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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]

To reveal the catalytic function of Brønsted acid sites (BAS) and different Zn Lewis acid sites (LAS) over SSZ‐39 and Zn modified SSZ‐39 in the direct dehydrogenation of propane (DHP) and CO2‐mediated oxidative dehydrogenation (CO2‐ODHP) to propylene, a series of Zn‐modified H(Na)SSZ‐39 catalysts with various Zn loadings was prepared and conducted comparative studies between DHP and CO2‐ODHP. Detailed characterization results reveal the Zn‐loading‐dependent formation of Zn sites, primarily including Zn2+ and [Zn−O−Zn]2+, as well as their contributions in generating Lewis acid sites while neutralizing Brønsted acid sites of HSSZ‐39, namely bridged Si(OH)Al groups. In DHP, in comparison to bare HSSZ‐39, Zn/HSSZ‐39 catalysts exhibited a significantly enhanced C3H8 conversion. The presence of CO2 even further promoted C3H8 conversion in comparison to DHP. Given the above observations, we prepared Zn/NaSSZ‐39, in which the incorporation of Na further enriches the Lewis acid sites while neutralizing Brønsted acid sites of zeolite. Zn/NaSSZ‐39 even outperforms Zn/HSSZ‐39 catalysts with almost doubled C3H6 yield for CO2‐ODHP. The BAS has a poor CO2‐ODHP performance but can enhance the CO2 conversion towards CO significantly, while the Zn LAS is favorable for the CO2‐ODHP reaction, and plausible reaction paths of CO2‐ODHP on active sites are proposed. [ABSTRACT FROM AUTHOR]

The Born–Oppenheimer ab initio equilibrium structures of propane (CH3)2CH2 and 2,2-difluoropropane (CH3)2CF2 were computed at the CCSD(T) level of theory using a basis set of quadruple zeta quality. The semiexperimental structure of propane was also determined from the ground state rotational constants corrected for rovibrational corrections calculated at the MP2 level of theory. Structural comparisons are made with other molecules and are discussed in terms of the quantum theory of atoms in molecules. [ABSTRACT FROM AUTHOR]

The performance of CO 2 -assisted oxidative dehydrogenation of propane to propylene is investigated. The energy performance matrices are defined as energy efficiency and exergy efficiency at both the reactor level and the overall system level. Oxidants are the main factor that dictates the performance of the dehydrogenation of propane. Oxygen is a strong oxidant which helps in promoting the endothermic dehydrogenation of propane. CO 2 is considered a mild oxidant that hinders the over-oxidation of propane. The addition of CO 2 promotes propane conversion but sacrifices the other performance matrices including propylene selectivity and the H 2 /CO ratio of the syngas. Consequently, the energy and exergy efficiencies of the reactor as well as the DHP system decrease with increasing CO 2 supply. The addition of O 2 has positive impacts on the energy performance matrices at a certain temperature range (from 863 K to 1273 K). However, the addition of O 2 leads to an adverse impact on the propylene selectivity and H 2 /CO ratio of the syngas. Under the absence of O 2 , the DHP exhibits a propane conversion of 91% with the propylene selectivity and system exergy efficiency of 90% and 86%, respectively when the CO 2 /C 3 H 8 ratio of 0.25 at 973.15 K. This work provides strong evidence that the reaction performance matrices have a strong relation to the energy performance matrices and offers a baseline for future research and optimization in the presence of O 2 and CO 2. [Display omitted] • The performances of dehydrogenation of propane (DHP) are investigated. • The main product are propylene and syngas. • CO 2 and O 2 enhances propane conversion but suppresses propylene selectivity. • CO 2 and O 2 has an adverse effect on energy and exergy efficiencies. • DHP shows propane conversion and selectivity of 91% and 90%, respectively. [ABSTRACT FROM AUTHOR]

The unimolecular reactions of protonated myrcene and linalool were investigated by collision‐induced dissociation and density functional theory calculations. Experiments on a triple quadrupole mass spectrometer showed that protonated myrcene undergoes two major unimolecular reactions losing propene and isobutene, and two minor reactions of ethene and propane loss. In each case, the product ion consists of a substituted five‐member ring. Protonation of myrcene was found to form four distinct protomers, three of which can be significantly populated in the ion source. The observed fragmentation reactions were calculated and found to depend on the starting protomer. Each pathway consisted of several hydrogen‐migration and ring‐forming/opening steps on the way to the observed products. Likewise, protonation of linalool also produces three distinct protomers, with the global minimum being formed by protonation of a central double bond. The major reaction is water loss to form protonated myrcene, but two minor channels were also observed resulting in loss of acetone and isobutene. The calculated minimum energy reaction pathways were found to be consistent with the relative abundances of the ions in the experimental breakdown diagrams. [ABSTRACT FROM AUTHOR]

