Reaction Of Hydrogen Chloride Research Articles

Multiscale Model for Hydrogen Chloride Uptake on Aluminum for Spacecraft Fire Safety

An electrical fire within spacecraft environments often produces poisonous gases, such as hydrogen chloride (HCl). These gases adsorb on the interior materials of the spacecraft, primarily treated aluminum surfaces. A safe design of the spacecraft can be facilitated by modeling the spacecraft compartment. In this study, a multiscale model is developed to predict HCl uptake by anodized aluminum, which has a thick oxide layer covering its surface compared to other treatments. X-ray photoelectron spectroscopy revealed that aluminum chloride is found deep in the oxide layer of anodized aluminum, implying that the pore-scale transport and reaction of HCl within the oxide layer covering the aluminum surface must be considered. Hence, a multiscale approach is warranted. A pore-scale model is first developed, wherein the HCl reacts with the aluminum oxide pore walls to create an aluminum chloride layer. The HCl then diffuses through that layer for further reaction, until the layer (diffusion resistance) grows too large and the uptake of HCl stops. This pore-scale model is coupled with a reactor-scale model to predict overall HCl uptake. Results show that this new multiscale approach predicts the uptake of HCl far more accurately when compared to experimental data than previously used single (reactor)-scale models.

Transformation of HCl during pyrolysis of biomass and its model compounds

The release behavior of chlorine (Cl) during biomass pyrolysis has not been fully understood yet due to the complex transformation of hydrogen chloride (HCl). Here, we systematically investigate the transformation of HCl in vapor phase and its interactions with pyrolyzing biomass/char particles during biomass pyrolysis. Four biomass model compounds (cellulose, xylan, pectin, and alkali lignin) and an acid-washed wood were pyrolyzed in a fixed-bed reactor at 300–600 ℃ to produce Cl-free volatiles that reacted with the HCl injected downstream of the reactor. To explore the vapor–solid interactions of HCl with pyrolyzing biomass/char particles, the acid-washed wood was also pyrolyzed in a HCl atmosphere. The role of potassium (K) in the transformation of HCl was revealed via pyrolyzing a wood loaded with potassium carbonate (K2CO3). For all the experiments, the Cl distributed in char, heavy oil (condensed at 110 ℃), light oil (condensed at 0 ℃), and pyrolytic gases (as CH3Cl) was quantified. The results demonstrate that the vapor-phase reactions of HCl with the volatiles from pectin, lignin, and the acid-washed wood generate considerable amounts of methyl chloride (CH3Cl) but do not contribute to organic Cl in bio-oil. Increasing the temperatures of both pyrolysis and vapor-phase reaction promotes the generation of CH3Cl. The vapor–solid interactions of HCl with pyrolyzing biomass/char particles substantially enhance the formation of CH3Cl during the pyrolysis of the acid-washed wood at 300–500 ℃ because of the possible combination of HCl with the methyl radicals released in the initial stage of lignin pyrolysis. In addition, the vapor–solid interactions cause 120–490 μg/g feedstock of water-soluble Cl and 410–1120 μg/g feedstock of water-insoluble Cl being retained in the chars, which are produced from the capture of HCl by pores and carbon active sites in chars, respectively. The addition of K2CO3 catalyzes the cracking of lignin and thereby enhances the methylation of HCl in both vapor-phase reactions and vapor–solid interactions. It also increases the retention of Cl in the chars due to its capture by K.

Gas Altered Hierarchical Porous Graphene Aerogel with High Energy Density

A hierarchical porous graphene aerogel (HP-GA) with hand tearing bread like macro-morphology is achieved through hydrothermal treatment a mix suspension of manganese dioxide (MnO2) and hydrogen chloride (HCl) containing graphite oxide (H-GO) before freeze drying. The chlorine gas (Cl2 as a result of the reaction of HCl and MnO2 is responsible for the formation of the hierarchical porous microstructure and hand tearing bread like macro-morphology. When used as the active electrode material in supercapacitors, the HP-GA exhibits a large specific capacitance of 284 F g-1 at 1 A g-1 and ultrahigh energy density of 10 Wh kg-1 at 250 W kg-1 in aqueous electrolyte. This work provides a versitile, simple and easy-to-controlled way to alter the microstructure and macromorphology of graphene-based areogels that have promissing applications in many areas including adsorption, energy storage, heat insulation, acoustical insulation and intelligent sensing.

