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The aim of this study is to unravel the influence of single, double and triple bonds in hydrocarbons on the mechanisms of adsorption on zeolites. Therefore, the adsorption of the C2 hydrocarbons ethane, ethene and ethyne on different adsorbents is studied by adsorption calorimetry. As adsorbents pure sodium LTA (NaA) and FAU (NaX) zeolites and calcium exchanged CaNaA and CaNaX zeolites are used. Based on experimental loadings and heat of adsorption, the influence of the number and distribution of cations on different cation positions are discussed in detail. With increasing degree of exchange the increasing number of Ca2+-cations introduce energetically more valuable adsorption sites into the zeolites. On the other hand, the decreasing total number of cations has a negative effect on saturation loading. The impact of these opposing effects and the different occupation of cation positions on the interactions and mechanisms occurring are discussed. The loading increases from ethane to ethene to ethyne and shows higher values on FAU compared to LTA. In terms of interactions, due to the single bond, in ethane only dispersion and induction interactions are formed. In ethene and ethyne due to the double and triple bonds, respectively, additional quadrupole cation and π-interactions occur. In this study, for the first time the formation of a π-complex with Ca2+-cations at position I in LTA and at positions II, III, and III' in FAU is demonstrated. For ethyne, additional π-complex formation with Na+-cations on the identical positions is also detected, which was previously unknown in literature. [ABSTRACT FROM AUTHOR]

The cost-effective separation of ethylene (C2H4), ethyne (C2H2), and ethane (C2H6) poses a significant challenge in the contemporary chemical industry. In contrast to the energy-intensive high-pressure cryogenic distillation process, zeolite-based adsorptive separation offers a low-energy alternative. This review provides a concise overview of recent advancements in the adsorptive separation of C2H4, C2H2, and C2H6 using zeolites or zeolite-based adsorbents. It commences with an examination of the industrial significance of these compounds and the associated separation challenges. Subsequently, it systematically examines the utilization of various types of zeolites with diverse cationic species in such separation processes. And then it explores how different zeolitic structures impact adsorption and separation capabilities, considering principles such as cation-π interaction, π-complexation, and steric separation concerning C2H4, C2H2, and C2H6 molecules. Furthermore, it discusses methods to enhance the separation performance of zeolites and zeolite-based adsorbents, encompassing structural design, modifications, and ion exchange processes. Finally, it summarizes current research trends and future directions, highlighting the potential application value of zeolitic materials in the field of C2H4, C2H2, and C2H6 separation and offering recommendations for further investigation. [ABSTRACT FROM AUTHOR]

The author considers the main patterns characteristic of the processes of hydrogen chloride oxidation (the Deacon reaction) and oxidative methane and ethane chlorination. It is shown that the most widely recognized and best studied catalysts of these processes are copper chloride systems that are based on different supports and contain alkali and rare-earth metal chlorides, which reduce the entrainment of an active phase from the surface of a catalyst with a simultaneous increase in its activity. The prospects for using ruthenium catalysts are also noted. The main kinetic and technological patterns of oxychlorination are considered. Conditions are described that allow the yield of target products (lower methane chlorides) to be increased in the oxychlorination of methane and vinyl chloride during the oxychlorination of ethane. Variants of reactor units for oxychlorination are proposed. [ABSTRACT FROM AUTHOR]

The thermodynamic characteristics of adsorption (TCAs) of methane and ethane on the basal face of a semi-infinite graphite crystal were calculated by the Monte Carlo method in the Gibbs ensemble. The results obtained using the described calculation algorithm are in good agreement with the literature data. The calculations were performed in the approximation of additivity of atom-atom potentials (AAPs), taken in the Lennard-Jones form (6, 12). When varying the AAP parameters, a quasi-rigid methane molecule was used as a reference. The same AAP parameters make it possible to calculate the adsorption of ethane on graphite under the assumption that the height of the internal rotation barrier does not change during adsorption, but the potential energy of the adsorbed molecule depends on the internal rotation angle. [ABSTRACT FROM AUTHOR]

Zeolitic imidazolate frameworks based on 2-methylimidazolate linkers with different particle size (200–1000 nm) and controlled content of Zn2+ and Co2+ ions have been synthesized by microwave (MW) assisted technique according to original procedures and room-temperature method. The produced materials including monometallic ZIF-8 and ZIF-67 samples, bimetallic ZIF-Zn/Co (or ZIF-8/ZIF-67) system, and "core-shell" ZIF-8@ZIF-67 and ZIF-67@ZIF-8 composites have been studied in the practically relevant process of selective adsorption of ethane and methane (25 °C). The adsorption isotherms for both gases on the obtained ZIF materials were measured in a wide pressure range (1–20 atm) for the first time. For ZIF-67, the isosteric heats of adsorption for both gases were obtained also for the first time. It was found that the nature of the coordination centers in the ZIF frameworks influences their adsorption characteristics. Thus, the obtained materials with Co2+ ions show an increased adsorption capacity towards ethane, which exceEDX the capacity measured for the Zn2+-based samples, while the highest methane adsorption value is achieved on a "core-shell" ZIF-67@ZIF-8 composite. [ABSTRACT FROM AUTHOR]

Chromium and molybdenum incorporated MgO and MgO–C catalysts were synthesized for hydrogen production from a non-oxidative ethane dehydration reaction. Hydrogen production studies were carried out using a microwave-heated reactor system. The study investigated the effects of reaction temperature, type of active metal, and catalyst preparation method (physical mixture or core–shell structure) on hydrogen selectivity and ethane conversion during dehydrogenation reactions. The results showed that the optimal reaction temperature for the non-oxidative ethane dehydration reaction was 450 °C. Above this temperature, the selectivity of undesired byproducts increased. Catalysts containing molybdenum exhibited higher ethane conversion. Moreover, a comparison of MgO–C-supported catalysts with MgO-supported catalysts revealed that the core–shell catalysts exhibited superior ethane conversion. Notably, the 5Mo@MgO–C catalyst demonstrated exceptional catalytic activity, achieving a high ethane conversion rate of 72% along with excellent stability. [ABSTRACT FROM AUTHOR]

