Gas Conditions Research Articles

Enhanced CO2 capture potential of UiO-66-NH2 synthesized by sonochemical method: experimental findings and performance evaluation

The excessive release of greenhouse gases, especially carbon dioxide (CO2) pollution, has resulted in significant environmental problems all over the world. CO2 capture technologies offer a very effective means of combating global warming, climate change, and promoting sustainable economic growth. In this work, UiO-66-NH2 was synthesized by the novel sonochemical method in only one hour. This material was characterized through PXRD, FT-IR, FE-SEM, EDX, BET, and TGA methods. The CO2 capture potential of the presented material was investigated through the analysis of gas isotherms under varying pressure conditions, encompassing both low and high-pressure regions. Remarkably, this adsorbent manifested a notable augmentation in CO2 adsorption capacity (3.2 mmol/g), achieving an approximate enhancement of 0.9 mmol/g, when compared to conventional solvothermal techniques (2.3 mmol/g) at 25 °C and 1 bar. To accurately represent the experimental findings, three isotherm, and kinetic models were used to fit the experimental data in which the Langmuir model and the Elovich model exhibited the best fit with R2 values of 0.999 and 0.981, respectively. Isosteric heat evaluation showed values higher than 80 kJ/mol which indicates chemisorption between the adsorbent surface and the adsorbate. Furthermore, the selectivity of the adsorbent was examined using the Ideal Adsorbed Solution Theory (IAST), which showed a high value of 202 towards CO2 adsorption under simulated flue gas conditions. To evaluate the durability and performance of the material over consecutive adsorption–desorption processes, cyclic tests were conducted. Interestingly, these tests demonstrated only 0.6 mmol/g capacity decrease for sonochemical UiO-66-NH2 throughout 8 consecutive cycles.

SOFIA FEEDBACK Survey: The Pillars of Creation in [C ii] and Molecular Lines

We investigate the physical structure and conditions of photodissociation regions (PDRs) and molecular gas within the Pillars of Creation in the Eagle Nebula using SOFIA FEEDBACK observations of the [C ii] 158 μm line. These observations are velocity resolved to 0.5 km s−1 and are analyzed alongside a collection of complimentary data with similar spatial and spectral resolution: the [O i] 63 μm line, also observed with SOFIA, and rotational lines of CO, HCN, HCO+, CS, and N2H+. Using the superb spectral resolution of SOFIA, APEX, CARMA, and BIMA, we reveal the relationships between the warm PDR and cool molecular gas layers in context of the Pillars’ kinematic structure. We assemble a geometric picture of the Pillars and their surroundings informed by illumination patterns and kinematic relationships and derive physical conditions in the PDRs associated with the Pillars. We estimate an average molecular gas density cm−3 and an average atomic gas density n H ∼ 1.8 × 104 cm−3 and infer that the ionized, atomic, and molecular phases are in pressure equilibrium if the atomic gas is magnetically supported. We find pillar masses of 103, 78, 103, and 18 M ⊙ for P1a, P1b, P2, and P3, respectively, and evaporation times of ∼1–2 Myr. The dense clumps at the tops of the pillars are currently supported by the magnetic field. Our analysis suggests that ambipolar diffusion is rapid and these clumps are likely to collapse within their photoevaporation timescales.

Rapid and dual optical CO2-responsive polydimethylsiloxane elastomer with fluorinated cyanine dye.

We found that our optically CO2-responsive polydimethylsiloxane (PDMS) elastomer rapidly and reversibly underwent both visible and fluorescent color changes in the presence of CO2 gas. Unlike conventional optically CO2-responsive polymeric materials, it functions in totally dry gaseous conditions. The visible color and fluorescence of the elastomer sheet change after only 1 min of exposure to CO2, and the sheet exhibits excellent repeatability in terms of color switching that persists for at least 20 times.

