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This study introduces recommendations for conducting molecular simulations of vapor adsorption, with an emphasis on enhancing the accuracy, reproducibility, and comparability of results. The first aspect we address is consistency in the implementation of some details of typical molecular models, including tail corrections and cutoff distances, due to their significant influence on generated data. We highlight the importance of explicitly calculating the saturation pressures at relevant temperatures using methods such as Gibbs ensemble Monte Carlo simulations and illustrate some pitfalls in extrapolating saturation pressures using this method. For grand canonical Monte Carlo (GCMC) simulations, the input fugacity is usually calculated using an equation of state, which often requires the critical parameters of the fluid. We show the importance of using critical parameters derived from the simulation with the same model to ensure internal consistency between the simulated explicit adsorbate phase and the implicit bulk phase in GCMC. We show the advantages of presenting isotherms on a relative pressure scale to facilitate easier comparison among models and with experiment. Extending these guidelines to a practical case study, we evaluate the performance of various isoreticular metal–organic frameworks (MOFs) in adsorption cooling applications. This includes examining the advantages of using propane and isobutane as working fluids and identifying MOFs with a superior performance. [ABSTRACT FROM AUTHOR]

In this study, we used a high-throughput computational screening approach to examine the potential of metal–organic frameworks (MOFs) for capturing propane (C3H8) from different gas mixtures. We focused on Quantum MOF (QMOF) database composed of both synthesized and hypothetical MOFs and performed Grand Canonical Monte Carlo (GCMC) simulations to compute C3H8/N2/O2/Ar and C3H8/C2H6/CH4 mixture adsorption properties of MOFs. The separation of C3H8 from air mixture and the simultaneous separation of C3H8 and C2H6 from CH4 were studied for six different adsorption-based processes at various temperatures and pressures, including vacuum-swing adsorption (VSA), pressure-swing adsorption (PSA), vacuum–temperature swing adsorption (VTSA), and pressure-temperature swing adsorption (PTSA). The results of molecular simulations were used to evaluate the MOF adsorbents and the type of separation processes based on selectivity, working capacity, adsorbent performance score, and regenerability. Our results showed that VTSA is the most effective process since many MOFs offer high regenerability (>90%) combined with high C3H8 selectivity (>7 × 103) and high C2H6 + C3H8 selectivity (>100) for C3H8 capture from air and natural gas mixtures, respectively. Analysis of the top MOFs revealed that materials with narrow pores (<10 Å) and low porosities (<0.7), having aromatic ring linkers, alumina or zinc metal nodes, typically exhibit a superior C3H8 separation performance. The top MOFs were shown to outperform commercial zeolite, MFI for C3H8 capture from air, and several well-known MOFs for C3H8 capture from natural gas stream. These results will direct the experimental efforts to the most efficient C3H8 capture processes by providing key molecular insights into selecting the most useful adsorbents. [ABSTRACT FROM AUTHOR]

Before hydrates can be widely used in industry, we should better understand the problematic issues of hydrate nucleation, particularly its stochastic nature. Here, we report on measurements of the nucleation probability of mixed-gas hydrates in which the guest molecules are a mixture of methane and propane. For the pure cases, at a supersaturation near 1.0, we had previously measured an induction time for the methane hydrate of about 1 h, whereas for the propane hydrate, it was over one day. Using the same experimental setup, we examine here the nucleation probability for a mixture of 90% methane and 10% propane as the guest gas for a range of supersaturations. For the experiments, the temperature was 274 ± 0.5 K and the stirring rate was about 300 rpm. The experiments were repeated at least ten times under the same condition, exchanging the sample water every time. We define the nucleation probability at a given time as the fraction of trials that nucleated by that time and then determine the nucleation probability distribution. The resulting nucleation frequency is found to have a power-law relation to supersaturation. Then, we examine how the nucleation frequency is affected by the existence of ultrafine bubbles in the initial water. We find that the ultrafine bubbles increase the nucleation frequency but much less than that of typical changes in supersaturation. [ABSTRACT FROM AUTHOR]

Oxidative dehydrogenation (ODH) of propane is a promising alternative route for propene production. In this work, we developed a series of vanadium and gallium oxides supported on γ-Al2O3 catalysts by an incipient wetness impregnation method. Among the employed catalysts, the VGA-2 showed superior catalytic activity, and the catalyst was demonstrated for longevity in ODH of propane with a stable activity using a continuous flow fixed bed reactor at 400 °C. H2-TPR and UV-visible spectra showed the presence of highly dispersed monomeric VOx species with tetrahedral coordination geometry, which influences product selectivity. The characterization results also conferred that the redox nature of vanadium (V5+ and V4+) oxide and higher V5+ content on the surface of the VGA-2 catalysts are more favourable for C–H activation. In addition, the pyridine-FTIR and 71Ga solid-state NMR studies further substantiated the presence of Lewis acid sites and tetrahedrally coordinated Ga3+Ox species that are highly responsible for the ODHP activity, respectively. Furthermore, in situ-DRIFTS studies conferred that the propane adsorption at ambient temperature showed the formation of intermediate propoxide species with the evolution of σ-bonds and with further increase in the temperature to 325 °C; the stretching vibrations of the ＝C–H and –C–H bonds in the propylene molecule were observed. The spent catalysts were also analyzed by thermogravimetric analysis, where the optimized catalyst (VGA-2) showed the least coke deposition. [ABSTRACT FROM AUTHOR]

The electronic structure of active metal centers plays an indispensable role in regulating catalytic reactivity in heterogeneous catalysis, developing other metals as promoters to decorate electronic state is a common strategy, while non‐metal component of carbon as electronic additives to regulate d‐band center has rarely been studied in thermal‐catalysis field. Herein, we report electron‐deficient tetrahedral Co(II) (Td‐cobalt(II)) centers through carbon‐layer modulation for propane dehydrogenation (PDH). It is indicated that bifunctional sites of both Td‐cobalt(II) and metallic‐cobalt are designed, and the in situ generated carbon through the disproportionation of CO on metallic‐cobalt can cover the inactive metallic‐cobalt and tailor d‐band of active Td‐cobalt(II) simultaneously. More importantly, the pre‐deposited carbon‐layer is proposed to decrease electron density of Td‐cobalt(II) and make d‐band center closer to Fermi level, consequently promotes C−H activation in PDH reaction. This study provides new perspective for the utilization of inactive carbon as electronic promoters and unlocks new opportunity to fabricate efficient PDH and other heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

In this work, MoVTeNbOx catalysts was doped with Cr by using spray drying method. The effect of Cr doping on the crystalline phase, physicochemical properties, and catalytic performance of selective oxidation of propane to acrylic acid of MoVTeNbOx was investigated. The results showed that the samples as-prepared by spray drying method present unique spherical morphology stacked by rod particles. In addition, Cr doping induced a change in the mesopore structure formed by rod stacking, reducing the pore radius of the catalysts from 5-10 nm to 2-4 nm. Meanwhile, Cr doping dramatically reduced the average particle size of MoVTeNbOx catalysts, decreasing the rod cross-section diameter of catalysts from 234.21 to 134.96 nm and the rod length from 1.096 μm to 485.71 nm, which significantly increased the amount of (001) active crystalline plane. Moreover, an appropriate amount of Cr doping increased the number of reducible species in the catalyst and reduced its acidity. At the same time, the surface V5+ content of the catalyst was increased from 35.8% to 72.6%. Cr-doped MoVTeNbOx with mesoporous structure showed excellent performance in catalyzing selective oxidation of propane to acrylic acid reaction. Among them, S-3 sample (V: Cr = 1:0.015) increased the selectivity and yield to acrylic acid from 67.5% to 84.3% and from 26.4% to 43.2%, respectively, at reaction temperature of 380 °C. [ABSTRACT FROM AUTHOR]

