Mixture Of CO Research Articles

Anodic Reaction in Syngas-Fueled Proton-Conducting Solid Oxide Fuel Cells

Anode-supported proton-conducting solid oxide fuel cells (PC-SOFCs) fabricated with two representative proton-conducting oxides, BaCe0.7Zr0.1Y0.1Yb0.1O3-δ (BCZYYb) and BaZr0.8Y0.2O3-δ (BZY), were compared to obtain the insight into the electrochemical performances when fueled with syngas at 700°C and the correlation between the anode thickness (0.4, 0.8, and 1.6 mm) and operational stability. We have demonstrated that, in stability tests, the BCZYYb cells exhibited significantly higher maximum power density (MPD) than the BZY cells when operating on H2, 1.22 and 0.48 W/cm2 for the BCZYYb and BZY cells, but the BCZYYb cells degraded more rapidly than the BZY cells when operating on syngas. In addition, decreasing the anode thickness significantly enhanced the stability of BCZYYb cells operating on syngas, a reduction of 81, 76, and 71% in MPD for 1.6, 0.8, and 0.4 mm anode after 30 min. The electrochemical impedance spectra and X-ray diffraction patterns indicated that the rapid degradation of cerate-based cells with syngas could be mainly attributed to the considerable increase in polarization resistance due to the phase decomposition of the electrolyte powder in the anode. Heterogeneous catalysis was performed to study the catalytic reaction of the H2–CO mixture over anode powders prepared with the two proton-conducting oxides (Ni-BCZYYb and Ni-BZY) in a fixed bed reactor, and the CO conversion and selectivity to CO2 and CH4 were determined. For all anode powders, continuous CO2 production was initially observed with CH4 formation, and no significant difference in catalytic activity trends was observed between both anode powders. An increased residence time substantially decreased the normalized CO2 yield, which was associated with the potential secondary reaction of CO2 with H2, CH4, or perovskite oxide. Based on the results of heterogeneous catalysis with both anode powders, the observed cell degradation on both cells during operation with syngas may be primarily attributed to carbon coking due to CO disproportionation; however, more than 4 times rapid degradation of the cerate-based cell when operating with syngas was clearly demonstrated to be attributed to the decomposition of the electrolyte powder in anode by the resulting CO2 from the catalytic reaction of the H2–CO mixture.

Solubility of Cortisone and Hydrocortisone in Supercritical Carbon Dioxide and Ethanol

Cortisone and hydrocortisone are poorly water-soluble corticosteroids widely used to treat many inflammatory and immune diseases. In the prospect of employing them in pharmaceutical applications or analytical techniques involving cosolvent-modified supercritical fluids, their solubility has been determined, for the first time, in a mixture of supercritical CO2 and 2, 3, or 4 mol % of ethanol, at 318.15, 328.15, 348.15, and 373.15 K, and in the pressure range of 13–27 MPa. Tests were conducted in a semi-flow laboratory apparatus, and results were fitted with the most popular density-based correlations reported in the literature for ternary systems. Even though the two drugs exhibit similar molecular structures, the solubility of cortisone in the ethanol-scCO2 mixtures is on average 3.5 times higher than that of hydrocortisone. This is congruent with the fact that the solubility of cortisone in pure ethanol is higher. The seven-parameter Reddy–Madras model (adjusted absolute average percent deviation (AARD%) = 8.8%) proved to be the best correlating one for cortisone while the six-parameter Garlapati–Madras approach (AARD% = 11.6%) provided the best fitting for hydrocortisone. The reliability of the experimental results was also confirmed by the positive response to the Méndez-Santiago–Teja self-consistency test.

