DD200782A1 - METHOD FOR REGENERATING A SUSPENSION CATALYST - Google Patents

Abstract

The invention relates to a process for the regeneration of a suspension catalyst, in particular a finely divided copper acetylide catalyst for the production of butyne-2-diol-1,4 by Aethinilierungsreaktion from formaldehyde and acetylene in aqueous medium. The object of the invention is to develop a regeneration process which is cost-effectively designed for the catalyst preparation. According to the invention, the object is achieved in that the exhausted old contact with hydrochloric acid is decomposed to form the hydrochloric acid copper (I) chloride complex at elevated temperature. By injecting air into the suspension, an equivalently neutralized copper II chloride solution is obtained, from which, after removal of undissolved residue, synthetic malachite is prepared in a continuous process, which undergoes further purification by the action of sodium hypochlorite. The malachite obtained by washing and decanting several times can then be converted into the active form of the catalyst after resuspension in concentrated formaldehyde solution in a known manner under the action of acetylene with a gradual increase in the reaction temperature, wherein the catalyst formation process increasingly flows into the ethynilation process.

Description

Title of the invention

Process for! Regeneration of a suspension catalyst

Application age "T he for the invention

The invention relates to a process for! Regenerating a suspension catalyst, in particular a finely divided copper acetylide catalyst for the preparation of butyne-2-diol-i, 4 by Athiniiierungsreaktion from formaldehyde 'and acetylene in an aqueous medium.

Characteristic of the known technical solutions

In the industrial production of butyne-2-diol-1,4 from acetylene and formaldehyde only copper-containing catalysts are used, which are obtained by He action of a copper compound with acetylene in the presence of an aqueous solution of formalin as poorly soluble, copper acetylidhaltige compounds. So far, numerous processes have been described for the preparation of butyneol and the catalysts used for this purpose, as described in the patents

2,939,844, 3,154,589, 3,294,849,

3 560 576, 3 920 759, -

2 445 303, 2 519 088, 2 735 465

The catalysts used for the initiation include

US-PS 2 768 215 3 650 985, DB-OS 1 804 696, DD-PS 114 589

usually to the class of supported catalysts in which a copper compound on a suitable support material

Impregnation is applied to the catalyst support or combined by co-precipitation with the carrier and converted into the oxidic form in a final annealing process. Immediately prior to its use, the oxidic material, referred to in this form as a catalyst precursor, is under the conditions of the thyration reaction Reacted acetylene and formaldehyde in an aqueous medium and converted into the catalytically active form in which the copper in the 1-valent Cöcidationsstufe acetylidartig bound is present as a complicated complex compound,

While at the beginning of the technical development of the Ithinilierungsverfahrens lumpy, fixed catalysts came to Sinsats and the process had to be operated at an operating pressure of 5-7 atü, today's efforts go in the direction of using the catalysts in finely divided form as suspension catalysts with the possibility a lowering of the process pressure to approximately atmospheric pressure,

US Pat. No. 3,560,576 / US Pat. No. 3,650,985 (DS-OS 1 804 696) discloses the preparation of an ethylation catalyst which comprises, as catalyst precursor, a synthetic malachite, a basic copper carbonate of the defined composition Cu (OH) .p Due to the simple production conditions, the malachite precursor gains considerable importance for the ethinilization process in the event that it is possible to compensate for the higher copper dosage associated with its use by means of a suitable, economically advantageous copper recovery. As is known, the production costs of the butynediol are greatly influenced by the cost of the catalyst, which in turn is associated with the catalyst

- 3 - 2 3 Z / 1

typical parameters such as activity, lifetime, specific material consumption coefficients and technological complexity for its production,

In accordance with their economic significance, the overall catalyst strategy is to be assigned a decisive importance for butynediol production, the catalyst regeneration process routes to be determined being determined by the catalyst systems used. The generation of supported catalysts differs fundamentally from the carrier-free systems. Thus, supported catalysts can be roughened due to their relatively low Kupferaoetylidkonsentration generally safe, ideally approaching the initial state of the catalyst precursor again achievable and the reuse of the regenerated precursor is given in principle, Sin undisturbed circulation of the catalyst is not given by such a method, however irreversible adverse changes are associated with each recycling, such as unfavorable particle size distribution and loss of activity due to concentration changes of the catalyst composition. A general solution results from the substitution of the used old catalyst by a fundamentally reformed catalyst. The use of bevyed copper solutions contaminated by organic solvent scavenging particles is not detrimental to supported catalysts subjected to a final annealing process.

