Deactivation of barium oxide-based NO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> storage and reduction catalyst by hydrothermal treatment

The deactivation of a barium oxide-based NO _x storage and reduction (NSR) catalyst with hydrothermal treatment was studied by treating it with 10 vol% water vapor diluted in nitrogen at 850°C. XRD, XPS, SEM, IR of CO adsorption, and the N₂ adsorption was used to investigate the physical and chemical changes of the NSR catalyst caused by the hydrothermal treatment. The 12 h hydrothermal treatment decreased its NO₂ storage capacity by 20%. However, the hydrothermal treatment significantly decreased its ability to reduce the stored NO₂. The formation of an inactive phase consisting of platinum and aluminum is believed to be the cause of the severe deactivation of the NSR catalyst.     

Low Activation Energy Pathway for the Catalyzed Reduction of Nitrogen Oxides to N<Subscript>2</Subscript> by Ammonia

A low activation energy pathway for the catalytic reduction of nitrogen oxides to N₂, with reductants other than ammonia, consists of two sets of reaction steps. In the first set, part of the NO _x is reduced to NH₃; in the second set ammonium nitrite, NH₄NO₂ is formed from this NH₃ and NO + NO₂. The NH₄NO₂ thus formed decomposes at ~100 °C to N₂ + H₂O, even on an inert support, whereas ammonium nitrate, NH₄NO₃, which is also formed from NH₃ and NO₂ + O₂, (or HNO₃), decomposes only at 312 °C yielding mainly N₂O. Upon applying Redhead's equations for a first order desorption to the decomposition of ammonium nitrite, an activation energiy of 22.4 is calculated which is consistent with literature data. For the reaction path via ammonium nitrite a consumption ratio of 1/1 for NO and NO₂ is predicted and confirmed experimentally by injecting NO into a mixture of NH₃ + NO₂ flowing over a BaNa/Y catalyst. This leads to a yield increase of one N₂ molecule per added molecule of NO. Little N₂ is produced from NH₃ + NO in the absence of NO₂.     

Mechanistic Investigation of Co Containing NO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> Traps

Co-containing NO _x storage and reduction catalysts were investigated to identify the mechanism of Co promotion. X-ray diffraction and temperature programmed reduction demonstrated that Co exists in a highly oxidized state (Co₃O₄) and that the surface oxygen could be removed from the catalyst a typical operating conditions around 300 °C. Electron microscopy showed that Co is more uniformly distributed over the catalyst surface, as compared to Pt, with particle sizes ranging between 20 and 80 nm. In situ IR studies illustrated that NO _x storage occurs on Co-containing NSR catalyst via formation of nitrites and nitrates as surface intermediates. Finally, it was found that, similar to Pt, the addition of Co to Ba catalysts enhances the nitrite to nitrate transition rate and also increases the overall formation of nitrates. Therefore, the promotional effect shown by Co is the result of the combination of increased NO to NO₂ oxidation and improved surface area for NO₂ spillover to the Ba storage sites.     

An on-line infrared spectroscopic system with a modified multipath White cell for direct measurements of N<Subscript>2</Subscript>O from NH<Subscript>3</Subscript>-SCR reaction

An on-line, continuous IR-based N₂O measurement system has been developed by combining with a variable multipath “White cell” to avoid a huge amount of the well-known artifact errors in actual N₂O concentrations determination when analyzing grab samples taken from stationary sources, such as fossil fuel-fired power plants. For solving the problems confronted in earlier stages of this study, the gas cell had to have modifications of the feed through of gas sample flows, the multilayer coatings of stainless steel mirrors, and the thermal efficiency to provide high cell inner temperatures in flowing gas samples. These modifications allow good tolerance of the gas cell to gases and chemicals, such as NO _x and NH₃, and NH₄NO₃ driven from them, and its usage for a long lifetime even under harsh conditions. They also offer excellent performance not only in directly determining the extent of N₂O formation during the course of NH₃-SCR reaction over a sample of a commercial V₂O₅-WO₃/TiO₂ catalyst, but also in simultaneously monitoring changes in concentrations of NO, NO₂ and NH₃ during the reaction. Each reference peak was chosen in gasphase spectra for N₂O, NO _x , NH₃ and H₂O, and CO₂ as a possible interference, and the modified gas cell was finely tuned to obtain their spectra with a high resolution under optimal operating conditions. The catalyst gave significant amounts of N₂O formation at reaction temperatures greater than 350 °C, and attention should be paid to the possibility of N₂O production from commercial NH₃-SCR deNO _x processes with V₂O₅/TiO₂-based catalysts.     