• Cyclic thermodynamic perfection decreases by 20.3 % when prototype's speed increases from 6000 rpm to 10,800 rpm. • Prototype's vane and roller separate by 0.38 mm at 10,800 rpm. • Double-valve structure decreases over-compression loss by 45.0 % at 10,800 rpm. • Double-valve alleviates separation by 10.5 %. With the trend towards miniaturization of rotary compressors, increasing the speed of compressors and improving performance at high speed have become important research directions. Simultaneously, due to the need for refrigerants with low global warming potential (GWP), R290 has become an important alternative to hydrofluorocarbons (HFCs). Under the same compressor structure size, meeting the cooling/heating demands with R290 necessitates higher operating speed owing to its lower cooling capacity per unit volume. In this paper, the performance loss distribution of an ultra-high-speed R290 rotary compressor has been studied theoretically and experimentally, and the accuracy of theoretical calculation was verified through experiments. According to the calculation, the primary factor influencing the performance of the ultra-high-speed rotary compressor is over-compression loss. Consequently, corresponding solutions to improve the performance of the ultra-high-speed compressor were proposed. The internal parameters of the compressor were measured, thereby validating the conclusions and assessing the efficacy of the proposed solutions. Finally, the structure parameters were further optimized, which was also verified by experiments. It is found that the double-valve structure can effectively reduce the over-compression loss. When operating at 10,800 rpm under the ASHRAE T1, compared with the prototype, the compressor with double-valve structure can reduce the over-compression loss by 45.0 %, and increase the cyclic thermodynamic perfection by 7.85 %. [ABSTRACT FROM AUTHOR]

This study investigated the effect of a mixed obstacle layout on the deflagration mechanism of propane--air premixed gases. Most previous studies focused on a single type of obstacle, changing the shape and number of the obstacles to observe the effect on the flame deflagration characteristics. However, in real explosion accident sites, obstacles are often a mixture of different types. Little literature exists on the deflagration characteristics of hybrid barriers in semiconfined spaces. In this paper, the deflagration characteristics of propane-air premixed gas with a mixed structure of hurdles and square obstacles was studied. First, the effectiveness of numerical simulations was demonstrated by comparing experimental and large eddy simulation (LES) results for the flame dynamics with a single flat plate obstacle. Based on this, the flame behavior for different layouts of square obstacles in a mixed obstacle configuration was further simulated using the large eddy simulation method, focusing on the flame behavior, overpressure characteristics, and flow field structure in the vicinity of the obstacle. The results showed that a mixed obstacle promoted flame evolution more than a single obstacle when the square obstacle was within a critical distance from the ignition source location at the same moment in time. When the flame front crossed the first hurdle-type obstacle, the flame pattern spread in a "cat's paw" pattern to the unburned portion of the tube. In addition, the increased distance of the square obstacle from the ignition source did not allow the peak overpressure and the peak rate of overpressure rise to show a positive feedback mechanism. Finally, the strength of the vorticity in the flow field was positively correlated with the distance of the square obstacle from the ignition source. The results of study provide theoretical for the prevention of explosions. [ABSTRACT FROM AUTHOR]

Charge-neutral hexadecanuclear nanoclusters [Co16(OH)4(ib)20(thme)2(Hthme)2(H2O)6]·MeCN·4H2O (1) and [Co16(OH)4(ib)20(thmp)2(Hthmp)2(H2O)6]·MeCN·4H2O (2) have been prepared from the reaction of Co(II) isobutyrate (Co(ib)2) with 1,1,1-tris(hydroxymethyl)ethane (H3thme) or 1,1,1-tris(hydroxymethyl)propane (H3thmp) and comprehensively characterized. Single-crystal X-ray diffraction reveals that the common mixed-valent centrosymmetric {Co(II)14Co(III)2} core of 1 and 2 represents an unprecedented arrangement of two planar {Co7} disk-like fragments with a central Co(III) ion surrounded by six Co(II) ions connected by two additional Co(II) ions. The two {Co7} fragments are non-coplanar and lie in parallel planes separated by a distance of 2.772 Å, with two additional Co(II) centers between these planes. Hirshfeld surface (HS) analysis was used to gain additional insight into the interactions responsible for the packing of nanoclusters in the title compounds. Magnetic characterization of 1 revealed that the 14 Co(II) centers exhibit predominantly ferromagnetic exchange interactions, but some antiferromagnetic exchange pathways are also present. [ABSTRACT FROM AUTHOR]

The oxidation of propane to produce propylene is a vital industrial process. However, traditional methods for producing propylene require harsh conditions such as high temperatures and pressures. These methods lead to high energy consumption, environmental pollution, and low product selectivity, resulting in difficulty in product separation and high cost. Thus, it is urgent to find new and efficient catalysts and regulatory means to catalyze the oxidation of propane to propanol or propylene with high efficiency and selectivity. Here, the mechanism of propane oxidation reaction catalyzed by O–Fe-corrolazine under mild conditions was investigated, and the precise modulation of its oxidation products by oriented external electric fields (OEEFs) was also explored. The calculations show that in the absence of OEEFs, O–Fe-corrolazine can catalyze propane conversion to propanol or propylene through OH transfer or dehydrogenation reactions, but its product selectivity is not high. However, the OEEFs can effectively regulate the reaction. Especially for the OEEFs in the direction of the Fe–O bond, increasing the negative electric field intensity significantly reduces the energy barrier for the dehydrogenation of the intermediate. This greatly increases the selectivity of propylene. Note that when the intensity of the OEEFs exceeds −0.007 a.u., the reaction does not go through the INT1, and directly generates propanol from T–S1, with its selectivity reaching 100%. Therefore, precise regulation of the propane oxidation reaction can be achieved through OEEFs. [ABSTRACT FROM AUTHOR]

In this study, we successfully fabricated a three‐dimensional Co3O4@SiO2 3D Monolith catalyst. This process allowed for the effective and straightforward anchoring of Co3O4 nanoparticles onto SiO2 3D Monoliths. The active Co3O4 phase was primarily identified through XRD and XPS analyses, complemented by Co3O4 loading measurements (1.7 %). This innovative catalyst displayed remarkable proficiency in selectively converting propane to carbon dioxide. Additionally, it was demonstrated that the catalytic activity remained unimpaired even upon the catalyst's reuse in 5 successive reaction cycles. This performance was observed across various heating ramps, showcasing the catalyst's stability over time. [ABSTRACT FROM AUTHOR]