Geochemical Characterization of Laminated Crystalline Crust Travertines Formed by Ca2+-Deficient Hot Springs at Sobcha (China)

Travertines formed of crystalline crust have been widely reported, but there has not been focus on their geochemical characteristics. We therefore carefully conducted a series of geochemical investigations and U-Th dating on a travertine mound mainly composed of crystalline crust from Sobcha (southwest China) to determine their geochemical features and geological implications. The Sobcha travertines dominantly consist of granular crystals and fan crystals and show δ13C from 3.4‰ to 4.9‰ V-PDB, δ18O from −26.7‰ to −23.7‰ V-PDB, and 87Sr/86Sr from 0.712458 to 0.712951. When normalized to PASS, the Sobcha travertines exhibit MREE enrichment relative to HREE and LREE, HREE enrichment relative to LREE, and positive Eu anomalies. The δ13C signatures and mother CO2 evaluation of the Sobcha travertines show that the Sobcha travertines were thermogene travertines largely receiving mother CO2 from (upper) mantle (i.e., magmatic CO2) or a mixture of soil-derived CO2 and CO2 related to carbonate decarbonation. The 87Sr/86Sr of the Sobcha travertines is out of the 87Sr/86Sr ranges of local deposits exposed at Sobcha and surrounding areas but is well matched with the mean 87Sr/86Sr of Nadi Kangri volcanic rocks which cropped out to the northeast of the studied travertines (over 20 km away). This might indicate the important role of the Nadi Kangri volcanic rocks in suppling Sr to the studied travertines, but more studies are required. The LREE depletion compared to MREE and HREE in the Sobcha travertines was interpreted to be caused by the difference in geochemical mobility between LREEs and HREEs during water–rock interaction at depth, while the MREE enrichment compared to HREE was considered to be most likely inherited from reservoir/aquifer rocks. The positive Eu anomalies of the Sobcha travertines may result from very high reservoir temperatures and/or preferential dissolution of Eu-rich minerals/rocks (especially plagioclase). The Sobcha travertine mounds displays no or very slight vertical variations in δ13C, 87Sr/86Sr, and REE patterns, indicating the compositional stability of mother CO2 and paleo-fluids. However, a significant vertical increase in δ18O was observed and was explained as the result of gradual water temperature decrease related to climate cooling, self-closure of the vents, or mound vertical growth. The findings in this study might help us better understand the deposition of crystalline crust in Ca2+-deficient hot spring systems.

Negative DC Dielectric Breakdown Characteristics and Synergistic Effect of HFO-1336mzz(E) Mixtures

HFO-1336mzz(E), a substitute for sulfur hexafluoride (SF6), has received much attention owing to its excellent insulation and environmental performance. To provide a reference for selecting suitable buffer gas type and mixing ratio in engineering applications, this article investigated the saturated vapor pressure characteristics, negative direct current (−dc) breakdown properties, and synergistic effect of HFO-1336mzz(E)/CO2 and HFO-1336mzz(E)/N2 mixtures. Experimental results show that although the allowable percentage of HFO-1336mzz(E) in the HFO-1336mzz(E)/CO2 mixture is lower than that of the HFO-1336mzz(E)/N2 at the same gas pressure and limiting temperatures, the former one has a higher breakdown voltage in the gas pressure range from 0.1 to 0.7 MPa. Compared with HFO-1336mzz(E)/N2, the shorter distance within the bimolecular composite structures of HFO-1336mzz(E)/CO2 leads to stronger interaction energy ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{\text {int}}$ </tex-math></inline-formula> ). As a result, HFO-1336mzz(E)/CO2 has a better synergistic effect in view of breakdown voltage. Based on the comprehensive analysis of saturated vapor pressure, liquefaction temperature, and insulation properties of HFO-1336mzz(E)/buffer gas mixtures, CO2 is superior as a buffer gas to N2 being mixed with HFO-1336mzz(E). The negative dc breakdown voltage of 0.7 MPa HFO-1336mzz(E)/CO2 occupies 99.17%, 93.03%, and 85.92% of that of 0.7 MPa 20%SF6/80%N2 mixture under −5 °C, −15 °C, and −25 °C limiting temperatures, guaranteeing its application as an insulation medium in electrical equipment under 220 kV.

Phase equilibria for the mixtures of the deep eutectic solvent L-menthol + thymol plus CO2 at high pressure

The Vapour-Liquid Equilibrium (VLE) of different mixtures of CO2 + L-menthol, CO2 + thymol and CO2 + L-menthol + thymol has been determined at 35, 40, 50 and 60 °C and pressures up to 220 bar using a variable volume view cell. Menthol + Thymol form a deep eutectic solvent (DES) mixture at a 1:1 molar ratio. For selected conditions, the composition of the vapour phase was determined by 1H NMR. By interpolation of the experimental values, ternary diagrams were built. The mutual solubility between CO2 and DES decreased as the proportion menthol:thymol approached the eutectic composition (1:1). Mutual miscibility also decreased with temperature and increased with pressure. The composition of the mixture of menthol + thymol (1:1) does not remain stable at 60 °C but it does at lower temperatures. The intermolecular interactions between menthol and thymol are responsible for this behaviour. The Peng-Robinson equation of state was used to correlate the results with promising results.