Prediction of thermodynamic properties of formation of HCl at temperatures 200–1000 K

In this work, the thermodynamic properties of the formation reaction of hydrogen chloride from the reactants chlorine and hydrogen are studied by employing the developed Manning-Rosen potential. A closed-form expression for the vibration part of the molecular partition function is used to calculate the vibrational contribution of the thermodynamic properties. The results obtained are used to investigate the change in the thermodynamic functions for the formation reaction of HCl at a high temperature range. The predicted results are compared with the ones obtained from the other theoretical approaches based on the harmonic and an-harmonic oscillator models.

Modeling the impact of chlorine emissions from coal combustion and prescribed waste incineration on tropospheric ozone formation in China

Abstract. Chlorine radicals can enhance atmospheric oxidation, which potentially increases tropospheric ozone concentration. However, few studies have been done to quantify the impact of chlorine emissions on ozone formation in China due to the lack of a chlorine emission inventory used in air quality models with sufficient resolution. In this study, the Anthropogenic Chlorine Emissions Inventory for China (ACEIC) was developed for the first time, including emissions of hydrogen chloride (HCl) and molecular chlorine (Cl2) from coal combustion and prescribed waste incineration (waste incineration plant). The HCl and Cl2 emissions from coal combustion in China in 2012 were estimated to be 232.9 and 9.4 Gg, respectively, while HCl emission from prescribed waste incineration was estimated to be 2.9 Gg. Spatially the highest emissions of HCl and Cl2 were found in the North China Plain, the Yangtze River Delta, and the Sichuan Basin. Air quality model simulations with the Community Multiscale Air Quality (CMAQ) modeling system were performed for November 2011, and the modeling results derived with and without chlorine emissions were compared. The magnitude of the simulated HCl, Cl2 and ClNO2 agreed reasonably with the observation when anthropogenic chlorine emissions were included in the model. The inclusion of the ACEIC increased the concentration of fine particulate Cl−, leading to enhanced heterogeneous reactions between Cl− and N2O5, which resulted in the higher production of ClNO2. Photolysis of ClNO2 and Cl2 in the morning and the reaction of HCl with OH in the afternoon produced chlorine radicals which accelerated tropospheric oxidation. When anthropogenic chlorine emissions were included in the model, the monthly mean concentrations of fine particulate Cl−, daily maximum 1 h ClNO2, and Cl radicals were estimated to increase by up to about 2.0 µg m−3, 773 pptv, and 1.5 × 103 molecule cm−3 in China, respectively. Meanwhile, the monthly mean daily maximum 8 h O3 concentration was found to increase by up to 2.0 ppbv (4.1 %), while the monthly mean NOx concentration decreased by up to 0.5 ppbv (6.1 %). The anthropogenic chlorine emissions potentially increased the 1 h O3 concentration by up to 7.7 ppbv in China. This study highlights the need for the inclusion of anthropogenic chlorine emission in air quality modeling and demonstrated its importance in tropospheric ozone formation.

Reactions of Hydrogen Chloride with Carbonaceous Materials and the Formation of Surface Chlorine Species

Secondary reactions of hydrogen chloride (HCl) during high-temperature combustion processes were elucidated using a model carbon prepared from a commercially available phenol resin. This resin was O2-activated, followed by doping with K+, Ca2+, Cu2+, or Zn2+, and subsequently exposed to a stream of 100 ppm of HCl in N2 at 500 °C, during which HCl reacts with the carbon samples to form surface chlorine species. In the absence of metal cations, the extent of reaction increases almost linearly up to 500 °C as the number of carbon active sites, determined by temperature-programmed desorption, increases. The addition of Ca, Cu, or Zn but not K significantly promotes the formation of carbon sites as well as the reaction with HCl, with the latter effect increasing in the order of Ca < Cu < Zn on a molar basis. Cl 2p X-ray photoelectron spectroscopy (XPS) data show that inorganic chlorides of Ca, Cu, and Zn are formed and that the organic Cl/C ratio is 2.0–2.3 times greater when using these additives. It is thus ...

