DD200422A1 - METHOD FOR REMOVING DIPHOSPHAN FROM MONOPHOSPHIC-CONTAINING GASES - Google Patents

Abstract

The invention relates to a process for the quantitative removal of diphosphane including higher phosphines from monophosphane-containing gases. The object and the object of the invention is to develop a technologically simple process in which the catalysts are to be used for thermal decomposition below the boiling point of the yellow phosphorus by suitable catalysts. It has been found that a monophosphane contaminated with diphosphane and higher phosphines, which may contain foreign gases may be added with an inert gas, by means of a Fluigigabscheiders easily condensable impurities such as water and P ind 4 are partially deposited and via a contact tower, the porous and contains surface-active solids, is passed at temperatures of 100-280 degrees C and residence times of 1-100 sec, then as known yellow phosphorus condensed and the P-separation is completed by a laundry with concentrated phosphoric acid. Phosphane can be used as a starting compound for the production of organic P compounds and the highly pure form as a doping gas in the microelectric industry.

Description

233692

, O ₁ LLJl. XZXX YYYY. JLAiJ. OJ- CxXiUIiX V OjU 1 / J.pllOö MXlCUJ. CiUo iUW

phane-containing gases

Field of application of the invention;

The invention relates to a process for the quantitative removal of diphosphane including higher phosphines from monophosphane-containing gases, as they are preferably obtained in the reaction of yellow phosphorus with alkalis in aqueous medium bs7v ', hydrolysis of phosphides with water or acids,

Phosphane (PHo) is a technically versatile starting compound for the production of organic P-compounds. In high purity Porm it is also needed as a doping gas in the microelectronic industry.

Characteristic of the known technical solutions

In order to meet high quality requirements of the pH7 evaluation, PH recovery processes are used on an industrial scale, which in some cases require very high raw material input:

Reaction of PCI with Hydrides (GB Pat. No. 1,049,216 of May 26, 1965, C 01 b 3/00), Preparation and Hydrolysis of Magnesium Phosphide (SU Pat 497,224 of 15.02.1974, C 01 b 25/6) , Use of combustible solvents such as alcohols for the reaction of yellow phosphorus with ITaOH (DE-OS 2,632,316 from 17.7.1776, C 01 b 25 / Ob). To

233692 4

These processes produce diphosphane-free or very low-diphosphane gases.

The incurred in the implementation of yellow phosphorus, including in the form of P-sludge, with alkalis in aqueous solution PH ~ -containing gases are mitbedingt by their high Diphosphanghalt for various purposes unsuitable. Diphosphine is known to decompose already slowly at room temperature to form solid phosphine. This leads b.ei the processing of such gases to a variety of technological difficulties:

The solid hydrogen phosphide precipitates on the apparatus, on the inner walls of pipelines, in valves and shut-off devices and easily leads to blockages.

They impair the action of sorbents and catalysts, e.g. in purification and reaction reactions of the phosphine.

- The resulting from the phosphane end products are contaminated by the deposition of solid phosphine.

- The subsequent cleaning of occupied with solid phosphine apparatus parts is difficult, laborious and time consuming.

For the separation of diphosphane from such gases, various process options come into question. Unsuitable for quantitative diphosphane separation are the methods of fractional condensation or catalytic decomposition by mineral acids. Even at moderate flow rates, it is practically impossible to remove small amounts of diphosphane from monophosphane-containing gas streams even when using high cooling capacities. Mineral acids such as HCl and Η-, ΡΟ. Although accelerating the diphosphate decomposition to solid phosphines, it is possible to

233692 4

but no quantitative decomposition. In addition, occur in a short time technological difficulties such as blockages, when trying to bring about an intimate mixing of the gas stream with the mineral acid by means of frit soils. Volatile mineral acids such as .HCl additionally contaminate the phosphorus gas stream.

