Production Of Hydrogen Chloride Research Articles

Copyrolysis characteristics of polyvinyl chloride, polyethylene and polypropylene based on ReaxFF molecular simulation

Reactive force field molecular dynamics (ReaxFF MD) simulation was used to study the copyrolysis behaviour of waste plastics i.e., polyvinyl chloride (PVC), polyethylene (PE), and polypropylene (PP) from three perspectives: (1) gas phase products, (2) reaction route, and (3) activation energy. The results demonstrate that the thermogravimetric (TG) experiment's findings and the weight loss characteristics of PVC/PE/PP copyrolysis obtained by ReaxFF MD simulation were consistent. Copyrolysis changed the amount of gas phase products generated, the direction of free radical movement, and the range of temperatures at which they were produced in considerable quantities. Due to the transfer of chloride (Cl) radicals, both PE and PP had a detrimental synergistic impact on the production of hydrogen chloride (HCl). Based on the first-order reaction kinetics model, the copyrolysis of waste plastics significantly lowered the total activation energy of the mixture, and the activation energy of PVC/PE/PP ternary blend system decreased most significantly.

Performance and Sensitivity Properties of Solid Heterogeneous Rocket Propellant Based on a Binary System of Oxidizers (PSAN and AP)

Solid heterogeneous rocket propellants (SHRP) containing ammonium perchlorate (AP) emit a lot of hydrogen chloride (HCl) during combustion, which poses various environmental issues and makes the detection of the rockets easier. Part of the AP can be replaced by ammonium nitrate (V) (AN), which does not lead to the production of HCl. AN is a commonly used environmentally friendly oxidizer, but it is not usually applied in SHRP due to its disadvantages. One of these disadvantages is a phase transition near room temperature, which causes the density change of AN. Three types of phase stabilized ammonium nitrate (V) (PSAN) with inorganic potassium salts were obtained in order to shift this transition into higher temperatures (above the temperature range of the storage and the usage of SHRP). The SHRP with the PSAN were obtained, and the measurements of the heat of combustion, density, hardness, the sensitivity to mechanical stimuli and the thermomechanical properties were performed. The obtained propellants were characterized by similar operational parameters or were slightly lower than those without the PSAN. This means that AP can be partially replaced without significantly compromising the handling, safety or functionality of the propellants, while increasing the environmental performance of the solution.

A new developed integrated process configuration for production of hydrogen chloride using geothermal and wind energy resources

Ethylene dichloride thermal cracking is one of the conventional methods for hydrogen chloride production. A critical issue concerned with this method is to provide thermal energy for cracking reaction, which is generally provided by the flammable gasses inside the furnace. Utilizing renewable energy sources can be an interesting topic in this case. Hence, in this paper, the thermal integration feasibility of an ethylene dichloride cracking unit with a hybrid renewable plant, based on geothermal and wind energies, is investigated, while the case study for wind turbines system (Alstom ECO 74/1670/ Class II model) is Meshkin Shahr, located in Iran. To utilize geothermal energy, a high-temperature heat pump cycle is developed to transfer heat energy from the heat source (geothermal reservoir) to the system. Moreover, the excess thermal energy produced by the geothermal heat pump cycle is used in an organic Rankine cycle to generate power. The parametric study's results show that the wind turbines and organic Rankine cycle generate 54532 kW and 19107 kW power, respectively. The geothermal plant provides 10490 kW and 103778 kW heat duty required by the cracking unit and organic Rankine cycle, respectively. Moreover, the integrated structure's main product is hydrogen chloride with a molar flow rate of 131.13 kgmole/h and a purity of 81.71%. The results of the economic analysis of the hybrid system illustrate that the period of return and additive value are 2.735 years and 0.0642 US$/kg HCl.

Ecological and economic aspects of vinyl chloride production based on the use of raw materials of coking plant

Ecological and economic aspects of vinyl chloride production are considered as the main resource for production of polyvinyl chloride using by-products of coking enterprise, including low-grade coke, as well as coke gas. Implementation of this project is possible based on carbon technologies and technology of conversion of methane contained in coke gas into acetylene using hydrogen-arc pyrolysis. It is proposed to include cryogenic separation of coke gas into methane and hydrogen, needed for implementation of this technology and production of hydrogen chloride as a component for production of vinyl chloride in process of raw material preparation. Rational use of resources of two Kemerovo enterprises - “Cock” PJSC and “Khimprom” PJSC for this product manufacturing allows optimization of added value chain. Currently, “Coke” PJSC has inoperative volumes of coke gas, which can be used as a raw material for vinyl chloride production. Carbon technology of PVC production, as international practice has shown, is economically advantageous if cost of coal raw materials and waste coke production is 40% lower than cost of oil or natural gas. Analysis of economic expenditures and cost of vinyl chloride production based on added value chains have identified the most “narrow” elements of technological process, requiring innovative solutions to reduce costs and environmental impact of production.