K-doped MoVTeNbOx were prepared rapidly and simply by spray drying method and applied to catalyze the selective oxidation of propane to acrylic acid. Results show that doping of K could affect the relative content of M1 and M2 phases in MoVTeNbOx. The as-prepared K-doped MoVTeNbOx exhibited a unique spherical structure agglomerated by needle particles. These needles shaped particles interlaced and stacked with each other to form a mesoporous structure with an average pore size range of 27.26 to 50.78 nm. Moreover, compared with undoped catalysts, doping of K increased the surface V5+ active sites content of the MoVTeNbOx from 60 to 75%. For the conversion of propane to acrylic acid, an appropriate amount of M2 increased the conversion of propane. The selectivity of K-doped MoVTeNbOx catalyst for acrylic acid was significantly improved, possibly due to the distinct reduction in the number of medium acid sites caused by the introduction of K. Furthermore, the special mesoporous structure formed boosted the adsorption and activation of the catalyst for propane and the diffusion of product, which is important to improve the catalytic performance of MoVTeNbOx. Under the optimal reaction condition, the maximum selectivity and yield of K-doped catalyst (K/Mo = 0.005) for acrylic acid reached 72.06% and 49.57%, respectively. Mesoporous K-doped MoVTeNbOx catalyze the direct oxidation of propane to acrylic acid [ABSTRACT FROM AUTHOR]

Oxidative dehydrogenation of propane (ODHP) is a reaction with significant practical significance. As for the industrial application of ODHP, it is challenging to achieve high activity and high propylene selectivity simultaneously. In this study, to overcome this obstacle, we designed a series of Cu/BN catalysts with unique morphologies for establishing a photothermal ODHP system with high efficiency and selectivity. Characterization and evaluation results revealed that Cu/BN-NS and Cu/BN-NF with enlarged specific surface areas exhibited higher catalytic activities. The localized surface plasmon resonance (LSPR) effect of Cu nanoparticles further enhanced the photothermal catalytic performances of Cu/BN catalysts under visible light irradiation. To the best of our knowledge, it is the first time to establish a BNbased photothermal ODHP catalytic system. This study is expected to pave pathways to realize high activity and propylene selectivity for the practical application of ODHP. [ABSTRACT FROM AUTHOR]

Designing highly active and stable catalytic sites is often challenging due to the complex synthesis procedure and the agglomeration of active sites during high-temperature reactions. Here, we report a facile two-step method to synthesize Pt clusters confined by In-modified ZSM-5 zeolite. In-situ characterization confirms that In is located at the extra-framework position of ZSM-5 as In+, and the Pt clusters are stabilized by the In-ZSM-5 zeolite. The resulting Pt clusters confined in In-ZSM-5 show excellent propane conversion, propylene selectivity, and catalytic stability, outperforming monometallic Pt, In, and bimetallic PtIn alloys. The incorporation of In+ in ZSM-5 neutralizes Brønsted acid sites to inhibit side reactions, as well as tunes the electronic properties of Pt clusters to facilitate propane activation and propylene desorption. The strategy of combining precious metal clusters with metal cation-exchanged zeolites opens the avenue to develop stable heterogeneous catalysts for other reaction systems. Designing highly active and stable catalytic sites is often challenging due to complex synthesis procedures and the agglomeration of active sites during high-temperature reactions. Here the authors present a two-step method to synthesize Pt clusters in In-modified ZSM-5, resulting in superior propane dehydrogenation performance. [ABSTRACT FROM AUTHOR]

The industrial catalysts utilized for propane dehydrogenation (PDH) to propylene, an important alternative to petroleum-based cracking processes, either use expensive metals or metal oxides that are environmentally unbenign. We report that a typically less-active oxide, titanium oxide (TiO2), can be combined with earth-abundant metallic nickel (Ni) to form an unconventional Ni@TiOx catalyst for efficient PDH. The catalyst demonstrates a 94% propylene selectivity at 40% propane conversion and superior stability under industrially relevant conditions. Complete encapsulation of Ni nanoparticles was allowed at elevated temperatures (>550°C). A mechanistic study suggested that the defective TiOx overlayer consisting of tetracoordinated Ti sites with oxygen vacancies is catalytically active. Subsurface metallic Ni acts as an electronic promoter to accelerate carbon-hydrogen bond activation and hydrogen (H2) desorption on the TiOx overlayer. [ABSTRACT FROM AUTHOR]

The study aims to address the need for cleaner and more efficient combustion technologies in the context of global energy demand and sustainability goals. It focuses on microflame techniques to enhance the performance of gas turbines and water heating boilers. This research investigated, for the first time, the operation of a micromodular burner for hot water boilers and a microflame burner for gas turbines, based on patented inventions. Methods for assessing efficiency included analyzing heat flows, fuel conversion rates to thermal energy, and emission analysis. Using high-precision measuring equipment, such as TESTO 350-XL, thermocouples, flow meters, and others, optimal operating modes were determined for the gas turbine combustion chamber and hot water boiler. This resulted in achieving high efficiency and reducing harmful emission levels (NOx < 15 ppm, CO < 140 ppm). Theoretical calculations were compared with experimental data, confirming the reliability of the results obtained. [ABSTRACT FROM AUTHOR]

This abstract presents a catalytic mechanism diagram, illustrating the catalyst's subtle changes during the reaction process and providing a deeper understanding of its underlying mechanisms. [Display omitted] The pressing demand for propylene has spurred intensive research on the catalytic dehydrogenation of propane to produce propylene. Gallium-based catalysts are regarded as highly promising due to their exceptional dehydrogenation activity in the presence of CO 2. However, the inherent coking issue associated with high temperature reactions poses a constraint on the stability development of this process. In this study, we employed the electrospinning method to prepare a range of Ga 2 O 3 -Al 2 O 3 mixed oxide one-dimensional nanofiber catalysts with varying molar ratios for CO 2 oxidative dehydrogenation of propane (CO 2 -OPDH). The propane conversion was up to 48.4 % and the propylene selectivity was high as 96.8 % at 500 °C, the ratio of propane to carbon dioxide is 1:2. After 100 h of reaction, the catalyst still maintains approximately 10 % conversion and exhibits a propylene selectivity of around 98 %. The electrospinning method produces one-dimensional nanostructures with a larger specific surface area, unique multi-stage pore structure and low-coordinated Ga3+, which enhances mass transfer and accelerates reaction intermediates. This results in less coking and improved catalyst stability. The high activity of the catalyst is attributed to an abundance of low-coordinated Ga3+ ions associated with weak/medium-strong Lewis acid centers. In situ infrared analysis reveals that the reaction mechanism involves a two-step dehydrogenation via propane isocleavage, with the second dehydrogenation of Ga-OR at the metal–oxygen bond being the decisive speed step. [ABSTRACT FROM AUTHOR]

Co-based catalysts have shown great promise for propane dehydrogenation (PDH) reactions due to their merits of environmental friendliness and low cost. In this study, ordered mesoporous molecular sieve-supported CoOx species (CoOx/Al-SBA-15 catalyst) were prepared by one-step organometallic complexation. The catalysts show worm-like morphology with regular straight-through mesoporous pores and high external specific surface area. These typical features can substantially enhance the dispersion of CoOx species and mass transfer of reactants and products. Compared with the conventional impregnation method, the 10CSOC (10 wt.% Co/Al-SBA-15 prepared by the organometallic complexation method) sample presents a smaller CoOx size and higher Co2+/Co3+ ratio. When applied to PDH reaction, the 10CSOC delivers higher propane conversion and propylene selectivity. Under the optimal conditions (625 °C and 4500 h−1), 10CSOC achieves high propane conversion (43%) and propylene selectivity (83%). This is attributed to the smaller and better dispersion of CoOx nanoparticles, more suitable acid properties, and higher content of Co2+ species. This work paves the way for the rational design of high-performance catalysts for industrially important reactions. [ABSTRACT FROM AUTHOR]