Influence of the V/III ratio in the gas phase on thin epitaxial AlN layers grown on (0001) sapphire by high temperature hydride vapor phase epitaxy

Thin (0001) epitaxial aluminum nitride (AlN) layers were grown on c-plane sapphire using high temperature hydride vapor phase epitaxy. The experimental set-up consists of a vertical cold-wall quartz reactor working at low pressure in which the reactions take place on a susceptor heated by induction. The reactants used are ammonia and aluminum chlorides in situ formed via hydrogen chloride reaction with high purity aluminum pellets. As-grown AlN layers have been characterized by scanning electron microscopy, atomic force microscopy, X-ray diffraction, transmission electron microscopy, photoluminescence and Raman spectroscopies. The influence of the V/III ratio in the gas phase, from 1.5 to 15, on growth rate, surface morphology, roughness and crystalline quality is investigated in order to increase the quality of thin epitaxial AlN layers grown at high temperature. Typical growth rates of around 0.45μm/h were obtained for such thin epitaxial AlN layers. The growth rate was unaffected by the V/III ratio. An optimum for roughness, crystalline quality and optical properties seems to exist at V/III=7.5. As a matter of fact, for a V/III ratio of 7.5, best root mean square roughness and crystalline quality — measured on 0002 symmetric reflection — as low as 6.9nm and 898arcsec were obtained, respectively.

Factors Affecting Mercury Oxidation by SCR Catalysts

The application of selective catalytic reduction (SCR) system may affect mercury speciation in coal-combustion flue gas. The factors affecting mercury oxidation efficiency by SCR catalysts have been evaluated in this research. The influencing factors investigated included hydrogen chloride (HCl), sulfur dioxide (SO2), ammonia (NH3) injection rate and space velocity. HCl had been found to promote mercury oxidation significantly. The Eley-Rideal mechanism was proven to be suitable to explain the reaction of Hg0 and HCl. NH3 injection had a strong negative effect to mercury oxidation. The deactivation of aged SCR catalysts was mainly due to loss of active sites.

Thermal decomposition of poly(vinyl chloride) in organic solvents under high pressure

In order to study chlorination of the plastics derived liquid products by secondary reaction of hydrogen chloride, thermal decomposition of poly(vinyl chloride) (PVC) was carried out in decalin or tetralin at 300–460 °C for 0–90 min under 4.0 MPa of initial nitrogen pressure. Dechlorination of PVC was completed in 30 min at 300 °C, and further slight degradation of the dechlorinated PVC was observed in both solvents. Conversion of PVC to its liquid product proceeded with time at 400 °C, and much more liquid product was produced in tetralin than in decalin. In the liquid product, 1,4-dichlorobutane was observed as the dominant organic chlorine product at 300 °C, and its yield increased with the reaction time in both solvents. We detected 1,3-dichlorobutane, 1-chlorobutane, 2-chlorobutane, and chlorinated solvents as minor organic chlorine products. These results suggest that 1,4-dichlorobutane is a unique product of the secondary reaction between gaseous hydrogen chloride and the polyene chain derived from the dechlorination of PVC. In decalin, the yield of 1,4-dichlorobutane decreased with temperature, and the maximum yield of chlorodecalin was observed at 400 °C. Conversely, yields of all organic chlorine compounds decreased with the reaction time in tetralin, and this hydrogen donorable solvent effectively prevented the production of organic chlorine compounds.

Reaction of hydrogen chloride with microfibrous filtering materials

The resistance of microfibrous filtering materials based on cellulose diacetate, polystyrene, and fluoroplastic to prolonged action of high concentratoins of humid hydrogen chloride in air at room temperature was examined.

