Degree Of Deactivation Research Articles

Deactivation Patterns of Potassium-Based γ-Alumina Dry Sorbents for CO2 Capture

Gamma-alumina (γ-Al2O3) is an essential support material in dry sorbents used to capture CO2 from flue gas. This study explores the deactivation of potassium-based γ-Al2O3 sorbents due to by-products such as KAl(CO3)(OH)2 during CO2 capture. We synthesized sorbents with K2CO3 loadings of 5, 10, 20, and 30 wt% and subjected them to repeated capture and regeneration cycles. The results show significant variations in the deactivation degree: the sorbent with 5 wt% K2CO3 exhibited a 100% deactivation rate, while the 30 wt% variant showed a markedly reduced rate of 44.6%. These findings highlight the impact of the formation of KAl(CO3)(OH)2 at the interface between K2CO3 and γ-Al2O3 on sorbent deactivation. An equation that can be used to predict the final CO2 capture capacity based on the ratio of active material to support was proposed using these results.

Coke formation on different metal-modified (Co, Mo and Zr) ZSM-5 in the catalytic pyrolysis of cellulose to light aromatics

Catalytic pyrolysis of biomass is regarded as a promising method for preparing value-added products. However, the main factors limiting the development of the process at present are the low yield of value-added products and poor selectivity, especially for rapid catalyst deactivation due to coke deposition. The present study focuses on the catalytic pyrolysis of cellulose over metal Co-, Mo-, and Zr-loaded catalysts using a falling fixed bed at 600 °C to evaluate the type of coking of the catalysts as well as the effect of the different metal active sites on the formation of coke deposits. The introduction of Co and Mo metal sites increased the light aromatics yield of ZSM-5 from 128.9 mg/g to 147.2 mg/g and 143.0 mg/g. And the yield of coke deposits decreased from 8.3 to 6.8 and 5.1 wt%. The stability evaluation of the catalyst showed that the deactivation degree of ZSM-5 of the supported metal Co was lower than that of commercial ZSM-5, while the ZSM-5 of the supported metal Mo was rapidly deactivated. The deactivation of the catalysts depended more on the morphology or location of the accumulated coke than on the total amount deposited. The clogging of metal and acidic sites on the surface of the zeolite and the pore channels by the amorphous encapsulating coke was the main cause of catalyst deactivation. The metal Mo active sites promoted dehydrogenation coupling and hydrogen transfer during coke formation, forming a more highly disordered multiring structure, and the metal Co active sites were more capable of decomposing macromolecular compounds, olefins and alkanes, and promoted the formation of graphite-like structural carbon.

Rock music improvisation shows increased activity in Broca’s area and its right hemisphere homologue related to spontaneous creativity

ObjectiveThe neural correlates of creativity are not well understood. Using an improvised guitar task, we investigated the role of Broca's area during spontaneous creativity, regardless of individual skills, experience, or subjective feelings.ResultsTwenty guitarists performed improvised and formulaic blues rock sequences while hemodynamic responses were recorded using functional near-infrared spectroscopy. We identified a new significant response in Broca’s area (Brodmann area [BA] 45L) and its right hemisphere homologue during improvised playing but not during formulaic playing. Our results indicate that bilateral BA45 activity is common during creative processes that involve improvisation across all participants, regardless of subjective feelings, skill, age, difficulty, history, or amount of practice. While our previous results demonstrated that the modulation of the neural network according to the subjectively experienced level of creativity relied on the degree of deactivation in BA46L, our current results independently show a common concurrent activity in BA45 in all participants. We suggest that this is related to the sustained execution of improvisation in “motor control,” analogous to motor planning in speech control.