In this paper, a dual-functional Brønsted acidic ionic liquid (BAIL) catalyst, namely 1,3-(4,4'-dipyridinium disulfonic acid)propane dimethanesulfonate (DPDSPDM), was produced, and its structure was identified using TGA, FT-IR, 13C NMR, 1H NMR, and mass spectrometry techniques. Then, it was utilized as a versatile, homogeneous, and recyclable catalyst in preparing N,N'-Methylene bisamides (1a-14a, 5–13 min, 90–98%, 50 °C, solvent-free), Tetrahydrochromeno-chromenes (1b-12b, 8–20 min, 91–98%, 60 °C, solvent-free), and Pyrido-dipyrimidines (1c-12c, 2–5 min, 93–98%, 25 °C, H2O). In all three synthetic routes, the catalytic activity scope of DPDSPDM was remarkable and general due to having basic (MeSO3ˉ) and acidic (SO3H) sites, and reasonable mechanisms were displayed to support this high performance. The reproducibility of this homogeneous catalyst along with advantages such as appropriate TOF (turnover frequency) and TON (turnover number) values, mild conditions, simplicity of the workup, short reaction times, high yields, non-metallic nature of the catalyst, and the use of cheap and available raw materials in its synthesis; making it a potential candidate for future research. [ABSTRACT FROM AUTHOR]

PtSn/Al2O3 and PtSnSr/Al2O3 were prepared by the incipient wetness impregnation method. The added Sn and Sr are uniformly distributed on the surface without damaging the original crystal structure and surface texture properties. The addition of Sn not only changes the dispersion of Pt, reduces the reduction temperature of Pt, but also provides electrons to Pt, increases the electron cloud density on the surface of Pt, and reduces the deep propylene adsorption. The addition of Sr reduces the number of total acid sites and strong acid sites, reduces the generation of adverse effects and carbon deposition, slows down the deactivation of the catalyst, and improves the selectivity of propylene. Pt1.5Sn1.5Sr/Al2O3 showed the best catalytic reaction performance and remained stable after five cycles of regeneration. [ABSTRACT FROM AUTHOR]

Atmospheric volatile organic compounds (VOCs) constitute a wide range of species, acting as precursors to ozone and aerosol formation. Atmospheric chemistry and transport models (CTMs) are crucial to understanding the emissions, distribution, and impacts of VOCs. Given the uncertainties in VOC emissions, lack of evaluation studies, and recent changes in emissions, this work adapts the European Monitoring and Evaluation Programme Meteorological Synthesizing Centre – West (EMEP MSC-W) CTM to evaluate emission inventories in Europe. Here we undertake the first intensive model–measurement comparison of VOCs in 2 decades. The modelled surface concentrations are evaluated both spatially and temporally, using measurements from the regular EMEP monitoring network in 2018 and 2019, as well as a 2022 campaign. To achieve this, we utilised the UK National Atmospheric Emissions Inventory to derive explicit emission profiles for individual species and employed a tracer method to produce pure concentrations that are directly comparable to observations. The degree to which the modelled and measured VOCs agree varies depending on the specific species. The model successfully captures the overall spatial and temporal variations of major alkanes (e.g. ethane, n -butane) and unsaturated species (e.g. ethene, benzene) but less so for propane, i -butane, and ethyne. This discrepancy underscores potential issues in the boundary conditions for the latter species and in their primary emissions from, in particular, the solvent and road transport sectors. Specifically, potential missing propane emissions and issues with its boundary conditions are highlighted by large model underestimations and smaller propane-to-ethane ratios compared to the measurement. Meanwhile, both the model and measurements show strong linear correlations among butane isomers and among pentane isomers, indicating common sources for these pairs of isomers. However, modelled ratios of i -butane to n -butane and i -pentane to n -pentane are approximately one-third of the measured ratios, which is largely driven by significant emissions of n -butane and n -pentane from the solvent sector. This suggests issues with the speciation profile of the solvent sector, underrepresented contributions from transport and fuel evaporation sectors in current inventories, or both. Furthermore, the modelled ethene-to-ethyne and benzene-to-ethyne ratios differ significantly from measured ratios. The different model performance strongly points to shortcomings in the spatial and temporal patterns and magnitudes of ethyne emissions, especially during winter. For OVOCs, the modelled and measured concentrations of methanal and methylglyoxal show a good agreement, despite a moderate underestimation by the model in summer. This discrepancy could be attributed to an underestimation of contributions from biogenic sources or possibly a model overestimation of their photolytic loss in summer. However, the insufficiency of suitable measurements limits the evaluation of other OVOCs. Finally, model simulations employing the CAMS inventory show slightly better agreements with measurements than those using the Centre on Emission Inventories and Projections (CEIP) inventory. This enhancement is likely due to the CAMS inventory's detailed segmentation of the road transport sector, including its associated sub-sector-specific emission profiles. Given this improvement, alongside the previously mentioned concerns about the model's biased estimations of various VOC ratios, future efforts should focus on a more detailed breakdown of dominant emission sectors (e.g. solvents) and the refinement of their speciation profiles to improve model accuracy. [ABSTRACT FROM AUTHOR]

Pt single atoms catalysts with precise coordination environment and high stability are expected to achieve high performance of propane dehydrogenation (PDH). In this work, an innovative synthetic strategy is proposed to construct the S-1@0.1Pt9Zn@DPS-1 nanocomposite as a highly efficient PDH catalyst. Defect engineering is applied to induce the formation of defective porous silicalite-1 (DPS-1), which is favorable for achieving the uniformly distributed ZnO nanoclusters. The ZnO nanoclusters were further served as anchoring sites to stabilize the isolated Pt atoms. The structural characterization revealed that penta-O coordinated Pt single atom coupled with ZnO nanoclusters decorated on the DPS-1. Moreover, the atomically dispersed Pt atoms with the ideal coordination environment could act as the predominant active sites for PDH process. As expected, the optimal S-1@0.1Pt9Zn@DPS-1 catalyst delivered an excellent PDH performance (propane conversion of 40.7%, propylene selectivity of 97.5%) and good cycling regeneration stability. This work provides a new way for improving the activity and stability of catalysts in the field of industrial catalysts. [ABSTRACT FROM AUTHOR]

Explosion in the military zone emergency response plan includes the process of preparedness, risk reduction, and normalization of the emergency. A bomb blast causes human and financial losses to people. Therefore, to prepare and reduce the risk, it is necessary to simulate a bomb blast in a military zone. For this purpose, in this study, the risk of a bomb blast containing ethane, methane, and propane fuel was simulated by the Baker-Strehlow-Tang explosion method in the form of 3 scenarios. According to this method, at a distance of 6, 4.5, and 5 km from the place of ethane, methane, and propane bombs explosion, respectively, the amount of impulse caused by the explosion is reduced by 50%. According to these results, it is clear that the overpressure explosion of ethane, methane, and propane bombs in the military zone is not directly related to the distance from the site of the explosion. The pulse from the explosion of ethane, methane, and propane bombs occurs in one second and will be the same at all distances. [ABSTRACT FROM AUTHOR]

Abstract Hydrocarbon fuels contain approximately 50 times more energy per unit mass than commercial batteries, thus converting even 10% of the energy contained in hydrocarbon fuels to electrical energy could present a more mass-efficient electrical energy source than batteries. Considering the storability of hydrocarbon fuels compared to hydrogen, the viability of direct hydrocarbon polymer electrolyte membrane fuel cells was examined. With extremely pure (> 99.99%) propane, the cell Open-Circuit Voltage (OCV) was only 0.05 V and produced negligible power. However, with addition of trace quantities of unsaturated hydrocarbons, the cell had an OCV of 0.85 V and produced power, even after the unsaturated hydrocarbon addition was discontinued. At sufficiently high current densities, power output gradually decreased then the cell rapidly “extinguished” but by periodically shutting off the current for short time intervals the average power density could be increased significantly. Chemical analysis revealed that no significant amounts of hydrocarbon intermediates or CO were present in the effluent and that conversion of the hydrocarbon fuel to CO2 and H2O was nearly complete. An analytical model incorporating the relative rates of conversion of active anode catalyst sites to inactive sites and vice versa was developed to interpret this behavior. The model predictions were consistent with the experimental observations; possible physical mechanisms are discussed.