Biodegradation of 1,4-Dioxane at environmentally relevant concentrations usually requires the addition of a primary electron-donor substrate to sustain biomass growth. Ethane is a promising substrate, since it is available as a degradation product of 1,4-Dioxane's common co-contaminants. This study reports kinetic parameters for ethane biodegradation and co-oxidations of ethane and 1,4-Dioxane. Based on experiments combined with mathematical modeling, we found that ethane promoted 1,4-Dioxane biodegradation when the initial mass ratio of ethane:1,4-Dioxane was < 9:1 mg COD/mg COD, while it inhibited 1,4-Dioxane degradation when the ratio was > 9:1. A model-independent estimator was used for kinetic-parameter estimation, and all parameter values for 1,4-Dioxane were consistent with literature-reported ranges. Estimated parameters support competitive inhibition between ethane as the primary substrate and 1,4-Dioxane as the secondary substrate. The results also support that bacteria that co-oxidize ethane and 1,4-Dioxane had a competitive advantage over bacteria that can use only one of the two substrates. The minimum concentration of ethane to sustain ethane-oxidizing bacteria and ethane and 1,4-Dioxane-co-oxidizing bacteria was 0.09 mg COD/L, which is approximately 20-fold lower than the minimum concentration reported for propane, another common substrate used to promote 1,4-Dioxane biodegradation. The minimum 1,4-Dioxane concentration required to sustain steady-state biomass with 1,4-Dioxane as the sole primary substrate was 1.3 mg COD/L. As 1,4-Dioxane concentrations at most groundwater sites are less than 0.18 mg COD/L, providing ethane as a primary substrate is vital to support biomass growth and consequently enable 1,4-Dioxane bioremediation. [ABSTRACT FROM AUTHOR]

Photocatalytic CH4 coupling into high-valued C2H6 is highly attractive, whereas the photosynthetic rate, especially under oxygen-free system, is still unsatisfying. Here, we designed the negatively charged metal supported on metal oxide nanosheets to activate the inert C–H bond in CH4 and hence accelerate CH4 coupling performance. As an example, the synthetic Au/ZnO porous nanosheets exhibit the C2H6 photosynthetic rate of 1,121.6 µmol gcat−1 h−1 and the CH4 conversion rate of 2,374.6 µmol gcat−1 h−1 under oxygen-free system, 2 orders of magnitude higher than those of previously reported photocatalysts. By virtue of several in situ spectroscopic techniques, it is established that the generated Auδ− and O− species together polarized the C–H bond, while the Auδ− and O− species jointly stabilized the CH3 intermediates, which favored the coupling of CH3 intermediate to photosynthesize C2H6 instead of overoxidation into COx. Thus, the design of dual active species is beneficial for achieving high-efficient CH4-to-C2H6 photoconversion. [ABSTRACT FROM AUTHOR]

The efficient conversion of ethane has attracted more and more attention because of the shale gas revolution. The coupling of ethane dehydrogenation (EDH) and benzene alkylation over the 1.5Pt/HZSM-5 realize high activity close to the thermodynamic equilibrium of EDH at 500 ℃ and 0.9 bar ethane partial pressure. Meanwhile, the coupled reaction shows long-term stability during 22 h with a slightly decreased ethane conversion of 0.03% per hour and as high as 42% selectivity of ethylbenzene. Based on various characterization, including XRD, HR-TEM, NH3-TPD, Py-IR, TGA, it is confirmed that the coupling reaction could convert ethylene, formed by EDH over Pt sites, to ethylbenzene via benzene alkylation over Brönsted acidic sites (BAS) subsequently, and suppressing the sintering of Pt species and coke deposition induced by aromatization and deep dehydrogenation, resulting in high activity and long-time steady state. [ABSTRACT FROM AUTHOR]

A system of mutually consistent equations for ethane is developed that describes pressure , vapor density , liquid density , derivative , and heat of vaporization on the phase equilibrium line in the range of the triple point to the critical point. The system also includes apparent heat of vaporization , which is associated with heat of vaporization : . It is established on the basis of the thermodynamic analysis that (1) the condition of average diameter is fulfilled at each point of the saturation line except for the critical point, at which , and (2) the average diameter is reduced sharply in the interval of . The system of mutually consistent equations reproduces the phase equilibrium line of ethane within the experimental uncertainty data of Funke et al. (2002) in the range of the triple point ( , , ) to the critical point ( , , ). It also reproduces features of the critical point in accordance with the renormalization group (RG) theory developed by Zhou et al. (2022) for a system of asymmetric systems. Based on the Clausius–Clapeyron equation and renormalization group theory, an expression is obtained for the apparent heat of vaporization. Analysis of average diameter for two groups of complexes shows that (a) , , and , and (b) , , and , which correspond to values , , and obtained by Wang et al. (2013) in the RG theory and the modeling of experimental data for ethane on the saturation line. Based on the proposed system of mutually consistent equations, average diameter of ethane is found for complexes (a) and (b), and it is established that the average diameter determined on the basis of data by Funke et al. (2002) is given most accurately by the system of mutually consistent equations in the range of to with parameters , , and . [ABSTRACT FROM AUTHOR]

We studied the C–H activation of ethane on the palladium (Pd) atomic clusters at the CCSD(T)/TZ//B3LYP/DZ level of theory, where TZ and DZ denote the LANL2 valence triple-ζ and double-ζ basis sets that include a relativistic pseudopotential for the Pd core electrons. In this study, we globally optimized first the Pdn clusters (n = 1–8) and then the transition state (TS) structures of Pdn + C2H6 → H−Pdn−C2H5. For each cluster size, we studied four spin states (S = 0, 1, 2, 3). The Pd atom is in the singlet electronic state ([Kr]4d10) at the CCSD(T) level. The CCSD(T) global minima of the Pd3, Pd7, and Pd8 clusters are also in the singlet electronic state, whereas the CCSD(T) global minima of Pd2, Pd4, Pd5, and Pd6 are in the triplet electronic state. The atomization energy of Pdn increases monotonically with the cluster size. Pd4 and Pd6 are particularly stable relative to their neighboring sizes. Among all sizes, Pd4 is the least active toward the C–H bonds in ethane, followed by sizes 5, 7, 3, and 1, whereas Pd2, Pd6, and Pd8 are the most active: the enthalpy of activation of the Pdn + C2H6 → H−Pdn−C2H5 reaction at room temperature are –29, –21, and 8 kJ/mol at these three sizes, respectively, indicating their strong ability to activate ethane. Among these three sizes, Pd2 is highly unstable and thus less ideal. Pd6 and Pd8 are both energetically stable and active toward the C–H bonds of ethane. [ABSTRACT FROM AUTHOR]

