Butane Oxidation Research Articles

Back flux during anaerobic oxidation of butane support archaea-mediated alkanogenesis

Microbial formation and oxidation of volatile alkanes in anoxic environments significantly impacts biogeochemical cycles on Earth. The discovery of archaea oxidizing volatile alkanes via deeply branching methyl-coenzyme M reductase variants, dubbed alkyl-CoM reductases (ACR), prompted the hypothesis of archaea-catalysed alkane formation in nature (alkanogenesis). A combination of metabolic modelling, anaerobic physiology assays, and isotope labeling of Candidatus Syntrophoarchaeum archaea catalyzing the anaerobic oxidation of butane (AOB) show a back flux of CO2 to butane, demonstrating reversibility of the entire AOB pathway. Back fluxes correlate with thermodynamics and kinetics of the archaeal catabolic system. AOB reversibility supports a biological formation of butane, and generally of higher volatile alkanes, helping to explain the presence of isotopically light alkanes and deeply branching ACR genes in sedimentary basins isolated from gas reservoirs.

Nitrate-driven anaerobic oxidation of ethane and butane by bacteria.

The short-chain gaseous alkanes (ethane, propane, and butane; SCGAs) are important components of natural gas, yet their fate in environmental systems is poorly understood. Microbially mediated anaerobic oxidation of SCGAs coupled to nitrate reduction has been demonstrated for propane, but is yet to be shown for ethane or butane-despite being energetically feasible. Here we report two independent bacterial enrichments performing anaerobic ethane and butane oxidation, respectively, coupled to nitrate reduction to dinitrogen gas and ammonium. Isotopic 13C- and 15N-labelling experiments, mass and electron balance tests, and metabolite and meta-omics analyses collectively reveal that the recently described propane-oxidizing "Candidatus Alkanivorans nitratireducens" was also responsible for nitrate-dependent anaerobic oxidation of the SCGAs in both these enrichments. The complete genome of this species encodes alkylsuccinate synthase genes for the activation of ethane/butane via fumarate addition. Further substrate range tests confirm that "Ca. A. nitratireducens" is metabolically versatile, being able to degrade ethane, propane, and butane under anoxic conditions. Moreover, our study proves nitrate as an additional electron sink for ethane and butane in anaerobic environments, and for the first time demonstrates the use of the fumarate addition pathway in anaerobic ethane oxidation. These findings contribute to our understanding of microbial metabolism of SCGAs in anaerobic environments.

Anaerobic oxidation of ammonium and short-chain gaseous alkanes coupled to nitrate reduction by a bacterial consortium.

The bacterial species "Candidatus Alkanivorans nitratireducens" was recently demonstrated to mediate nitrate-dependent anaerobic oxidation of short-chain gaseous alkanes (SCGAs). In previous bioreactor enrichment studies, the species appeared to reduce nitrate in two phases, switching from denitrification to dissimilatory nitrate reduction to ammonium (DNRA) in response to nitrite accumulation. The regulation of this switch or the nature of potential syntrophic partnerships with other microorganisms remains unclear. Here, we describe anaerobic multispecies cultures of bacteria that couple the oxidation of propane and butane to nitrate reduction and the oxidation of ammonium (anammox). Batch tests with 15N-isotope labelling and multi-omic analyses collectively supported a syntrophic partnership between "Ca. A. nitratireducens" and anammox bacteria, with the former species mediating nitrate-driven oxidation of SCGAs, supplying the latter with nitrite for the oxidation of ammonium. The elimination of nitrite accumulation by the anammox substantially increased SCGA and nitrate consumption rates, whereas it suppressed DNRA. Removing ammonium supply led to its eventual production, the accumulation of nitrite, and the upregulation of DNRA gene expression for the abundant "Ca. A. nitratireducens". Increasing the supply of SCGA had a similar effect in promoting DNRA. Our results suggest that "Ca. A. nitratireducens" switches to DNRA to alleviate oxidative stress caused by nitrite accumulation, giving further insight into adaptability and ecology of this microorganism. Our findings also have important implications for the understanding of the fate of nitrogen and SCGAs in anaerobic environments.