AbstractA set of mono-metallic nanoparticles catalysts, including palladium, platinum, and gold supported on titania, were prepared via the sol-immobilization technique, and evaluated for the total oxidation of propane as a model reaction of volatile organic compounds (VOCs) oxidation, which is a wide-ranging group of organic pollutants that contribute to serious atmospheric problems. The results showed that 1 wt.% Pt/TiO2 was the most active catalyst toward CO2, as the catalyst was very active, and the complete conversion of propane was achieved with full selectivity toward CO2. The effect of the support type was investigated through the immobilization of platinum nanoparticles on CeO2 and γ-Al2O3. The results indicated that the catalytic activity follows the order 1% Pt/TiO2 > 1% Pt/CeO2 > 1% Pt/Al2O3. For the Pt/TiO2 catalyst, the influence of the calcination temperature and metal loading on the catalytic activity was investigated. There is a slight increase in the Pt particle size when raising the calcination temperature from 300 °C to 500 °C, which enhances the catalytic activity of 1% Pt/TiO2 at 500 °C. Furthermore, increasing the metal loading from 0.1 to 1 wt.% enhances the catalytic activity as a result of the increase in particle size. Different characterization techniques were utilized, including XRD, TEM, XPS, and MP-AES, to determine the structure-activity relationship, and together they indicate that the catalytic activity is influenced more by the particle size of Pt nanoparticles than by the oxidation state.

Herein, we report the hydrogenation of carbon dioxide to sodium formate catalyzed by low-valent molybdenum phosphine complexes. The 1,3-bis(diphenylphosphino)propane (DPPP)-based Mo complex was found to be an efficient catalyst in the presence of NaOH affording formate with a TON of 975 at 130 °C in THF/H2O after 24 h utilizing 40 bar (CO2 : H2 = 10 : 30) pressure. The complex was also active in the hydrogenation of sodium bicarbonate and inorganic carbonates to the corresponding formates. Mechanistic investigation revealed that the reaction proceeded via an intermediate formato complex. [ABSTRACT FROM AUTHOR]

High transformation of the propane and CO2 reaction to propylene (PDH–CO2) is impelled by the reverse water–gas shift entails strong catalysts toward the reverse water–gas shift (RWGS) as well as propane dehydrogenation (PDH). A series of Co-modified Fe2O3–ZrO2 with proportions of 3–9 wt% (nCoFe–ZrO2) were synthesized using an oxalate coprecipitation method and their catalytic activity for PDH–CO2 at 550 °C was studied. 7CoFe–ZrO2 displayed the highest conversion to both CO2 and propane (37.6% and 47.4%) and propylene yield (38.1%) at a lower apparent activation energy. The interaction between Co species and Fe species and its effects on the active Fe3O4 and the adsorption of propane/CO2 were revealed using XRD, UV-Vis DRS, SEM/TEM, XPS, NH3/CO2/C3H8-TPD, and H2-TPR analysis. With Co-modification, the reduction of Fe2O3 to Fe3O4 was enhanced, which accelerated RWGS in addition to PDH. The key role of the *OOCH intermediate for promoting PDH and RWGS during PDH–CO2 reaction was traced through in situ DRIFTS characterization. [ABSTRACT FROM AUTHOR]

The robust electronegativity of the [BO3]3− structure enables the extraction of electrons from adjacent metals, offering a strategy for modulating oxygen activation in propane oxidative dehydrogenation. Metals (Ni 1.91, Al 1.5, and Ca 1.0) with varying electronegativities were employed to engineer borate catalysts. Metals in borate lacked intrinsic catalytic activity for propane conversion; instead, they modulated [BO3]3− group reactivity through adjustments in electron density. Moderate metal electronegativity favored propane oxidative dehydrogenation to propylene, whereas excessively low electronegativity led to propane overoxidation to carbon dioxide. Aluminum, with moderate electronegativity, demonstrated optimal performance. Catalyst AlBOx-1000 achieved a propane conversion of 47.5%, with the highest propylene yield of 30.89% at 550 °C, and a total olefin yield of 51.51% with a 58.92% propane conversion at 575 °C. Furthermore, the stable borate structure prevents boron element loss in harsh conditions and holds promise for industrial-scale catalysis. [ABSTRACT FROM AUTHOR]

The distribution of stable isotopes in organic compounds within geochemical systems reflects the reactions they undergo, which are often kinetically governed and can be elucidated through quantification based on first principles: employing quantum chemical simulations to derive energy barriers and kinetic isotope effects (KIEs), followed by kinetic calculations using these parameters. In this paper, the distribution of 13C in hydrocarbon gases during the thermal generation and decomposition of ethane and propane has been addressed. The work is based on abundant and systematic isotopic data, including the compound- and position-specific 13C compositions, recent improvements in kinetic networks in hydrocarbon generation, and state-of-the-art quantum chemical methods that can process organic geochemical systems involving solid phases. Density Functional Theory computations validate the carbonium path of hydrocarbon generation and the free-radical path of their decomposition under geological conditions. The first step of each path (alkyl sidechain protonation for generation and hydrogen abstraction for decomposition) is the rate-limiting step and determines the 13C fractionations of gaseous hydrocarbons, with the reaction rate constrained by the concentration or accessibility of the active species (hydrated protons and surface free radicals in the two paths, respectively). Alkyl protonation has normal 13C KIEs, but hydrogen abstraction on the surfaces of solid organic matter has inverse ones (substituting 12C by 13C accelerates the reaction). These inverse KIEs explain three isotopic phenomena in gaseous hydrocarbons in their late thermal evolution: 1) the depletion of 13C in ethane and propane accompanied by their decreased fraction in hydrocarbon gases (isotope "rollover"); 2) the reversed 13C sequence with carbon number (δ13C methane > δ13C ethane > δ13C propane); and 3) the depletion of 13C in the center carbon atoms of residual propane. Isotopic fractionation between gaseous hydrocarbons upon generation is evaluated using the Successive Random Chain-Scission model. The covariation of δ13C in alkanes shows a depletion in CH 4 compared with the values expected from the reciprocal of the carbon numbers, indicating that this deviation may be intrinsic instead of mixing with microbial methane. The comparison of intramolecular 13C fractionation of propane between computational and observed data suggests the contribution of isoprenoids at the beginning of the generation, in addition to isotopic homogenization between the center and end carbon atoms through the ring closure of intermediate cations. The 13C–13C clumping exhibits a weak KIE in both the generation and decomposition of ethane; the clumping is essentially stochastically governed. This work demonstrates how first-principle calculations can provide significant insights into the details of geochemical reactions governing the isotopic distributions. [ABSTRACT FROM AUTHOR]