Subsoil <Superscript>15</Superscript>N-N<Subscript>2</Subscript>O Concentrations in a Sandy Soil Profile After Application of <Superscript>15</Superscript>N-fertilizer

Studies on emissions of nitrous oxide (N₂O) from agricultural soils mostly focus on fluxes between the soil and the atmosphere or are limited to the atmosphere in the topsoil. However, in soils with shallow water tables, significant N₂O formation may occur closer to the groundwater. The aims of this study were (i) to determine the importance of subsoil N₂O formation in a sandy soil; and (ii) to obtain a quantitative insight in the contribution of subsoil N₂O to the overall losses of N₂O to the environment. We applied ¹⁵N labeled fertilizer at a rate of 5.22 kg ¹⁵N ha⁻¹; 50% as Ca(NO₃)₂ and 50% as NH₄Cl, on a mesic typic Haplaquod seeded with potatoes (Solanum tuberosum L.), and traced soil N₂O concentrations and fluxes over a one-year period. Throughout the year, total N₂O and the amount of ¹⁵N recovered in soil N₂O were highest in the subsoil, with a maximum concentration at 48 cm depth in mid-February of 19900 μl m⁻³ and 24 μg ¹⁵N m⁻³, respectively. The maximum concentration coincided with the highest water-filled pore space of 71%. The cumulative flux of N₂O was 446 g N₂O-N ha⁻¹, the recovery of ¹⁵N in this flux was 0.06%. During the summer, maximum fluxes followed high soil N₂O concentrations. During winter, no such relation was found. We concluded that the formation of N₂O was the highest in the subsoil, largely controlled by water-filled pore space rather than NO₃⁻ concentration or temperature. Although high subsoil N₂O concentrations did not lead to high surface fluxes of N₂O in the winter, artificial draining may lead to high indirect N₂O emissions through supersaturated drainage water.     

Dynamics and Selectivity of N<Subscript>2</Subscript>O Formation/Reduction During Regeneration Phase of Pt-Based Catalysts

The formation of N₂O has been studied by means of isothermal lean-rich experiments at 150, 180 and 250 °C over Pt–Ba/Al₂O₃ and Pt/Al₂O₃ catalysts with H₂ and/or C₃H₆ as reductants. This allows to provide further insights on the mechanistic aspects of N₂O formation and on the influence of the storage component. Both gas phase analysis and surface species studies by operando FT-IR spectroscopy were performed. N₂O evolution is observed at both lean-to-rich (primary N₂O) and rich-to-lean (secondary N₂O) transitions. The production of both primary and secondary N₂O decreases by increasing the temperature. The presence of Ba markedly decreases secondary N₂O formation. FT-IR analysis shows the presence of adsorbed ammonia at the end of the rich phase only for Pt/Al₂O₃ catalyst. These results suggest that: (i) primary N₂O is formed when undissociated NO in the gas phase and partially reduced metal sites are present; (ii) secondary N₂O originates from reaction between adsorbed NH₃ and residual NO_x at the beginning of the lean phase. Moreover, N₂O reduction was studied performing temperature programming temperature experiments with H₂, NH₃ and C₃H₆ as reducing agents. The reduction is completely selective to nitrogen and occurs at temperature higher than 250 °C in the case of Pt–Ba/Al₂O₃ catalyst, while lower temperatures are detected for Pt/Al₂O₃ catalyst. The reactivity order of the reductants is the same for the two catalysts, being hydrogen the more efficient and propylene the less one. Having H₂ a high reactivity in the reduction of N₂O, it could react with N₂O when the regeneration front is developing. Moreover, also ammonia present downstream to the H₂ front could react with N₂O, even if the reaction with stored NO_x seems more efficient.     

