DE2363867C3 - Process for purifying cyanogen chloride - Google Patents

Description

23

867

by heating to 2 (XD-SOO ⁰ C, preferably to 350-400 ° C, and at the same time passing air through.

Even after 12 months of operation, ' ^Λρ ί could purify the cyanogen chloride using the invention
Process still no reduction in the activity of the activated carbon catalyst can be observed.

The technical progress of the process according to the invention is that by a technical simple pre-cleaning of the cyanogen chloride, which may be produced by chlorination of hydrocyanic acid in the presence of Water was produced, the service life of the activated carbon catalyst in the trimerization reactor on a previous level unknown height was increased. In addition, the cyanogen chloride obtained in this way is not only for them Trimerization, but can also be used for all previously known reactions.

example 1

A glass reaction tube with a clear width of 9 mm and a length of 250 mm was ^{filled with 12 g »y-aluminum oxide (m 2} / g = 250, pore size 90 Å, alkali content 0.05% by weight, grain size 2-3 mm ) charged, ^{heated to 60 0} C and passed hourly 18 g of a cyanogen chloride gas containing 0.7% by weight of water, 0.08% by weight of hydrogen cyanide, 0.1% by weight of benzene and 5.0% by weight % Contained chlorine.

The treated cyanogen chloride was condensed and then analyzed.

To determine the water content, 10 ml of condensed cyanogen chloride were added to 85 ml of carbon tetrachloride dissolved and the solution cooled so deep that it became cloudy. The analyzes showed in one Temperature of -40 ° C still no cloudiness, d. H. that the water content Was <0.02 wt%. Gas chromatography could neither benzene nor js Hydrogen cyanide can be detected.

After each 350 g of cyanogen chloride had been cleaned, the γ- aluminum oxide was regenerated in a stream of air at 400 ° C. and then used again. Even after being used 17 times, the γ-aluminum oxide still showed no loss of activity.

Example 2

For performing an endurance test were two parallel 50 mm wide and 2000 mm long, heatable pure nickel tubes each with 2.8 kg y-alumina (m ² / g = 360, NV = 40 cm ^3/100 g alkali content of 0.6 wt ° / o, grain size 5 to 7 mm). To clean technical cyanogen chloride, one of the two tubes was heated to 35 ° C. and an hourly 2.6 kg of cyanogen chloride with 0.2 to 0.3% by weight of water, 0.05 to 0.06% by weight of benzene and 3 to 3.5% by weight of chlorine passed through. After 72 hours in each case, a switch was made to the second tube and the first tube was regenerated within 2 hours by heating it to 350 to 400 ° C. and blowing air through it

The thus purified cyanogen chloride was continuously added to activated carbon in a downstream reactor at 350.degree tr'imerized. Even after an operating time of 12 months there was still no decrease in the trimerization activity determine the activated carbon (MV = micropore volume).

Example 3

The procedure is as in Example 1, but using a cyanogen chloride gas that contains 0.1% by weight of one instead of benzene Mixture of benzene, chlorobenzene, 1,2-dichlorobenzeneGi and 1,2,4-trichlorobenzene The analyzes showed that the cyanogen chloride treated with γ-aluminum oxide is less than 0.02% by weight of water and is neither detectable Amounts of hydrogen cyanide still contained the aromatics originally present. Even after 17 times Regeneration and subsequent renewed use of the γ-aluminum oxide showed no loss of activity.

Claims (1)

