RU2170133C1 - Method of removing organoarsenic compounds from emission gases - Google Patents

Abstract

FIELD: gas treatment. SUBSTANCE: emission gases are passed at velocity 0.5 m/s and 10-30 C through specially selected activated carbon bed with pH value 7.1- 7.5. In particular, trialkylarsines with nonpolar groups but also with polar groups such as chloro, chlorovinyl, and ethoxy, butoxy, and isobutyloxy groups are removed. EFFECT: improved gas purification efficiency. 2 cl, 2 tbl, 12 ex

Description

 The invention relates to the field of environmental protection, specifically to a technology for cleaning gas emissions from organo-arsenic compounds by solid sorbents.

 Arsenic compounds contained in the exhaust gases of a number of industries (the production of semiconductors, medical preparations, alloys, modified glasses, etc.) pose a great environmental hazard.

The scientific, technical and patent literature describe methods for purifying gas from arsine (AsH ₃ ) by sorption by solid sorbents (Journal of Chemical Industry News, 1984, vol. 28, No. 10, pp. 790-791, auth. Sh. H Iankhye "Cleaning of waste gases from arsine", aut. USSR USSR N 158151, MKI B 01 D 53/02, published August 7, 1990. "Method for gas purification from arsine", US patent N 4578236 MKI C 07 C 7/12, NKI 423/10, publ. 04/25/80, "Method for the removal of toxic gases", US patent N 4743435 MKI B 01 D 53/34 NKI 423/20, publ. 10.05.88, "Method for cleaning the waste gas ", US patent N 5087624, MKI C 07 B 63/02 NKI 423/10" Composition, device and method for sorption of gaseous compounds group II-VII elements ").

 However, these cleaning methods are not suitable for removing organo-arsenic compounds from the exhaust gases.

Known methods for purification of exhaust gases from organo-arsenic compounds - trialkylarsins. The term "trialkylarsine" refers to compounds having the general chemical formula R ₃ As, where R is a free radical from an alkyl group having from one to six carbon atoms, preferably from one to three.

 A known method for sorption of trialkylarsines, which consists in contacting the cleaning gas with a solid sorbent containing gold as at least one of the components (mainly aluminum oxide and / or silicon oxide (US patent N 4971608, MKI B 01 D 53/04, NKI 55/72 , publ. 20.11.90, "Sorption and determination of triakylarsins").

 In another known method, the sorption of triakylarsins from gas is carried out by contact with an sorbent containing copper sulfide, mainly monovalent sulfide and an inorganic carrier, mainly zinc and / or aluminum oxide (US patent N 5024683 MKI B 01 D 53/04, NKI 55 / 74 "Sorption of triakylarsins").

 However, the known methods do not provide the purification of gases of organosilicon compounds with polar groups.

 Closest to the technical nature of the proposed method is a method in which triakylarsins are removed from gas by contact with a sorbent containing elemental sulfur and an inorganic carrier, mainly aluminum oxide and / or silicon oxide and / or titanium oxide and / or activated coal. The sulfur content in the sorbent is 1 to 50 wt.%, Mainly from 3 to 25 wt.% (US patent N 5085844, MKI B 01 D 53/14, NCI 423/210, publ. 4.02.92, "Sorption of triakilarsins" )

 This method, however, also does not provide purification of gases from organo-arsenic compounds with polar substituents.

The aim of the invention is to develop a method for purifying gases from a wide range of arsenic-organic compounds, including organo-arsenic compounds, both with non-polar groups and with polar groups - chlorine - chlorovinyl, as well as ethoxy group (RO) ₃ , where R is ethyl, butyl and isobutyl . This goal is achieved by the proposed method, in which the cleaned gas mixture is passed at a speed of 0.1-0.5 m / s at 10-30 ^o C through a layer of activated carbon with a pH value of 7.16-7.5. As the sorbent, activated carbon of the SKT-3 and SKT6-A brands is used.

 The proposed method is illustrated by the following examples. All experiments were carried out on a dynamic adsorption device (application N 2000105654/12 of 03/10/2000) in a continuous mode.

 The change in the speed of the vapor-air mixture was provided by changing the diameter of the column with the adsorbent, as a result of which a constant amount of impurity was supplied to the sorbent. The diameter of the column ranged from 5.5 to 22.0 mm.

 In all examples, for the same sorbed substance, the breakdown concentration was also constant and was determined by the sensitivity of the gas analyzer used. The amount of cleaned steam-air mixture (PVA) per minute was 1.5 l in all experiments.

