Ethylene Carbon Monoxide Research Articles

Rapid and high-accuracy concentration prediction of gas mixtures based on PMH-TCN

In industrial environments, the flammable gas ethylene (C2H4) and toxic gas carbon monoxide (CO) often coexist. To ensure worker safety, it is essential to predict these gas concentrations quickly and accurately. Many studies lack prediction accuracy or speed due to insufficient time feature extraction and loss of critical features. In this work, a novel approach called the Parametric Rectified Linear Unit (PReLU)-based Multi-Head Attention Temporal Convolutional Network (PMH-TCN) model was devised to efficiently and precisely predict gas concentrations in mixtures. The model is capable of accurately predicting the gas concentration within 5 s after the introduction of the target gas. In the 5-fold cross-validation, the values of Adjusted R-Square (R2), Mean Absolute Error (MAE) and Root Mean Square Error (RMSE) of the PMH-TCN model reached 0.9850, 0.0448, and 0.0651 respectively. It was shown that the PMH-TCN model offered a very efficient method for the quick identification of electronic noses.

Controlled Radical Polymerization of Acrylates and Isocyanides Installs Degradable Functionality into Novel Copolymers.

Installing ketones into a polymer backbone is a known method for introducing photodegradability into polymers; however, most current methods are limited to ethylene-carbon monoxide copolymerization. Here we use isocyanides in place of carbon monoxide in a copolymerization strategy to access degradable nonalternating poly(ketones) that either maintain or enhance the thermal properties. A cobalt-mediated radical polymerization of acrylates and isocyanides synthesizes nonalternating poly(acrylate-co-isocyanide) copolymers with tunable incorporation using monomer feed ratios. The kinetic product of the polymerization is a dynamic β-imine ester that tautomerizes to the β-enamine ester. Hydrolysis of this copolymer affords a third copolymer microstructure─the elusive nonalternating poly(ketone)─from a single copolymerization strategy. Analysis of the copolymer properties demonstrates tunable thermal properties with the degree of incorporation. Finally, we show that poly(acrylate-co-isocyanide) and poly(acrylate-co-ketone) are photodegradable with 390 nm light, enabling chain cleavage.

Nickel–cobalt oxides decorated Chitosan electrocatalyst for ethylene glycol oxidation

A composite of NiCo2O4 modified electrocatalyst is prepared to enhance the ethylene glycol electrooxidation. Chitosan matrix is used to improve the activity and adsorption ability of the surface to enhance ethylene glycol conversion. A Comparative study is investigated between pristine NiCo2O4 and Chitosan-modified spinel oxide to evaluate the synergistic effect between spinel oxide and chitosan. The composite is studied in an alkaline solution using electrochemistry techniques. The electrochemical activity towards ethylene glycol electrooxidation is studied as a function of anodic oxidation current density. Thus, the oxidation current values for NiCo2O4 and NiCo2O4@Chitosan in 1.0 M EG and 1.0 M KOH are 36 and 42 mA cm−2, respectively. The long-term stability of the electrode is measured by constant potential chronoamperometry. Kinetic parameters like diffusion coefficient, Tafel slope, surface coverage, and transfer coefficient are calculated. The density-functional theory estimates the adsorption of small molecules like ethylene glycol, urea, and carbon monoxide. The adsorption energy is studied on the top site of Ni and Co atoms of NiCo2O4. Forcite model is used to study the interaction between spinel oxide and chitosan. The energy calculation assumes that chitosan is adsorbed on the spinel oxide surface and enhances chitosan's ability for the adsorption of small molecules.

Effect analysis on hydrocarbon adsorption enhancement of ZSM-5 zeolite modified by transition metal ions in cold start of gasoline engine