Effect of timing and duration of midseason aeration on CH<Subscript>4</Subscript> and N<Subscript>2</Subscript>O emissions from irrigated lowland rice paddies in China

Midseason aeration (MSA) of rice paddy fields functions to mitigate CH₄ emission by a large margin, while simultaneously promoting N₂O emission. Alternation of timing and duration of MSA would affect CH₄ and N₂O emissions from intermittently irrigated rice paddies. A pot trial and a field experiment were conducted to study the effect of timing and duration of MSA on CH₄ and N₂O emissions from irrigated lowland rice paddy soils in China. Four different water regimes, i.e., early aeration, normal aeration (the same as the local practice in timing and duration of aeration), delayed aeration, and prolonged aeration, were adopted separately and compared with respect to global warming potential (GWP) of CH₄ and N₂O emissions and rice yields as well. Total emission of CH₄ from the rice fields ranged from 28.6 to 64.1 kg CH₄ ha⁻¹, while that of N₂O did from 1.71 to 6.30 kg N₂O–N ha⁻¹ during the study periods. Compared with the local practice, early aeration reduced CH₄ emission by 13.3–16.2% and increased N₂O emission by 19.1–68.8%, while delayed aeration reduced N₂O emission by 6.8–26.0% and increased CH₄ emission by 22.1–47.3%. The lowest GWP of CH₄ and N₂O emissions occurred in prolonged aeration treatment, however, rice grain yield was reduced by 15.3% in this condition when compared with normal practice. It was found in the experiments that midseason aeration starting around D 30 after rice transplanting, just like the local practice, would optimize rice yields while simultaneously limiting GWPs of CH₄ and N₂O emissions from irrigated lowland rice fields in China.     

Effects of copper loading on NH<Subscript>3</Subscript>-SCR and NO oxidation over Cu impregnated CHA zeolite

Cu/CHA catalysts with various Cu loadings (0.5 wt%–6.0 wt%) were synthesized via incipient wetness impregnation. The catalysts were applied to the selective catalytic reduction (SCR) of NO with NH₃ and NO oxidation reaction. XRD and N₂ adsorption-desorption data showed that CHA structure was maintained with the incorporation of Cu, while specific surface areas decreased with increasing Cu loading. At intermediate Cu loading, 4 wt%, the highest NH₃-SCR activity was observed with ～98% N₂ selectivity from 150 °C to 300 °C. Small amounts of water, 2%, slightly increased NO conversion in addition to the remarkable N₂O and NO₂ reduction at high temperature. Water effects are attributed to the improved Cu ion reducibility and mobility. NO oxidation results provided no relation between NO₂ formation and SCR activity. Physicochemical properties, NO conversion, N₂ selectivity, and activation energy data showed that impregnated samples’ molecular structure and catalytic activity are comparable to the conventional ion-exchanged (IE) samples’ ones.     

N<Subscript>2</Subscript>O fluxes and CO<Subscript>2</Subscript> exchange at different N doses under elevated CO<Subscript>2</Subscript> concentration in boreal agricultural mineral soil under <Emphasis Type="Italic">Phleum pratense</Emphasis>