Tracking deactivation of zeolite beta with and without a detailed structure model: XRD analysis and in situ studies

This paper introduces two versatile new models for assessing the deactivation level of the industrially useful catalyst Beta zeolite. 1) a stacking disorder (SD) model: in which supercells built from stacked layers with refined faulting probability are generated, averaged and fitted to the powder pattern, and dummy carbon atoms in the pore system allow estimation of the degree of deactivation by coke; 2) a semi-empirical (SE) model: in which a reduced tetragonal unit cell is used to fit the sharp Bragg reflections in the PXRD pattern in a Le Bail-type fit and the broad, diffuse peaks are fitted individually to obtain intensities and positions. The reduced cell gives very precise lattice parameters, which can be determined quickly for a series of in situ data, while the ratio between the scale factor of the sharp reflection part in the model and the intensity of the first broad peak gives a measure of the degree of deactivation by coke. The models are validated, and their strengths and weaknesses compared by fitting of in situ PXRD data collected during temperature programmed oxidation of coke from two Beta zeolite samples fully deactivated in the MTH process. Analysis of such data from Beta zeolites has not been demonstrated before and could provide a convenient and useful tool for the chemical industry.

On the applicability of PdAg membranes in propane dehydrogenation processes

The applicability of PdAg membranes in the propane dehydrogenation process has been evaluated in this work. The integration of membranes into the propane dehydrogenation process has the potential of making a significant step forward in energy and resource efficiency of the selective production of propylene. To assess the compatibility of the PdAg membrane with the process conditions of propane dehydrogenation, two double-skin PdAg membranes were exposed to the emulated process conditions of two cases: 1. A fully integrated membrane-reactor system (higher temperature) and 2. A cascade of catalyst and membrane separator units (lower temperature). The results of this study showed that at high temperature (475–500 °C) strong reduction of the hydrogen flux is observed during exposure to reactant and product containing mixtures. The reason for this is the deposition of carbonaceous species on the active sites of the membrane. Additionally, also the lifetime of the membrane (in terms of selectivity) was significantly lower due to the regeneration performed at high temperature in diluted air. The lower temperature experiments (300–350 °C) showed a much lower degree of deactivation and at the same time the membrane could be regenerated in air repeatedly without visible reduction of its selectivity. These findings show that the DS-PdAg membrane can be repeatedly exposed to reaction-regeneration cycles at acceptable activity and without significant loss of selectivity when operated in a cascade configuration at a temperature at or below 350 °C.

Effect of hydrothermal aging on CO and C3H6 oxidation over a Pt-Pd-based wiremesh catalyst as a motorcycle aftertreatment device

Motorcycles are major contributors to air pollutants, i.e. CO, VOCs, and PM, emissions to the atmosphere in some regions around the world. Hydrothermal aging of the Pd-Pt-based wiremesh catalyst, as an emission control device for 4-stroke carburetor motorcycles, was studied under laboratory-simulated aging conditions. Aging temperature and reaction atmosphere were selected as independent variables affecting aging. Catalyst properties were characterized by ICP, XPS, BET, EDS, and FE-SEM analysis. Increasing aging temperature and oxidizing atmosphere led to a more pronounced particle size growth and sintering after aging. Regardless of the aging temperature, surface inhibition effects gradually disappeared by shifting the light-off curves to higher temperatures, whether the reason for this shift is oxygen deficiency in the reaction mixture or hydrothermal aging of the catalyst. The surface concentration of the most active phase of platinum, Pt0, decreased in the following order: fresh sample > reducing-aged at 750 °C ≈ reducing-aged at 900 °C > oxidizing-aged at 750 °C > oxidizing-aged at 900 °C. The overall trend of activity for different samples is as follows: fresh sample > reducing-aged at 750 °C > oxidizing-aged at 750 °C > reducing-aged at 900 °C > oxidizing-aged at 900 °C. The less extent of deactivation under reducing atmosphere was attributed to the preservation of metallic Pt content and limited particle size growth under such aging conditions. Analysis of the effect of the air-fuel ratio on the light-off profiles indicated that under all aging conditions, the rich atmosphere resulted in the highest degree of deactivation compared to stoichiometric and lean conditions.