The adsorption effects of transition metal modified ZSM-5 zeolite on the main hydrocarbon emission components of gasoline engine cold start include acetylene (C2H2), ethylene (C2H4), acetaldehyde (C2H4O), propylene (C3H6), 1-butene (C4H8) and benzene (C6H6) carbon monoxide (CO), carbon dioxide (CO2) and water vapor (H2O) were studied by experiments and molecular simulation. Through the hydrocarbon adsorption breakthrough experiment, the promotion effect of Fe-ZSM-5 zeolite on the adsorption of hydrocarbon emissions from cold start was confirmed. Results showed that the Fe modification improved the adsorption rate of zeolite on C4H8 and C2H4O. With the increase of Fe mass fraction, the adsorption capacity of zeolite for C2H4O increased, while the adsorption capacity for C4H8 decreased. The adsorption mechanisms of 9 main exhaust components from cold start on M2+ (M = Fe, Cu and Zn) modified ZSM-5 zeolite were studied by molecular simulation. Under the cold start condition, the adsorption capacity of H2O is the largest, between 1.5 and 4 mmol/gzeo, one order of magnitude higher than that of CO2 (0–0.3 mmol/gzeo), C6H6 (0–0.16 mmol/gzeo), C2H4O (0–0.5 mmol/gzeo) and C4H8 (0–1.6 mmol/gzeo), and 3–4 orders of magnitude higher than that of CO, C2H2, C2H4, C3H6. Results showed that the adsorption priority of molecules on transition metal ion modified ZSM-5 zeolite was determined by functional group charge number, molecular weight and molecular polarity. The zeolite with higher ion exchange ratio has a larger adsorption capacity for oxygen-containing molecules such as H2O, CO2 and C2H4O. Reducing the ion exchange ratio was conducive to the adsorption of hydrocarbons such as C4H8.

Mechanistic Insights into Ni(II)-Catalyzed Nonalternating Ethylene-Carbon Monoxide Copolymerization.

Polyethylene materials with in-chain-incorporated keto groups were recently enabled by nonalternating copolymerization of ethylene with carbon monoxide in the presence of Ni(II) phosphinephenolate catalysts. We elucidate the mechanism of this long-sought-for reaction by a combined theoretical DFT study of catalytically active species and the experimental study of polymer microstructures formed in pressure-reactor copolymerizations with different catalysts. The pathway leading to the desired nonalternating incorporation proceeds via the cis/trans isomerization of an alkyl-olefin intermediate as the rate-determining step. The formation of alternating motifs is determined by the barrier for the opening of the six-membered C,O-chelate by ethylene binding as the decisive step. An η2-coordination of a P-bound aromatic moiety axially oriented to the metal center is a crucial feature of these Ni(II) catalysts, which also modulates the competition between the two pathways. The conformational constraints imposed in a 2′,6′-dimethoxybiphenyl moiety overall result in a desirable combination of disfavoring ethylene coordination along the alternating incorporation pathway, which is primarily governed by electronics, while not overly penalizing the nonalternating chain growth, which is primarily governed by sterics.

Numerical Investigation of Exergy Loss of Ammonia Addition in Hydrocarbon Diffusion Flames.

In this paper, a theoretical numerical analysis of the thermodynamics second law in ammonia/ethylene counter-flow diffusion flames is carried out. The combustion process, which includes heat and mass transfer, as well as a chemical reaction, is simulated based on a detailed chemical reaction model. Entropy generation and exergy loss due to various reasons in ammonia/ethylene and argon/ethylene flames are calculated. The effects of ammonia addition on the thermodynamics efficiency of combustion are investigated. Based on thermodynamics analysis, a parameter, the lowest emission of pollutant (LEP), is proposed to establish a relationship between the available work and pollutant emissions produced during the combustion process. Chemical reaction paths are also analyzed by combining the chemical entropy generation, and some important chemical reactions and substances are identified. The numerical results reveal that ammonia addition has a significant enhancement on heat transfer and chemical reaction in the flames, and the total exergy loss rate increases slightly at first and then decreases with an increase in ammonia concentration. Considering the factors of thermodynamic efficiency, the emissions of CO2 and NOx reach a maximum when ammonia concentration is near 10% and 30%, respectively. In terms of the chemical reaction path analysis, ammonia pyrolysis and nitrogen production increase significantly, while ethylene pyrolysis and carbon monoxide production decrease when ammonia is added to hydrocarbon diffusion flames.

Heat capacity and thermodynamic functions of poly(1-(hydroxyimino)trimethylene)

In the present work, the temperature dependence of the molar heat capacity of a partially crystalline poly(1-(hydroxyimino)trimethylene) has been measured over the range of T = (6–500) K using a precise automated adiabatic calorimeter and a heat-flux differential scanning calorimeter. In the above temperature interval, the glass transition has been detected, and the standard thermodynamic characteristics of polyoxime have been determined and analysed. The standard thermodynamic functions of the studied polyoxime, namely, the heat capacity Cpo(T), the enthalpy [H°(T) − H°(0)], the entropy [S°(T) − S°(0)], and the potential Φ°(T) have been calculated for the range from T → (0 to 400) K based on the experimental data. The standard thermodynamic properties of poly(1-(hydroxyimino)trimethylene) have been discussed and compared with the previously studied alternating polyketone (copolymer of ethylene C2H4 and carbon monoxide CO).