The existing fundamental similarities in the chemistry of structurally related carbon and silicon compounds have been demonstrated. Stable silicon analogs of ethylene, silenes or silaethylenes R2C=SiR2 and disilenes R2Si=SiR2, as well as ethyne (acetylene) analogs, disilynes RSi≡SiR, have been considered. A number of unique branched (bulky) organic and organosilicon substituents have been described; the introduction of such substituents to double- or triple-bonded silicon atoms makes it possible to protect the latter from the action of atmospheric oxygen and moisture and prevent secondary dimerization (oligomerization) processes. Examples are given of steric protection for obtaining kinetically stable unsaturated silicon compounds which were characterized by IR, NMR, and UV-Vis spectroscopy and X-ray analysis. [ABSTRACT FROM AUTHOR]

A series of cobalt doped hexagonal mesoporous silica (Co-HMS) with the different hydrothermal time was prepared by direct hydrothermal method and applied for oxidative dehydrogenation (ODH) reaction of ethane with carbon dioxide. Structural and chemical properties of the catalysts were characterized by nitrogen adsorption, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), electron dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Raman and ultraviolet–visible (UV–vis) spectroscopy. These characterizations showed that cobalt not only entered the framework of Co-HMS catalysts but also was evenly dispersed in the bulk. The valence state and coordination mode of cobalt played an important role in the whole ODH reaction system of ethane with carbon dioxide. 1%Co-HMS (1 h) with dominant Co2+ had the highest conversion of ethane (26.0%). The formation of tetrahedral coordination Co2+(Td) is beneficial to the breaking of ethane hydrocarbon bond and the improvement of ethylene selectivity. 1%Co-HMS (1 h) with more Co2+(Td) performed the highest ethylene selectivity of 92.6%, which was stable during the 10 h reaction time. [ABSTRACT FROM AUTHOR]

A series of cobalt doped hexagonal mesoporous silica (Co-HMS) with the different hydrothermal time was prepared by direct hydrothermal method and applied for oxidative dehydrogenation (ODH) reaction of ethane with carbon dioxide. Structural and chemical properties of the catalysts were characterized by nitrogen adsorption, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), electron dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Raman and ultraviolet–visible (UV–vis) spectroscopy. These characterizations showed that cobalt not only entered the framework of Co-HMS catalysts but also was evenly dispersed in the bulk. The valence state and coordination mode of cobalt played an important role in the whole ODH reaction system of ethane with carbon dioxide. 1%Co-HMS (1 h) with dominant Co2+ had the highest conversion of ethane (26.0%). The formation of tetrahedral coordination Co2+(Td) is beneficial to the breaking of ethane hydrocarbon bond and the improvement of ethylene selectivity. 1%Co-HMS (1 h) with more Co2+(Td) performed the highest ethylene selectivity of 92.6%, which was stable during the 10 h reaction time. [ABSTRACT FROM AUTHOR]

This article is devoted to the study of natural gas production by such methods as hydraulic fracturing, drilling, and underwater extraction. The authors analyzed the dynamics of gas production in Russia from old and new wells, as well as recovered from inactive wells, during the period from 2012 to 2021. Mathematical models have been selected to accurately represent the changes in the parameters under study. A forecast for natural gas production in 2025 has also been made, indicating an increase in natural gas production through hydraulic fracturing, drilling, and underwater extraction methods. [ABSTRACT FROM AUTHOR]

Comparative results of studying the oxidative dehydrogenation of ethane (ODE) on catalytic vanadium-phosphorus oxide systems deposited by the molecular layering method on the surface of oxide supports (Al2O3, SiO2) have been presented. It has been found that the highest activity in ODE and selectivity for ethylene are exhibited by vanadium-phosphorus-containing catalysts. The influence of the acidity of catalytic systems on the activity and selectivity of the process has been revealed. The selectivity of the ODE process for ethylene reaches 90%. An increase in the oxygen concentration in the initial mixture from 3.5 to 20% leads mainly to a decrease in the selectivity of the ODE process with respect to the ethylene yield. [ABSTRACT FROM AUTHOR]

The process of oxidative dehydrogenation of ethane (ODE) at an elevated pressure over a MoVNbTeOx mixed oxide catalyst is studied. It is found that when the reaction is carried out at 280°C, the fraction of the total amount of reacted oxygen consumed for the formation of ethylene decreases from 100 to 68% with the increase in pressure from 0.1 to 10.0 MPa, which may indicate an increase in the role of chemisorbed oxygen in the ODE process at a high pressure. Here, the productivity with respect to ethylene at 280°C and 10.0 MPa is higher in comparison with the value obtained at 360°C and 0.1 MPa. [ABSTRACT FROM AUTHOR]

Co/Al2O3 catalysts with different Co loadings and different calcination temperatures exhibit totally various catalytic performances for ethane dehydrogenation. At lower loadings, isolated Co2+ species in the framework of CoAl2O4 formed via strong interaction between Co and alumina leads to selective activation of C–H bond and the resulting high selectivity to ethylene. While a higher Co loading with the formation of aggregated metallic Co species through the in-situ reduction of Co3O4 on the catalyst surface results in C–C bond cracking to methane. Moreover, given the results of structural characterization and activity test, the increased calcination temperature enhances the interaction between Co species and alumina and facilitates the formation of CoAl2O4 even at a relatively high Co loading of 5%, contributing to the significant improvement of the catalytic behavior from undesired C–C bond breakage to C–H bond rupture. [ABSTRACT FROM AUTHOR]