Enhanced Carbon Storage Process from Flue Gas Streams Using Rice Husk Silica Nanoparticles: An Approach in Shallow Coal Bed Methane Reservoirs

Carbon capture and storage (CCS) is considered a key process to reach net-zero emission by the 2050 aim of limiting global warming. Coal bed methane (CBM) is considered potential geological reservoirs for underground CCS due to the CO2–CH4 exchange feasibility by adsorptive phenomena. Global implementation has been focused only on deep reservoirs to provide methane recovery. Thus, this work proposes a modified CCS process based on silica nanoparticle inclusion for shallow CBM reservoirs (<300 m). The nanomaterials were evaluated at high pressure in two main stages including i) CO2 sorption on a single CO2 stream and ii) CO2 selectivity on a flue gas stream (N2–CO2 mixture). This work includes silica nanomaterial synthesized from rice husk as agro-waste sources with better technical-economic feasibility framed in a circular economy to reduce costs and maximize the use of available resources. Rice husk silica (RSi) nanoparticles were doped with 1.0, 3.0, and 5.0 wt % of urea (Si–U), diethylamine (Si-DE), triethylamine (Si-TE), and ethylenediamine (Si-EM) to enhance the CO2 sorption. First, CO2 sorption was evaluated at 30 °C and between 0.084 and 3 MPa using a CO2 stream to determine the best-doped amount of each N-source. Then, the best nanoparticles were used to impregnate CBM at 10 and 20 wt %, and the subsequent CO2 storage on the flue gas stream (70% v/v N2 and 30% v/v CO2) was done. The results showed that CO2 sorption on RSi increases with the N-group coating in the order RSi-DE < RSi-TE < RSi-U < RSi-EM. Also, the best-doped amount for each N-source was 3 wt %. For CBM impregnation, the nanofluid containing 20 wt % of RSi-EM3 presented the best yield increasing the CO2 sorption from 0.05 to 0.75 mmol g–1, meaning an increase of more than 1000% in the sorption capacity.

The excitation of CO in CO-dominated cometary comae

ABSTRACTAn abundance of CO significantly surpassing the abundance of H2O is observed in the comae of comets at large heliocentric distances. In these environments, CO molecules can be the most abundant species and they may be therefore the dominant projectiles inducing collisional excitation of the cometary molecules. It is thus of high interest to investigate the excitation of CO by CO. This article provides a new set of CO–CO collisional rate coefficients for temperatures up to 150 K and for CO rotational levels j1 up to 10. These data are obtained from quantum scattering calculations using the coupled states approximation. They are used in a simple radiative transfer model in order to test their impact on the excitation of cometary CO. Because mutual (de-)excitations of the target and projectile are important, the CO projectile was assumed to be thermalized at the kinetic temperature. We found that the non-local thermodynamical equilibrium regime extends for CO densities in the range 103–107 cm−3. We also observed that as soon as the CO/H2O ratio is larger than 70 per cent/30 per cent, the contribution of H2O collisions can be neglected. Similarly, the excitation of CO by CO may be ignored for relatively low CO/H2O density ratios (≤30 per cent/70 per cent). Finally, when the coma is a ∼50 per cent/50 per cent mixture of CO and H2O, the contribution of both colliders is similar and has to be considered.