OXİDATİVE CONVERSİON OF METHANE. EFFECT OF CATALYST AND PERSPECTİVE DİRECTİONS OF REACTİON

The well-known MnNaW catalysts based on SiO2 for oxidative condensation of methane (OCM) were synthesized by various methods, characterized by X-ray diffractometry (XRD), scanning electron microscopy with energy dispersive elemental analysis (SEM/EDX), electron magnetic resonance (EMR) spectroscopy, N2 adsorption-desorption measurements, and tested as OCM catalysts at atmospheric pressure to convert into a mixture of ethylene + carbon oxides for further hydroformylation to propylene. The structural and catalytic features of the synthesized systems are discussed. The necessity of using mainly X-ray diffraction, Raman, and EMR methods for studying catalysts in situ mode in combination with online MS analysis of gasphase reaction products to establish the nature of catalytically active phases, centers, their mechanism of functioning, activation of CH4 with the formation of C-C bond for the synthesis of hydrocarbons C2 and C2+ is considered. Keywords: oxidative conversion of methane, NaMnW/SiO2 catalyst, ethylene-carbon monoxide mixture, magnetic, texture properties

Selective, Catalytic Oxidations of C–H Bonds in Polyethylenes Produce Functional Materials with Enhanced Adhesion

Summary The synthesis of functional and processable polyethylenes from simple vinyl monomers with controlled molecular weights and architectures has been a grand challenge of polymer chemistry. Post-polymerization modification of the homopolymers of ethylene is attractive for this purpose but has been hampered by the lack of efficient methods for the selective functionalization of C–H bonds in polyolefins. We report the selective, catalytic oxidation of C–H bonds in commodity polyethylenes with varying molecular weights and architectures. Remarkably, the functionalized materials, even at low levels of functionalization, exhibit physical properties that are absent in unmodified polyolefins, such as strong adhesion and the ability to be painted with common waterborne latex paint. Such observations indicate that selectively modified polyethylenes as described here may help to transform existing commodity plastics into more valuable and potentially more sustainable materials.

Dissociation Chemistry of 3-Oxetanone in the Gas Phase

3-Oxetanone is a strained cyclic molecule which plays an important role in synthetic chemistry. A few studies exist in the literature about the equilibrium properties of this molecule and the dissociation patterns of substituted 3-oxetanones. For the unsubstituted 3-oxetanone, formation of ketene (CH2CO) and formaldehyde (HCHO) was considered to be the major dissociation pathway. In a recent work, pyrolysis products of 3-oxetanone molecule in the gas phase were investigated by Fourier transform infrared spectroscopy and photoionization mass spectrometry. In this study, an additional dissociation channel forming ethylene oxide (c-C2H4O) and carbon monoxide CO was reported. In the present work, gas phase dissociation chemistry of 3-oxetanone was investigated by electronic structure theory, ab initio classical chemical dynamics simulations, and Rice-Ramsperger-Kassel-Marcus (RRKM) rate constant calculations. The barrier height for the ethylene oxide channel was found to be much higher than the ketene pathway. The dynamics simulations were performed at three different total energies, viz., 150, 200, and 300 kcal/mol, and multiple reaction pathways and varying branching ratios observed. A new dissociation channel involving a ring-opened isomer of ethylene oxide was identified in the simulations. This pathway has a lower energy barrier and was dominant in our dynamics simulations.