Performance analysis of a novel biomass gasification system coupled to a coal-fired power plant based on heat and water recovery

Biomass gasification co-firing is a technology that can be implemented instantly in almost all coal-fired power plants in a relatively short period to reduce the consumption of fossil fuel. Most studies have focused on improving the system according to variations in the gasification conditions, biomass types, co-firing ratio, and boiler loads. However, the whole system process analysis and structural improvement based on the matter and energy of the co-firing system require further investigation. In this study, a novel biomass air–steam circulating fluidized bed gasification co-firing system based on waste heat and flue gas water recovery with different co-firing ratios (approximately 10 %–40 %) was simulated and compared with the original air gasification co-firing system using Aspen Plus software. The impacts of recovered water participate in gasification process and the optimal steam to biomass ratio (S/B) when it varied from 0.5 to 2, on the syngas quality, thermal characteristics of flue gas, recovered water, coal consumption, exergy loss, and efficiency of the system were analyzed. Compared with the air gasification co-firing system, the results showed that the N2 content in syngas reduced from 41.14 % to 28.92 %, and the heat yield of syngas increased by 7.73 %, along with a 110 t/h recovered water surplus at a 40 % co-firing ratio when steam to biomass ratio was equal to 1. The maximum coal saving amount was 2.26–9.11 t/h and the volume of atmospheric pollutants emissions, such as carbon dioxide (CO2), sulfur oxides (SOx) and nitrogen oxides (NOx), reduced by 0.95 %–6.02 %, 0.91 %–0.95 %, and 11.38 %–36.47 % at a co-firing ratio of approximately 10 %–40 %. Furthermore, the exergy loss can be reduced by 4.35 %–10 % with a 1.72 %–3.96 % increase in exergy efficiency, indicating that the new system mode improves the comprehensive performance of the co-firing system.

Influence of pre-treatment of straw biomass and additives on the release of nitrogen species during combustion and gasification

The aim of this study is to investigate how pre-treatment of herbaceous straw biomass for ash control affects the release of nitrogen species during combustion and gasification. To comprehend the formation of NO and its precursors, NH3 and HCN, the release of these species was investigated and compared under both combustion and gasification-like conditions at 950 °C. The effects of various upgrading methods, such as torrefaction, water-leaching, a combination of leaching and torrefaction, and CaCO3 addition, were studied. The assessment of nitrogen release was divided into two consecutive conversion steps – devolatilization/pyrolysis and ash/char reactions. The release of nitrogen is highly dependent on the reaction conditions. For instance, the emissions of NO from the combustion conditions (3 vol% O2) for all fuel samples were, on average, six times higher than under gasification conditions (14.5 vol% H2O and 5 vol% CO2). The emissions of NO from the combustion and gasification of torrefied biomass were, on average, 20 % higher than those from raw biomass. Water-leaching had a suppressing effect on NO formation during char conversion. Approximately 62 % of the char-N formed NO for raw and torrefied material, whereas only 26 %–35 % was formed for pre- or postwashed samples. The effect of the applied pre-treatment approaches on the release of nitrogen was particularly significant during char conversion. Increasing calcium and decreasing potassium content had catalytic effects, mainly on the conversion of volatile-N to NH3. The Ca-doped biomass feedstock showed approximate 10 % increase in volatile-N to NH3 conversion compared to the source material.

Research Progress and Prospects on Hydrogen Damage in Welds of Hydrogen-Blended Natural Gas Pipelines