Formation and emission of hydrogen chloride in indoor air

To improve our understanding of chlorine chemistry indoors, reactive chlorine species such as hydrogen chloride (HCl) must be analyzed using fast time-response measurement techniques. Although well studied outdoors, sources of HCl indoors are unknown. In this study, mixing ratios of gaseous HCl were measured at 0.5Hz in the indoor environment using a cavity ring-down spectroscopy (CRDS) instrument. The CRDS measurement rate provides a major advance in observational capability compared to other established techniques. Measurements of HCl were performed during three types of household activities: (a) floor exposure to bleach, (b) chlorinated and nonchlorinated detergent use in household dishwashers, and (c) cooking events. Surface application of bleach resulted in a reproducible increase of 0.1 ppbv in the affected room. Emissions of HCl from automated dishwashers were observed only when chlorinated detergents were used, with additional HCl emitted during the drying cycle. Increased mixing ratios of HCl were also observed during meal preparation on an electric element stovetop. These observations of HCl derived from household activities indicate either direct emission or secondary production of HCl via chlorine atoms is possible. Calculations of photolysis rate constants of chlorine atom precursors provide evidence that photolysis may contribute to indoor HCl levels.

Dynamics of Cl (2Pj) Atom Formation in the Photodissociation of Fumaryl Chloride (ClCO − CH = CH − COCl) at 235 nm: A Resonance Enhanced Multiphoton Ionization (REMPI) Time-of-Flight (TOF) Study

The photodissociation dynamics of fumaryl chloride (ClCO-CH═CH-COCl) has been studied in a supersonic molecular beam around 235 nm using resonance enhanced multiphoton ionization (REMPI) time-of-flight (TOF) technique by detecting the nascent state of the primary chlorine atom. A single laser has been used for excitation of fumaryl chloride and the REMPI detection of chlorine atoms in their spin-orbit states, Cl ((2)P(3/2)) and Cl* ((2)P(1/2)). We have determined the translational energy distribution, the recoil anisotropy parameter, β, and the spin-orbit branching ratio for chlorine atom elimination channels. To obtain these, measured polarization-dependent and state-specific TOF profiles are converted into kinetic energy distributions, using a least-squares fitting method, taking into account the fragment recoil anisotropies, β(i). The TOF profiles for both Cl and Cl* are found to be independent of laser polarization; i.e., β is well characterized by a value of 0.0, within the experimental uncertainties. Two components, namely, the fast and the slow, are observed in the translational energy distribution, P(E(T)), of Cl and Cl* atoms, and assigned to be formed from different potential energy surfaces. The average translational energies for the fast components of the Cl and Cl* channels are 14.9 ± 1.6 and 16.8 ± 1.6 kcal/mol, respectively. Similarly, for the slow components, the average translational energies of the Cl and Cl* channels are 3.4 ± 0.8 and 3.1 ± 0.8 kcal/mol, respectively. The energy partitioning into the translational modes is interpreted with the help of various models, such as impulsive and statistical models. Apart from the chlorine atom elimination channel, molecular hydrogen chloride (HCl) elimination is also observed in the photodissociation process. The HCl product has been detected, using a REMPI scheme in the region of 236-237 nm. The observation of the molecular HCl in the dissociation process highlights the importance of the relaxation process, in which the initially excited parent molecule relaxes to the ground state from where the molecular (HCl) elimination takes place.

Hemispheric distributions of HCl above and below the Venus’ clouds by ground-based 1.7 μm spectroscopy

The abundance of hydrogen chloride (HCl) in the Venus atmosphere was measured by ground-based IR spectroscopy. The dayside measurements were performed in May 2007 with a resolution of 40,000, and the nightside measurements in October 1999 with a resolution of 1000. The hemispheric distributions of the HCl mixing ratio measured above the Venus’ clouds show no significant structure with a disc-averaged value of 0.74±0.06 ppm which is in the similar range as the previous report of 0.6±0.2 ppm. The representative height for the dayside measurements is estimated to be 60–66 km. Recent results by Venus Express/SPICAV/SOIR show much smaller values of 0.1–0.2 ppm at 64–94 km; however the direct comparison is difficult due to the different spatial conditions. The hemispheric distributions of the 35Cl/ 37Cl isotope ratio are also found to show no significant structure with a disc-averaged value of 3.1±0.4 which coincides with the terrestrial value of 3.1. The HCl mixing ratios below the clouds are also found to show no significant structure with a disc-averaged value of 0.40±0.05 ppm, which is similar to the previous reports of 0.4–0.5 ppm. The larger HCl mixing ratio above the clouds than below suggests the production of HCl in the cloud region or above. Also, a uniform hemispherical distribution of H 2O is found below the clouds with a disc-averaged mixing ratio of 25±5 ppm; this is in the same range as the previous measurements. Those uniform distributions of HCl and H 2O support the fact that their chemical lifetimes are much longer than that of mixing as has been discussed so far.