Insight into the reactions of n-, iso-, sec- and tert-Butylperoxy radicals with hydroperoxyl radical in the Atmosphere: Reaction Mechanism, thermodynamic analysis and kinetics

Butylperoxy radical (C4H9O2) is recognized today as an important atmospheric intermediate which formed by the oxidation of butane (C4H10), playing a crucial role in the cycling of carbon. This work gives a theoretical investigation of the reaction mechanism, thermodynamic analysis and kinetics of the reactions between HO2 and four isomers (n-, iso-, sec- and tert-Butylperoxy radicals) of C4H9O2, which has been computed using the CCSD(T)/aug-cc-pVDZ//B3LYP/6-311G(d,p) level of theory. As a result, the above four reactions proceed on both singlet and triplet potential energy surfaces have been demonstrated. Additionally, the formation of alkylhydroperoxides and 3O2via triplet hydrogen abstraction from the four reactions are the major reaction channels while other singlet product channels are negligibly small. Besides, rate coefficients for the title reactions were estimated using the transition state theory (TST) over the temperature range 258 – 378 K, and these results exhibit a negative temperature dependence.

Phosphorus Dosing during Catalytic n-Butane Oxidation in a μ-Reactor: A Proof of Concept

Phosphorus Dosing during Catalytic <i>n</i>-Butane Oxidation in a μ-Reactor: A Proof of Concept

Decomposition and O&lt;sub&gt;3&lt;/sub&gt;-Catalytic Oxidation of &lt;i&gt;n-&lt;/i&gt;С&lt;sub&gt;4&lt;/sub&gt;Н&lt;sub&gt;10&lt;/sub&gt;

The activity of transition metal oxides (V, Cr, Mn, Fe, Co, Ni, Cu, Zn) deposited on γ-Al2O3 in the ozone decomposition reaction has been studied. The catalytic characteristics of samples with high (NiO/Al2O3), low (Cr2O3/Al2O3) and intermediate (MnOx/Al2O3) activity in ozone decomposition were studied in the process of ozone-catalytic oxidation (OZCO) of butane. The obtained results allow us to conclude that the optimal activity of transition metal oxide in the decomposition of O3 is of key importance in the OZCO process. At a low rate of ozone decomposition, the oxidation of hydrocarbons is limited by the rate of formation of atomic oxygen, in the case of too high - the conversion of hydrocarbons is reduced due to the “inappropriate” process of recombination of atomic oxygen. The best catalytic characteristics in the oxidation of h C4H10 have been established for a catalyst based on Mn oxide, which has optimal activity in the decomposition of O3.

Liquid-Phase Oxidation of Butene–Butane Mixtures with N2O to Ketones and Aldehydes

Conventional methods for the production of ketones and aldehydes are usually quite complicated and require the use of specific catalysts. Thus, methyl ethyl ketone (MEK) is currently manufactured through a two-step catalytic process involving the hydration of n-butenes and dehydration of the formed alcohol. The non-catalytic oxidation of olefins with nitrous oxide (N2O) via the 1,3-dipolar cycloaddition mechanism opens a potential route for the direct synthesis of carbonyl compounds. In this work, the oxidation of the commercial butene–butane mixture (BBM) with N2O in the liquid phase at 220–260 °C and elevated pressure was studied using the gas chromatography, gas chromatography–mass spectrometry, and nuclear magnetic resonance analytical methods. It was shown that only butene isomers in BBM are selectively oxidized by N2O to yield ketones and aldehydes with a total selectivity of up to 86.6%, including MEK as the major product. During oxidation, alkyl-substituted cyclopropanes are also formed from butenes with a selectivity of up to 15%.