Brazilian nuts are native to the Amazon rainforest and are considered a non-timber forest-product of extreme economic importance to local populations. This study evaluated the lipid profile, bioactive compounds, and oxidative stability of semi-defatted Brazilian nut flour oil (BNSDFO) obtained using pressurized fluids (n-propane at 40 °C and 2, 4, and 8 MPa or a CO2/n-propane mixture at 40 °C and 12 MPa). A Brazilian nut kernel oil (BNKO) processed by conventional cold pressing was also obtained. The BNKO showed a higher concentration of total phenolic compounds and saturated fatty acids, higher antioxidant activity, and the presence of gallic acid derivatives. The oils extracted using pressurized fluids showed a higher concentration of linoleic acid, β-sitosterol, and polyunsaturated fatty acids. The utilization of pressurized n-propane resulted in higher yields (13.7 wt%), and at intermediate pressures (4 MPa), the product showed myricetin 3-O-rhamnoside and higher oxidative stability (OSI, 12 h) than at lower pressures (2 MPa). The CO2/n-propane mixture of pressurized solvents resulted in higher concentrations of squalene (4.5 times), the presence of different phenolic compounds, and a high OSI (12 h) but lower yield (2.2 wt%). In conclusion, oils with better fatty acid profiles (oleic e linoleic acids), phytosterol composition, and suitable radical scavenging activity may be obtained using pressurized fluids and Brazilian nut flour, a byproduct of oil extraction. The mixture of solvents may improve the concentration of squalene, whereas using only n-propane may increase oil yield. [ABSTRACT FROM AUTHOR]

Acetone serves as an important solvent and building block for the chemical industry, but the current industrial synthesis of acetone is generally accompanied by the energy-intensive and costly cumene process used for phenol production. Here we propose a sustainable route for acetone synthesis via propane wet reforming at a moderate temperature of 350 oC with the use of platinum-tin nanoparticles supported on γ-aluminium oxide (PtSn/γ-Al2O3) as catalyst. We achieve an acetone productivity of 858.4 μmol/g with a selectivity of 57.8% among all carbon-based products and 99.3% among all liquid products. Detailed spectroscopic and controlled experiments reveal that the acetone is formed through a tandem catalytic process involving propene and isopropanol as intermediates. We also demonstrate facile ketone synthesis via wet reforming with the use of different alkanes (e.g., n-butane, n-pentane, n-hexane, n-heptane, and n-octane) as substrates, proving the wide applicability of this strategy. The authors propose a sustainable route for acetone synthesis by directly reacting propane and water with PtSn nanoparticles on γ-Al2O3 as the catalyst [ABSTRACT FROM AUTHOR]

Asymmetric carbon molecular sieve (CMS) hollow fiber membranes with tunable micro‐ and macro‐structural morphologies for energy efficient propylene‐propane separation are reported here. A sub‐glass transition temperature (sub‐Tg) thermal oxidative crosslinking strategy enables simultaneous optimization of the intrinsic molecular sieving properties while also reducing the thickness of the CMS “skin” derived from the 6FDA : BPDA/DAM polyimide precursors. Such synergistic tuning of CMS microstructure and macroscopic morphology of CMS hollow fibers enables significantly increased propylene permeance (reaching 186.5 GPU) while maintaining an appealing propylene/propane selectivity of 13.3 for 50/50 propylene/propane mixed gas feeds. Our findings reveal a more refined and versatile tool than available with previous O2‐doping pretreatments. The advanced approach here should be broadly useful to other polyimide precursors and diverse gas pairs. [ABSTRACT FROM AUTHOR]