The effects of elevated atmospheric CO₂ concentration on N₂O fluxes, instant CO₂ exchange and the biomass production of timothy (Phleum pratense) were studied in the laboratory. Three sets of 12 farmed sandy soil mesocosms sown with Phleum pratense were fertilised with a commercial fertiliser in order to add 5, 10 and 15 g N m⁻², and equally distributed in four thermo-controlled greenhouses. In two of the greenhouses, the CO₂ concentration was kept at atmospheric concentration (360 μmol mol⁻¹), and in the other two at double the ambient concentration (720 μmol mol⁻¹). Forage was harvested and the plants fertilised twice during the N₂O measurements. This was followed by an extra fertilisation and harvesting. After the third harvest, the growth of P. pratense was maintained at a height of 18 cm for measurements of instant CO₂ exchange, performed in two growth chambers. N₂O exchange was monitored using a closed chamber technique and a gas chromatograph. Instant CO₂ exchange was monitored using an infrared gas analyser. N₂O was emitted from the soil in the low, moderate and high N treatments at both CO₂ concentrations when the moisture content was low, the N₂O probably being mainly derived from nitrification. The highest flux (3303 μg N₂O m⁻² h⁻¹) occurred in the highest N treatment before thinning the stand of P. pratense under elevated CO₂ concentration. P. pratense was acclimated to the elevated CO₂ concentration: the NEE and P _G of the elevated growth of P. pratense decreased, in contrast to the fluxes of the normal ambient growth, when measured at the changed CO₂ concentration (ambient). The rate of respiration (R _TOT) in the agroecosystem did not increase due to the elevated CO₂ concentration, but instead the results indicated decreased R _TOT (on average 2049 and 1808 mg CO₂ m⁻² h⁻¹ at ambient and elevated CO₂ concentration, respectively) when there was an abundant N supply. This infers the possibility of enhanced C accumulation in agriculture mineral soil via P. pratense under an increased atmospheric CO₂ supply.     

Separation characteristics of tetrapropylammoniumbromide templating silica/alumina composite membrane in CO<Subscript>2</Subscript>/N<Subscript>2</Subscript>, CO<Subscript>2</Subscript>/H<Subscript>2</Subscript> and CH<Subscript>4</Subscript>/H<Subscript>2</Subscript> systems

Nanoporous silica membrane without any pinholes and cracks was synthesized by organic templating method. The tetrapropylammoniumbromide (TPABr)-templating silica sols were coated on tubular alumina composite support ( γ-Al₂O₃/ α-Al₂O₃ composite) by dip coating and then heat-treated at 550 °C. By using the prepared TPABr templating silica/alumina composite membrane, adsorption and membrane transport experiments were performed on the CO₂/N₂, CO₂/H₂ and CH₄/H₂ systems. Adsorption and permeation by using single gas and binary mixtures were measured in order to examine the transport mechanism in the membrane. In the single gas systems, adsorption characteristics on the α-Al₂O₃ support and nanoporous unsupport (TPABr templating SiO₂/ γ-Al₂O₃ composite layer without α-Al₂O₃ support) were investigated at 20–40 °C conditions and 0.0–1.0 atm pressure range. The experimental adsorption equilibrium was well fitted with Langmuir or/and Langmuir-Freundlich isotherm models. The α-Al₂O₃ support had a little adsorption capacity compared to the unsupport which had relatively larger adsorption capacity for CO₂ and CH₄. While the adsorption rates in the unsupport showed in the order of H₂> CO₂> N₂> CH₄ at low pressure range, the permeate flux in the membrane was in the order of H₂≫N₂> CH₄> CO₂. Separation properties of the unsupport could be confirmed by the separation experiments of adsorbable/non-adsorbable mixed gases, such as CO₂/H₂ and CH₄/H₂ systems. Although light and non-adsorbable molecules, such as H₂, showed the highest permeation in the single gas permeate experiments, heavier and strongly adsorbable molecules, such as CO₂ and CH₄, showed a higher separation factor (CO₂/H₂=5-7, CH₄/H₂=4-9). These results might be caused by the surface diffusion or/and blocking effects of adsorbed molecules in the unsupport. And these results could be explained by surface diffusion. This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University.     

Promoting Effect of Triglyme on Lean NO<Subscript>x</Subscript> Reduction Over Ag/Al<Subscript>2</Subscript>O<Subscript>3</Subscript>

Abstract  

The highly oxygenated hydrocarbon triethylene glycol dimethyl ether or triglyme (CH₃O–(C₂H₄O–)₃CH₃) was found to efficiently reduce NO_x under lean conditions over Ag/Al₂O₃, but gave a low NO_x conversion over Cu-ZSM-5. Furthermore, triglyme showed an extraordinary promoting effect when added together with propene as reducing agent for NO_x over Ag/Al₂O₃ at low temperature. This is most likely due to that triglyme promotes the activation of propene.     