Normal butane oxidation: Measurements of autoxidation products in a jet-stirred reactor

The autoxidation of n-butane was studied experimentally in a jet-stirred reactor at 1 atm (560–720 K) and 10 atm (530–1030 K) for an equivalence ratio of 1. Samples of reacting mixtures were analysed in the gas phase by gas chromatography (GC) using several detectors (Flame ionization detector, thermal conductivity detector, quadrupole mass spectrometer), hydrogen peroxide analyser, and Fourier transform infrared spectroscopy. In addition to the fuel and oxygen, 37 products were quantified. Liquid phase samples were obtained by trapping the reacting mixtures in cooled acetonitrile (273 K). The liquid samples were analysed by high resolution mass spectrometry (HRMS Orbitrap Q-Exactive), either after flow injection or separation by high pressure liquid chromatography (HPLC). Besides stable species, several other low-temperature oxidation products, such as hydroperoxides and ketohydroperoxides, were detected. Products of third O2 addition on fuel’s radicals were also detected by high resolution mass spectrometry. To assess the presence of hydroxyl or hydroperoxyl groups in the products of oxidation we performed H/D exchange with D2O. Qualitative and quantitative results showed the same trends in terms of variation of mole fractions and signal intensities versus reacting temperature. Kinetic modelling was performed using a literature detailed kinetic reaction mechanism already used to simulate previous n-butane oxidation experiments in the cool-flame regime, showing that improvements are needed to better describe the oxidation of n-butane under the present conditions.

Research of the oxidation process of N-Butane waste of “Sho’rtangazkimyo” LLC in heterogeneous catalysts

In the article, n-butane, which is a waste of “Shortangazkimyo” LLC, has a porosity of 33% obtained by reaction with potassium permanganate solution in aqueous solutions at temperatures above 100 ℃ and pressures above 1 atmosphere. In the presence of a catalyst containing xTiO2•(1-x)SiO2 (x=0.0001-0.04), the influence of concentration, the ratio of n-butane to potassium permanganate, solvent, temperature, pH and other factors on the rate of oxidation reaction was studied. The best solvent for oxidation of butane with potassium permanganate solution is ethyl alcohol, it provides maximum selectivity for the formation of butanone-2 and is stable under oxidative conditions. Increasing the ratio from 2:1 to 6:1 increases the butanone-2 yield from 28 to 44% and the selectivity from 50.7% to 63%. It was found that the productivity of butanone-2 (17%) and selectivity (20%) decreased in the ratio of n-butane, a waste product of “Shortangazkimyo” LLC, to potassium permanganate solution=1:2, which is related to the formation of a two-phase system. As the temperature increases from 50 ℃ to 90 ℃, the yield of butanone-2 increases from 13.4 % to 30.5 % and the conversion rate of potassium permanganate solution increases from 37 to 97 %. The dependence of the selectivity of potassium permanganate solution on butanone-2 is unusual with a maximum of 70 ℃ (54.15%). Thus, the conducted research allows us to conclude that the optimal conditions for the synthesis of butanone-2 are: temperature - 70 ℃; Catalyst concentration of xTiO2•(1-x)SiO2 (x=0.0001-0.04) with 33% porosity obtained by reaction in aqueous solutions at temperatures above 100 ℃ and pressures above 1 atmosphere is 38.99 g/l; The molar ratio of nbutane, which is a waste of "Sho’rtangazkimyo" LLC: potassium permanganate solution - 3:1; pH=7.

Novel Nanosized Spinel MnCoFeO4 for Low-Temperature Hydrocarbon Oxidation.

The present paper reports on MnCoFeO4 spinels with peculiar composition and their catalytic behavior in the reactions of complete oxidation of hydrocarbons. The samples were synthesized by solution combustion method with sucrose and citric acid as fuels. All samples were characterized by powder X-ray diffraction, N2-physisorption, scanning electron microscopy, thermal analysis, X-ray photoelectron spectroscopy, and Mössbauer spectroscopy. The catalytic properties of the spinels with Mn:Co:Fe = 1:1:1 composition were studied in reactions of complete oxidation of methane, propane, butane, and propane in the presence of water as model pollutants. Both prepared catalysts are nanosized materials. The slight difference in the compositions, structure, and morphology is due to the type of fuel used in the synthesis reaction. The spinel, prepared with sucrose, shows a higher specific surface area, pore volume, higher amount of small particles fraction, higher thermal stability, and as a result, more exposed active sites on the sample surface that lead to higher catalytic activity in the studied oxidation reactions. After the catalytic tests, both samples do not undergo any substantial phase and morphological changes; thus, they could be applied in low-temperature hydrocarbon oxidation reactions.