Theoretical Study of the Kinetics and Mechanism of the Thermal Decomposition of 3-Oxetanone in the Gas Phase

The kinetics and mechanism of the thermal decomposition reaction of 3-oxetanone in the gas phase were studied using quantum chemical calculations. The major products of this reaction are formaldehyde, ketene, carbon monoxide, ethylene oxide, ethylene and methyl radical. Formaldehyde, ketene, carbon monoxide and ethylene oxide are the initial decomposition products and other species are the products of ethylene oxide decomposition. The results of B3LYP and QCISD(T) calculations reveal that thermal decomposition of 3-oxetanone to ethylene oxide and carbon monoxide is more probable than to formaldehyde and ketene from an energy viewpoint. Moreover, quantum theory of atoms in molecules and natural bond orbital analysis indicate that 3-oxetanone decomposition to formaldehyde, ketene, carbon monoxide and ethylene occurs via a concerted mechanism and bonds that are involved in the transition states have a covalent character. Moreover, the calculated changes in bond lengths in the transition states reveal that bond breaking and new bond formation occur asynchronously in a concerted mechanism.

Carbonylation of Ethylene Oxide to β-Propiolactone: A Facile Route to Poly(3-hydroxypropionate) and Acrylic Acid

We report an improved synthesis of poly(3-hydroxypropionate) (P3HP) from ethylene oxide (EO) and carbon monoxide (CO) through the intermediate β-propiolactone (PL). The optimized carbonylation of EO resulted in high selectivity for PL using a bimetallic [Lewis acid]+[Co(CO)4]− catalyst. Anionic ring-opening polymerization of PL by organic ionic compounds to afford P3HP was also investigated. A phosphazenium carboxylate initiator displays the highest activity for the polymerization and produces polyesters with molecular weights over 100 kDa and narrow molar mass distributions. Furthermore, the known rearrangement of PL and the thermolysis of P3HP provide efficient EO-based routes to the important commodity chemical acrylic acid.

Consciousness disorders from toxicological view

Poisoning with impaired mental state is a frequent cause for hospital admission. The initial management includes assessment of vital functions and airway management followed by focussed diagnostics. Poison Emergency Centers can provide valuable assistance in acute intoxications. Clinically important agents causing mental state alterations include opiates, benzodiazepines, tricyclic antidepressants, alcohol, methanol and ethylene glycol, carbon monoxide and salicylates. Most important therapeutic measures comprise supportive care, decontamination or elimination. For certain toxins specific antidotes are available. In presence of severe intoxications and impaired vital functions, the patient should be transferred to the intensive care unit (ICU).

Pyrolysis Reactions of 3-Oxetanone.

The pyrolysis products of gas-phase 3-oxetanone were identified via matrix-isolation Fourier transform infrared spectroscopy and photoionization mass spectrometry. Pyrolysis was conducted in a hyperthermal nozzle at temperatures from 100 to 1200 °C with the dissociation onset observed at ∼600 °C. The ring strain in the cyclic structure of 3-oxetanone causes the molecule to decompose at relatively low temperatures. Previously, only one dissociation channel, producing formaldehyde and ketene, was considered as significant in photolysis. This study presents the first experimental measurements of the thermal decomposition of 3-oxetanone demonstrating an additional dissociation channel that forms ethylene oxide and carbon monoxide. Major products include formaldehyde, ketene, carbon monoxide, ethylene oxide, ethylene, and methyl radical. The first four products stem from initial decomposition of 3-oxetanone, while the additional products, ethylene and methyl radical, are believed to be due to further reactions involving ethylene oxide.

Thermodynamics of triple alternating copolymer ethylene—carbon monoxide—propylene

The temperature dependence of heat capacity of triple alternating copolymer ethylene—carbon monoxide—propylene with 23.4 mol.% of propane fragments was studied for the first time by adiabatic and dynamic calorimetry over the range of 6–480 K. The energy of copolymer combustion at 298.15 K was measured in isothermic calorimeter with stationary bomb. The thermodynamic parameters of phase and physical transitions were determined. The standard thermodynamic functions Cp○(T), H○(T) − H○(0), S○(T) − S○(0) and G○(T) − H○(0), for region from T→ 0 to 320 K, the standard enthalpy of combustion and thermodynamic characteristics of formation of the studied compound at 298.15 K were calculated from the experimental data. The thermodynamic parameters of alternating copolymerization of CO with ethylene and propylene at standard pressure over 0–300 K region were detemined.