Redox conversion of ethane at 600 °C on Mo-containing oxide systems differing in the composition and preparation method was studied. The ethane conversion and the selectivity of the ethylene formation increase in the series of MoO3 samples supported on SiO2 (silica gel), TiO2 (anatase), and alumina. The efficiency of the MoO3/Al2O3 systems increased when HNO3 was added to a (NH4)6Mo7O24 solution used to impregnate the support, and also when γ-Al2O3 was replaced with Al(OH)3. Gallium oxide additives improve the properties of the MoO3/Al2O3 system, increasing the ethane conversion to 44% at ethylene formation selectivity of more than 96%. The systems under consideration are characterized by high stability and retain their activity after five reaction—regeneration cycles. Based on the data obtained during the reaction of ethane with the Mo systems and in the course of regeneration of the reduced samples with oxygen, the content of active oxygen corresponding to the MoO3 ↔ MoO2 transformation was assessed. [ABSTRACT FROM AUTHOR]

The thermal pyrolysis of ethane and propane at a pressure of 1–3 atm was experimentally studied in a through-flow reactor. Kinetic modeling of the process under these conditions showed good agreement with experimental data in terms of both the conversion of alkanes and the yield of pyrolysis products, which allowed us to expand the modeling range of pressure. The results obtained show that the pressure change in the range of 1–15 atm has no noticeable effect on the pyrolysis of light alkanes. On this basis, we concluded that the previously established effect of pressure on the oxidative cracking of ethane was associated with its effect on the oxidative stages of the process. [ABSTRACT FROM AUTHOR]

The rapid deactivation caused by coke deposits is the major obstacle to the ethane aromatization of Zn-based catalysts. We have successfully synthesized a Zn-embedded inside HZSM-5 crystal catalyst (Zn@HZSM-5) by hydrothermal synthesis using preformed Zn/SiO2 as the only silicone source. Based on various characterization results, including in situ etching XPS, operando DRIFTS, as well as NMR, it is found that Zn(OH)+ and [Zn–O–Zn]2+ species are active sites for ethane aromatization for zinc-based catalysts, and their dynamic transformation significantly changes reaction performance of ethane dehydrogenation. For the Zn/HZSM-5 catalyst, the existence of a large number of [Zn–O–Zn]2+ species causes higher initial ethane conversion and higher selectivity of aromatics, resulting in a large amount of coke deposits. Moreover, [Zn–O–Zn]2+ species on the Zn/HZSM-5 catalyst fast transit to Zn(OH)+ species and subsequently form the sintered ZnO species, leading to rapid deactivation. For the Zn@HZSM-5 catalyst, the embedded structure contributes to forming more Zn(OH)+ species and delays the transformation of the Zn(OH)+ species to [Zn–O–Zn]2+ species, resulting in slowly increased selectivity of aromatics during the reaction. Therefore, the Zn@HZSM-5 catalyst realizes stable ethane conversion with dynamic selectivity. [ABSTRACT FROM AUTHOR]

In order to have an economic absorption process design with the lowest energy consumption, it is necessary to measure the solubility of the gas in the desired solvent and evaluate its non-ideality at different operating conditions. Thermodynamic modeling is also used to predict solubility so that it can be used with good confidence in a wide range of temperature and pressure. For this purpose, the solubility of pure ethane gas in N-methyl-2-pyrrolidone (NMP) solvent at different temperatures (278.1, 298.1, and 328.1 K) and different pressures up to 14 bars was investigated using a batch stirred experimental absorption pressure decaying setup. The kinetic and equilibrium data of the absorption including the solubility coefficient, heat of absorption, entropy, and Gibbs free energy changes were calculated at different temperatures. Then, the solubility was predicted after adjusting the binary interaction parameters using ϕ - ϕ and ϕ - γ approaches by implementing PR-EOS, Wilson and UNIQUAC activity coefficient models. The absolute mean deviations produced by the models were less than 18.5% for PR-PR, less than 12.3% for PR-Wilson, and less than 12.0% for PR-UNIQUAC, indicating the reliability of these thermodynamic models for the present chemical system. [ABSTRACT FROM AUTHOR]

Membrane technologies are widely used in various modern technological processes. In the chemical industry, membranes are used to solve several problems from increasing the efficiency of targeted processes to ensuring strict environmental legislation. A special synergistic effect is expected in the field of membrane catalysis when it becomes possible not only to accelerate the main reaction using a catalyst affecting the kinetics of the process but also shift the reaction equilibrium toward the products due to the membrane separation of one or more products from the main reaction volume. This advantage of membrane catalytic technologies is especially in demand for endothermic processes. This mini review is devoted to the dehydrogenation of hydrocarbons exemplified by the production of the high demand monomers ethylene, propylene, and styrene and the dehydrogenation of alcohols exemplified by methanol as a key compound of the C1 chemistry. [ABSTRACT FROM AUTHOR]

The results of an experimental study of the partial oxidation of ethane in the temperature range 773–1023 K and at pressures of 1 and 2 atm in a flow reactor with chromatographic analysis of the gas mixture were presented. Oxygen and nitrogen were used as an oxidizer and carrier gas, respectively. The excess fuel ratio was varied from 7.0 to 15.3. Numerical simulation with a detailed description of the complex kinetics of ethane oxidation was performed. The necessity of taking into account heterogeneous processes on the reactor surface under these conditions was shown and a method for this was proposed. When the detailed gas-phase mechanisms of ethane oxidation are complemented with stages describing heterogeneous processes on the surface of the quartz reactor, the results of numerical modeling are in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