Enhanced carbon tolerance of hydrotalcite-derived Ni-Ir/Mg(Al)O catalysts in dry reforming of methane under elevated pressures

Pressurized dry reforming of methane (DRM) is highly desirable in terms of economy and efficiency, but imposes increased risk of catalyst carbon deposition. Here, hydrotalcite-derived Ni-Ir/MgAl(O) catalysts with various Ir/Ni molar fractions (0, 5, 10, 15, 20, 25 and 30%) have been successfully prepared by one-step co-precipitation method. The promoting effect of Ir on the catalytic performance of catalysts in pressurized DRM was focused. After adding Ir, the catalyst stabilities (reflected by the deactivation degree) were significantly improved and were comparable when the amount of Ir was high (≥15%). Long-term stability for 180 h at 1.0 MPa and 850 °C under 60,000 mL·gcat−1·h−1 was achieved on catalyst 100Ni20Ir, and the final CH4 conversion was still above 68.5%. Detailed characterizations disclosed that the addition of Ir favored the formation of smaller Ni particles and enhanced the carbon tolerance properties of catalysts. The effective inhibition of the formation of encapsulated graphitic carbon and better carbon nanotubes removal characteristics were responsible for the enhanced carbon tolerance behaviors. The carbon deposition, especially the encapsulated graphitic carbon, was proved to be the major cause of catalyst deactivation. Our findings bring us one step closer to developing durable and coke-resistant catalysts suitable for high pressure DRM.

Effective delamination of a layered two-dimensional MCM-22 zeolite: Quantitative insights into the role of the delaminated structure on acid catalytic reactions

A layered precursor of MCM-22 (Mobil Composition of Matter-22), a representative two-dimensional MWW type zeolite, is a flexible, reliable platform for structural transformation via inter-layer swelling and subsequent pillaring or delamination. In particular, the delaminated MWW type zeolite, which is a few nanometers thick, is desirable for overcoming diffusional limits. Despite its promise, the conventional procedure to acquire the delaminated MCM-22 is complicated; the resulting particle is known as ITQ-2 (Instituto de Tecnologia Quimica Valencia-2). Here, we propose a simple, effective method for delaminating MCM-22 precursors into nanosheets; the calcination of swollen MCM-22 precursors resulted in successful delamination. A rigorous analysis of the structural and textural properties of the resulting delaminated forms revealed that a majority of the nanosheets had a 3–4 unit cell thickness along the c-axis, which were further formed via aggregation of particles having ca. 1–2 unit cell thickness and retaining the original intra-layer zeolite structure. In addition, we applied the MCM-22 zeolite and its derivatives (i.e., the aforementioned delaminated MCM-22 zeolite and ITQ-2) to two conventional acid catalytic reactions (methanol to hydrocarbons and toluene methylation). Furthermore, we could quantitatively correlate the catalytic performance as well as the deactivation degree of the three catalysts with the corresponding structural and acidic properties. Notably, unlike an initial expectation, the delaminated MCM-22 zeolite lowered both the catalytic activity and long-term stability. These could be attributed to the decreased acid sites in the two-dimensional micropores (mainly, those used to be present in the inter-layer) and the increased non-zeolitic acid sites (other than the micropores), respectively, by the delamination, hindering the proper uses as conventional acid catalysts.

The Impact of Support Material of Cobalt‐Based Catalysts Prepared by Double Flame Spray Pyrolysis on CO2 Methanation Dynamics