Ethylene and Styrene Carbon Monoxide Copolymerization Catalyzed by Pyrazolyl Palladium(II) Complexes

The pyrazolyl pyridylimine ligands [2-(3,5-dimethylpyrazol-1-yl)ethyl]pyridin-2-ylmethyleneimine (L1) and [2-(3,5-di-tert-butylpyrazol-1-yl)ethyl]pyridin-2-ylmethyleneimine (L2) and pyrazolyl thienylimine ligands [2-(3,5-dimethylpyrazol-1-yl)ethyl]thiophen-2-ylmethyleneimine (L3), [2-(3,5-di-tert-butyl-pyrazol-1-yl)ethyl]thiophen-2-ylmethyleneimine (L4), [2-(3,5-dimethylpyrazol-1-yl)ethyl]-2-bromothiophen-2-ylmethyleneimine (L5), and [2-(3,5-di-tert-butyl-pyrazol-1-yl)ethyl]-2-bromothiophen-2-ylmethyleneimine (L6) were synthesized by condensation of the appropriate pyrazolylamine and the corresponding aldehyde. Reactions of L1–L6 with [PdCl(Me)(cod)] gave the corresponding palladium(II) complexes [PdCl(Me)(L)] (where L = L1 (1a), L2 (2a), L3 (3a), L4 (4a), L5 (5a), L6 (6a)) in very good yields. The pyridylimine ligands L1 and L2 were found to coordinate via the imine and pyridine nitrogen atoms, while the thienylimine ligands L3–L6 coordinate via imine and pyrazolyl nitrogen atoms to the palladium. The ca...

Dielectric behavior of alternating ethylene, propylene, and carbon monoxide co‐ and terpolymers via impedance spectroscopy

AbstractDielectric behavior of alternating ethylene–carbon monoxide (ECO) and ethylene–carbon monoxide/propylene–carbon monoxide elastic terpolymer (EPEC‐48) (48% mole ratio of ECO) have been investigated by impedance spectroscopy. At intermediate frequencies, the co‐ and terpolymer samples display a relaxation peak with an activation energy of 1.40 and 1.12 eV, respectively, due to a rotational motion of the carbonyl groups in the relatively more polar ECO block. However, at low frequency, a relaxation peak was observed only in the EPEC‐48 terpolymer impedance and admittance spectra due to the rotational motion of the polar groups of propylene–carbon monoxide (PCO) block which is attached to ECO repeating units. In addition, it has been found that below 100°C the ECO material is highly resistive, and both dielectric constant and loss factor are dependent on frequency and temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Comparative Study on the Degradation Behavior of Ethylene-carbon Monoxide Copolymers under Natural Environment in Japan and China

Comparative Study on the Degradation Behavior of Ethylene-carbon Monoxide Copolymers under Natural Environment in Japan and China

Surface oxidation of low‐density polyethylene films to improve their susceptibility toward environmental degradation

AbstractPolyethylene wastes, particularly as films, have accumulated over the last several decades resulting in a major visual litter problem. The aim of this study was to investigate the ability of chemical reagents to oxidize the low‐density polyethylene (LDPE) film surface to increase their susceptibility toward photodegradation and thermal degradation. Three chemical agents, namely, potassium permanganate, potassium persulfate, and benzoyl peroxide, were used to oxidize the film surface to generate chromophoric groups, such as carbonyl groups, which are the main reason for the enhanced environmental degradation of photolytic polymers, such as ethylene–carbon monoxide and ethylene–vinyl ketone copolymers. For the chemical treatment, LDPE films of 70 ± 5 μm thickness were prepared by a film‐blowing technique and subsequently reacted with the aforementioned oxidizing agents. To aid the oxidation process, the reaction with potassium persulfate and potassium permanganate was performed under microwave irradiation heating. In the case of benzoyl peroxide aided oxidation, the films were subjected to repeated coating–heating treatments up to a maximum of 10 cycles. The treated films were subjected to accelerated aging, that is, xenon‐arc weathering and air‐oven aging (at 70°C), for extended time periods. The chemical and physical changes induced as a result of aging were followed by the monitoring of changes in the mechanical, structural, and thermal properties. The results indicate that the surface‐oxidized LDPE films exhibited enhanced susceptibility toward degradation; however, the extent was reduced as compared to photolytic or other degradable compositions. The ability of the chemicals to initiate degradation followed the order potassium persulfate < potassium permanganate < benzoyl peroxide. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Effect of Wavelength of Irradiated Light on the Photodecomposition of Ethylene-carbon Monoxide Copolymers

Effect of Wavelength of Irradiated Light on the Photodecomposition of Ethylene-carbon Monoxide Copolymers