One of the most active and high-selective catalytic systems for oxidative dehydrogenation of ethane is the MoVNbTeOx catalyst. However, this catalytic system has the low thermal stability and is prone to deactivation at temperatures above 350 °C. At the first time it was proposed to use oxygen ((Tcr = –119 °C, Pcr = 48 atm) and ethane (Tcr = 32 °C, Pcr = 51 atm) in supercritical state in the oxidative dehydrogenation process. Carrying out the process at supercritical conditions (T = 240–300 °C, P = 60–100 atm) leads to high selectivity up to 90% for ethylene under growth conversion of ethane and oxygen. At the same time, it manages to keep M1 phase crystallinity unchanged throughout the experiment (more than 40 h). Dependences of ethylene productivity on pressure (Reaction conditions: T = 280 °C, C2H6:O2:N2 = 31:23:46, 2 g of catalyst, the density of the reagent mixture varies from 0.65 (at 1 atm) to 63.15 kg/m3 (at 100 atm) [ABSTRACT FROM AUTHOR]

The conversion of methane–ethane, methane–ethylene, hydrogen–ethane, and hydrogen–ethylene mixtures on an electrically heated resistive fechral catalyst is studied. In the course of conversion, the catalyst surface is covered with graphite-like carbon deposits that have an additional catalytic effect resulting in the formation of C3 and C4 hydrocarbons. The latter are apparently formed with participation of ethylene formed from ethane. Hydrogen suppresses coking on the catalyst's surface and reduces the yield of C3 and C4 hydrocarbons. [ABSTRACT FROM AUTHOR]

An effect of hydrogen additions to the initial mixture on the parameters of the oxidative cracking of propane at atmospheric pressure, temperatures of 500–750°C, reaction time of 2 s, and С3H8/О2 initial ratio ~2 was experimentally investigated. It was shown that small amounts of hydrogen promote the process due to the formation of additional active radicals OH• and H•. Performance of the oxidative cracking of propane in a large excess of hydrogen results in an increase in the yield of methane and ethane, while the yield of ethylene, the target product of the process, decreases. [ABSTRACT FROM AUTHOR]

Owing to the similar physicochemical properties between ethane (C2H6) and ethylene (C2H4), obtaining polymerization-grade C2H4 (≥99.95% pure) is still tricky problem in the petrochemical industry. Here, we report a robust scandium-based metal-organic framework (ScBPDC), which is connected by oxygen-rich phenyl ligand with exceptionally high thermal stability (up to 873 K) and capacity of C2H6 (4.94 mmol/g at 100 kPa and 283 K), exhibiting superior separation performance of C2H6/C2H4 mixture (the IAST selectivity is up to 1.7 at 283 K). Importantly, ScBPDC can produce 8.96 L/kg C2H4 with ≥99.99% purity while the C2H4/C2H6 (50:50, v/v) as the mixture injection and the low isosteric heat of ScBPDC (16.4 kJ/mol for C2H6) validates the facility of adsorbent regeneration. Furthermore, theoretical calculations demonstrate the C2H6 molecules are trapped in the nonpolar pore surface via C-H⋯π and C-H⋯O interactions between multiple hydrogen atoms of C2H6 and the host framework. [ABSTRACT FROM AUTHOR]

A comparative study of the catalytic properties for the oxidation of C2-C3 alkanes and olefins has been carried out over unpromoted and M-promoted NiO catalysts (Me = K, La, Ce, al, Zr, Sn, Nb). The catalysts have been characterized by several physico-chemical techniques (UV Raman, Visible Raman, FTIR of adsorbed CO and XPS). The characteristics of promoter elements are of paramount importance, since they are able to modify both the nature of the active nickel and the concentration of electrophilic O2−/O− oxygen species. Thus, a relatively high acidity and valence of the promoter oxide (with oxidation state higher than + 3) are necessary to achieve high selectivity to olefins during the oxidative dehydrogenation (ODH) of C2–C3 alkanes. In addition, an inverse correlation between the selectivity to the corresponding olefin and the concentration of electrophilic oxygen species has been observed, although the selectivity to propene during propane ODH is lower than the selectivity to ethylene achieved during ethane ODH. On the other hand, a very low influence of alkane conversion on the selectivity to the corresponding olefins is observed. This behaviour can be explained by considering that the reaction rate for olefin combustion is lower than the reaction rate for alkane oxidation. However, the comparative study of the oxidation of alkanes and olefins suggest that the differences observed between the ODH of propane and ethane are not related to the reactivity of olefins, but to the different number and reactivity of C–H bonds in both alkanes. A discussion on the importance of the concentration of active sites and the characteristics of the alkanes fed on the selectivity to olefin during the alkane ODH is also presented. [ABSTRACT FROM AUTHOR]

A simple synthesis of 1,2-bis(2,6-dimethylphenylphosphino)ethane is reported. Synthesis involves reaction of in situ prepared lithium salt of 2-bromo-m-xylene with 1,2-bis(dichlorophosphino)ethane in diethylether. The title compound, [C34H40P2], crystallized in the triclinic space group, P-1 with cell parameters: a = 6.977(5) b = 9.186(5) c = 11.629(5) Å, α = 109.880(5) β = 92.993(5) γ = 94.362(5)°, V = 696.4(7) A3, Z = 1. The compound has been characterized by NMR and single crystal X-ray crystal structure analysis and the purity was confirmed by elemental analysis. The solid state data were also calculated by DFT. A simple synthesis and structure of 1,2-bis(2,6-dimethylphenylphosphino) ethane, an important but missing member of the phosphine ligand family is reported. [ABSTRACT FROM AUTHOR]

The need for on-purpose techniques for the conversion of cheaper and abundant light alkanes to petrochemical products has revitalized research interests on light alkanes aromatization. Here ethane/propane aromatization and ethylene oligomerization over the representative Zn-HZSM-5 and Pt/HZSM-5 catalysts have been studied by the step-perturbation transients to provide insight into the kinetics and mechanisms leading to higher olefins and aromatics formation from ethane aromatization. The time-dependent catalytic behavior during the build-up and back-transient between ethane and inert, ethane and propane, as well as ethylene and inert, has been extensively discussed. We suggested that the hydrocarbon-pool mechanism be involved once ethylene was produced from the dehydrogenation of ethane. The oligomerization/cracking, cyclization, and dehydrogenation/hydride transfer reactions involved with the hydrocarbon-pool species reach the thermodynamic equilibrium quickly. The initial ethane dehydrogenation and the final formation of aromatics from their corresponding intermediates are slow surface-reactions. The rate constants k for benzene, toluene, and xylene formation from the "lumped hydrocarbon-pool" have been evaluated based on the first-order kinetic model of the back-transient. The rate constants k for aromatics over the Pt0 clusters/particles in the Pt/HZSM-5 are ⁓ 20–30% higher than that over the Zn (II) cations in the Zn-HZSM-5 catalyst. [ABSTRACT FROM AUTHOR]