Fungal and bacterial contributions to codenitrification emissions of N<Subscript>2</Subscript>O and N<Subscript>2</Subscript> following urea deposition to soil

Grazed pastures contribute significantly to anthropogenic emissions of N₂O but the respective contributions of archaea, bacteria and fungi to codenitrification in such systems is unresolved. This study examined the relative contributions of bacteria and fungi to rates of denitrification and codenitrification under a simulated ruminant urine event. It was hypothesised that fungi would be primarily responsible for both codenitrification and total N₂O and N₂ emissions. The effects of bacterial (streptomycin), fungal (cycloheximide), and combined inhibitor treatments were measured in a laboratory mesocosm experiment, on soil that had received ¹⁵N labelled urea. Soil inorganic-N concentrations, N₂O and N₂ gas fluxes were measured over 51 days. On Days 42 and 51, when nitrification was actively proceeding in the positive control, the inhibitor treatments inhibited nitrification as evidenced by increased soil NH ₄ ⁺ -N concentrations and decreased soil NO ₂ ^? -N and NO ₃ ^? -N concentrations. Codenitrification was observed to contribute to total fluxes of both N₂O (≥ 33%) and N₂ (≥ 3%) in urine-amended grassland soils. Cycloheximide inhibition decreased NH ₄ ⁺ –¹⁵N enrichment and reduced N₂O fluxes while reducing the contribution of codenitrification to total N₂O fluxes by ≥ 66 and ≥ 42%, respectively. Thus, given archaea do not respond to significant urea deposition, it is proposed that fungi, not bacteria, dominated total N₂O fluxes, and the codenitrification N₂O fluxes, from a simulated urine amended pasture soil.     

Numerical simulation of the effect of the addition of NO and NO<Subscript>2</Subscript> on a rich hydrogen flame using the tracer method

The effect of the addition of nitric oxides (NO and NO₂) on rich hydrogen-air flames was studied using the tracer method in numerical simulation. It is shown that the effects of these additives are not similar. Both oxides promote the formation of OH and H₂O in the low-temperature zone of the front. The addition of NO reduces the first maximum of the OH profile and the burning velocity. The addition of NO₂ increases the first maximum of the OH profile and does not change the burning velocity. __________ Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 3, pp. 19–25, May–June, 2009.     

Phase behavior and structural properties for the triton X-100/<Emphasis Type="Italic">n</Emphasis>-C<Subscript>n</Subscript>H<Subscript>2n+1</Subscript>COOH/H<Subscript>2</Subscript>O system

In the Triton X-100/n-C_nH_2n+1COOH/H₂O system, n-C_nH_2n+1COOH can be used as a cosurfactant. As its chain length increases, the regions of the microemulsions showing oil-in-water (O/W), water-in-oil (W/O), and bicontinuous structures decrease and at the same time, the region of the lamellar liquid crystal increases. In the O/W region, the distribution coefficient K of n-C_nH_2n+1COOH between Triton X-100 micellar phase and water phase increases with the chain length of saturated unbranched monocarboxylic acid. The relationship between the standard solubilization Gibbs free energy of saturated unbranched monocarboxylic acid and the number of methylene groups in the saturated unbranched monocarboxylic acid is given by the equation: ΔG _m ⁰=−2.364−2.818 n(CH₂) kJ·mol⁻¹ in the Triton X-100 micellar system. In the lamellar liquid crystal region, small-angle X-ray diffraction shows that the thickness of the bilayer d ₀ is independent of the weight ratio of n-C_nH_2n+1COOH to Triton X-100, but the volume of the solvent penetrating from the solvent layer to the amphiphilic bilayer increases with the weight ratio of n-C_nH_2n+1COOH to Triton X-100. Furthermore, the d ₀ value increases with the chain length of saturated unbranched monocarboxylic acid, which will contribute to the formation and stabilization of the lamellar liquid crystal.     