Collision‐induced dissociation (CID) of the mass‐selected cation [(bipy)Pt(CH3)2(CH2SCH3)]+ in an ion‐trap mass‐spectrometer results in the losses of the neutrals ethane, ethene, dimethyl sulfide, methane, ethyl methyl sulfide, and propane. The generation of the first four neutrals is also observed, when the isolated, dimeric complex [(bipy)Pt(CH3)2(CH2SCH3)]2[SbF6]2 is heated in the condensed phase. While the product distribution is very similar regardless of whether the complex is heated in the solid state or in solution, ethane loss, i. e. the quite rare event of an sp3‐sp3 C−C reductive elimination from a platinum(IV) complex, dominates in the gas‐phase experiment. However, when the counter anion [SbF6]− is exchanged by the more weakly coordinating anion [BAr4F]−, the amounts of ethane and ethene are increased also in the condensed phase. These sum of observations indicates the similarities of the fragmentation of [(bipy)Pt(CH3)2(CH2SCH3)]+ in both phases. Thus, a correlation of processes in both environments is possible for selected systems (and particularly for unimolecular processes), but the choice of the proper conditions is crucial for a meaningful comparison. [ABSTRACT FROM AUTHOR]

The catalytic production of propylene via propane dehydrogenation (PDH) is a key reaction in the chemical industry. By combining operando transmission electron microscopy with density functional theory analysis, we show that the intercalation and ordering of carbon on Pt interstitials to form Pt−C solid solutions is relevant for increasing propylene production. More specifically, we found that at the point of enhanced propylene formation, the structure of platinum nanoparticles is transformed into a transient caesium chloride‐type Pt−C polymorph. At more elevated temperatures, the zincblende and rock salt polymorphs seemingly coexist. When propylene production was highest, multiple crystal structures consisting of Pt and carbon were occasionally found to coexist in one individual nanoparticle, distorting the Pt lattice. Catalyst coking was detected at all stages of the reaction, but did initially not affect all particles. These findings could lead to the development of novel synthesis strategies towards tailoring highly efficient PDH catalysts. [ABSTRACT FROM AUTHOR]

Collision‐induced dissociation (CID) of the mass‐selected cation [(bipy)Pt(CH3)2(CH2SCH3)]+ in an ion‐trap mass‐spectrometer results in the losses of the neutrals ethane, ethene, dimethyl sulfide, methane, ethyl methyl sulfide, and propane. The generation of the first four neutrals is also observed, when the isolated, dimeric complex [(bipy)Pt(CH3)2(CH2SCH3)]2[SbF6]2 is heated in the condensed phase. While the product distribution is very similar regardless of whether the complex is heated in the solid state or in solution, ethane loss, i. e. the quite rare event of an sp3‐sp3 C−C reductive elimination from a platinum(IV) complex, dominates in the gas‐phase experiment. However, when the counter anion [SbF6]− is exchanged by the more weakly coordinating anion [BAr4F]−, the amounts of ethane and ethene are increased also in the condensed phase. These sum of observations indicates the similarities of the fragmentation of [(bipy)Pt(CH3)2(CH2SCH3)]+ in both phases. Thus, a correlation of processes in both environments is possible for selected systems (and particularly for unimolecular processes), but the choice of the proper conditions is crucial for a meaningful comparison. [ABSTRACT FROM AUTHOR]

The reaction of the complex [(dpp-bian)2−Yb2+(THF)4] (dpp-bian is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) with two molar equivalents of 1,3-bis(pyridin-4-yl)propane (bpp) in tetrahydrofuran (THF) afforded the 2D coordination polymer [{(dpp-bian)Yb(bpp)2} • 3 THF]n (1). The reaction of [(dpp-bian)2−Yb2+(DME)2] with phenazine (phz) gave the dimeric complex [{(dpp-bian)Yb(DME)}2(μ-η3:η3-phz)] • 2 DME (2), in which two cationic {(dpp-bian)Yb(DME)} units are connected via a bridging phenazine dianion. Compounds 1 and 2 were characterized by elemental analysis and IR spectroscopy. Their molecular structures were determined by single-crystal X-ray diffraction analysis. Thermal stability of compound 1 was studied by thermogravimetric analysis. [ABSTRACT FROM AUTHOR]

Refrigerants used in the commercial equipment of supermarkets are the object of the research. The Montreal Protocol calls for a complete phase-out of hydrochlorofluorocarbons (HCFCs) by 2030, and the Kigali Amendment regulates the use of hydrofluorocarbons (HFCs) from 2019. Developed countries began phasing out HFC use in 2019, while developing countries plan to freeze HFC consumption from 2024. These global efforts are aimed at reducing the depletion of the ozone layer and combating climate change. The number of supermarkets in the world varies greatly: in Europe they number from 110 thousand to 115 thousand, and in China – from 65 thousand to 70 thousand, which reflects various needs in refrigeration equipment. Stringent environmental regulations are forcing the commercial refrigeration sector to remain globally competitive. Modernization of supermarkets using natural refrigerants is important for solving emerging challenges. The results of the study show significant improvements in energy efficiency ratio (EER) and coefficient of performance (COP) when using a mixture of hydrocarbons (R290: 85 %, R600a: 15 %) compared to traditional refrigerants R404a, R449a and R502. Specifically, at the evaporation temperature of Tevap=–10 °C, EER increased by 38–44 % and COP by 26–31 % compared to R404a and R449a, respectively. At Tevap=–25 °C, EER increased by 17–34 % and COP by 2–22 % compared to R404a and R449a. Additionally, compared to R502, the hydrocarbon blend showed a 38–44 % increase in EER and 28–31 % COP at Tevap=–10 °C, and a 17–34 % increase in EER and 5–22 % COP at Tevap=–25 °C. These results highlight the advantages of the hydrocarbon mixture at different evaporation temperatures, indicating its potential to improve energy efficiency in refrigeration applications. The obtained data suggest the possibility of a wider application of the mixture of hydrocarbons in commercial refrigeration plants, offering both improved performance and compliance with safety regulations. [ABSTRACT FROM AUTHOR]

In the propane dehydrogenation process, the structure and catalytic performance stability of the catalyst are determined by its regeneration process, which includes oxidation of coke and oxychlorination to redisperse the supported metal particles. A commercial Pt-Sn catalyst was used in this work to investigate the impact of oxidation temperature on oxychlorination performance. The catalysts after oxidation and oxychlorination were characterized by H2-TPR, CO-DRIFTS, HAADF-STEM, XPS, and CO chemisorption. It was found that mild sintering of Pt occurred during oxidation in the temperature range of 550–650 °C, and the catalyst could be fully restored in the subsequent oxychlorination treatment. Upon oxidation of the catalyst at 700 °C, a severe aggregation of Pt and SnOx could be observed, and the catalyst could not be fully regenerated under the given oxychlorination conditions. However, PDH catalyst deactivation caused by sintering is not irreversible. By tailoring the oxychlorination conditions, the detrimental effect of high oxidation temperature on regeneration could be ruled out. During the oxidation and oxychlorination treatment, the metal tends to migrate to anchor on sites with stronger metal–support interaction, which was helpful for enhancing the catalytic activity. [ABSTRACT FROM AUTHOR]