Influence of Gas from Long-Flame Coal Spontaneous Combustion on Gas Explosion Limit

To investigate the impact of multiple combustible gases produced by long-flame coal spontaneous combustion on the gas explosion limit and to guide the reoperation of the coal mine goaf and fire area, the influence of gas generated by coal spontaneous combustion on gas explosion limit is investigated in this paper using a temperature-programmed device and a 20 L spherical explosion device. The results show that the volume fraction of CO produced during the spontaneous combustion of coal samples is 0.47%, followed by CH4 and C2H6, and C2H4 has the lowest content. Simultaneously, the coal spontaneous combustion is divided by 30°C, 80°C, and 170°C as the threshold, depending on the different gas characteristics. Organic C2H4 and C2H6 produced by coal spontaneous combustion have a greater impact on the CH4 explosion limit than inorganic CO. The lower and upper limits of CH4 explosion were reduced to 2.98% and 12.2%, respectively, by 0.8% C2H6. C2H4 and C2H6 explosion limits change dramatically when mixed with CH4. The CO and CH4 mixture explosion limit decreases first and then increases. C2H4 and C2H6 have a significant impact on the explosion pressure of mixed gas and the lower explosion limit of gas. The lower explosion limit falls from 5.1% to 4.3% as the explosion pressure rises from 0.25 MPa to 0.29 MPa.

Understanding the mechanism of CO2-Assisted electrospray ionization for parameter optimization in supercritical fluid chromatography mass spectrometry

Supercritical fluid chromatography (SFC) is often coupled with electrospray ionization mass spectrometry (ESI-MS) for analyte detection because of its detection capability to a wide range of chemical properties. However, MS sensitivity is highly dependent on the chromatographic conditions, so that it is important to understand the ionization mechanism to determine the optimal chromatographic conditions. The ionization mechanism in SFC/ESI-MS is different to that of liquid chromatography because of the use of CO2 as a mobile phase. Some studies have suggested that alkoxycarbonic acids are formed in the mixture of CO2 and the alcohol modifier, and these species contribute to ionization in CO2-assisted SFC/ESI-MS. Therefore, in this study, we investigated CO2-assisted ESI to test this hypothesis, and we confirmed that methoxylcarbonic acid is generated in CO2/methanol mixtures and contributed to ion generation and detection because it acts as a proton donor in positive-ion mode. However, methoxylcarbonic acid interfered with ionization in negative-ion mode. Addition of ammonium acetate, which is often added to the modifier for negative ion detection in SFC/MS analysis, did not contribute to the recovery of MS sensitivity, although it tended to suppress the formation of metoxylcarbonic acid. This is likely due to ion suppression and neutralization of the negative sites of the analytes by anions or cations derived from ammonium acetate in the negative ion mode. Thus, additive-free methanol/CO2 was the most suitable mobile phase for obtaining high sensitivity in SFC/MS. To demonstrate the practicality of these findings, we tested our optimal mobile phase selection for pesticide analysis. In addition, we tested the addition of 0, 1, and 5 mM ammonium formate to the modifier and make-up solvent, and found that the addition of 1 mM ammonium formate gave the best results in pesticides analysis. In SFC/MS, salt is often added to improve separation or prevent desorption, but our findings suggest that the concentration of salt must be kept as low as possible to achieve highly sensitive MS detection. The results of this study reveal the best selection of the optimal conditions for the modifier and make-up solvent for CO2-assisted SFC/MS analysis and will be useful for the method development in SFC/MS.

Mathematical modeling of supercritical CO2 extraction of Monteverdia aquifolia Mart. Biral leaves: Simple models approaching

The supercritical extractions of Monteverdia aquifolia leaves were conducted using neat CO2 at different temperatures, CO2 flow rates, and pressures. The highest yield was obtained at 300 bar, 6 mL min-1, and 50 °C. In this condition, extraction kinetics were obtained using mixtures of supercritical CO2 with ethanol and ethyl acetate. Other studies have proven that leaves are a good source of bioactive and antioxidant compounds. In this way, seeking to better understand obtaining these extracts via the supercritical method, simplified mathematical models were tested regarding their performance to predict the extraction kinetics. Equilibrium isotherms obtained were analytically solved and coupled to a mass balance in the extractor resulting in five simplified models that describe the extraction kinetics. The accuracy of the models was tested in the prediction of the experimental yield and compared to the results of the classic Sovová model. Results obtained demonstrated All five simplified models were able to describe the experimental supercritical extraction, still provide insights, and conduct procedures, to solve problems or optimize a situation. The Halsey-type equilibrium model was the most accurate, even when compared to the Sovová model, with an R2 of 0.981 and a relative mean deviation of 9.7%. Considering that M. aquifolia extracts are already a reality in the herbal medicine industry, the data reported here may contribute to the dissemination of the extraction methodology, as well as to the more effective acquisition of the extract, with its biological effects preserved.