Example 1. A PVA stream containing 2-chloro-vinyldichlorarsin at a speed of 0.3 m / s at 20 ^° C. was fed into a glass column with a diameter of 10 mm filled with activated carbon of the SKT-3 grade. The height of the sorbent layer is 4.5 cm. The content of 2-chlorovinylchloroarsin in PVA after passing through the adsorbent was continuously recorded using an ionization gas analyzer. The sorbent operating time was 180 min.

 The results are presented in table. 1.

Example 2. Analogously to example 1, PVA was purified containing butoxydichloroarsine as an impurity. The PVA flow velocity is 0.5 m / s at 10 ^° C. The height of the sorbent layer was 6 cm. The cleaning time was 60 minutes.

 The results are presented in table. 1.

Example 3. Analogously to example 1, PVA was purified containing triethoxyarsine as an impurity. The speed of the PVA flow is 0.1 m / s at 15 ^o C. The height of the sorbent layer was 2 cm. The operating time of the sorbent is 15 minutes The results of the experiment are presented in table. 1.

Example 5. Analogously to example 1, PVA was purified containing tributoxyarsin as an impurity. The PVA flow velocity contained 0.5 m / s at 30 ^° C. The height of the sorbent layer was 105 min. The results of the experiment are presented in table. 1.

Example 6. Analogously to example 1, PVA was purified containing isotributoxyarsine. The PVA flow velocity is 0.4 m / s at 30 ^o C. The height of the sorbent layer was 0.7 cm. The operating time of the sorbent is 14 minutes. The cleaning results are presented in table. 1.

Example 8. Analogously to example 1, PVA was purified containing tributylarsin as an impurity. The PVA flow velocity was 0.4 m / s at 20 ^° C. The height of the sorbent layer was 2.5 cm. The sorbent operating time was 99 min. The results of the experiment are presented in table. 1.

 Example 9. Analogously to example 1, PVA was purified containing 2-chlorodivinylchloroarsin as an impurity. The flow rate of the PVA was 0.05 m / s. An adsorption column with a diameter of 22 mm was used. The operating time of the sorbent was 1080 min with a height of the sorbent layer of 4.5 cm. The results are presented in table. 1.

 Example 10. Analogously to example 1, PVA was purified containing 2-chlorovinyl dichlorarsin as an impurity. Only the speed was different, which was 0.8 m / s. An adsorption column with a diameter of 5.5 mm was used. The operating time of the sorbent was 102 min with a height of the sorbent layer of 4.5 cm

Example 11. Analogously to example 1, PVA was purified containing 2-chlorovinyl dichlorarsin as an impurity. Only the process temperature was different, which was 5 ^o C. The operating time of the sorbent was 220 min at a height of the sorbent layer of 4.5 cm. The experimental results are presented in table. 1.

Example 12. Analogously to example 1, PVA was purified containing 2-chlorovinyl dichlorarsin as an impurity. Only the process temperature differed, which was 35 ^o C. The sorbent operating time was 170 min at a layer height of 4.5 cm. The experimental results are presented in table. 1.

 Adsorption purification of PVA from all of the above impurities was also carried out on activated carbon grade SKT6A (pH 7.5). The values of the concentrations of each impurity before the sorbent and after the sorbent corresponded to the values of the same impurities specified in examples NN 1-12.

 The data of the following examples are presented in table. 2.

 As can be seen from the above examples, the proposed method of adsorption purification provides effective purification of gases from a wide range of arsenic-organic compounds.

 A decrease in the flow rate of PVA to a low recommended reduces the productivity of the process with an increase in the size of the adsorption column (see example No. 9).

 A flow velocity> 0.5 m / s leads to a decrease in the capacity of the sorbent and its operating time (see example 10).

Lowering the process temperature below 10 ^o C (example 11) and increasing the temperature above 30 ^o C (example 12) does not lead to significant improvements in the characteristics of adsorption treatment, but requires additional energy costs for heating or cooling the mixture.

 The proposed method for the purification of gases from organo-arsenic impurities does not require special equipment and materials, allows the extraction of toxic impurities from large volumes of gases and can be used at chemical, metallurgical and other industries, as well as at facilities for the destruction of arsenic-containing toxic substances.

Claims (2)

1. The method of purification of gases from organo-arsenic compounds by contacting gas from a solid sorbent, characterized in that the gas stream is passed at a speed of 0.1 - 0.5 m / s at 10 - 30 ^o C through a layer of activated carbon with a pH of 7.16 - 7.5.  2. The method according to claim 1, characterized in that the activated carbon of the SKT-3 and SKT-6A brands is used as the sorbent.

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