AbstractMethanation is capable of chemical storage of fluctuating renewable energy, which requires fundamental understanding of the dynamics of the kinetic processes taking place on the catalyst surface. In order to elucidate the impact of the catalyst support on the dynamics, Co‐based model catalysts were synthesized via double flame spray pyrolysis (DFSP) differing only in the support materials. In particular, Co nanoparticles of identical particle size distributions are supported on SiO2, TiO2 and SiO2‐TiO2 mixtures by independent formation of the support and the active metal by means of DFSP. The transient catalyst behavior was studied by step changes of the feed gas composition and the analysis of the reactor response with high temporal resolution, according to the periodic transient kinetics method. It was revealed that H2O adsorption strongly depends on the support with increasing sorption capacity from SiO2, via SiO2‐TiO2 to TiO2. The storage of H2O on the support induces a sorption‐enhancement effect and thereby promotes the transient CH4 formation rate for Co/TiO2 catalysts. Transient experiments before and after a steady‐state operation period under CO2 methanation reveal an unchanging reaction mechanism, while changes in selectivity towards CH4 and CO are observed together with a certain degree of deactivation. Hence, the support material was identified to play a major role in activity, selectivity and deactivation behavior for supported Co catalysts in CO2 methanation.

Simultaneous removal of NO and dioxins over V2O5-WO3/TiO2 catalyst for iron ore sintering flue gas: The poisoning effect of Pb

V2O5-WO3/TiO2 (VWTi) catalyst is widely used for simultaneously eliminating the NO and dioxins from the iron ore sintering flue gas. However, the catalyst is confronted with deactivation by heavy metals during operation. Here, we studied the effects of PbCl2 and PbO on catalytic elimination NO and dioxins over VWTi catalyst based on the presence of lead species in sintering flue gas. Variations of catalytic activity, surface acidity, and regeneration performance were evaluated. The results confirmed that the deactivation degree was in correlation with the lead content, the influence of the existing forms of lead on the catalyst surface on denitrification, and dioxin removal activities were following the sequence: PbO > PbCl2. The introduction of lead species could occupy acidic sites on the catalyst surface, resulting in a decrease in the V5+/V4+ molar ratio, the surface chemisorbed oxygen, and the amount of acid on the catalyst surface. XRD investigations show that the formation of PbSO4 precipitates by the reaction of lead ions with sulfate groups on the catalyst's surface reduced the number of acidic sites provided by sulfate groups. Besides, the formation of PbSO4 on the catalyst's surface also led to the failure of lead ion removal by regeneration treatment, consequently resulting in the catalytic activity can handly be effectively repaired.

Different lead species deactivation on Mn-Ce activated carbon supported catalyst for low-temperature SCR of NO with NH3: Comparison of PbCl2, Pb (NO3)2 and PbSO4

Due to the accumulation of heavy metal compounds produced by the sintering process in steel industry, the catalysts used for low-temperature selective catalytic reduction of NO with NH3 (NH3-SCR) might be seriously deactivated. In this work, the deactivation effect of PbCl2, Pb(NO3)2, and PbSO4 on Mn-Ce activated carbon supported catalyst for low-temperature NH3-SCR of NO was investigated and compared. Poisoned catalysts were provided by impregnating fresh catalysts with Pb(NO3)2, PbSO4 and PbCl2 aqueous solutions, respectively. Deactivation could be observed on the poisoned samples, and the deactivation degree was following PbCl2 > PbSO4 > Pb(NO3)2. The catalytic activities of all samples were tested, and the physicochemical properties of fresh and poisoned catalysts were assessed. PbCl2 caused the most severe deactivation of the catalyst, owing to its poor redox property and surface acidity. Cl- could also react with Mn active sites to form -O-Mn-Cl bonds, resulting in additional acid sites, although these newly generated sites were not reactive in NH3-SCR reaction process. PbSO4 exhibited moderate poisoning effect due to the addition of SO42-, which created new Brønsted acid sites, facilitating the NH3 adsorption and NO reduction. Pb(NO3)2 had the least poisoning impact on the catalyst due to the NO3–, promoting the NH3 activation. The in situ DRIFTS results revealed that NH3-SCR reaction over all samples was governed by Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanism, and did not change due to the lead poisoning. Finally, a possible mechanistic model for different lead salts poisoning over Mn-Ce/AC catalyst was proposed.