Mixed matrix metal–organic framework membranes for efficient CO2/N2 separation under humid conditions

AbstractMixed matrix metal–organic framework (MOF) membranes show excellent application prospects in gas separation. However, their stability in various practical application scenarios is poor, especially under humid conditions. Herein, we encapsulated a hydrophobic ionic liquid (IL) into the cavity of MOFs, which effectively mitigated the competition between H2O and CO2 in humid gas mixtures, leading to stable and high‐performance gas separation. For this reason, the resulting membranes using polymer of intrinsic miroporosity‐1 (PIM‐1) as a polymer matrix show good CO2/N2 separation performance and long‐term test stability under humid environment. In particular, the 20 wt% IL‐UiO/PIM‐1 shows a high permeability of 13,778 Barrer and competitive CO2/N2 separation factor of ~35.2, transcending the latest upper bound. Besides, the according membrane module exhibits slightly decreased CO2 permeability and selectivity, promoting the application of self‐supporting membranes. This work provides a reliable strategy for the rational design of MOF‐based hybrid membranes under extreme conditions.

Effect of Steam to Carbon Dioxide Ratio on the Performance of a Solid Oxide Cell for H2O/CO2 Co-Electrolysis

The mixture of H2 and CO, the so-called syngas, is the value-added product of H2O and CO2 co-electrolysis and the feedstock for the production of value-added chemicals (mainly through Fischer-Tropsch). The H2/CO ratio determines the process in which syngas will be utilized and the type of chemicals it will produce. In the present work, we investigate the effect of H2O/CO2 (steam/carbon dioxide, S/C) ratio of 0.5, 1 and 2 in the feed, on the electrochemical performance of an 8YSZ electrolyte-supported solid oxide cell and the H2/CO ratio in the outlet, under co-electrolysis at 900 °C. The B-site iron doped lanthanum strontium chromite La0.75Sr0.25Cr0.9Fe0.1O3-δ (LSCF) is used as fuel electrode material while as oxygen electrode the state-of-the art LSM perovskite is employed. LSCF is a mixed ionic-electronic conductor (MIEC) operating both under a reducing and oxidizing atmosphere. The cell is electrochemically characterized under co-electrolysis conditions both in the presence and absence of hydrogen in the feed of the steam and carbon dioxide mixtures. The results indicate that under the same concentration of hydrogen and different S/C ratios, the same electrochemical performance with a maximum current density of approximately 400 mA cm-2 is observed. However, increasing p(H2) in the feed results in higher OCV, smaller iV slope and Rp values. Furthermore, the maximum current density obtained from the cell does not seem to be affected by whether H2 is present or absent from the fuel electrode feed but has a significant effect on the H2/CO ratio in the analyzed outlet stream. Moreover, the H2/CO ratio seems to be identical under polarization at different current density values. Remarkably, the performance of the LSCF perovskite fuel electrode is not compromised by the exposure to oxidizing conditions, showcasing that this class of electrocatalysts retains their reactivity in oxidizing, reducing, and humid environments.

Overflow metabolism at the thermodynamic limit of life: How carboxydotrophic acetogens mitigate carbon monoxide toxicity.

Carboxydotrophic metabolism is gaining interest due to its applications in gas fermentation technology, enabling the conversion of carbon monoxide to fuels and commodities. Acetogenic carboxydotrophs play a central role in current gas fermentation processes. In contrast to other energy-rich microbial substrates, CO is highly toxic, which makes it a challenging substrate to utilize. Instantaneous scavenging of CO upon entering the cell is required to mitigate its toxicity. Experiments conducted with Clostridium autoethanogenum at different biomass-specific growth rates show that elevated ethanol production occurs at increasing growth rates. The increased allocation of electrons towards ethanol at higher growth rates strongly suggests that C.autoethanogenum employs a form of overflow metabolism to cope with high dissolved CO concentrations. We argue that this overflow branch enables acetogens to efficiently use CO at highly variable substrate influxes by increasing the conversion rate almost instantaneously when required to remove toxic substrate and promote growth. In this perspective, we will address the case study of C.autoethanogenum grown solely on CO and syngas mixtures to assess how it employs acetate reduction to ethanol as a form of overflow metabolism.