CO2 oxidative dehydrogenation of propane (CO2-ODHP), being not only favorable for olefin production but also beneficial for CO2 emission control, has recently attracted great attention. Here, a series of single metal (Cr) and bimetal (Zr, La, Fe) modified ZSM-5 zeolites were prepared via an impregnation method. It was found that the bimetal modified ZSM-5 possessed much higher C3H8 and CO2 conversion than that of monometallic modified Cr3%-ZSM-5 (Cr3%-Z5), especially for Cr3%Zr2%-ZSM-5 (Cr3%Zr2%-Z5), which displayed the highest activity (65.4%) and olefin yield (1.65 × 103 μmol· g c a t − 1 h−1). Various characterizations were performed, including XRD, N2 adsorption-desorption, H2-TPR, Raman, XPS, HAAD-STEM, and TEM. It was revealed that Zr not only favored an improvement in the redox ability of Cr, but also contributed to the surface dispersion of loaded Cr species, constituting two major reasons explaining the superior activity of Cr3%Zr2%-Z5. To further improve CO2-ODHP catalytic behavior, a series of Cr3%-ZSM-5@SBA-15-n composite zeolite catalysts with diverse (ZSM-5/SBA-15) mass ratios were prepared (Cr3%-ZS-n, n = 0.5, 2, 6, 16), which screened out an optimum mass ratio of six. Based on this, the Cr3%Zr2%-ZS-6 compound was further prepared, and it eventually achieved even higher CO2-ODHP activity (76.9%) and olefin yield (1.72 × 103 μmol· g c a t − 1 h−1). Finally, the CO2-ODHP reaction mechanism was further investigated using in situ FTIR, and it was found that the reaction followed the Mars–van Krevelen mechanism, wherein CO2 participated in the reaction through generation of polydentate carbonates. The Cr6+ constituted as the active site, which was reduced to Cr3+ after the dihydrogen reaction, and was then further oxidized into Cr6+ by CO2, forming polydentate carbonates, and thus cycling the reactive species Cr6+. Additionally, assisted by a Brönsted acid site (favoring breaking of the C-C bond), C2H4 and CH4 were produced. [ABSTRACT FROM AUTHOR]

Defect manipulation in metal oxide is of great importance in boosting catalytic performance for propane oxidation. Herein, a selective atom removal strategy was developed to construct a defective manganese oxide catalyst, which involved the partial etching of a Mg dopant in MnOx. The resulting MgMnOx-H catalysts exhibited superior low-temperature catalytic activity (T50 = 185 °C, T90 = 226 °C) with a propane conversion rate of 0.29 μmol·gcat.−1·h−1 for the propane oxidation reaction, which is 4.8 times that of pristine MnOx. Meanwhile, a robust hydrothermal stability was guaranteed at 250 °C for 30 h of reaction time. The comprehensive experimental characterizations revealed that the catalytic performance improvement was closely related to the defective structures including the abundant (metal and oxygen) vacancies, distorted crystals, valence imbalance, etc., which prominently weakened the Mn-O bond and stimulated the mobility of surface lattice oxygen, leading to the elevation in the intrinsic oxidation activity. This work exemplifies the significance of defect engineering for the promotion of the oxidation ability of metal oxide, which will be valuable for the further development of efficient non-noble metal catalysts for propane oxidation. [ABSTRACT FROM AUTHOR]

[Display omitted] Propane dehydrogenation (PDH) has been an outstanding technique with a bright prospect, which can meet the growing global demand for propylene. However, undesired side reactions result in the deactivation of the Pt-based catalysts, which contribute to the insufficient lifetime of the catalysts. Herein, we describe a novel catalyst by encapsulating bimetallic CoCu-modified Pt species in S-1 zeolite for efficient dehydrogenation of propane, which synergizes the confinement of zeolites and the geometric and electronic effects on Pt species for enhancing the catalyst stability. The introduction of bimetallic additives efficiently promotes the dispersion of platinum and the electron transfer between Pt species and the additives, which greatly prolongs the lifetime of the catalysts. Particularly, no obvious deactivation is observed on 0.2Pt0.3Co0.5CuK@S-1 after 93 h on stream with a weight hourly space velocity (WHSV) of 5.4 h−1, revealing an ultralow deactivation constant of 0.0011 h−1 (t = 909 h). The formation rate of propylene still maintains at a high value of 407 mol g Pt -1 h−1 (WHSV = 21.6 h−1) at 580 ℃ even after on pure propane stream for 42 h. The catalyst with the bimetallic CoCu-modified Pt species in S-1 zeolite reveals ultra-high activity and stability for PDH, which is ascribed to the highly dispersed Pt species and the stabilization effect of bimetallic additives on Pt species. [ABSTRACT FROM AUTHOR]

A Pt‐ZSM5 catalyst, coked during propane dehydrogenation and regenerated with lean air, was studied by various in‐situ and ex‐situ methods. A newly developed isothermal ceramic flat‐bed reactor with inert surfaces is described and used in the experiments. Comparative measurements successfully demonstrated that temperature alone has no effect on the catalyst and that changes in conversion and selectivity are due to coke formation. Nuclear magnetic resonance (NMR) studies using triphenylphosphine probe molecules of activated and deactivated samples showed the localization of the Pt clusters inside and outside the zeolite pores. It was shown that the Pt clusters are mainly located inside the zeolites and that the mobilization of Pt by contact with oxygen leads to permanent aging. [ABSTRACT FROM AUTHOR]

The effect of the ratio of the reagents on a stabilized cool flame (CF) of rich propane-oxygen mixtures is investigated. It is found that with an increase in the initial concentration of propane in the mixture, its consumption, as well as the concentration of propylene, has a maximum at a ratio of C3H8 : O2 = 1 : 1. In this case, the selectivity of propylene formation reaches a maximum at a ratio of C3H8 : O2 = 4 : 1. It is shown that an increase in the initial propane concentration in the mixture increases the yield of methane, but reduces the yield of propylene, ethylene, hydrogen, CO, CO2, methanol, formaldehyde and acetaldehyde. At a ratio of C3H8 : O2 = 6 : 1, ethane was also found in the reaction products. The possibility of ethanol formation in the reactions of ethoxyl and hydroxyethyl radicals with acetaldehyde is analyzed using the CBS-QB3 quantum-chemical method. [ABSTRACT FROM AUTHOR]

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The trapped-vortex combustor (TVC) is an alternative combustor design to conventional aeroengine combustors. The separate fuel and air injection of this combustor and its compact design make it a perfect candidate for conventional fuel usage. Moreover, the performance of a trapped-vortex combustor with alternative fuels such as ammonia and hydrogen in the actual operating conditions of an aeroengine is not well understood. The present paper focused on the performance evaluation of TVCs with the futuristic fuels ammonia and hydrogen including under the realistic operating conditions of a combustor. The investigated fuels were injected into a cavity with 0-,15-, 30- and 45-degree transverse-angled air injectors to evaluate the mixing enhancement of the air and fuel under idle and low-power conditions. The mixing behavior of hydrogen showed a significant difference from the conventional fuel, i.e., propane. It was also noticed that the transverse injection of the air helped to improve the mixing efficiency as compared to the normal injection configuration. Mixing efficiency was higher for the 30- and 45-degree transverse-angled air injectors compared to the 0- and 15-degree transverse-angled air injectors. [ABSTRACT FROM AUTHOR]