Using the main statements of the Dubinin theory of volume filling of micropores (TVFM) the amount of adsorbed ethane was estimated at pressures up to 4 MPa in the temperature range lower and higher than the critical temperature (303–333 K) on the superactive microporous carbon adsorbent with the bimodal micropore size distribution and a total micropore volume of 1.44 cm3 g−1. Two approaches were applied for comparison of the accuracy of calculations: the approach based on the calculation of "standard states" of adsorption and pressure and the approach taking into account the property of linearity of adsorption isosteres of gases in broad ranges of thermodynamic parameters. Both thermodynamic approaches showed good agreement of the results with experimental data and can be recommended for precalculations of adsorption equilibria of gases and vapors on the basis of the minimum physicochemical information about the adsorbent and adsorptive. The high agreement of the experimental and calculated data provides the basis for using the adsorption characteristics obtained in the framework of the TVFM for the calculation of differential molar isosteric heats of adsorption. [ABSTRACT FROM AUTHOR]

Silica-supported catalysts of cation composition V0,3Mo1Te0,23Nb0,12 are produced using slurry method with the nature of the initial compound for the support (TEOS, silica sol, silica gel, aerosil) being varied. The synthesized catalysts are characterized via nitrogen thermodesorption, chemical and X-ray analysis, and high resolution electron microscopy. Catalytic properties are studied in the reaction of ethane oxidative dehydeogenation at a temperature of 400°С in a reaction mixture with the composition С2Н6 : О2 : N2 = 10 : 10 : 80 (vol %). It is found that samples obtained with silica gel display the greatest activity, due to the formation of nanodomens of active phase M1 in the amorphous support matrix and its partial dispersion. [ABSTRACT FROM AUTHOR]

Cometabolic biodegradation of 1,4-dioxane (dioxane) in the presence of primary substrates is a promising strategy for treating dioxane at environmentally relevant concentrations. Seven aqueous amendments (i.e., tetrahydrofuran (THF), butanone, acetone, 1-butanol, 2-butanol, phenol and acetate) and five gaseous amendments (i.e., C1–C4 alkanes and ethylene) were evaluated as the primary substrates for dioxane degradation by mixed microbial consortia. The aqueous amendments were tested in microcosm bottles and the gaseous amendments were tested in a continuous-flow membrane biofilm reactor with hollow fibers pressurized by the gaseous amendments. Ethane was found to be the most effective gaseous substrate and THF was the only aqueous substrate that promoted dioxane degradation. A diverse microbial community consisting of several putative dioxane degraders—Mycobacterium, Flavobacterium and Bradyrhizobiaceae—were enriched in the presence of ethane. This is the first study showing that ethane was the most effective substrate among the short-chain alkanes and it promoted dioxane degradation by enriching dioxane-degraders that did not harbor the well-known dioxane/tetrahydrofuran monooxygenase. [ABSTRACT FROM AUTHOR]

The mechanism of C-H bond activation of ethane was catalyzed by palladium halide cations (PdX+ (X = F, Cl, Br, H, and CH3)), which was investigated using density functional theory (DFT) at B3LYP level. The reaction mechanism was taken into account in triplet and singlet spin state potential energy surfaces. For PdF+, PdCl+, and PdBr+, the high spin states were the ground states, whereas the ground states were the low spin states in PdH+ and PdCH3+. The reaction of PdF+, PdCl+, and PdBr+ with ethane occurred via a typical "two-state reactivity" mechanism. In contrast, for PdH+ and PdCH3+, the overall reaction performed on the ground state PESs in a spin-conserving manner. The crossing points between two potential energy surfaces were observed and effectively decreased the activation barrier in PdX+/C2H6 (X = F, Cl, and Br). The minimum energy crossing points (MECP) were obtained used the algorithm in Harvey method. The natural valence electron configuration calculations were analyzed by natural bond orbital. The distribution and contribution of the front molecular orbital of the initial complexes could be further understand by the density of states. The feature of the bonding evolution in the main pathways was studied using topological analysis including localized orbital locator and atoms in molecules. [ABSTRACT FROM AUTHOR]

It is shown that the method of synthesis and source of bismuth greatly affect the physicochemical properties of modified MoVTeNbO catalysts. Adding an organic bismuth compound with a neutral pH at the stage of mixing the solutions of the initial components is accompanied by precipitation and the formation of inactive phases when the required M1 phase is missing. Regardless of the nature of the initial bismuth compound, introducing it into a dry MoVTeNb precursor leads to considerable destruction of it, resulting in a lower content of the M1 phase and the formation of binary V–Mo and Te–Мo oxides. It has been established that the ethylene yield attains a maximum (76.5 %) in the oxidative ethane dehydrogenation (OED)reaction, when the calcined MoVTeNb oxide catalyst is impregnated with a bismuth organic compound solution. The yield of acrylic acid is ≈48% over the same catalyst in the reaction of propane oxidation. Introducing bismuth nitrate into a solution of the initial components is nevertheless a more technologically advanced way of preparing bismuth-containing catalysts. The maximum ethylene yield is ≈76% in the OED reaction over the catalyst obtained using bismuth nitrate. [ABSTRACT FROM AUTHOR]