Line shape parameters of air-broadened 12CO2 transitions in the 2.0 µm region, with their temperature dependence

The 20013–00001 and 20012–00001 bands of 12C16O2 in the 2 µm region are used by many instruments on-board satellites and in ground-based networks to monitor the CO2 column-averaged dry air mole fraction in the Earth's atmosphere. An accurate knowledge of the corresponding spectroscopic parameters and their temperature dependence is thus needed to map sources and sinks of carbon dioxide. In this work, we retrieve the line-shape parameters and their temperature dependence exponents/coefficients for the P(16) and P(28) transitions of the 20012–00001 band, and the R(24) and R(30) transitions of the 20013–00001 band. These parameters are obtained from a multi-spectrum fit procedure using a speed-dependent Nelkin-Ghatak profile including the line-mixing effect in its first-order approximation. High signal-to-noise spectra (quality factor between typically 3000 and 6000) are recorded at different conditions of pressure (from 50 to 750 Torr) and temperature (from 245 to 330 K) for mixtures of CO2 in air using a comb-assisted cavity ring down spectrometer with a temperature stabilized high finesse cavity. Air-broadening coefficients are measured with an estimated uncertainty better than 0.1% and absolute frequencies of the transitions are obtained with uncertainty better than 100 kHz. The determined line-shape parameters are consistent with previous values derived in the 1.6 µm region confirming the absence of significant vibrational dependence (except for the air-pressure shift coefficient). The retrieved parameters agree well with literature values by Fourier transform spectroscopy and classical molecular dynamic simulations. The parameters of the speed-dependent Voigt profiles provided by the HITRAN2020 database are mostly validated. The comparison to the CO2 line parameters adopted for the OCO missions is discussed.

Recovery of anthocyanin-rich extracts from black carrots using ternary compressed mixtures of CO2–ethanol–water

Recovery of anthocyanin-rich extracts from black carrots using ternary compressed mixtures of CO2–ethanol–water

Binary systems for the trimethylolpropane triacrylate and trimethylolpropane trimethacrylate in supercritical carbon Dioxide: Experiment and modeling

The phase equilibrium data for two binary mixes of trimethylolpropane triacrylate (TMPTA) and trimethylolpropane trimethacrylate (TMPTMA) in supercritical CO2 are given. The mixture's experimental isotherms were determined at five different temperature windows, ranging from 313.2 K to 393.2 K, and maximum pressure of 32.23 MPa. The continuous critical mixture plot displayed by both binary mixtures indicates type-I behavior. At any temperature and composition, none of the systems under study exhibited three phases. The critical point for TMPTA + supercritical CO2 mixtures shifts to a higher pressure as temperature increases; however, no critical point was found for TMPTMA + supercritical CO2 mixture.Experimental phase behavior data is correlated with the Peng-Robinson two parameter cubic equation of state. Using two mixing parameters, all the isotherms in (P, x) space are predicted with satisfactory accuracy.

Reduction disintegration behavior of vanadium titanomagnetite pellets in H2–CO–CO2–N2 mixtures

In this paper, the low–temperature disintegration behavior of vanadium titanomagnetite (VTM) pellets in H 2 –CO–CO 2 –N 2 mixtures was investigated. Thermodynamic calculations indicated that pseudobrookite (Fe 2 TiO 5 ) was reduced in the order Fe 2 TiO 5 → Fe 2 TiO 4 → FeTiO 3 → FeTi 2 O 5 , and the reduction potentials of H 2 and CO were mainly depended on the temperature. The experiments were carried out at temperatures of 400–700 °C with H 2 /(H 2 + CO) of 0–1. The experimental results revealed that disintegration mainly occurred over the temperature range of 500–600 °C, because hematite/pseudobrookite was reduced to magnetite/titanomagnetite resulted in the lattice expansion. A maximum RDI −3.15mm of 45.30% was obtained at 550 °C with a H 2 /(H 2 + CO) ratio of 0.26, and the corresponding reduction degree was 13.31%. Moreover, cracks were observed with a H 2 /(H 2 + CO) ratio of 0.20. A certain interaction between H 2 and CO reduction exists, owing to their different diffusion coefficients and reduction potentials. The reduction by individual CO gases tended to follow the topochemical reaction mode, whereas the non-topochemical reaction mode was dominant with H 2 –CO mixtures. • Thermodynamically, the reduction of pseudobrookite (Fe2TiO5) by H2 and CO is studied. • The disintegration behavior under different conditions is investigated. • The effect of different parameters on disintegration is obtained, and the reason is revealed. • The reaction modes named topochemical and non–topochemical under different gas mixtures are discussed.