Conifer trees (Noble-fir) were used to study the vegetative combustion process under an applied wind field. Three ignition methods were considered. First, a special T-shaped propane burner was used. The second ignition method considered the use of firebrand showers impinging onto the trees. The third method was to use one tree to ignite another tree. Temporally resolved mass loss profiles, as well as firebrand distributions were determined. Results are presented for individual conifer trees combusting under an applied wind field. Additional experiments that made use of up to two trees per experiment were used to observe fire spread processes from tree to tree. These experiments provide the much needed experimental understanding to be able to model vegetative combustion processes. [ABSTRACT FROM AUTHOR]

Propylene serves as a crucial feedstock for a wide range of industries engaged in the production of diverse petrochemical products. Propane dehydrogenation, an appealing technology aimed at supplanting conventional methodologies, confronts significant hurdles attributable to coke deposition and sintering in Pt‐based catalysts. Here, we report an Ir single atom encapsulated in silicalite‐1 zeolite modified with Sn single atoms as electronic promoters, displaying remarkable activity and stability, which is significantly greater than the previously reported Ir‐based catalysts and comparable to the majority of Pt‐based catalysts under similar industrial conditions (600°C, C3H8/H2 = 2/1). Spectroscopies results reveal that the introduction of Sn atoms promotes the transfer of electrons from Sn atoms to Ir atoms, forming electron‐rich Irδ+ species. DFT calculations show that the unique electronic structure lowers the energy barrier for two‐step dehydrogenation as well as favors the adsorption of propane and desorption of propylene, thus enhancing the activity and stability. [ABSTRACT FROM AUTHOR]

The peak explosion pressure and maximum rate of pressure rise of explosions in confined spaces are key safety parameters to evaluate the hazard of processes running in closed vessels and to design enclosures able to withstand explosions or of their vents used as relief devices. These properties are examined in the present paper, for hydrogen-hydrocarbon-air mixtures at sub-atmospheric pressures, using propane and n -butane as test fuels and variable hydrogen ratios between 0 and 0.3. The experimental study was carried out in a sphere and a cylindrical chamber at room temperature and sub-atmospheric pressures (between 0.3 and 1.0 bar). On the basis of pressure recordings, the characteristic explosion indices, i.e., the maximum explosion pressure (p max), maximum rate of pressure rise ((dp/dt) max), deflagration index (K G), and time to peak pressure (θ max) were derived. Numerical simulations were used to determine the adiabatic explosion pressures and adiabatic flame temperatures of isochoric combustion. The effects of initial pressure (p 0), hydrogen concentration, and shape and size of the explosion vessel on explosion indices are discussed. For each hydrogen concentration of the blended fuels, linear correlations p max = f(p 0) and (dp/dt) max = f(p 0) were found. In addition, the heat loss to the walls during explosion propagation was estimated on the basis of the difference between the adiabatic and experimental explosion pressures. The amount of heat lost increases with the increase of hydrogen blending ratio and vessel asymmetry. • Hydrogen-blended propane-air and butane-air explosions were studied in two closed vessels. • The experiments were performed at various initial pressures between 0.3 and 1.0 bar. • As Hydrogen blending ratio increases, the explosion pressure, the maximum rate of pressure rise, and the severity factor increase. • The increase of hydrogen blending ratio results in the decrease of the explosion times. • The observed variations depend largely on the volume and shape of the explosion vessel. [ABSTRACT FROM AUTHOR]

Radiolysis of α-pinene by 61.3 MeV 84Kr15 + ions was analysed with the scope to simulate the effects of heavy ion cosmic ray bombardment on chiral molecules in the interstellar medium. The α-pinene ice samples were irradiated at 10 K and their chemical evolution was monitored by mid-infrared Fourier transform (FTIR) spectroscopy to characterize the reaction products and to determine the extent of racemization. The integrated band strengths have been obtained for all the neutral α-pinene vibrational bands using the experimental band integrated absorbances and the theoretical absolute intensities calculated along the column densities. In the current heavy ion bombardment experiments, small molecules were formed and the precursor, α-pinene, was destroyed instead of being racemized. Twelve hydrocarbons were produced (final fluence of 2.0 × 1012 ions cm−2): methane (CH4), acetylene (C2H2), ethylene (C2H4), propylene (C3H6), propane (C3H8), n-butane (C4H10), butene (C4H8), propyne (C3H4), benzene (C6H6), ethane (C2H6), vinylacetylene (C4H4), and 2-methyl-1,3-butadiene or isoprene (C5H8). The highest formation cross-section (∼ 40 × 10−15 cm2) was observed for the C3H4 and the lowest was for C3H8 (∼ 3 × 10−15 cm2). The radiochemical yields for these molecules follow the same trends as those of their cross-sections. The atom budget calculation confirms that all the expected products have been generated during the radiolysis and supports the conclusion that the proposed A values are accurate. The α-pinene sputtering yield for this ion beam was found to be Y0  = 1.84 × 106 molecules per impact. [ABSTRACT FROM AUTHOR]

Noble metals have become a research hotspot for the oxidation of light alkanes due to their low ignition temperature and easy activation of C-H; however, sintering and a high price limit their industrial applications. The preparation of effective and low-noble-metal catalysts still presents profound challenges. Herein, we describe how a Ru@CoMn2O4 spinel catalyst was synthesized via Ru in situ doping to promote the activity of propane oxidation. Ru@CoMn2O4 exhibited much higher catalytic activity than CoMn2O4, achieving 90% propane conversion at 217 °C. H2-TPR, O2-TPD, and XPS were used to evaluate the catalyst adsorption/lattice oxygen activity and the adsorption and catalytic oxidation capacity of propane. It could be concluded that Ru promoted synergistic interactions between cobalt and manganese, leading to electron transfer from the highly electronegative Ru to Co2+ and Mn3+. Compared with CoMn2O4, 0.1% Ru@CoMn2O4, with a higher quantity of lattice oxygen and oxygen mobility, possessed a stronger capability of reducibility, which was the main reason for the significant increase in the activity of Ru@CoMn2O4. In addition, intermediates of the reaction between adsorbed propane and lattice oxygen on the catalyst were monitored by in situ DRIFTS. This work highlights a new strategy for the design of a low-noble-metal catalyst for the efficient oxidation of propane. [ABSTRACT FROM AUTHOR]

Propylene is an important resource for large petrochemicals production. Propane dehydrogenation (PDH), which directly produces propylene while producing hydrogen as a by-product, has attracted extensive attention in recent years. Among various PDH catalysts, Zn-based catalyst has great potentials in industrial implementation because of its low cost and eco-friendly. Herein, we synthesized Zn– O –Zr active center via atom trapping strategy for effectively catalyzing PDH reaction. The ability of phase transition upon Zn deposition is supposed to be a possible indicator to assess active degree of ZrO 2 , which is directly related to the proportion of surface absorbed oxygen species (SAOS) on ZrO 2. We demonstrate that SAOS concentration can be promoted through stabilizing tetragonal-phase and doping Hf, results in more Zn–O–Zr species, lower active energy, and easier phase transition. This study reveals the electronic effect on atom trapping process used in Zn–ZrO 2 system and provides guidance to design and prepare high-performance Zn-based PDH catalysts. [Display omitted] • An efficient Zn–O–Zr structure was prepared by atom trapping method. • The interaction between metals is quantified by binding energy shifting. • Periodic phase transition of support during the reaction. • The surface defect degree of Zn species was regulated by crystal phase. [ABSTRACT FROM AUTHOR]