In a carrier-free catalyst, two fundamental problems arise for copper regeneration or contact making. In the foreground are safety aspects, as well as the used old contact because of its high acetylide content has a high energy content and in the dry state is a slightly noxious substance, whereby the roasting is associated with significant security risk.

-. 232715 2

Second, the old contact contains increasing amounts of organic condensation product with increasing operating time

O J ± .Kj UUi ₁ J-icXfcJ £ jC? IL JLi-VA ^ -JU C3 ^. CA. WUL. Cl.4 · »JW Λ. UU

go into solution and interfere with the further processing to the catalyst precursor, the malachite, as they also result in the Malachitfällung sparingly soluble copper compounds. Since the malachite precursor production does not require an annealing process, the organic impurities remain in the catalyst, the activity of which is thereby impaired.

There are two ways known to circumvent the difficulties mentioned. According to DD-PS 134 840 gives the copper from spent Altkontakten in oxidic form and free of organic impurities by incineration, the separated catalyst is indicated sludge with an organic thickener and au stirred as water-containing pasty mass combustion process. Disadvantages of this method are the multitude of process steps and the difficult working conditions associated with the ashing process,

It is also known to decompose the isolated Katalysatorrückst and in ammoniacal medium with molecular oxygen at tree temperature and dissolve after distillative separation of the ammonia, the present Euphor TI oxide with equivalent amounts of nitric acid at low 'temperatures. The disadvantage of this process is above all the high energy expenditure for the ammonia recovery.

Object of the invention

The aim of the invention is the large-scale production of butynediol from formaldehyde and acetylene by a, secycling process for the system used in the catalyst

2715 2

To simplify copper and thus to make it more economic, taking into account the specific safety-related issues and the quality requirements .

Explanation of the essence of the invention;

It is an object of the invention to develop a process for the production of butyne-2-diol-1,4 from acetylene and formaldehyde with the aid of a carrier-free malachite catalyst which satisfies the above requirements.

According to the invention, the object is achieved in that the special property of the hydrochloric acid to form a soluble Kugfer-I-chloride acid complex is exploited to decompose the catalyst compound. Thus, in contrast to the application of other, non-oxidizing acids a complete running under acetylene evolution Achieve decomposition "When using oxidizing acids, such as" concentrated nitric acid ", one obtains strongly acidic solutions of copper (II) chloride contaminated by soluble organic osidation products, the preparation of which for malachite preparation requires unreasonably high costs.

The amount of hydrochloric acid required for the decomposition of the spent catalyst can be limited to a molar ratio of copper of less than 2: 1. As a result of the decomposition, a strongly acidic decomposition suspension is obtained in which, in addition to the undissolved residue, a smaller amount of copper than insoluble Copper-I-chloride, the major part of which is soluble copper-1-chloro-hydrochloric acid, is completely soluble. By oxidation by means of air, the copper passes into the divalent state, with concomitant lowering of the acidity of the system until the equilibrium of the copper-II balance is established. Chlorides in aqueous solution »

232715 2

According to the amount of hydrochloric acid used, after oxidation, in addition to the equivalently neutralized soluble copper (II) chloride, insoluble copper oxychloride is in the bag

It is a feature of the Irf indung that the hydrochloric acid used is fully implemented and that after filtration always set with the same acidity, concentrated copper-II-chloride solutions are obtained and that no blunting by alkalis is required and also no corresponding disadvantageous increase Blektrolytkonzentration by alkali salts occurs.

The remaining in the filter residue copper oxychlor or id can now be completely dissolved in a second dissolution process with excess hydrochloric acid, this solution is to be used taking into account the salt excess acid for a subsequent 1 "decomposition process, Dia equivalent neutralized copper-II-Ghloridlösungen of 1, Decomposition process may, if appropriate, after interim storage and stacking, or after supplementing any plucking losses incurred by externally supplied copper salt solution, where it is insignificant to use copper nitrate solution, be used for the process stage of malachite production, although the purity of these solutions is insufficient to allow a standard Precursor in the usual way of implementing the copper salt with soda ·

Sine oxidative aftertreatment of the precipitated malachite with sodium hypochlorite solution is required as additional sizing operation.

For the preparation of a malachite precursor suitable for butynediol production, it is crucial that the two starting components. Copper salt solution and soda solution, are added at the same time in continuous amounts in the reaction vessel at equivalent amounts at a pH of 7 to 9.