Minimizing Pt loading in dehydroaromatization (DHA) catalysts is critical to the cost-efficient transformation of abundant light alkanes for energy and chemical production. Recent studies in our group show that Pt-Zn/HZSM-5 catalysts with Pt loading of 0.001–0.05 wt% (10–500 ppm) are highly active and stable for ethane DHA (J Am Chem Soc 144(26):11831–11839, 2022). Here, we investigated the catalytic behavior of such catalysts, especially with further decreased Pt loading (< 10 ppm), in both propane and ethane DHA. For propane DHA, we show that the bimetallic Pt-Zn/HZSM-5 catalysts with Pt loading of 50–500 ppm are significantly more active and/or stable than the monometallic counterparts. Such enhancement becomes less significant when decreasing Pt loading to ≤10 ppm. For ethane DHA, the mass-specific activity of the Pt-Zn/HZSM-5 catalysts decreases almost linearly with decreasing Pt loading from 10 to 2.5 ppm, indicating a constant molar-specific activity (TOF) of up to 132 s−1 (molethane/molPt). This breakthrough is achieved owing to the formation of [Pt1-Znn]δ+ ensemble in the micropores of ZSM-5 zeolite. [ABSTRACT FROM AUTHOR]

The concept of a new technology for obtaining ethylene from ethane was developed and implemented. In this technology, the process is performed in two separate apparatus, reactor and regenerator between which a microspherical catalyst containing active lattice oxygen is permanently circulating. In experiments carried out in a pilot unit with a fluidized bed of the microspherical catalyst and separate delivery of the raw material and oxidizing agent, the following process parameters of the oxidative dehydrogenation of ethane into ethylene were reached: degree of ethane conversion, 35–47.5 wt %; selectivity 86–89%, and output capacity (yield of ethylene) 0.93–1.17 kg of ethylene per hour per kg of the catalyst. The technology being developed has a number of advantages over the conventional pyrolysis: higher formation selectivity of the target product, lowered process temperature, continuity, ecological safety, and lower capital expenditure. [ABSTRACT FROM AUTHOR]

A microporous carbon adsorbent MPU-007 with a wide pore size distribution (specific micropore volume W0 calculated within the framework of the theory of micropore volume filling is 1.44 cm3 g−1; first-mode micropore diameter X01 is 1.5 nm; second-mode micropore diameter X02 is 3.5 nm; specific surface area SBET is 2520 m2 g−1) was prepared by chemical activation of a mixture of corn dextrin, ethylene glycol, and phenol formaldehyde resin. Adsorption of ethane on this adsorbent was studied at pressures up to 4 MPa at T = 303, 313, 323, and 333 K. The maximum ethane adsorption value attained in the experiments was 25 mmol g−1 or 75 wt%. The adsorption isosteres plotted in the ln P–1/T coordinates using the data obtained can be well approximated by linear functions at constant adsorption values. The dependences of the differential molar isosteric heats of adsorption of ethane on MPU-007 on the amount adsorbed in the temperature range of 303–333 K were calculated. The heat of adsorption of ethane equal to 23 kJ mol−1 remained constant throughout the initial range of micropore fillings up to ∼7 mmol g−1 and then gradually decreased to 8 kJ mol−1 at an uptake of 24 mmol g−1 at 333 K. Such a pattern of the dependence of the heat of adsorption can be due to a wide pore size distribution and to the formation of associates in the adsorbate. [ABSTRACT FROM AUTHOR]

The effect of selenium additives on the structure, physicochemical, and catalytic properties of VMoTeNbO catalysts in the oxidative dehydrogenation of ethane was studied. It was shown that the introduction of selenium on the first stage of catalyst preparation (mixing of the initial solutions) makes it possible to obtain in the course of subsequent heat treatment highly crystallized samples, which mainly include the M1 phase. Despite the fact that, in the process of heat treatment, selenium is completely removed from the samples, the prepared catalysts differ markedly from unmodified samples and demonstrate a higher selectivity to ethylene at a conversion of ethane of 93%. The observed effects are due to the influence of selenium on the process of formation of the M1 phase resulting in increase of its crystallinity. [ABSTRACT FROM AUTHOR]

Cr/MgO(x)–CeO2(100−x) nanocatalysts were synthesized by a coprecipitation method and characterized by X-ray diffraction (XRD) analysis, field-emission scanning electron microscopy (FESEM), energy-dispersive x-ray (EDX) spectroscopy, diffuse reflectance spectroscopy (DRS), and Brunauer–Emmett–Teller (BET) analysis. The effect of ceria addition on their physicochemical characteristics was investigated, and the results were correlated with their catalytic performance in oxidative dehydrogenation of ethane. A decrease in the size of the metal particles was found when adding a suitable content of ceria to the support. Crystalline Cr2O3 was not found in the calcined samples, indicating good dispersion of Cr species on the support. All samples showed nanosized particles with uniform morphology, with the best surface morphology for the Cr/MgO(50)–CeO2(50) sample, on which the particle distribution mainly lay in the range of 40–60 nm. Variation of the amount of Ce in the support led to an enhancement of the Cr6+/Cr3+ ratio, with the highest value for the Cr/MgO(50)–CeO2(50) sample. This catalyst effectively dehydrogenated ethane to ethylene with CO2 at 700 °C even after 5 h on-stream, giving 42.76 % ethylene yield. [ABSTRACT FROM AUTHOR]

Comparative studies of oxidative transformations of ethane and ethylene were performed on multi-component oxide catalysts of the preset cationic composition, V0.3Mo1Te0.23Nb0.12, differing in the final calcination temperature. The highest (∼74%) ethylene yield in oxidative dehydrogenation of ethane is reached on the catalysts calcined in the temperature interval 550–650°C, which is due to the formation of the maximal amount of the active M1 phase. [ABSTRACT FROM AUTHOR]

The present work aims to investigate the possibility of substituting ethane, usually used as pyrolysis feedstock, by the Algerian gas condensate compounded with ethane. Several experiments have been setup using different percentage dilutions (5, 10, and 20%) of Algerian gas condensate and its fractions (light, medium and heavy) compounded with ethane. The impacts of temperature, steam flow and flows of material on the yield and composition of pyrolysis products have also been investigated. High yields of ethylene (19 to 36%) and propylene (9 to 20%) were obtained in the pyrogas. The present study demonstrates the potential of the Algerian gas condensate product which can be valorized and used to enhance the yields of ethylene and propylene used in the production process of polyethylene and polypropylene. [ABSTRACT FROM AUTHOR]