Correction to “Improved Kinetics of n-Butane Oxidation to Maleic Anhydride: The Role of Byproducts”

Correction to “Improved Kinetics of <i>n</i>-Butane Oxidation to Maleic Anhydride: The Role of Byproducts”

Formation of Organic Acids and Carbonyl Compounds in n‐Butane Oxidation via γ‐Ketohydroperoxide Decomposition

AbstractA crucial chain‐branching step in autoignition is the decomposition of ketohydroperoxides (KHP) to form an oxy radical and OH. Other pathways compete with chain‐branching, such as “Korcek” dissociation of γ‐KHP to a carbonyl and an acid. Here we characterize the formation of a γ‐KHP and its decomposition to formic acid+acetone products from observations of n‐butane oxidation in two complementary experiments. In jet‐stirred reactor measurements, KHP is observed above 590 K. The KHP concentration decreases with increasing temperature, whereas formic acid and acetone products increase. Observation of characteristic isotopologs acetone‐d3 and formic acid‐d0 in the oxidation of CH3CD2CD2CH3 is consistent with a Korcek mechanism. In laser‐initiated oxidation experiments of n‐butane, formic acid and acetone are produced on the timescale of KHP removal. Modelling the time‐resolved production of formic acid provides an estimated upper limit of 2 s−1 for the rate coefficient of KHP decomposition to formic acid+acetone.

Gas-Phase Selective Oxidation of Butenes in the C4 Fraction by Nitrous Oxide

Direct oxidation of n-butenes is the preferred but yet unrealized route to methyl ethyl ketone (MEK). At the same time, N2O is a promising selective oxidant for conversion of olefins mainly to ketones. In this work, we studied the possibility of producing MEK via the gas-phase noncatalytic oxidation with N2O of butene isomers in the C4 refinery stream from catalytic cracking. The oxidation was performed at 573–823 K and a pressure of up to 2 MPa. NMR and gas chromatography methods were used to identify the reaction products. It was shown that N2O selectively oxidizes only butenes in the C4 fraction to form nitrogen and carbonyl products, among which MEK is predominant. The reaction proceeds through the 1,3-dipolar cycloaddition of N2O to the C═C bond of butenes. The proposed method allows obtaining valuable oxygenates without the separation of the C4 fraction and opens a potential way for the rational utilization of waste N2O, a powerful greenhouse gas.

Genome and proteome analyses show the gaseous alkane degrader Desulfosarcina sp. strain BuS5 as an extreme metabolic specialist.

The metabolic potential of the sulfate-reducing bacterium Desulfosarcina sp. strain BuS5, currently the only pure culture able to oxidize the volatile alkanes propane and butane without oxygen, was investigated via genomics, proteomics and physiology assays. Complete genome sequencing revealed that strain BuS5 encodes a single alkyl-succinate synthase, an enzyme which apparently initiates oxidation of both propane and butane. The formed alkyl-succinates are oxidized to CO2 via beta oxidation and the oxidative Wood-Ljungdahl pathways as shown by proteogenomics analyses. Strain BuS5 conserves energy via the canonical sulfate reduction pathway and electron bifurcation. An ability to utilize long-chain fatty acids, mannose and oligopeptides, suggested by automated annotation pipelines, was not supported by physiology assays and in-depth analyses of the corresponding genetic systems. Consistently, comparative genomics revealed a streamlined BuS5 genome with a remarkable paucity of catabolic modules. These results establish strain BuS5 as an exceptional metabolic specialist, able to grow only with propane and butane, for which we propose the name Desulfosarcina aeriophaga BuS5. This highly restrictive lifestyle, most likely the result of habitat-driven evolutionary gene loss, may provide D. aeriophaga BuS5 a competitive edge in sediments impacted by natural gas seeps. Etymology: Desulfosarcina aeriophaga, aério (Greek): gas; phágos (Greek): eater; D. aeriophaga: a gas eating or gas feeding Desulfosarcina.