The highly selective catalytic hydrogenation of CO2 to CO over transition metal nitrides

Three transition metal-like facet centered cubic structured transition metal nitrides, γ-Mo2N, β-W2N and δ-NbN, are synthesized and applied in the reaction of CO2 hydrogenation to CO. Among the three nitride catalysts, the γ-Mo2N exhibits superior activity to target product CO, which is 4.6 and 76 times higher than the other two counterparts of β-W2N and δ-NbN at 600 °C, respectively. Additionally, γ-Mo2N exhibits excellent stability on both cyclic heating–cooling and high space velocity steady state operation. The deactivation degree of cyclic heating–cooling evaluation after 5 cycles and long-term stability performance at 773 and 873 K in 50 h are all less than 10%. In-situ XRD and kinetic studies suggest that the γ-Mo2N itself is able to activate both of the reactants CO2 and H2. Below 400 °C, the reaction mainly occurs at the surface of γ-Mo2N catalyst. CO2 and H2 competitively adsorbe on the surface of catalyst and CO2 is the relatively stronger surface adsorbate. At a higher temperature, the interstitial vacancies of the γ-Mo2N can be reversibly filled with the oxygen from CO2 dissociation. Both of the surface and bulk phase sites of γ-Mo2N participate in the high temperature CO2 hydrogenation pathway.

A Model of Catalytic Cracking: Catalyst Deactivation Induced by Feedstock and Process Variables

Changes in the quality of the feedstocks generated by involving various petroleum fractions in catalytic cracking significantly affect catalyst deactivation, which stems from coke formed on the catalyst surface. By conducting experimental studies on feedstocks and catalysts, as well as using industrial data, we studied how the content of saturates, aromatics and resins (SAR) in feedstock and the main process variables, including temperature, consumptions of the feedstock, catalyst and slops, influence the formation of catalytic coke. We also determined catalyst deactivation patterns using TG-DTA, N2 adsorption and TPD, which were further used as a basis for a kinetic model of catalytic cracking. This model helps predict the changes in reactions rates caused by coke formation and, also, evaluates quantitatively how group characteristics of the feedstock, the catalyst-to-oil ratio and slop flow influence the coke content on the catalyst and the degree of catalyst deactivation. We defined that a total loss of acidity changes from 8.6 to 30.4 wt% for spent catalysts, and this depends on SAR content in feedstock and process variables. The results show that despite enriching the feedstock by saturates, the highest coke yields (4.6–5.2 wt%) may be produced due to the high content of resins (2.1–3.5 wt%).

ОСОБЕННОСТИ ДЕЗАКТИВАЦИИ БИФУНКЦИОНАЛЬНОГО КОБАЛЬТОВОГО КАТАЛИЗАТОРА СИНТЕЗА ФИШЕРА–ТРОПША ПРИ ДЛИТЕЛЬНЫХ РЕСУРСНЫХ ИСПЫТАНИЯХ

In this work, several ways to decrease the deactivation degree were proposed. To prevent local overheating, exfoliated graphite was used as a heat-conductive additive in catalyst composition. To decrease the deposition of heavy waxes, H-Beta zeolite was used for secondary reactions intensification and decreasing hydrocarbons chain length in the product. In this work, pelletized zeolite-containing cobalt catalyst with exfoliated graphite as a heat-conductive additive was investigated. The test run was 2200 h long and included continuous synthesis in a 6-meter high pilot reactor. The deactivation degree after 2200 h of the test run was 13%. The investigation of catalyst samples after synthesis by means of scanning electron microscopy showed that heavy hydrocarbons did not block the pore structure of catalytic pellets. Deactivation of cobalt catalyst was decelerated seriously due to zeolite-induced decrease in molecular weight of formed hydrocarbons. Investigation of catalysts before and after the test by means of transmission electron microscopy and X-ray diffraction analysis showed an increase in the size of clusters by 3–5 times, which is another important cause for catalyst deactivation. As a result, it was found that investigated cobalt catalyst for Fisher–Tropsch synthesis has a low deactivation rate. Its implementation in the industry can help gaining better economic performance for the synthetic fuel production process.