Porous substances such as coal, pumice, and calcium chloride also accelerate the decomposition of Bipho3phaas into solid phosphorus compounds (A * Stock, W * Böttger and W. Lenger, Ber. Deut. Cheni. Ges. 42 (1909) 2839, DD-AP 131.009 = DE-OS 2,632 · 316 from 17.07.1976). As the surface of the porous material rapidly charges with solid hydrogen phosphide, its effectiveness in accelerating diphosphorus decomposition rapidly decreases. The use of such porous substances is thus preferably limited to processes such as the reaction of P with ITaOH in alcoholic solution, where only very small amounts of diphosphane are formed. However, the use of combustible solvents such as alcohols al3 reaction medium requires not inconsiderable work safety expenses.

The thermal decomposition higher phosphines, in particular from I * 2 ^ 4 * "^ ^ ²¹ ^ ^{ο3 Ρ ο; Ε1"} monophosphane and hydrogen requires very high temperatures (450 ⁰ C: M. Baudier, H, and J. Ständeke Dobbers, Z . anorg. gen · Chem. 353 (1967) 122). with the help of a quartz contact the decomposition temperature of polyphosphanes in phosphorus and monophosphane can to 300 ⁰ C lower (M. Baudier and L. Schmidt, Uaturwiss. 46 (1959) 577) ,

^{3 P} n ^H n + 2 * ⁽ⁿ * ^{2) PH} 3 + (2 η - 2) P

However, a fairly high decomposition temperature, which is above the boiling point of the yellow phosphorus, is still required. The hitherto known processes for the separation of diphosphane are based on this set forth

233692 4

Deficiency unsuitable for technical use, or associated with excessive costs and expenses

Object of the invention

The aim of the invention is the removal of diphosphane and higher phosphines from monophosphane-containing gases, without causing by the deposition of solid phosphine technical disturbances and difficulties ·

Explanation of the essence of the invention

The object of the invention is to develop a technologically simple process for the removal of diphosphane and higher phosphines from monophosphorus-containing gases by thermal decomposition, which should be carried out by suitable catalysts, the decomposition below the boiling point of the yellow phosphorus. It has been found that a monophosphane contaminated with diphosphane and higher phosphines, which may contain further premegases, can be quantitatively freed from the diphosphane and higher phosphines if the crude gas, optionally admixed with an inert gas or inert gas mixture, is at temperatures of from 100 to 280 ⁰ C, preferably 150 to 250 ⁰ C by a contact tower containing porous and surface-active pesticides, at Yerweilzeiten of 1 to 100 see, preferably 5 to 20 see, wherein the diphosphane and the higher phosphines in monophosphine, yellow phosphorus and optionally Hydrogen decomposable * Suitable starting gas mixtures are all occurring in the synthesis of monophosphane gas mixtures, depending on the technological conditions and raw materials starting impurities such as water, nitrogen, argon, helium, CO ₂ , CO, acetylene, alkanes, olefins, elemental phosphorus, Arsine, hydrogen

233692 A

and. May contain acids. "It is preferable to use phosphine gas mixtures which are obtained in the hydrolysis of phosphides with 7" acid or acids, which are formed by the addition of elemental phosphorus (also in the form of P-sludge) to lyes. "Phosphane-containing gases are also suitable Depending on the amount of foreign gas present, the content of diphosphane and higher phosphines and the temperature in the contact zone, an inert gas or inert gas mixture may be mixed, preferably nitrogen, helium, argon or In this way it is achieved that the partial vapor pressure of the elementary phosphor formed is below the equilibrium vapor pressure of the P. at the respective temperature, so that condensation of the yellow phosphorus in the contact mass and in the contact tower is avoided can be a constant effectiveness of the porous and surfaces active substances. The process is preferably suitable for production variants where certain inert gas components, eg H.sub.1, are formed during the conversion process or where additional carrier gases are required, inter alia, for the subsequent phosphine reduction process. But it is also applicable to phosphine-containing gases containing larger amounts of inert and foreign gases and where the PH., - Content <10 % ,