Hydrogen energy represents a crucial pathway towards achieving carbon neutrality and is a pivotal facet of future strategic emerging industries. The safe and efficient transportation of hydrogen is a key link in the entire chain development of the hydrogen energy industry’s “production, storage, and transportation”. Mixing hydrogen into natural gas pipelines for transportation is the potential best way to achieve large-scale, long-distance, safe, and efficient hydrogen transportation. Welds are identified as the vulnerable points in natural gas pipelines, and compatibility between hydrogen-doped natural gas and existing pipeline welds is a critical technical challenge that affects the global-scale transportation of hydrogen energy. Therefore, this article systematically discusses the construction and weld characteristics of hydrogen-doped natural gas pipelines, the research status of hydrogen damage mechanism, and mechanical property strengthening methods of hydrogen-doped natural gas pipeline welds, and points out the future development direction of hydrogen damage mechanism research in hydrogen-doped natural gas pipeline welds. The research results show that: ① Currently, there is a need for comprehensive research on the degradation of mechanical properties in welds made from typical pipe materials on a global scale. It is imperative to systematically elucidate the mechanism of mechanical property degradation due to conventional and hydrogen-induced damage in welds of high-pressure hydrogen-doped natural gas pipelines worldwide. ② The deterioration of mechanical properties in welds of hydrogen-doped natural gas pipelines is influenced by various components, including hydrogen, carbon dioxide, and nitrogen. It is necessary to reveal the mechanism of mechanical property deterioration of pipeline welds under the joint participation of multiple damage mechanisms under multi-component gas conditions. ③ Establishing a fundamental database of mechanical properties for typical pipeline steel materials under hydrogen-doped natural gas conditions globally is imperative, to form a method for strengthening the mechanical properties of typical high-pressure hydrogen-doped natural gas pipeline welds. ④ It is essential to promptly develop relevant standards for hydrogen blending transportation, welding technology, as well as weld evaluation, testing, and repair procedures for natural gas pipelines.

The crystallization kinetics analysis and the new prediction index of melilite-bearing slag under solid fuel gasification condition

Melilite represents a prevalent crystalline phase precipitated from the gasification slag produced by various solid fuels, including coal and biomass. The crystallization of melilite can lead to gasifier blockage, posing significant challenges. This study investigated the crystallization behavior of melilite-bearing slags during slag tapping. To achieve this, FactSage, XRD, SEM-EDS, and DSC were employed to investigate the crystallization thermodynamics and kinetics of 12 synthetic melilite-bearing slag samples. The results revealed that the crystallization temperatures of slags with the mass fraction of SiO2 + Al2O3 is 50 wt% (SiO2 + Al2O3 = 50 wt%) ranged between 1150 and 1100 °C. Slags with the SiO2 + Al2O3 = 60 wt% and mass ratio of SiO2 to Al2O3 > 1.0 (Si/Al > 1.0) showed no crystals precipitate, which is conducive to slag tapping. Thermodynamics plays a crucial role in melilite crystallization, as it involved the uphill diffusion of Ca and Al. To quantify the thermodynamic crystallization ability, a parameter called Thermodynamic Crystallization Ability (TCA) is defined. Increasing Si/Al contributes significantly to reducing TCA. When the TCA is less than 0.33 wt%/K, the melilite-bearing slag will not crystallize. Furthermore, the kinetic analysis results demonstrated that the crystallization activation energy (EC) of melilite-bearing slag ranged from 310.64 to 458.54 kJ/mol. Moreover, the rate-determining step is the surface reaction, which was influenced by cluster structure. The essential short-range ordered structure that composes the melilite crystal is Al-O-Al; however, due to higher Si/Al, the concentration of the Al-O-Al structure in the slag decreases, resulting in higher EC value. These findings provide theoretical guidance for the stable operation of the gasifier.

Modelling of metal nanoparticles’ structures and dynamics under reaction conditions

Metal nanoparticles (NPs) are widely used in heterogeneous catalysis. Their performance in catalytic reactions is closely related to the shape, surface structure, and composition. In the past two decades, a number of in-situ experiments have observed that under real reaction conditions, the structures of metal NPs are not static, but undergo remarkable dynamic evolution due to the presence of gas molecules. Therefore, it is imminent to develop reliable theoretical models to provide accurate predictions and comprehensive understandings of the structure reconstructions and dynamic behaviors of catalysts in response to the different reactive environments. In this review, we summarize a series of progress and achievements made by first-principle-based theoretical models in analyzing the shape evolution of metal NPs and surface segregation of alloys under different gas conditions in recent years. We also discuss the understanding of the catalytic performance of NPs by considering the reaction-condition-dependent structures. In addition, the real-time dynamic simulation methods of catalysts under reaction conditions are introduced. The perspective of simulating the kinetic process of in situ structural change is provided at last.