Model Ag/CeO2 catalysts for soot combustion: Roles of silver species and catalyst stability

Ag/CeO2 has been regarded as a promising recipe for soot catalytic combustion in gasoline particulate filters, while lots of information about its reaction mechanism and practicability is yet missing. In this work, the reducibility and activity of three Ag/CeO2 model catalysts with different types of silver species (Agn+ nanoclusters, metallic Ag nanoclusters and metallic Ag nanoparticles) supporting on CeO2 nanorods were studied. It was suggested that silver facilitated the generation of Oxn- via Ag+-(Ce3+-VO)-induced O2 activation or ceria bulk-to-surface oxygen migration, both of which resulted in boosted soot combustion. From a practical point of view, the thermal ageing-induced silver sintering could be alleviated by the defective sites on CeO2, though certain degree of catalyst deactivation was still inevitable.

Deactivation of platinum on chlorinated alumina catalyst in the light naphtha isomerization process

In order to maintain and increase the lifetime of platinum on chlorinated alumina catalyst, its deactivation was investigated in the presence of oxygenated compounds or mercaptans in the light naphtha hydroisomerization process. A high concentration of methanol or dimethyl disulfide (DMDS) in the feed resulted in irreversible and reversible deactivation of the catalyst. The degree of deactivation and activity recovery of the catalysts measured in the light naphtha isomerization and benzene hydrogenation reactions. The experimental results indicated that when the catalyst was deactivated with oxygenated compounds such as methanol, the catalyst activity was lost drastically, and the regeneration treatment was unable to restore the catalyst’s initial activity. However, a full recovery of the catalyst may obtain when deactivation occurred with dimethyl disulfide. It found that oxygenated compounds affect the acidic functional groups, but mercaptans had an important influence on metallic sites of the catalyst.

Applications of Neutron Scattering in Technical Catalysis: Characterisation of Hydrogenous Species on/in Unsupported and Supported Palladium

Recent results from inelastic neutron scattering (INS) measurements are reviewed that show the synergy between research on hydrogen adsorption/absorption on/in catalysts and chemical engineering. The proton dynamics of catalysts for large scale reactor technology are compared. The focus is the identification and quantification of hydrogenous species on, and inside, fresh, hydrogenated and dehydrogenated palladium black and supported palladium catalysts of different particle size, type of support and, therefore, morphology. INS studies of in-situ hydrogenation/ dehydrogenation of catalysts of 25–60 g size per sample are carried out in stainless steel cans as a function of varying hydrogen pressures. Differences in hysteresis effects in retaining hydrogen inside the catalyst in desorption from palladium hydrides and hydrogen bonding in adsorption sites in varying particle morphologies on different supports were evaluated. This aids the understanding of hydrogen/palladium interactions in catalytic processes with varying local hydrogen partial pressure, e.g. in loop reactors. The importance of the measured on-top Pd–H site in catalytic hydrogenation reactions is discussed together with previous INS results on the degree of deactivation of a technical catalyst by molecular blocking of the on-top site.

A predictive model of catalytic cracking: Feedstock-induced changes in gasoline and gas composition

One way to improve and predict unsteady processes of petroleum fuel production is to develop a mathematical model, that considers the feedstock composition. A study of various feedstock deep refining processes is particularly important. In this paper, we present the prediction of the catalytic cracking unit under feedstock base expansion by using oil fractions with a higher boiling point. The zeolite-containing catalyst with ZSM-5/Y ratio = 0.11 was used in this work. A new kinetic model involving the high molecular weight of C13–C40 hydrocarbons, gasoline groups, gas individual hydrocarbons and coke formation reactions was developed. The feed comprehensive studies, the development and application of a mathematical model allow assessing the feasibility of various feedstock types involvement. The impact of four feedstock types on the yield of catalytic cracking products, catalyst deactivation degree, gasoline and gas composition, and octane number were determined. Among the feedstocks under study are West Siberian oil vacuum gas oil, a mixture of Kazakhstan and West Siberian oil, a mixture of vacuum and atmospheric gas oil with residual feedstock (extract, slack waxes, petrolatum, deasphalting agent, raffinate), a mixture of vacuum distillate and residual feedstock (extracts, slack waxes).