Surprisingly, it has been found that porous and surfactants quantitatively decompose diphosphane and higher phosphines to monophosphine and yellow phosphorus at relatively low temperatures. Suitable porous and surface-active pesticides are substances such as zeolite, molecular sieves, silica gels, alumina gels, activated carbons, carbon molecular sieves. Porous and surface-active substances capable of ion exchange may also be present in a partially proton-loaded form

233692 A

(which is easily achieved by an acid treatment, e.g., phosphoric acid), so that additional acidic reaction oxides which accelerate the decomposition of the diphosphane are present. However, these acidic reaction centers unlike the mineral acids cause a di- and Pclyphosphanzeretzung to monophosphine and elemental phosphorus. In compliance with the above technological conditions after several weeks of operation still fully effective contact masses were virtually free of solid phosphine and elemental phosphorus, while a activated charcoal at room temperature cleaning tower in the same time unit was heavily phosphorylated products and no sufficient cleaning effect more «

The mode of action of the contact masses is thus not negative by present in the gas stream impurities such as CO-, acetylenes, olefins, alkanes ^ CO, arsenic, mainly in the processing of phosphorus sludges of different origin in more or less large quantities (ppm range to Prosentbereich) with incurred as well as impurities from the extra blended inert gases, influenced.

The proportion of water, which makes up a few percent in aqueous medium in the case of phosphorus phielding methods, likewise proves to be no problem.

It is expedient to proceed by passing the resulting crude phosphane gas through one or two liquid separators, e.g. for separating most of the water and elementary phosphorus amounts present in the gas stream and in the uncooled state directs the contact tower and there brings to the desired reaction temperature or that the gas is first sent through a heat exchanger and then with the desired reaction temperature in the contact tower »Then the main amount of the formed yellow phosphorus is condensed into further water portions in a cold trap.

233692 A

The residual separation of the yellow phosphorus is then carried out with the aid of concentrated phosphoric acid. If a transparent material is used in this washing unit, it is easy to make statements on the puncture mode (safety) of the contact tower based on the (non) precipitation of the solid yellow phosphine * Depending on the intended use, the gas stream freed from elementary phosphorus is subjected to further purification operations in most cases a subsequent drying ζ, B. with a 4 A molecular sieve can be made «

The advantage of the method is that in a technologically very simple way di- and polyphosphane-free Monopho3phan from the relatively cheap raw materials elemental phosphorus and alkalis such as ITaOH and / or Ca (OH) ρ can be obtained. The advantageous procedure is explained in more detail in subsequent embodiments. Example 1 is the procedure according to the prior art, the examples 2 to 4 illustrate the procedure according to the invention.

embodiments example 1

A raw gas obtained in the P-Schlannn workup using Ua0H-Ca (0H) ₂ suspension was used. Ss showed the following average composition after passing through a water separator (in parentheses: the variation of the gas composition during the test period) «

PH ₃ '~ 40 Vol. % (20-60 Vol.%)

Diphosphane -f higher phosphines - ^ 3 vol.% (1-5 vol.%) Water <5 vol.%

Nitrogen, hydrogen ~ 45-59 vol.% (30-65 vol.%) Acetylenes - ^ 2 vol.,% (1-5 vol.,%)

Olefins, alkanes, CO, CO ₂ , AsH-, P ₄ ~ <1 vol.%.

233692

The ΡΗ -, - containing crude gas was cooled to room temperature in a further water separator, wherein the largest part of the water, contaminated with alone solid yellow phosphine and P., was deposited · Then the gas mixture with a flow rate of about 40 l / h by means of a peristaltic pump at room temperature through a charcoal-filled tower (residence time 10 see) sucked through. The activated carbon contact had been freed earlier at temperatures of 300 ⁰ C by passing nitrogen largely adhering foreign gases "In the first few hours was H ~ gas stream free of diphosphine and higher phosphines?; in the downstream H ^ PO ^ wash bottle no yellow solid phosphine precipitated, the monophosphane was not selbstentzündlich. Already after operating sides of 15-2Oh was due to the not more complete cleaning effect of the activated carbon contact a significant separation of yellow phosphine in the EUPO, wash bottle observed · The monophosphane gas stream was selbstentzündlich in air.