Diagnosing the interstellar medium of galaxies with far-infrared emission lines

Context. Gas cooling processes in the interstellar medium (ISM) are key to understanding how star formation occurs in galaxies. Far-infrared (FIR) fine-structure emission lines can be used to infer gas conditions and trace different phases of the ISM. Aims. We model eight of the most important FIR emission lines and explore their variation with star formation rate (SFR) out to z = 6 using cosmological hydrodynamical simulations. In addition, we study how different physical parameters, such as the interstellar radiation field (ISRF) and metallicity, impact the FIR lines and line ratios. Methods. We implemented a physically motivated multi-phase model of the ISM by post-processing the EAGLE cosmological simulation and using CLOUDY look-up tables for line emissivities. In this model we included four phases of the ISM: dense molecular gas, neutral atomic gas, diffuse ionised gas (DIG), and H II regions. Results. Our model shows reasonable agreement (to ∼0.5 dex) with the observed line luminosity–SFR relations up to z = 6 in the FIR lines analysed. For ease of comparison, we also provide linear fits to our model results. Our predictions also agree reasonably well with observations in diagnostic diagrams involving various FIR line ratios. Conclusions. We find that [C II] is the best SFR tracer of the FIR lines even though it arises from multiple ISM phases, while [O III] and [N II] can be used to understand the DIG–H II balance in the ionised gas. In addition, line ratios such as [C II]/[O III] and [N II]/[O I] are useful for deriving parameters such as ISRF, metallicity, and specific SFR. These results can help interpret the observations of the FIR lines from the local Universe to high redshifts.

Experimental study of gas production and flame behavior induced by the thermal runaway of 280 Ah lithium iron phosphate battery

With the popularization and application of lithium-ion batteries in the field of energy storage, safety issue has attracted more attention. Thermal runaway is the main cause of lithium-ion battery accidents. A major trend in battery development is to increase the capacity of individual batteries, and large-capacity batteries tend to cause more serious damage when thermal runaway occurs. The paper studied the gas production and flame behavior of the 280 Ah large capacity lithium iron phosphate battery under different SOC and analyzed the surface temperature, voltage, and mass loss of the battery during the process of thermal runaway comprehensively. The thermal runaway of the battery was caused by external heating. The results show that the thermal runaway process can be divided into four stages, and there is a clear thermal runaway internal spreading phenomenon. TR temperature is almost the same under the ignition and the gas condition and is greatly affected by the state of charge. The hazards for the gas scenario are presented as toxicity, asphyxiation and combustion risk, and the flame scenario is presented as the thermal hazard. The work could provide a reference for the process safety design and reduce the fire risk.

HCN emission from translucent gas and UV-illuminated cloud edges revealed by wide-field IRAM 30 m maps of the Orion B GMC