Effect of Crystalline Phases for VPO Catalysts on the Oxidation of Butane: Thermodynamics and Kinetics

Serial VPO catalysts with different compositions of crystalline phases were prepared at various activation temperatures. The characterization results revealed that the proportion of V5+ species, the acidity levels, and the surface P/V ratios of VPO catalysts showed an increasing tendency with activation temperature. The performances of n-butane oxidation for serial VPO catalysts were tested at different conditions. It was shown that the S-405 catalyst (activated at 405 °C) presented the highest conversion of n-butane (75.2%) at a GHSV of 1000 h–1 and the highest selectivity for maleic anhydride (MA) (68.9%) at a GHSV of 1800 h–1, which were attributed to S-405’s high intensities at different crystalline faces, the highest amount of acidity (5.52 mL/g), the highest number of total removed oxygen atoms (2.88 × 1021 atom g–1), and the best reducibility. In addition, the kinetic and thermodynamic analyses confirmed that the S-405 catalyst possessed the best activity and selectivity of n-butane oxidation, and the effects of Lat-O and Sur-O on the selectivity for MA were also disclosed.

Exploring the interaction kinetics of butene isomers and NOx at low temperatures and diluted conditions

The oxidation of 1-butene and i-butene with and without addition of 1000 ppm NO was experimentally and numerically studied primarily at fuel-rich (ϕ = 2.0) conditions under high dilution (96% Ar) in a flow reactor operated at atmospheric pressure in the low temperature range of approximately 600-1200 K. Numerous intermediate species were detected and quantified using synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). An elementary-step reaction mechanism consisting of 3996 reactions among 682 species, based on literature and this work, was established to describe the reactions and interaction kinetics of the butene isomers with oxygen and nitrogenous components. Model predictions were compared with the experimental results to gain insight into the low- and high-temperature fuel consumption without and with NO addition and thus the respective interaction chemistry. This investigation firstly contributes a consistent set of temperature-dependent concentration profiles for these two butene isomers under conditions relevant for engine exhaust gases. Secondly, the observed oxidation kinetics is significantly altered with the addition of NO. Specifically, NO promotes fuel consumption and introduces for i-butene a low-temperature behavior featuring a negative temperature coefficient (NTC) region. The present model shows reasonable agreement with the experimental results for major products and intermediate species, and it is capable to explain the promoting effect of NO that is initiated by its contribution to the radical pool. Further, it can describe the observed NTC region for the i-butene/NO mixture as a result of the competition of chain propagation and chain terminating reactions that were identified by reaction flow and sensitivity analyses.

Development and application of a foundational fuel chemistry mechanism for pyrolysis and oxidation of propene and butenes

Propene and three butene isomers are mediate-sized foundational fuels during the conversion of large hydrocarbons, which play important roles in determining reactivities, combustion properties and emission behaviors of practical fuels. The objective of the present study was to develop a detailed foundational fuel chemistry mechanism to describe the decomposition of propene and three butenes, with emphasis on the molecular weight growth kinetics. In the first part of the paper, a new foundational fuel chemistry mechanism, TJU mechanism or TJU mech, containing 976 species and 11,505 reactions, was developed based on the CSM master pyrolysis mechanism along with the oxidation reactions stripped from the Aramco Mech 2.0. The thus-developed TJU mech was tested against a comprehensive speciation dataset from the oxidation and pyrolysis of propene and butenes over a wide range of operating conditions. Results showed that TJU mech provided good predictions for fuel conversions, formation of major and minor light products, and molecular weight growth species, including butadiene, cyclopentadiene, cyclohexadiene, benzene, toluene, etc. The second part of the paper involved the applications of TJU mech. Updated with improved understanding of the olefine reaction kinetics, TJU mech was firstly used to describe the formation of molecular weight growth species during pyrolysis of ethane and propane under high conversions, then it was utilized in Hybrid Chemistry model to predict formation of critical intermediates generated from i-octane and two jet fuels, Jet A and JP-10, respectively. Results highlighted importance of foundational fuel chemistry mechanism in describing the combustion kinetics of practical fuels.