BF<Subscript>3</Subscript>OEt<Subscript>2</Subscript>-coinitiated cationic polymerization of cyclopentadiene in the presence of water at room temperature

The cationic polymerization of cyclopentadiene (CPD) with 1-(4-methoxyphenyl)ethanol (1)/BF₃OEt₂ initiating system in CH₂Cl₂:CH₃CN 4:1 (v/v) mixture at room temperature and in the presence of water ([H₂O]/[BF₃OEt₂] up to 8) is reported. The number-average molecular weights of obtained polymers increased in direct proportion to monomer conversion or initial monomer concentration (M _n ≤ 4,000 g mol⁻¹) in agreement with calculated values, and were inversely proportional to initiator concentration. Polymer MWDs were relatively narrow (M _w/M _n = 1.4–1.7) up to 60% of monomer conversion. It was also shown that regioselectivity of CPD polymerization with 1/BF₃OEt₂ initiating system did not depend significantly on water, monomer, or initiator concentration (1,4-structures content was nearly 60% in all cases).     

Mitigation of N<Subscript>2</Subscript>O and CH<Subscript>4</Subscript> Emission from Rice and Wheat Cropping Systems Using Dicyandiamide and Hydroquinone

Agriculture contributes considerably to the emission of greenhouse gases, such as N₂O and CH₄. Here we summarize results from previous pot experiments assessing the effectiveness of urease and nitrification inhibitors reducing both N₂O and CH₄ emissions from wheat and rice cropping systems fertilized with urea (U). For the wheat cropping system, using a cambisol, we observed that the application of U with hydroquinone (HQ, a urease inhibitor), U with dicyandiamide (DCD, a nitrification inhibitor) and U with HQ plus DCD decreased the N₂O emissions by 11.4, 22.3 and 25.1%, respectively. For the rice copping system, using a luvisol, we found that the application of U with HQ, U with DCD and U with HQ plus DCD decreased N₂O emissions by 10.6, 47.0 and 62.3%, respectively, and CH₄ emissions by 30.1, 53.1 and 58.3%, respectively. In terms of total global warming potential (GWP) a reduction of 61.2% could be realized via the combined addition of HQ and DCD. The addition of wheat straw reduced the activity of HQ and DCD in the rice cropping experiments. In terms of total GWP only a reduction of 30.7% could be achieved. In general, both in upland and flooded conditions, the application of HQ and DCD alone was less effective than HQ in combination with DCD, but not significantly for U plus DCD treatment. Our observations may be further constrained, however, by practical, economic or social problems and should therefore be tested at the scale of a region (e.g. a watershed) and related to an integrated abatement of agricultural N losses.     

Investigation of the properties of decaoxyethylene <Emphasis Type="Italic">n</Emphasis>-dodecyl ether,C<Subscript>12</Subscript>E<Subscript>10</Subscript>, in the aqueous sugar-rich region

Interfacial, thermodynamic, and morphological properties of decaoxyethylene n-dodecylether [CH₃ (CH₂)₁₁(OCH₂CH₂)₁₀OH](C₁₂E₁₀) in aqueous solution were analyzed by tensiometric, viscometric, proton nuclear magnetic resonance (NMR), and small-angle neutron scattering (SANS) techniques. Dynamic and structural aspects at different temperatures in the absence and presence of sugars at different concentrations were measured. Critical micelle concentrations (CMC) were determined by surface tension measurements in the presence of ribose, glucose, and sucrose. The heat capacity (ΔC _p.m.), transfer enthalpy (ΔH _m.tr.), transfer heat capacities (ΔC _p.m.tr.), micellization constant (K _m ), Setchenow constant (K _S ^N ), and partition coefficient (q) were determined and discussed as an extension of the usual thermodynamic quantities of micellization and adsorption at the air-water interface. An enthalpy-entropy compensation effect was observed with an isostructural temperature (T _c ) of about 310 K for both micellization and interfacial adsorption. SANS measurements were taken to elucidate structural information, viz., aggregation number (N _agg), shape, size, and number density (N _m ) on C₁₂E₁₀ micelles in D₂O at different concentrations of sugars (0.05, 0.02, 0.3, and 0.5 M) and temperatures (30, 45, and 60°C). Intrinsic viscosity gave the hydrated micellar volume (V _h ), volume of the hydrocarbon core (V _c ), and volume of the palisade layer of the oxyethylene (OE) unit (V _OE). SANS, as well as rheological data, supported the formation of nonspherical micelles with or without sugars. By SANS, we also observed that at the studied temperature intervals, oblate ellipsoid micelles changed into prolate ellipsoids and the number density of micelles decreased with an increase in temperature both in the presence and in the absence of sugars and also on increasing the concentration of sugars. Proton NMR showed a change in chemical shift of the OE group of micelles above the CMC. We also studied the phase separation of C₁₂E₁₀ by sugars in cloud point measurements.     