Naphthalene photocatalysed decomposition of chlorobenzenes in exciplex forming systems

The photophysical behaviour of N,N-diethyl-2-(1-naphthyl)ethylamine I, N-benzyl-N-ethyl-2-(1-naphthyl)ethylamine VI and N-ethyl-2-(1-naphthyl)-N-(2,4,6-trichlorobenzyl)ethylamine VII, molecules that are able to form intramolecular exciplexes, has been examined in ethyl acetate. Compounds I and VI are fluorescent, but VII is non fluorescent and decomposes with formation of hydrogen chloride. The behaviour of the intermolecular exciplexes formed by naphthalene N and the bifunctional quenchers N,N-diethylbenzylamine II,4-chloro-N,N-diethylbenzylamine III, 3,5-dichloro-N,N-diethylbenzylamine IV and 2,4,6-trichloro-N,N-diethylbenzylamine V has also been studied.The photodechlorination quantum yields have been determined for the systems I+ trichloro-benzene, N+V and VII and compared with that of the system N+ triethylamine + trichlorobenzene. The production of hydrogen chloride in these reactions is explained by an electron transfer model in which the naphthalene behaves as a photocatalyst. Evidence is given for the quenching of exciplexes formed by naphthalene and an amine, by the electron acceptor trichlorobenzene, occurring from the acceptor (naphthalene) side of the exciplex.

Photodechlorination of trichlorobenzenes mediated by a naphthalene—triethylamine exciplex

The fluorescence quenching of the naphthalene—triethylamine exciplex by trichlorobenzenes was studied in cyclohexane and ethyl acetate solutions. In ethyl acetate the quenching is accompanied by the production of hydrogen chloride. A mechanism is proposed to explain the experimental results in which naphthalene behaves like a photocatalyst and the exciplex transfers an electron to the trichlorobenzenes. The rate constants for fluorescence quenching and the quantum yields of hydrogen chloride formation are reported.

Degradation of polymer mixtures. V. Blends of poly(vinyl chloride) with chlorinated rubber

AbstractBlends of PVC with purified commercial chlorinated rubber are substantially less stable than would be predicted from a comparison of the degradations of the constituent polymers. Hydrogen chloride is the sole volatile product in the temperature range of the main degradation reaction. By the use of PVC labeled with 36Cl together with inactive chlorinated rubber, it has proved possible to distinguish the production of hydrogen chloride from the PVC from that from the other polymer. In this way it has been established that it is the PVC component which is responsible for the greatly increased production of hydrogen chloride. Explanations are advanced for the effect of chlorinated rubber in destabilizing the PVC.

Polymer pyrolysis: hydrogen cyanide from the open burning of orlon.

Abstract While designing a freshman chemistry laboratory experiment to demonstrate the production of hydrogen chloride by burning polyvinyl chloride, we happened to recall the analogy between inorganic cyanide and halide. Orlon (“polyvinyl cyanide”) might, when burned, produce hydrogen cyanide. Subsequent experimentation confirmed the production of this highly toxic gas during the combustion of Orlon.

Hydrogen Chloride Vibrational Populations Produced by the H and D Atom Reactions with SCl2 and S2Cl2

Infrared emission intensities from HCl and DCl products in high vibrational levels have been used to measure energy partitioning in the reactions of H and D atoms with SCl2 and S2Cl2. The results are compared to the infrared chemiluminescence from the H and D atom reactions with Cl2. The relative vibrational level populations were measured under experimental conditions such that vibrational relaxation was minimized. The H atom reactions with SCl2 and S2Cl2 partitioned >37% and >36% of the available energy into vibrational energy of the hydrogen chloride product. Within our experimental error the fraction of energy partitioned to vibration was the same for the H and D atom reactions. In the reactions of H and D with SCl2 and S2Cl2 the distribution of rate constants for formation of HCl† and DCl† into the vibrational levels apparently peaks at levels intermediate between υ = 0 and the maximum possible level of vibrational excitation. The distributions are similar to those from the H and D atom reactions with Cl2. The additional internal degrees of freedom in S2Cl2 relative to SCl2 did not greatly affect the partitioning of energy to the HCl† product.

The role of added pyridine in substitution reactions of triphenylmethyl chloride in benzene solution

A detailed kinetic investigation has been made of the specific role of pyridine when added to the methanolysis and radiochloride exchange reactions of triphenylmethyl chloride in benzene. It is concluded that neither of the two proposals in the literature, i.e. that it reacts with the alkyl halide to form a quaternary ammonium salt or that it has no effect whatever except to take up the hydrogen chloride product, is correct. The present results indicate that pyridine forms a complex with the triphenylmethyl chloride, without strong covalent bonding, which has a distinctive effect on the kinetics of the reactions.

XLII.—On the Precipitation of Soluble Chlorides by Hydrochloric Acid

In a communication made to this Society on December 6, 1897, a tendency towards maximum specific electrolytic conductivity was shown to be a characteristic of many chemical reactions. This tendency is very marked in reactions in which strong acids play a part. Thus, to take a well-known example, chlorine decomposes water under the influence of light with production of hydrogen chloride and oxygen, but as the hydrogen chloride accumulates in the solution, the decomposition of the water is more and more retarded. This photo-chemical reaction is a reversible one, for in the case of highly concentrated solutions the hydrogen chloride is oxidised to water and free chlorine.