The improvement of Pt‐based catalysts for propane dehydrogenation (PDH) has progressed by recent investigations that have identified Zn as a promising promoter for Pt subnanometer catalysts. It is desirable to gain insights into the structure, stability, and activity of such active sites and the factors that influence them, such as Zn : Pt ratio, Pt coordination and nuclearity. Here, we employ density functional theory and microkinetic simulations to investigate the stability of PtxZny (x=1–3, y=0–3) active sites grafted on silanols of Silicalite‐1 and the PDH activity of Pt. We find that the coordination of a Pt atom to a nest of grafted Zn(II) atoms increases the stability of the Pt1Zny sites, whose activity is similar for y=0–2 and drops dramatically for y>2. We further demonstrate, via linear scaling relations and microkinetic simulations, that the turnover frequency obeys a volcano law as a function of propylene binding strength. The Pt2Zn1 and Pt3Zn1 sites are stable and exhibit activity similar to Pt1Zn2, but only Pt1Zn2 manifests reaction kinetics consistent with experimental data, strongly suggesting the active site composition in the synthesized catalyst samples. The methodology presented here suggests a general strategy for deducing active site information such as composition through simple kinetic experiments. [ABSTRACT FROM AUTHOR]

Current industrial propane dehydrogenation (PDH) processes predominantly use either toxic Cr‐based or expensive Pt‐based catalysts, necessitating urgent exploration for alternatives. Herein, we present Zn2SiO4, an easily prepared, cost‐effective material, as a highly efficient and stable catalyst for PDH. Uniquely, Zn2SiO4 nanocrystals do not require dispersion on support materials, commonly needed for catalytic active oxide clusters, but function as a self‐supporting catalyst instead. During the reaction‘s induction period, surface Zn species on the Zn2SiO4 crystal reduce to coordinately unsaturated ZnOx single sites, serving as highly active catalytic centers. The Zn2SiO4 catalyst demonstrates a stable performance over 200 hours of PDH operation at 550 °C. We further find that introducing a minuscule amount of CO2 into the propane feed significantly extends the catalyst lifespan to over 2000 hours. This enhancement arises from the special role of CO2 in facilitating the removal of strongly adsorbed H*, preventing the complete reduction of ZnOx. After prolonged reaction, the activity of Zn2SiO4 can be fully restored by etching the surface layer to expose fresh Zn species, available throughout the crystals. The combination of CO2introduction and catalytic site regeneration strategies is expected to enable a year‐long PDH operation using a single batch of Zn2SiO4 catalyst. [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]

Metal–organic framework (MOF)‐based membranes excel in molecular separation, attracting significant research interest. The crystallographic microstructure and selective adsorption capacity of MOFs closely correlate with their gas separation performance. Here, aniline was added to the ZIF‐8 synthesis in varying concentrations. Aniline, encapsulated within ZIF‐8 cavities, interacts strongly with the 2‐methylimidazole linker, resulting in both a shift in crystallographic phase from I_43 m to Cm in Rietveld refinement of X‐ray diffraction (XRD) patterns and the selective adsorption behavior between propylene and propane. Consequently, an aniline decorative ZIF‐8 (Anix‐ZIF‐8) membrane was prepared using a fast current‐driven synthesis method, which exhibits good propylene/propane separation selectivity of up to 85. Calculation of the interaction energy between aniline and the various crystallographic phases of ZIF‐8 using density functional theory (DFT) further verifies that aniline not only promotes the formation of crystallographic Cm phase, but also enhances the adsorption selectivity of propylene over propane. Aniline modification effectively tunes the crystallographic microstructure of ZIF‐8, thereby, improving molecular sieving capabilities. [ABSTRACT FROM AUTHOR]

Most C–H bond activations of natural gas alkanes rely on transition metal complexes. Activations by using main-group systems have been reported but required heating or photo-irradiation under high atmospheric pressure with rather low regioselectivity. Here we report that Lewis acid-carbene adducts facilely undergo oxidative additions to C–H bonds of ethane, propane and n-butane with high selectivity under room temperature and atmospheric pressure. The Lewis acids can be moved by the addition of a base and the carbene-derived products can be easily converted into aldehydes. This work offers a route for main-group element compounds to selectively functionalise C–H bonds of natural gas alkanes and other small molecules. Activation of natural gas alkanes using main-group systems typically requires heating or photo-irradiation under high atmospheric pressure with low regioselectivity. Here the authors report Lewis acid-carbene adduct activation of C–H bonds in ethane, propane and n-butane under one atmospheric pressure and at room temperature with high selectivity. [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]