Deciphering the role of water and a zinc-doping process in a polyol-based approach for obtaining Zn/Co/Al-based spinels: toward "green" mesoporous inorganic pigments.

Two new families of zinc/cobalt/aluminum-based pigments, with a unique composition, were obtained through the polyol method. The hydrolysis process of a mixture of Co(CH3COO)2, Zn(acac)2 and Al(acac)3 (acac- = acetylacetonate ion) in 1,4-butanediol afforded dark blue gels (wPZnxCo1-xAl), in the presence of a supplementary amount of water, and light green powders (PZnxCo1-xAl), respectively, for the water-free procedure (x = 0, 0.2, 0.4). The calcination of the precursors yielded dark green (wZnxCo1-xAl) and blue (ZnxCo1-xAl) products. XRD measurements and Rietveld refinement indicate the co-existence of three spinel phases, in different proportions: ZnxCo1-xAl2O4, Co3O4 and the defect spinel, γ-Al2.67O4. The Raman scattering and XPS spectra are in agreement with the compositions of the samples. The morphology of wZnxCo1-xAl consists of large and irregular spherical particle aggregates (ca. 5-100 mm). Smaller agglomerates (ca. 1-5 mm) with a unique silkworm cocoon-like hierarchical morphology composed of cobalt aluminate cores covered with flake-like alumina shells are formed for ZnxCo1-xAl. TEM and HR-TEM analyses revealed the formation of crystalline, polyhedral particles of 7-43 nm sizes for wZnxCo1-xAl, while for ZnxCo1-xAl, a duplex-type morphology, with small (7-13 nm) and larger (30-40 nm) particles, was found. BET assessment showed that both series of oxides are mesoporous materials, with different pore structures, with the water-free samples exhibiting the largest surface areas due, most likely, to the high percent of aluminum oxide. A chemical mechanism is proposed to highlight the role of the water amount and the nature of the starting compounds in the hydrolysis reaction products and, further, in the morpho-structural features and composition of the resulting spinel oxides. The CIE L*a*b* and C* colorimetric parameters indicate that the pigments are bright, with a moderate degree of luminosity, presenting an outstanding high blueness.

Double coaxial pipe jet control using DBD-PA and bluff body

In this study, a double-tube burner nozzle with a DBD-PA (dielectric barrier discharge plasma actuator) and flame holder was employed to regulate the lifted flame. The flame holder held the lifted flame and the DBD-PA regulated the lifted flame to suppress the lifted flame’s vertical oscillation. To form a lifted flame, pseudo-biogas, a mixture of CH4 and CO2 in the ratio of 6:4, was jetted out through an inner nozzle and air through an annular nozzle. To control the air jet and prevent the lifted flame’s vertical oscillation, the DBD-PA was installed inside an annular nozzle. The DBD-PA was driven intermittently at regular intervals to produce a tangential flow in the same direction as the jetting gas, and the flame holder was placed above the nozzle outlet on the nozzle center axis. The finding indicated that by driving the DBD-PA at the slightly lower frequency than the frequency of the naturally shedding vortices in the free jet, the lifted flame’s vertical oscillation can be reduced by collapsing the jet’s vortex ring at a steady position and with a steady cycle. By impeding the lifted flame’s vertical oscillation, it is forecasted to reduce the blowout of the lifted flame and combustion noise.

Syngas as a synergistic reducing agent for selective reductive amination—a mild route to bioactive amines

Syngas (a mixture of H2and CO) is a synergistic reducing agent working much better than its components independently. In particular it allows to aminate carbonyl compounds with unstable functional groups furnishing the potential fungicides.