Context. Massive stars form within dense clumps inside giant molecular clouds (GMCs). Finding appropriate chemical tracers of the dense gas (n(H2) > several 104 cm−3 or AV > 8 mag) and linking their line luminosity with the star formation rate is of critical importance. Aims. Our aim is to determine the origin and physical conditions of the HCN-emitting gas and study their relation to those of other molecules. Methods. In the context of the IRAM 30m ORION-B large program, we present 5 deg2 (~250 pc2) HCN, HNC, HCO+, and CO J =1–0 maps of the Orion B GMC, complemented with existing wide-field [C I] 492 GHz maps, as well as new pointed observations of rotationally excited HCN, HNC, H13CN, and HN13C lines. We compare the observed HCN line intensities with radiative transfer models including line overlap effects and electron excitation. Furthermore, we study the HCN/HNC isomeric abundance ratio with updated photochemical models. Results. We spectroscopically resolve the HCN J = 1–0 hyperfine structure (HFS) components (and partially resolved J = 2−1 and 3−2 components). We detect anomalous HFS line intensity (and line width) ratios almost everywhere in the cloud. About 70% of the total HCN J = 1−0 luminosity, L′(HCN J = 1−0) = 110 K km s−1 pc−2, arises from AV < 8 mag. The HCN/CO J = 1−0 line intensity ratio, widely used as a tracer of the dense gas fraction, shows a bimodal behavior with an inflection point at AV < 3 mag typical of translucent gas and illuminated cloud edges. We find that most of the HCN J = 1−0 emission arises from extended gas with n(H2) < 104 cm−3, and even lower density gas if the ionization fraction is χe ≥ 10−5 and electron excitation dominates. This result contrasts with the prevailing view of HCN J = 1−0 emission as a tracer of dense gas and explains the low-AV branch of the HCN/CO J = 1−0 intensity ratio distribution. Indeed, the highest HCN/CO ratios (~ 0.1) at AV < 3 mag correspond to regions of high [C I] 492 GHz/CO J = 1−0 intensity ratios (>1) characteristic of low-density photodissociation regions. The low surface brightness (≲ 1 K km s−1) and extended HCN and HCO+ J = 1−0 emission scale with IFIR – a proxy of the stellar far-ultraviolet (FUV) radiation field – in a similar way. Together with CO J = 1−0, these lines respond to increasing IFIR up to G0 ≃ 20. On the other hand, the bright HCN J = 1−0 emission (> 6 K km s−1) from dense gas in star-forming clumps weakly responds to IFIR once the FUV field becomes too intense (G0 > 1500). In contrast, HNC J = 1−0 and [C I] 492 GHz lines weakly respond to IFIR for all G0. The different power law scalings (produced by different chemistries, densities, and line excitation regimes) in a single but spatially resolved GMC resemble the variety of Kennicutt-Schmidt law indexes found in galaxy averages. Conclusions. Given the widespread and extended nature of the [C I] 492 GHz emission, as well as its spatial correlation with that of HCO+, HCN, and 13CO J = 1−0 lines (in this order), we argue that the edges of GMCs are porous to FUV radiation from nearby massive stars. Enhanced FUV radiation favors the formation and excitation of HCN on large scales, not only in dense star-forming clumps, and it leads to a relatively low value of the dense gas mass to total luminosity ratio, α (HCN) = 29 M⊙/(K km s−1pc2) in Orion B. As a corollary for extragalactic studies, we conclude that high HCN/CO J = 1−0 line intensity ratios do not always imply the presence of dense gas, which may be better traced by HNC than by HCN.

Multi-Oxidant Environment as a Suicidal Inhibitor of Myeloperoxidase.

Tissue inflammation drives the infiltration of innate immune cells that generate reactive species to kill bacteria and recruit adaptive immune cells. Neutrophil activation fosters the release of myeloperoxidase (MPO) enzyme, a heme-containing protein generating hypochlorous acid (HOCl) from hydrogen peroxide (H2O2) and chloride ions. MPO-dependent oxidant formation initiates bioactive oxidation and chlorination products and induces oxidative post-translational modifications (oxPTMs) on proteins and lipid oxidation. Besides HOCl and H2O2, further reactive species such as singlet oxygen and nitric oxide are generated in inflammation, leading to modified proteins, potentially resulting in their altered bioactivity. So far, knowledge about multiple free radical-induced modifications of MPO and its effects on HOCl generation is lacking. To mimic this multi-oxidant microenvironment, human MPO was exposed to several reactive species produced simultaneously via argon plasma operated at body temperature. Several molecular gas admixes were used to modify the reactive species type profiles generated. MPO was investigated by studying its oxPTMs, changes in protein structure, and enzymatic activity. MPO activity was significantly reduced after treatment with all five tested plasma gas conditions. Dynamic light scattering and CD-spectroscopy revealed altered MPO protein morphology indicative of oligomerization. Using mass spectrometry, various oxPTMs, such as +1O, +2O, and +3O, were determined on methionine and cysteine (Cys), and -1H-1N+1O was detected in asparagine (Asp). The modification types identified differed between argon-oxygen and argon-nitrogen plasmas. However, all plasma gas conditions led to the deamidation of Asp and oxidation of Cys residues, suggesting an inactivation of MPO due to oxPTM-mediated conformational changes.