¹ after treatment with phosphorus pentoxide or calcium St get into the trimerization reactor and there Claim: rien activated carbon catalyst damage, so were pv, h roentoxide and calcium sulfate for one really A process for purifying cyanogen chloride, the ^^ / purification of the cyanogen chloride satisfactory, by reaction of hydrogen cyanide with chlorine,> ^wl * £ ^s "PY _festg estellt that the d.eser optionally when used in the presence of water, manufactured" referred ^w _ Not even idle times has been, before entry of the cyanogen chloride in a iuDsian ϊ ^^ _{the cyanogen chloride noc} h additional reactor for trimerization to cyanuric chloride in ereu. _Amounts of aromatics contaminated. A Presence of activated charcoal, thereby marked- ° ^u [ ^cn . cyanogen chloride always falls on when to is characterized in that the cyanogen chloride over granulated .0 ^derarilg _{H tellung e} in aromatics Cyanwasser _y-alumina with an alkali or, where ^ Saw _Ex ielsweise in Akrylnitnlherstel- _{if alkaline earth content} from 0 to increasing to 3 f "" faUt _ is used. Percentage by weight, preferably 0-1 percent by weight, _{has already been tried out} at 20 to 100 ° C. Hp ^ activated carbon catalyst by increasing the ¹⁵ J the production of cyanogen chloride used Cyanwasuff when it contained aromatics, e.ner was subjected to expenditure (DT-PS 12 7, 091 and gÄX underwent The application relates to a method for ^l2 iP ⁶ 2neren _WUR de through their own experiments Festge-purifying cyanogen chloride, obtained by reacting 20 ue ^^ _{least Meng} en hydrocyanic acid in the hydrogen cyanide with chlorine, optionally in the counter ""^'1 V. _also if a considerable shortening of the amount of water that has been produced can lead to the entry of the uruoi y _{activated carbon catalyst.} Cyanogen chloride in a reactor for trimerization to nemeeeenüber was now in contrast to the, stand cyanuric chloride in the presence of activated carbon. » Technology found that all these difficulties. Such a process is according to DT-PS 8 42 067 *, Jer Techn.k getu ^ ^^ ^ _{activated carbon} catalyst. known. For the purification of the cyanogen chloride there is "3; can be extended extraordinarily if calcium chloride is used. The great disadvantage of this ⁵ ^ * _b X _deposition of hydrogen cyanide with chlorine desiccant is that it is necessary for a continuous, - ^^" ^ " enwart of water, cyanogen chloride produced, chen operation is unsuitable because it does not easily JJ _'eb | _nen case is chlorinated, can be regenerated before entering the manner ·>_{rimpr;. sieruniI} sreaktor over granulated y-aluminum the trimerizing Cyanogen chloride to cyanuric chloride trituration, _if necessary, alkaline earth has been known for a long time, see U 11 ma η η, Encyclopedia der οχ dm «A _{anstei nd to} 3 wt. O / o in Technical Chemistry, Volume 5, 1954, page 624. One the hak of _{ise at} 30-60 ⁰ C, is fed, most known industrial processes, the ^ i. _gegeb enenfalis alkaline earth metal content is trimerization of cyanogen chloride on activated carbon as 35 Der_ai BB ^ _G ew,%. of the candidate catalyst represents, namely at temperatures between schen ^ Jf ⁵ _{en Ulhium> Natriumi} Potassium and 300 and 450 ° C (DT-PS 8 33 490 and 11 47 592). «If magnesium, calcium, barium, is sodium It is known that in the trimerising of 8tenta »s g ^ Charcoal catalyst used in gaseous cyanogen chloride is always present when sator only a limited service life of 4-8 weeks 4 ° ^ J ^ ^{1 g of} _{toff and} chlorine not in equimolar amounts This has life has been on the moisture ^ ^at ^ ^sse ™ s _{countries w} ith a Chlorüberschüß to Sator only has a limited service life of 48 ^ J ^ _{toff and} chlorine not in equimoles owns. This standing time it has been on the moisture ^ ^at ^ ^sse ™ s _{countries m} a Chlorüberschüß recirculation of the cyanogen chloride. B · _{h den are} . In order to increase the service life of the activated carbon, Reak ion geora ^ ^^ _{Adsorptionsvorgan} . hence cyanogen chloride, which in its production normal- es law s ^ c reactions when passing over was obtained in water-saturated form, before E.ntr.tt in the 45 genes also cn _{aluminum oxide was} catalyzed _{Trimerization reactor} dried, either des ^ chlorine dere / _the ,, alumina more with the help of phosphorus pentoxide DT_OS 20 45 786) values ^ g ^ _chiorcyan ^^ _can "" _se , _ner or of calcium sulfate (DT-OS 20 45 82J). Tmcknune capacity corresponds. The professional world was also of the opinion that ⁷ ^ JfS, _table reactions can but other substances known as desiccants: such as S.hkagel, 50 Such ^ Ka y _{cyanogen chloride over} calcium sulfate activated alumina, concentrated sulfuric acid, poly- overpriced. of £ _{can be proven} , phosphoric acids or molecular sieves either ^od ^ ^{r. Ph} ° _o P3 _{s of} ,, aluminum oxide * are not critical Cyanogen chloride to react or other unwanted ° ^ie ^ g _{6n, however, "s0 wt} ählt that no Cause side reactions and therefore for a ^^^ greater back pressure when passing through Drying process was out of the question. ⁵ - _{rhlorcvan created by the} y-aluminum oxide tower. Zeolite molecular sieves, ie aluminum silicates. ^Ch '° ^ J ^ j _{1 k} ^r _{ann varies within wide} n limits on the other hand, instead of activated charcoal, the dwell time at Dk was between 1 and 600 Trimerization of cyanogen chloride recommended (set DT-OS g ^^ en; for economic reasons 2159 040). dwell times of 1-60 seconds are selected. Despite the measures outlined above to reduce use, cyanogen chloride is used Setting the moisture of the cyanogen chloride became the da ^ f ^ sending influences more on the activated carbon Lebensdaucr extended the activated carbon while but a f ^a ^ _m ^ S _{aII suitable for this purpose} $ t ^ XAVS £££ g ^ ^{hih Rktion} _k g ^ ¹ * ^{<> der} aas c _h , o _{r? T} ^ - «-