Catalytic performance of Na-Mn2O3-based catalysts towards oxidative coupling of methane

Various active materials (NaCl and Na2WO4 doped on Mn2O3) and supports (SiC, SiO2, WO4, CoO, La2O3, Ce2O3, ZnO, Al2O3, Cr2O3, La0.3Sr0.7Cr0.7Fe0.3O3-δ (LSCF), and clinker) were prepared and tested for use in the OCM reaction in a packed-bed reactor. NaCl-Mn2O3/SiO2 showed the best performance among the catalysts, with 37.5 % methane conversion, 60.5 % C2 selectivity, and 22.7 C2 yield at an optimum temperature of 750 °C under atmospheric pressure. The ethylene-to-ethane ratio of NaCl-Mn2O3/SiO2 (7.5) was found to be the highest, and higher than that of Na2WO4-Mn2O3/SiO2 (1.4), possibly due to its high basicity. Na2WO4-Mn2O3/SiO2 showed good catalytic stability during 12 h time-on-stream experiment whereas slight deactivation was observed in NaCl-Mn2O3/SiO2 due to the decomposition of NaCl, evidenced from traces of gaseous chloride compounds such as CH3CH2Cl, CH3Cl, and Cl2 in the outlet stream. However, the degree of deactivation was found to be more severe when (1) level of NaCl was lower (from 60 % to 10 %) and (2) time-on-stream experiment was tested for the longer period of time (12 h–62 h). The loss of chloride was estimated at 57 and 69 % (by weight) after 12 and 62 h TOS, respectively. The results were in good agreement with information received from XRD where Na2SiO3 was observed due to the loss of chloride, when the deactivation was extreme. From O2-TPSR result, Na2WO4-Mn2O3/SiO2 showed no coke deposition, which could be the result of the high surface oxygen (Os) contained in Na2WO4. Carbon formation at 56.36 μmol/g.hr was detected when using NaCl-Mn2O3/SiO2 as catalyst. The solid-gas mechanism of the catalytic OCM reaction was predicted using the CH4-TPSR technique.

Phraseological units with color names by types of idiomaticity

In this article, we suggest to consider the phraseological units of modern English, which contain color names, in order to determine the function and role of color names in the formation of connotative meanings of English phraseology. Despite the fact that the vocabulary to denote colors, and their shades is a constant object of experimentation in various linguistic theories, the peculiarities of its use in the phraseological units of the English language are incompletely studied. At the same time, the study of color symbols through the prism of phraseology helps to obtain thorough information about the holistic picture of the world, stereotypes, and values that characterize a particular ethnic group, which in turn helps to clarify linguistic phenomena, their etymology, and semantics. The object of this study are the types of phraseological idiomaticity with an element to denote colors in modern English. The subject of the research is phraseological units with a component for color designation (11 basic color names) in modern English. Since the de-actualization of a word in a phraseological unit is directly related to the idiomaticity of the expression itself, phraseology, which includes the name of the color, should be classified by types of idiomaticity, namely: phraseologycomparison, phraseology-metaphor, and phraseology-metoneology. In the course of the research we established that the composition of metonymic, periphrastic and euphemistic phraseology includes color names with their primary (color designation) semantics. As a rule, color names carry an attributive content. They not only affect the overall value of idioms, but also perform a semantic function. Also on the material of the research it is established that depending on the type of reinterpretation tokens for color designation have a different degree of deactivation. Thus, in phraseological comparisons, color designations necessarily denote color, in metonymies this component also has a color feature, but in metaphors, where the highest level of reinterpretation, the degree of deactivation of the word is the highest one.