Reaction of Hydrogen Chloride with Hydrated Lime for Flue Gas Cleaning of Incinerators

都市ゴミあるいは産業廃棄物焼却炉排ガスから塩化水素ガスなどの酸性ガスを除去する方法として，バグフィルタ上流の排ガス中に消石灰粒子を噴霧する方法がよく用いられる．本研究では，焼却炉排ガスを想定し，300°Cまでの高温において，塩化水素ガスと消石灰粒子との反応機構と反応速度をSTDR（Short Time Differential Reactor）を用いて検討した．その結果，湿潤空気中では消石灰粒子の最終反応率が最大になる温度が存在すること，また，反応速度は塩化水素ガス濃度とともに増加するが，最終反応率は塩化水素ガス濃度によって変化しないことがわかった．さらに，反応生成物のXRD分析を行った結果，塩化カルシウムは全く生成されず，CaClOHのみが生成していることがわかった．このことから，焼却炉排ガスにおいて通常報告されているように，消石灰1モルと塩化水素ガス1モルが反応するといえる．

Hydrogen chloride-induced surface disordering on ice.

Characterizing the interaction of hydrogen chloride (HCl) with polar stratospheric cloud ice particles is essential for understanding the processes responsible for ozone depletion. We studied the interaction of gas-phase HCl with ice between 243 and 186 K by using (i) ellipsometry to monitor the ice surface and (ii) coated-wall flow tube experiments, both with chemical ionization mass spectrometry detection of the gas phase. We show that trace amounts of HCl induce formation of a disordered region, or quasi-liquid layer, at the ice surface at stratospheric temperatures. We also show that surface disordering enhances the chlorine activation reaction of HCl with chlorine nitrate (ClONO(2)) and also enhances acetic acid (CH(3)COOH) adsorption. These results impact our understanding of the chemistry and physics of ice particles in the atmosphere.

1-4.石炭の熱分解過程におけるチャーと塩化水素の反応((1)石炭構造・熱分解,Session 1 石炭・重質油等)

1-4.石炭の熱分解過程におけるチャーと塩化水素の反応((1)石炭構造・熱分解,Session 1 石炭・重質油等)

Direct Experimental Evidence for Reactions between Dissolved Acid Halide and Chlorine Nitrate

Cluster chemistry employing a fast flow reactor was used to evaluate the enhanced reactivity of chlorine nitrate (ClONO2) with dissolved acid halide. Reactions of ClONO2 with deuterium chloride doped deuterated water clusters [D+(D2O)m(DCl)n, (m = 10−14, n = 1,2)] were investigated under thermal conditions over a temperature range of 148−158 K; deuterated species were employed in place of light hydrogen containing molecules to facilitate the determination of reaction mechanisms. Chemical reactions were found to occur between water clusters and chlorine nitrate only under conditions where dissolved deuterium chloride was present. Nitric acid is found to remain within the water cluster to yield gaseous chlorine (Cl2) from the water cluster. These results provide direct evidence that an ionic reaction mechanism is involved in the heterogeneous reaction of hydrogen chloride and chlorine nitrate on clusters that mimic polar stratospheric cloud surfaces.

Mechanism of the Heterogeneous Reaction of Hydrogen Chloride with Chlorine Nitrate and Hypochlorous Acid on Water Ice

The interactions of HOCl and ClONO2 with pure and HCl-doped water ice have been reinvestigated using infrared spectroscopy in conjunction with static and thermal desorption mass spectrometry in the temperature range 140−180 K to probe the detailed mechanisms of their heterogeneous atmospheric reactions. In agreement with earlier studies, HOCl was found to react with hydroxonium chloride species to directly produce molecular chlorine. This molecular chlorine desorbed from the surface above ca. 155 K either directly or in subsequent thermal desorption experiments, depending upon substrate temperature at the time of reaction. ClONO2 was observed to heterogeneously hydrolyze upon water ice to produce HOCl and hydrated H3O+NO3-. Below ca. 155 K, HOCl remains adsorbed on the ice surface, while above ca. 155 K, it desorbs directly into the gas phase. These results suggest that a long-lived, adsorbed state of HOCl is unlikely to play a direct role in heterogeneous chemistry at stratospheric temperatures. The dire...