- * - 232715 2

the, otherwise significant losses of catalyst activity occur. Bs is therefore indispensable, not only the copper chloride and soda concentration einzustallen exactly, but also toi: emanate a certain Ausgangsaciditat the copper chloride solution. It is therefore important that the copper chloride solutions with constant acidity and equivalently neutralized be obtained by the copper recovery process.

It has proved to be advantageous to use the two output skomponen th in the same molar concentration, since in this case equal amounts of both solutions are to be dosed and the control of the dosage is facilitated · The dosing of the solutions is carried out continuously in equal volume flows in a Eührreaktor at (Eeinperaturen of about 7O ⁰ C and in a time interval of about 2 to 4 hours. The precipitation operation Uachrührzeit a further 2 to 4 hours at 8O ⁰ O joins *

If one starts from pure copper salt solutions by. Dissolution of Slektrolytkupfer be obtained in nitric acid, so the synthetic malachite is present in its characteristic green color, with a largely uniform particle size distribution and very good

Sediment at ioas.

The average rope diameter is about 5 to 1GyOm, the largest dimensions of aggregated particles are not more than 40 / um.

According to the idea of the invention, however, the copper (II) chloride solution recovered from old contacts forms predominantly the starting point for the production of new contacts. In this case, the malachite precipitate shows a more or less brown-green color and the supernatant mother solution is slightly yellow colored. "Duroh an oxidizing after-treatment of the malachite suspension with aqueous Hatriumhypochloridlösung in the precipitation

- ⁸ - 232715 2

temperature, the precipitated precipitate adopts the typical malachite color without any change in the particle size distribution. The supernatant solution also changes color from yellow to colorless.

The catalyst precursor prepared according to the present invention does not differ in its chemical composition, particle size distribution and color from comparative products obtained from pure copper nitrate solutions. The copper and carbonate content corresponds to the formula

Gu (OH) ₂ · Ou COo.

The catalyst precursor prepared in the described manner, the immediate precursor of Ithinilierungskatalysators represents and is gradually converted into the active form · of the system pressure in the gas space by Se suspension dissolved in jQ% formalin in the presence of acetylene in the (temperature range of initially 60 to 7O ⁰ G of During the development of the catalyst and subsequently during the thyrilation reaction, the reactor is only slightly above the atmospheric pressure. The gas is distributed by a powerful turbine agitator. The pH of the suspension is determined over the entire period of the development phase by metering alkalis, ζ.Β. dilute sodium hydroxide solution, adjusted to 8 to 8 in the further course of the ithilination reaction to 6 to 7. "Following the catalyst development time of 2 to 4 hours, the reaction temperature is gradually increased to the value intended for a given conversion in the range of preferably e 75 to 95 ⁰ C * whereby the Proseß increasingly in the Äthinilierung of the formaldehyde, ie the Butindiol 1,4-Bildung, goes over ·

For the idea of invention it is irrelevant whether the

-. 9 -

232715 2

Performing of the .Ithinilierung in a discontinuous process in a Beaktor made or whether the process is continuously designed in several successive gesonaliieten Sea ·

Conveniently, however, one carries out the entire catalyst production process from the precipitation of the malachite via the aftertreatment with Hatriumhypoehlorid with the subsequent washing process to sur development of the active catalyst in one and the same Bührreaktor in order to achieve maximum simplification of the process · The process accumulating Beaktions- and washing liquids can be separated in the good Sediment at ionseigehschaf th the precursor without difficulty by siphoning the sediment.

The commercial butynediol synthesis on the basis of suspension catalysts is usually carried out in several series-connected stirred reactors, in the passage of which the initially metered formalin in the presence of the suspended catalyst reacts with the acetylene dispersed in the reaction suspension. The main part of the Beaktionslösung leaves via a continuously operating IPiltereinrichtung as a catalyst-free solution, the reaction system, while the catalyst is returned together with a small part of Be action solution as a pumpable, concentrated suspension in the first Beaktor and the Beaktorkaskade passes again.

For the inventive concept, it is irrelevant whether the catalyst is discharged in its entirety from the Beaktorsystem and the copper recovery is fed to ZweGke-the catalyst hay production after expiration of a scheduled operating time, or whether a continuous or portionwise partial substitution of the circulating catalyst during operation of Ithinilierung plant is provided.