Alternative sorbents for mercury capture in flue gas from lignite combustion

This paper presents an experimental study of two of alternative sorbents for mercury capture from the lignite combustion flue gas. The sorbents are based on calcium hydroxide and aluminosilicate, using different modifications. A commercially available activated carbon (AC) with bromine impregnation was selected as the reference sorbent. This sorbent is a state-of-the-art solution for mercury removal in industrial combustion facilities. However, its application is costly for power plants because of the market price of the AC and because the presence of carbon in the fly ash can complicate its further use, which gives a strong motivation for exploring new alternatives. Experimental investigation was carried out in a 500 kW pilot-scale bubbling fluidized bed combustor using a lignite with naturally high mercury content. A injection system of our own design and construction was used to supply the sorbents to the flue gas downstream of the combustor at a flow rate in the range of 100–500 mg/m3N of the flue gas. Continuous measurement of mercury concentration was used upstream the sorbent injection and downstream the fabric filter, simultaneously. Different sorbent injection rates and flue gas temperatures at the sorbent injection point were examined.The mercury capture ratio was evaluated considering the Hg balance in the combustor. It was shown that the mercury self-capture by the fly ash in the fluidized bed combustion system varies approximately from 30 to 90 %, depending on the SO2 concentration. The Hg capture ratio for calcium hydroxide was in a range of approximately 15–25 %, while for aluminosilicate it was 25–45 %, determined by the actual conditions of the flue gas and the initial Hg concentration. This is in the range of the reference AC, which typically reaches from 25 – 95%. The increased injection rate of the sorbents was reflected in the Hg capture ratio, but its promotion was observed only in the case of the aluminosilicate sorbent. A correlation of the Hg capture ratio with the flue gas temperature at the injection point was also clearly identified only for the aluminosilicate sorbent, when an increase in the temperature led to increasing in the capture ratio.

Surface Chemical Engineering of a Metal 3D-Printed Flow Reactor Using a Metal-Organic Framework for Liquid-Phase Catalytic H2 Production from Hydrogen Storage Materials.

The accurate positioning of metal-organic frameworks (MOFs) on the surface of other materials has opened up new possibilities for the development of multifunctional devices. We propose here a postfunctionalization approach for three-dimensional (3D)-printed metallic catalytic flow reactors based on MOFs. The Cu-based reactors were immersed into an acid solution containing an organic linker for the synthesis of MOFs, where Cu2+ ions dissolved in situ were assembled to form MOF crystals on the surface of the reactor. The resultant MOF layer served as a promising interface that enabled the deposition of catalytically active metal nanoparticles (NPs). It also acted as an efficient platform to provide carbonous layers via simple pyrolysis under inert gas conditions, which further enabled functionalization with organic modifiers and metal NPs. Cylindrical-shaped catalytic flow reactors with four different cell densities were used to investigate the effect of the structure of the reactors on the catalytic production of H2 from a liquid-phase hydrogen storage material. The activity increased with an increasing internal surface area but decreased in the reactor with the smallest cell size despite its high internal surface area. The results of fluid dynamics studies indicated that the effect of pressure loss becomes more pronounced as the pore size decreases.

Bio-engineering of carbon adsorbents to capture CO2 from industrial sources: The cement case

Pine cone leaves (PCL) and pine kernel shells (PKS), abundant by-products of the Spanish food industry, were selected as precursors for activated carbons (ACs) to adsorb CO2 selectively at industrial post-combustion capture conditions. The goal was to maximize the development of narrow microporosity in the final carbons to boost the CO2 adsorption capacity. We have designed kinetics and equilibrium of adsorption experiments with CO2/H2O/N2 on a selected AC derived from PCL in a thermogravimetric analyzer (TGA) at 50 °C and three partial pressures of CO2 to prove the suitability to capture CO2 from industrial off-gases. When humid flue gas streams were tested, competitive adsorption of CO2 and H2O occurred; however, the difference in the uptake rates favored CO2 adsorption in the early stages. The joint CO2 + H2O uptake was around 2 mmol g−1 at 50 °C in humid conditions, where CO2 reached the equilibrium uptake at the corresponding partial pressure for 15 and 32 vol% CO2 in the feed stream. Moreover, the dynamic performance was addressed by cyclic adsorption–desorption experiments representing different industrial post-combustion capture scenarios in a lab-scale fixed-bed rig. The selected AC showed a stable performance in adsorption-regeneration cycles and very remarkable CO2 capture capacity under dry conditions (up to 1.08 mmol g−1 at 50 ˚C for 30 vol% CO2). Kinetics analysis also supported the faster adsorption of CO2 under cement flue gas conditions.