Low-temperature anti-icing reagents in the Ca(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>-Mg(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>-CO(NH<Subscript>2</Subscript>)<Subscript>2</Subscript>-H<Subscript>2</Subscript>O system and their properties

The polytherms of ice melting in sections of the Ca(NO₃)₂-Mg(NO₃)₂-CO(NH₂)₂-H₂O system with different component ratios were studied in the temperature interval from 0 to −40°C. A series of nitrate and nitrate-carbonate reagents that are promising for the creation of anti-acing reagents were found, which form eutectics with ice at temperatures from −25 to −39°C. Their properties, viz., melting properties with respect to ice and corrosiveness on metals and alloys, were determined. An effective corrosion inhibitor was selected.     

Enhancement of NO absorption in ammonium-based solution using heterogeneous Fenton reaction at low H<Subscript>2</Subscript>O<Subscript>2</Subscript> consumption

A novel NO removal system is designed, where NO is initially oxidized by ?OH radicals from the decomposition of hydrogen peroxide (H₂O₂) over hematite and then absorbed by ammonium-based solution. According to the high performance liquid chromatography (HPLC) profile and the isopropanol injection experiments, the ?OH radicals are proved to play a critical role in NO removal. The NO removal efficiency primarily depends on H₂O₂ concentration, gas hourly space velocity (GHSV), H₂O₂ feeding rate and reaction temperature, while the flue gas temperature slightly affects the NO removal efficiency. The low H₂O₂ consumption makes this system a promising technique in NO removal process using wet-method. The evolution of catalyst in reaction is analyzed by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), Fourier Transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The nitrite ion and nitrate ion in aqueous solution are detected by the continuous phase flow analyzer. Finally, the macrokinetic parameters of the NO oxidation are obtained by using the initial rate method.     

Sorption studies of CO<Subscript>2</Subscript>, CH<Subscript>4</Subscript>, N<Subscript>2</Subscript>, CO,O<Subscript>2</Subscript> and Ar on nanoporous aluminum terephthalate [MIL-53(Al)]

Aluminum terephthalate, MIL-53(Al), metal–organic framework synthesized hydrothermally and purified by solvent extraction method was used as an adsorbent for gas adsorption studies. The synthesized MIL-53(Al) was characterized by powder X-Ray diffraction analysis, surface area measurement using N₂ adsorption–desorption at 77 K, FTIR spectroscopy and thermo gravimetric analysis. Adsorption isotherms of CO₂, CH₄, CO, N₂, O₂ and Ar were measured at 288 and 303 K. The absolute adsorption capacity was found in the order CO₂>CH₄>CO>N₂>Ar>O₂. Henry’s constants, heat of adsorption in the low pressure region and adsorption selectivities for the adsorbate gases were calculated from their adsorption isotherms. The high selectivity and low heat of adsorption for CO₂ suggests that MIL-53(Al) is a potential adsorbent material for the separation of CO₂ from gas mixtures. The high selectivity for CH₄ over O₂ and its low heat of adsorption suggests that MIL-53(Al) could also be a compatible adsorbent for the separation of methane from methane–oxygen gas mixtures.