Propane dehydrogenation (PDH) is an efficient technology for the direct production of propylene. Nevertheless, current PDH catalysts mainly rely on precious Pt or toxic Cr and especially undergo severe coke deposition. Herein, we report a Ru catalyst decorated by boron species (Ru-3B/Al2O3), which exhibits high catalytic performance for PDH. HAADF-STEM, EELS, and CO-FTIR characterization are used to identify the surface structure of the Ru active component, which shows that the high-energy unsaturated coordination sites, including corners, edges and step atoms for Ru-3B/Al2O3, are appropriately modified by BOx species. The encapsulation of high-energy active sites prone to C-C cracking and deep dehydrogenation leads to higher propylene selectivity (> 95%) and strong carbon resistance (kd 0.0007 min) over Ru-3B/Al2O3. The XPS and H2 -TPR results show that the migration of B species is driven by the reduction of B2 O3 to B2 O2 and that the coating degree of Ru particles is controlled by the chemical valance of Ru species. [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]

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]

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]

High-entropy alloys were produced by centrifugal self-propagating high-temperature synthesis and used as precursors for preparation of catalysts for CO and propane deep oxidation and CO2 hydrogenation. The precursors were converted into catalysts by aluminum leaching and stabilization with hydrogen peroxide solution. Prepared FeCoNiCu, FeCoNiCuMo, FeCoNiCuMn, and FeCoNiCuCr catalysts were characterized by XRD, SEM/EDS, and BET methods and tested in the processes of deep oxidation of CO and propane and methanation of CO2. The highest CO2 conversion, 50.6%, with methane selectivity of 77.5% was achieved on FeCoNiCu catalyst at 400°C. The best catalyst for the deep oxidation process was shown to be FeCoNiCuCr, on which the temperature of 100% CO conversion was 250°C and 100% conversion of propane was achieved at 450°C. [ABSTRACT FROM AUTHOR]

The capillary constant of a propane–methane solution was measured along the saturation line in the temperature range of 318.15–333.15 K at pressures from the saturation pressure of pure propane up to 4 MPa. The surface tension of the solution was determined. Equations approximating the concentration and pressure dependences of surface tension were constructed. [ABSTRACT FROM AUTHOR]

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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.

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.

ObjectivesA portable solid oxide fuel cell (SOFC) system includes a gas supply module, a fuel processing module, an SOFC power generation module, a thermal management module, an exhaust treatment module and a control module. There is a complex coupling relationship between the fuel processing module and the SOFC power generation module. Clarifying the coupling characteristics between them is crucial for improving system performance and operating time.MethodsThe effects of temperature, the carbon-to-oxygen ratio and other factors on the performance of catalytic partial oxidation (CPOx) of propane with Rh as catalyst were analyzed, and the coupling performance of CPOx and SOFC stack was further tested.ResultsWith the increasing of fuel flow rate, the reforming efficiency first increases and then decreases. The most suitable flow rate is 100 or 150 mL/min. An increase in temperature can continuously improve the reforming efficiency, but the improvement in reforming efficiency at high temperatures caused by an increase in temperature gradually decreases. The optimal C/O ratio obtained from the experiment is 1.0. Under the optimal operating conditions, the output power of SOFC stack reaches 8.38 W.ConclusionsUnder the conditions of propane flow rate of 150 min-1, carbon and oxygen mole fraction ratio of 1.0, and operating temperature of 800 ℃, the coupling performance between SOFC stack and CPOx is the best, the portable propane power generation system can generate 150 W of power with a volume of 12 L.

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]

A prerequisite for the development or optimization of heterogeneous catalysts is a comprehensive understanding of the reaction mechanism and kinetics at the level as elementary as possible. In comparison with steady‐state catalytic tests typically used for this purpose, non‐steady‐state (transient) studies provide deeper insights due to higher time resolution. For several decades, temporal analysis of products (TAP) and steady‐state isotopic transient kinetic analysis (SSITKA) have been successfully applied to the analysis of various heterogeneous reactions. In this review, we highlight the contributions made by TAP and SSITKA studies between 2017 and 2023 to the understanding of reaction mechanisms and to the derivation of microkinetics. The versatility of these methods is illustrated by the examples of oxidative coupling of methane, CO/CO2 hydrogenation to hydrocarbons or methanol, metathesis of ethylene with 2‐butenes to propene, acrolein oxidation to acrylic acid, methanol conversion to olefins and non‐oxidative propane dehydrogenation to propene. We also provide our personal views on possible developments in this area. [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]

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]

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]

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]

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Copyright of China Synthetic Fiber Industry is the property of Sinopec Baling Petrochemical Company and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

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]

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]

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]

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]