RESESRCH OF THE KINETIC CHARACTERISTICS OF THE SOLID-STATE TRANSFORMATION OF Kh30N60M9 and Kh23N65M13 ALLOYS IN THE TEMPERATURE RANGE OF 500-650 °C, ACCORDING TO THERMOGRAVIMETRIC ANALYSIS

The results of the study of the structural states of single-phase alloys Kh30N60M9 and Kh23N65M13 for the conditions of heating samples at a rate of 1.0 °C/min are presented. The structural states of the alloy samples were obtained by water quenching; the alloy quenching temperature was 1107 and 1135 °C, respectively. The article presents the results of thermal analysis of samples of the considered alloys in the conditions of an inert gas - argon, without carrying out its additional purification from oxygen, the volume fraction of which was up to 0.003 %. As a characteristic of the structure state, an indicator of the rate of weight gain is proposed. According to the experimental results of weight gain, an original method for calculating this kinetic indicator as the rate of solid-state transformation, then the conversion coefficient (k) is proposed. The true values of weight gain considered are referred to the true values of temperatures in the temperature range of 500-650 °C, when the scales of variables and values of variables are proposed in the range of true values (0..1). As a result of the work, confirmation of the improved thermophysical characteristics for the Kh30N60M9 alloy in the considered temperature range was found, in comparison with the Kh23N65M13 alloy. The calculated indicators of the conversion coefficients of the alloy samples were confirmed by experimental data on the amount of enthalpy in the considered gradations of the temperature range, for which the areas under the DTA graphs of the Kh30N60M9 and Kh23N65M13 alloy samples were calculated for the conditions of heating the samples at a rate of 1.0 °C/min. It was found in the work that the decomposition of the solid solution structure is more inherent and essential for the structure of the Kh23N65M13 alloy in the temperature range of 500–650 °C.

Effects of phytohormone on Chlorella vulgaris grown in wastewater-flue gas: C/N/S fixation, wastewater treatment and metabolome analysis

Chlorella vulgaris (C. vulgaris) can provide the means to fix CO2 from complicated flue gas, treat wastewater and reach a sustainable production of petrochemical substitutes simultaneously. However, a prerequisite to achieving this goal is to promote C. vulgaris growth and improve the CO2-to-fatty acids conversion efficiency under different conditions of flue gas and wastewater. Thus, the addition of indole-3-acetic acid (IAA) in C. vulgaris cultivation was proposed. Results showed that C. vulgaris were more easily inhibited by 100 ppm NO and 200 ppm SO2 under low nitrogen (N) condition. NO and SO2 decreased the carbon (C) fixation; but increased N and sulfur (S) fixation. IAA adjusted the content of superoxide dismutase (SOD) and malondialdehyde (MDA), improved the expression of psbA, rbcL, and accD, attenuated the toxicity of NO and SO2 on C. vulgaris, and ultimately improved cell growth (2014.64–2458.16 mgdw·L−1) and restored CO2 fixation rate (170.98–220.92 mg CO2·L−1·d−1). Moreover, wastewater was found to have a high treatment efficiency because C. vulgaris grew well in all treatments, and the maximal removal rates of both N and phosphorus (P) reached 100%. Metabonomic analysis showed that IAA, “NO and SO2” were involved in the down-regulated and up-regulated expression of multiple metabolites, such as fatty acids, amino acids, and carbohydrates. IAA was beneficial for improving lipid accumulation with 24584.21–27634.23 μg g−1, especially monounsaturated fatty acids (MUFAs) dominated by 16–18 C fatty acids, in C. vulgaris cells. It was concluded that IAA enhanced the CO2 fixation, fatty acids production of C. vulgaris and its nutrients removal rate.