Ab Initio Investigation of Proton Transfer in Ammonia−Hydrogen Chloride and the Effect of Water Molecules in the Gas Phase

The gas-phase proton-transfer reaction of ammonia−hydrogen chloride and the effect of the first three water molecules are investigated by high-level ab initio calculations on the molecular clusters NH3−HCl−(H2O)n, n = 0, 1, 2, 3. The equilibrium structures, binding energies, and harmonic frequencies of the clusters as well as the potential energy surfaces along the proton-transfer pathway of ammonia−hydrogen chloride are calculated at the second-order Møller−Plesset perturbation (MP2) level with the extended basis set 6-311++G(d,p). Either without water or with one water molecule, the ammonia−hydrogen chloride system exists as a usual hydrogen-bonded complex. With two or three water molecules, the system becomes an ion pair resulting from the complete transfer of a proton from hydrogen chloride to ammonia. The potential energy surfaces along the proton-transfer pathway are examined to understand the effect of the water molecules. The harmonic frequencies and infrared intensities of the clusters provide additional evidence in support of the transition from the hydrogen bond to the ion pair structure as the water molecules are stepwise introduced. On the basis of these results, we conclude that ammonium chloride might be formed by the gas-phase reaction of hydrogen chloride with ammonia in the presence of adequate water vapor.

Proton transfer reaction of hydrogen chloride with ammonia: is it possible in the gas phase?

The mechanism of proton transfer between HCl and NH 3 and the effects of individual water molecules on the reaction are investigated by calculating the structures and energetics of a series of molecule clusters HCl–NH 3–(H 2O) n ( n = 0, 1, 2, 3) using high level ab initio theory. Without water, the system exists as a simple hydrogen-bonded complex and no proton transfer occurs from HCl to NH 3. The first water molecule was found to induce a nearly flat potential energy pathway for proton transfer, but at least two water molecules must be involved for complete proton transfer from HCl to NH 3. The study supports the likelihood of gas phase proton transfer in HCl–NH 3 in the presence of water vapor.

96/02105 The kinetics of the reaction of hydrogen chloride with fresh and spent Ca-based desulfurization sorbents

96/02105 The kinetics of the reaction of hydrogen chloride with fresh and spent Ca-based desulfurization sorbents

A simple method to compute hydrogen chloride abatement in geothermal power plants

One of the most important problems affecting geothermal fields is the abatement of hydrogen chloride contained in the vapor phase. If the chloride concentration exceeds a few ppmw, steam scrubbing must be provided in order to prevent corrosion of the gathering system and turbine failure. In some fields at Larderello, one of the most important geothermal areas in Italy, steam scrubbing is performed by injecting a caustic solution directly into the steam pipeline. In particular, the abatement system depends on absorption with chemical reaction of hydrogen chloride by a sodium hydroxide solution. This paper describes some of the Larderello power plant abatement systems and presents analyses of the different solutions adopted for this purpose. Finally, some simplified models for computing abatement efficiency in sprays, pipelines, static mixers, cyclones and vane type demisters—the equipment generally used in these plants—are proposed. The proposed models are able to predict the data measured in these power plants with good accuracy, and so they can be regarded as useful tools for designing new abatement systems or optimizing the existing ones.

The kinetics of the reaction of hydrogen chloride with fresh and spent Ca-based desulfurization sorbents

The absorption of hydrogen chloride by spent desulfurization sorbents containing calcium carbonate, calcium oxide and calcium hydroxide was investigated. The experiments were carried out in a fixed-bed reactor in two temperature ranges: 423–523 K for slaked lime and 673–873 K for limestone and quicklime. The spent Ca-based sorbents can still react with hydrogen chloride, and after calcining and slaking they even show the same reactivity as pure Ca(OH) 2. A model combining both fixed-bed reactor and shrinking-core model was derived. The activation energy of the surface reaction between hydrogen chloride and limestone was determined to be 84 kJ mol −1 at 673–873 K. The pore diffusion activation energy was 11 kJ mol −1 for limestone at 673–873 K, 29 kJ mol −1 for CaO at 673–873 K and 12 kJ mol −1 for slaked lime at 423–523 K.