Effect of preparation modes on the properties of cobalt-containing honeycomb monolithic catalysts modified by rare-earth metal oxides

Two series of supported Co-containing catalysts modified with La and Ce oxides were synthesized by solution combustion with different amounts of glycine. Their properties were compared with characteristics of unmodified Co catalyst and modified catalysts synthesized by impregnation in an excess of solution without glycine. XRD, TEM, UV–vis DRS and differential dissolution were employed to investigate the phase and chemical composition, morphology and localization of catalytically active particles in the support matrix. Their redox and catalytic properties were characterized using H2-TPR and kinetic experiments on the oxidation of butane. Specific surface area, particle size, chemical composition of the active component and its localization as well as the reducibility by hydrogen were shown to depend on the synthesis mode and amount of fuel additive (glycine). A higher catalytic activity of the samples obtained by solution combustion synthesis as compared to those synthesized by impregnation is caused by the enrichment of subsurface layers of the support with Co(II,III) cations in the composition of simple (Co3O4) and mixed (CoAl2O4) nanosized oxides, by an increase in specific surface area and a decrease in the particle size of the active component and promotor. It was shown that the amount of glycine has a stronger effect on the properties of the catalyst than its modification with lanthanum or cerium oxides.

More Than a Methanotroph: A Broader Substrate Spectrum for Methylacidiphilum fumariolicum SolV.

Volcanic areas emit a number of gases including methane and other short chain alkanes, that may serve as energy source for the prevailing microorganisms. The verrucomicrobial methanotroph Methylacidiphilum fumariolicum SolV was isolated from a volcanic mud pot, and is able to grow under thermoacidophilic conditions on different gaseous substrates. Its genome contains three operons encoding a particulate methane monooxygenase (pMMO), the enzyme that converts methane to methanol. The expression of two of these pmo operons is subjected to oxygen-dependent regulation, whereas the expression of the third copy (pmoCAB3) has, so far, never been reported. In this study we investigated the ability of strain SolV to utilize short-chain alkanes and monitored the expression of the pmo operons under different conditions. In batch cultures and in carbon-limited continuous cultures, strain SolV was able to oxidize and grow on C1–C3 compounds. Oxidation of ethane did occur simultaneously with methane, while propane consumption only started once methane and ethane became limited. Butane oxidation was not observed. Transcriptome data showed that pmoCAB1 and pmoCAB3 were induced in the absence of methane and the expression of pmoCAB3 increased upon propane addition. Together the results of our study unprecedently show that a pMMO-containing methanotroph is able to co-metabolize other gaseous hydrocarbons, beside methane. Moreover, it expands the substrate spectrum of verrucomicrobial methanotrophs, supporting their high metabolic flexibility and adaptation to the harsh and dynamic conditions in volcanic ecosystems.

Thermogenic hydrocarbon biodegradation by diverse depth-stratified microbial populations at a Scotian Basin cold seep

At marine cold seeps, gaseous and liquid hydrocarbons migrate from deep subsurface origins to the sediment-water interface. Cold seep sediments are known to host taxonomically diverse microorganisms, but little is known about their metabolic potential and depth distribution in relation to hydrocarbon and electron acceptor availability. Here we combined geophysical, geochemical, metagenomic and metabolomic measurements to profile microbial activities at a newly discovered cold seep in the deep sea. Metagenomic profiling revealed compositional and functional differentiation between near-surface sediments and deeper subsurface layers. In both sulfate-rich and sulfate-depleted depths, various archaeal and bacterial community members are actively oxidizing thermogenic hydrocarbons anaerobically. Depth distributions of hydrocarbon-oxidizing archaea revealed that they are not necessarily associated with sulfate reduction, which is especially surprising for anaerobic ethane and butane oxidizers. Overall, these findings link subseafloor microbiomes to various biochemical mechanisms for the anaerobic degradation of deeply-sourced thermogenic hydrocarbons.