Abstract—: This paper presents a study of oxidative dehydrogenation of ethane (ODHE) on nanostructured single-component and multicomponent catalysts based on V5+, Mo5+, and Nb5+ oxides and produced on alumina by molecular layering. It has been shown that the molybdenum-containing catalysts exhibit higher activity for ODHE in both single-component and binary samples and ensure higher ethylene selectivity. We have demonstrated advantages of ODHE on membrane-catalyst systems in the form of asymmetric ceramic tubes, with catalysts placed inside of them. The membrane-catalyst systems produced by molecular layering offer considerably higher activity and selectivity in ODHE. [ABSTRACT FROM AUTHOR]

The upper flammability limit of ethane-air and ethane-oxygen mixtures was determined experimentally for various initial temperatures and pressures. In the experiments, the upper flammability limit increased with increasing initial temperature and pressure, which is consistent with literature data. The limit was determined in a closed vessel with central ignition. The obtained limit corresponds to the quenching of the flame propagating downward after its rise under the action of the Archimedes force. [ABSTRACT FROM AUTHOR]

Oxydative dehydrogenation of ethane to ethelene over Ga-, Fe- and Cr-oxide systems has been investigated. CO2 was used as an oxidizing agent. The activity and stability of the synthesized catalysts were studied. The most efficient catalytic system was selected and the experimental conditions for the optimal conversion/selectivity ratio were found. [ABSTRACT FROM AUTHOR]

Abstract: The oxygen-assisted dehydrogenation of ethane at 650 °C shows that adding Sn to the Pt catalyst results in increased conversion and selectivity to ethylene. Even the smallest amount of tin (0.16 wt%) has a significant effect. The addition of tin also increases the stability of the Pt/Al2O3 catalyst, in particular it reduces the amount of carbon or carbonaceous species. Adding hydrogen to the feed had a remarkable effect on the selectivity, but the conversion of ethane was almost unaffected for Pt-Sn catalysts. The selectivity to ethylene increased substantially and the selectivity to CO/CO2 decreased even for the smallest amount of tin used. Unexpected values for the selectivity to other compounds were also observed, in particular for the selectivity to acetylene. The importance of possible Pt-Sn alloys or the necessity of contact between Pt and Sn was studied using a physical mixture of Pt/Al2O3 and Sn/Al2O3. However, almost the same effect was obtained by using the physical mixture as with the co-impregnated sample, i.e. the Pt-Sn catalysts.Graphical Abstract: Selectivity of ethylene for the monometallic catalyst, the physical mixture and the coimpregnated catalyst. [ABSTRACT FROM AUTHOR]

The partial oxidation of ethane to ethylene and acetic acid on supported MoVNbPd/TiO2 (P25 of Degussa) has been investigated. Pd was added in a nano-metallic form. The catalyst composition was also different from similar studied catalysts. This results in a better selectivity towards acetic acid formation. The reaction was carried out in a tubular reactor at temperature range 225-275 °C, total pressure range 0-200 psig and oxygen percentage in the feed gas of 10-40%. The feed gas contains ethane and oxygen. In this work, we develop a kinetic model for the reaction for the developed catalyst. In this model, we assume that oxidation reactions take place on different sites; ethane oxidation takes place on one site, ethylene oxidation on another site, and CO is oxidized to CO2 on a third site. The model exhibits good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

The objective of this research was to evaluate the potential for two gases, methane and ethane, to stimulate the biological degradation of 1,4-dioxane (1,4-D) in groundwater aquifers via aerobic cometabolism. Experiments with aquifer microcosms, enrichment cultures from aquifers, mesophilic pure cultures, and purified enzyme (soluble methane monooxygenase; sMMO) were conducted. During an aquifer microcosm study, ethane was observed to stimulate the aerobic biodegradation of 1,4-D. An ethane-oxidizing enrichment culture from these samples, and a pure culture capable of growing on ethane ( Mycobacterium sphagni ENV482) that was isolated from a different aquifer also biodegraded 1,4-D. Unlike ethane, methane was not observed to appreciably stimulate the biodegradation of 1,4-D in aquifer microcosms or in methane-oxidizing mixed cultures enriched from two different aquifers. Three different pure cultures of mesophilic methanotrophs also did not degrade 1,4-D, although each rapidly oxidized 1,1,2-trichloroethene (TCE). Subsequent studies showed that 1,4-D is not a substrate for purified sMMO enzyme from Methylosinus trichosporium OB3b, at least not at the concentrations evaluated, which significantly exceeded those typically observed at contaminated sites. Thus, our data indicate that ethane, which is a common daughter product of the biotic or abiotic reductive dechlorination of chlorinated ethanes and ethenes, may serve as a substrate to enhance 1,4-D degradation in aquifers, particularly in zones where these products mix with aerobic groundwater. It may also be possible to stimulate 1,4-D biodegradation in an aerobic aquifer through addition of ethane gas. Conversely, our results suggest that methane may have limited importance in natural attenuation or for enhancing biodegradation of 1,4-D in groundwater environments. [ABSTRACT FROM AUTHOR]

Unmodified and sulfate-modified SBA-15-supported CrO catalysts were prepared by impregnation method. The physico-chemical properties of the supports and catalysts were determined by nitrogen adsorption/desorption, powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), laser-Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (UV-DRS), inductively coupled plasma optical emission spectroscopy (ICP-OES), transmission electron microscopy (TEM) and temperature-programmed reduction (TPR) techniques. Oxidative dehydrogenation of ethane to ethylene (ODE) with CO as oxidant was carried out on these catalysts in a fixed-bed reactor at temperatures in the range of 600-700 °C and at atmospheric pressure. The changes in structural and textural properties because of sulfate modification were identified. Sulfate modification affected the nature of interaction of CrO species with the SBA-15 support. During the evaluation, it was observed that sulfate modification enhances ethane conversion and ethylene selectivity of the catalyst. Better dispersion of CrO and the increase in Cr/Cr ratio seem to be the reasons for the higher performance of the sulfate-modified catalysts compared to that of the unmodified catalyst. [ABSTRACT FROM AUTHOR]