Example 2

The PE-5-raw gas with the procedure given in Example 1 composition was prepared by a container filled with a spherical zeolite 4 A-Mclekularsieb contact tower at temperatures of 150 - 200 ⁰ C conducted under otherwise analogous operating conditions. The preparation of the contact mass as well as the production of the operational readiness took place,

a) by treating the 4 A molecular sieve with excess dilute phosphoric acid,

b) washing with water,

c) drying and heating of the acid-treated molecule

23 3692

larsiebes u «a, to remove adhering foreign gases in the IT ₂ -St rom at 300 ⁰ C,

The majority of the yellow phosphorus formed in the decomposition of the di- and polyphosphane was condensed out in a cold trap conditioned with ice or ice-salt mixture. The residual separation was carried out in a wash bottle with 8% rUPO, "Hach an operating time of about 200 h was still no formation of yellow phosphine to determine, the -nonophosphanhaltige gas stream was not selbstentzündlich,

Example 3

A gas stream of the specified in Example 1. The composition was passed through a contact-charcoal-filled contact tower at temperatures of approximately 250 ⁰ G under otherwise analogous operating conditions with a residence time of 20 seconds. »The ELPO, -Waschturm showed no solid deposits in the form of yellow. Hydrogen phosphide, The purified ΡΗ -, - gas was not self-igniting »

Example 4

A gas stream of the composition given in Example 1 was passed with a residence time of 70 see through a silica gel filled contact tower at a temperature range of 100 - 150 ⁰ C under otherwise analogous operating conditions as in Example 2. The HoPO. wash tower did not show any solid deposits in the form of yellow phosphine, the purified Mcnophosphangas was not auto-ignitable.

Claims (7)

233692, claim 1 · Procedure for. Removal of diphosphane and hönerer phosphines from monophosphane-containing gases by thermal decomposition, characterized in that a diphosphane and higher phosphines contaminated monophosphane, which may contain foreign gases, if necessary. Is treated. With an inert gas with the aid of a Fiüssigabscheiders easily condensable impurities such as water, P Partially deposited and passed through a contact tower containing porous and surface-active solids, at temperatures of 100 to 280 ⁰ C, preferably 150 to 250 ⁰ C at residence times of 1 to 100 see, preferably 5 to 20 see, then yellow phosphorus condensed in a conventional manner, the P-separation completed by a wash with concentrated phosphoric acid and optionally the remaining gas mixture depending on the intended use further cleaning operations is subsurface « 2 » process for the removal of diphosphane and higher phosphines from monophosphane-containing gases according to item 1, characterized in that the proportion of foreign and inert gases in the gas mixture and the temperature in the contact zone are adjusted so that no condensation of elemental phosphorus takes place in the latter. 3 «process for the removal of diphosphane and higher phosphines from monophosphane-containing gases according to item 1 and 2, characterized in that as foreign gases nitrogen, hydrogen, argon, helium, Jüeon, CO ₂ , CO, AsH_, elemental phosphorus, water, alkanes, olefins, Acetylenes and acids can be contained. 233692 4 4. A process for the removal of diphosphane and higher phosphines aus.monophosphanhaltigen gases according to item 1 and 2, characterized in that are used as inert gases nitrogen, helium, argon and hydrogen · 5. A process for the removal of diphosphane and higher phosphines from monophosphane-containing gases according to item 1, characterized in that are preferably used as porous and surface-active substances zeolitic molecular sieves, silica gels, alumina gels, activated carbons and carbon molecular sieves. 6. A process for the removal of diphosphane and higher phosphines from monophosphane-containing gases by item and 5j characterized in that the porous and surface-active substances are preferably used in ball or strand form. 7. A process for the removal of diphosphane and higher phosphines from monophosphane-containing gases.After items 1, 5 and 6, characterized in that the porous and surface-active substances are used in the protonated form.