using polymethyl methacrylate (PMMA) colloidal crystals as a template. Differential scanning calorimetry (DSC) study shows that 3DOM-FeCo2O4 with a pore diameter of 176 nm has the best catalytic performance on the thermolysis of ammonium perchlorate (AP). The decomposition peak temperature and apparent activation energy were reduced by 116.5 ℃ and 26.1 kJ/mol, respectively. Thermogravimetry/mass spectrometry (TG/MS) was used to analyze the catalytic mechanism. The result indicates that 3DOM-FeCo2O4 can accelerate the electron transfer from ClO4– to NH4+ to form HClO4 and NH3 and the transformation from O2 to superoxide ion(O2–), thus providing active sites for intermediate products of AP and catalyzing the decomposition of AP. Furthermore, the heat release and ignition tests of thermites using 3DOM-FeCo2O4 as the oxidant were carried out. The thermite with a pore diameter of 215 nm exhibits higher heat release and better ignition characteristic compared to the thermites with other pore diameters.