Comparison of the aggressiveness of hydrogen sulfide media to steel in the vapor and water phases

Corrosion resistance in hydrogen sulfide-containing environments of the main structural steels used in infrastructure facilities of gas fields has been studied. Gas objects are distinguished by the fact that most of the internal space of equipment and pipelines is in contact with the vapor phase, the internal corrosion of which under hydrogen sulfide conditions has been little studied. The corrosion rates and the composition of the formed corrosion products, which differ depending on the type of medium (water or steam), are determined. The phase composition (crystalline or X-ray amorphous) of the resulting products affects their protective ability and differs in the vapor and aqueous phases. It has been established that under gaseous conditions of moisture condensation, local pitting lesions are formed under fragile corrosion products. The thickness of the iron sulfide film in the vapor phase turned out to be lower than in the aqueous medium. It was revealed that dangerous corrosion consequences (in the form of blisters and cracking) appear on the studied samples of carbon and low-alloy steels, which are characteristic of the process of hydrogenation under conditions of hydrogen sulfide corrosion.

Atom economy or product yield to determine optimal gasification conditions in biomass-to-olefins biorefinery

Biorefinery design uses various metrics for achieving biomass conversion with process efficiency and biochemical selectivity. A common optimization strategy targets the product yield expecting favorable waste reductions. As a green-chemistry metric, atom economy offers a novel approach to achieving mass efficiency by simultaneously computing products and waste. A comparison between the product yield and atom economy presumes different optimal operating conditions. This study applied atom economy to a biomass-to-olefins process to elucidate metric differences. An initial revision of the stoichiometric conditions determined the ideal product and waste generations. A realistic simulation predicted the mass flows to olefins via gasification, methanol synthesis, and methanol-to-olefins conversion. The gasifier operating conditions were modified to clarify interactions among the atom economy, reaction temperature, and steam-to-biomass mass ratio (S/B). The optimal atom-economic and product-yield conditions differed; a lower gasification temperature and atom-economic (S/B) ratio enhanced the olefins-to-waste ratio. The atom economy indicated that CO2 and H2O are inefficient transport molecules for releasing oxygen in biomass. Both wastes consume at best 33% g/g of feedstock carbon or hydrogen, complying to olefin and intermediate H/C ratios. A comprehensive revision of the energy performance is required to complement the atom economy as a performance indicator.

Abatement of photochemical smog precursors through complete hydrocarbon oxidation over commercial Pd catalysts under fuel-lean conditions with NO promoting effect

Currently, severe environmental issues have led to a great transition in the automotive industry from internal combustion engine vehicles to electric vehicles, but this transition will take time more than 10 years, which still requires the use of internal combustion engine vehicles. However, these vehicles emit a significant amount of hydrocarbons, in addition to nitrogen oxides (NOx), due to incomplete fuel combustion. They contribute to the formation of photochemical smog when they react with NOx in the presence of sunlight. To effectively remove these hydrocarbons from the exhaust gas of turbo-gasoline engines or diesel engines, we investigated the abatement of propane and iso-pentane, two typical hydrocarbons. In particular, we studied commercial Pd catalysts and revealed how the Pd loading and aging process simulating 4k and 100k mileage affected hydrocarbon abatement abilities, and their phases were identified using characterization technique, including CO chemisorption, X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HR-TEM). We also suggested the reaction pathway for the complete oxidation of propane over Pd catalyst based on the reaction orders of propane and oxygen: Propane adsorbs on O atoms of PdO, and the kinetically relevant C–H bond cleavage step occurs by the interaction with abundant neighboring O atoms of PdO. Finally, the propane and iso-pentane abatement ability of the Pd catalyst aged for 100k mileage were evaluated under realistic exhaust gas conditions, and the effect of each gas component in the realistic exhaust gas was identified; water inhibits the catalytic reaction of hydrocarbons by occupying the active sites, whereas NO catalyzes the hydrocarbon oxidation reaction by either changing the reaction pathway or active sites under fuel-lean conditions. These findings enable us to effectively reduce environmental pollution and facilitate a smoother transition from internal combustion engine vehicles to electric vehicles.