-10-23271

Appropriately, the procedure is such that in each case after seizure of a certain amount of discharged Ka

CA.

corresponds to the copper recovery and Heukontaktiierstellung be made in the manner described, which are to be illustrated by an embodiment.

- «- 232715 2

Execute us from e i ap i el ->

For the copper recovery, a catalyst is discharged from the Äthinilierungsprozeß after a service life of 1 000 h and used after exhaustive washing process as a water-moist filter residue with the following parameters:

Mass: 215 g Fixed content: 51.3 % Cu content: 23.3 % Water content: 38.7% Organic substance: 38.0% Smallest particle size: 0.5 - 1 μm Catalyst precursor: synthetic malachite

The filter residue is transferred to a 1 000 ml glass flask equipped with a stirrer, reflux condenser, dropping funnel, gas discharge tube and bottom-to-bottom gas inlet tube and suspended in 130 ml of water. Gradually adding 148 g of hydrochloric acid (37%) The decomposition proceeds under acetylene evolution and is completed by brief heating to boiling point. During the boiling, the acetylene escapes completely from the reaction suspension and also from the gas space of the decomposition vessel. During the subsequent cooling phase, it is passed through the gas inlet tube over a period of time from 6 to 8 hours a flow of air in an amount of about 50 liters per hour

The filtration of the suspension through a G 3 glass filter core, which is used in place of the gas inlet tube, provides 270 ml of an optically clear, black-green solution with a copper content of 37 g · In the first washing water, which is limited to a maximum of 150 ml 7 g copper included * Both solutions are combined and after exact analysis of the copper content

232715 2

diluted to a concentration of 100 g Gu ⁺⁺ / 1 with the required quantity of water (copper chloride solution 1).

process again with 100 ml of water and 25 g of hydrochloric acid (37%) at. By twice an economical addition of washing water, the copper content of the baking residue can be reduced to less than 1 % of the initial amount (480 mg copper = 0.96%). of the copper used for the recovery). The strongly hydrochloric filtrate and the wash water are combined to the copper chloride solution 2 containing 5 »5 g of copper with an excess of hydrochloric acid of 6.5 g (100%). The copper chloride solution 2 serves to supplement the decomposition acid in a subsequent first decomposition process, taking into account its excess hydrochloric acid and water content in the batch calculation *

Preparation of the catalyst precursor:

From two 1 1 graduated graduated templates filled with equal volumes of copper chloride solution 1 (100 g Cu / l) and a soda solution (173 g HapCO 2 / l), the same volume flows of the two components are passed through 2 piston metering pumps at a metering rate of in each case 2 l / h are metered into a 10 1-eeactor, in which just enough water is submitted that the stirrer of the Heaktors ensures a good mixing of the liquid content. At the beginning of the precipitation operation, the heating temperature is adjusted to 7O ⁰ O by indirect heating within about 5 minutes. Under these conditions, the reaction takes place at a pH of about 8, which is suitable for the control of a uniform equivalent dosing of the starting components · The increasing liquid level in the reactor with increasing dosing is limited by removal

327 15 Z

DER clear mother liquor over a G with a 3-overflow is provided to the allowable 5 · ¹ UIlstand

The dosage is terminated after addition of "each 4 1 of the starting solutions, the stirring of the suspension, however, continued for a further 2 hours at a temperature of 8G ⁰ G.

When the temperature is maintained, the dosing of concentrated sodium hypochlorite solution (200 g iTaOH / l, 160 g / l) is started, which must be stopped after reaching a stable positive iodine-starch concentration. The consumption is 200 ml of this Hatriumhypochloridlösung.

After stopping the agitator and sedimentation of malachite, the supernatant solution is drawn off via a dip tube and the precipitate is washed free of chloride by repeated addition of water.

The synthetic malachite consists of irregularly shaped particles (spheroids) with a largely uniform particle size distribution and a predominant diameter of 5-10 μm. Smaller and larger particles are virtually absent.

The development of the catalyst and the athililation reaction ; ; ^ ·

Following the catalyst precursor production, the 10 l seactor for preparing the malachite is also used to develop the catalyst and to carry out the ithynylation reaction. After decanting the last wash water, 695 g of malachite (40 g of Ou), containing 8 l of formalin, are contained in the reactor (30%) is suspended. In the suspension, a self-priming hollow-shaft stirrer disperses acetylene, the pressure of which above the liquid level is kept at 0.04 atm by dipping down. «

232715 2

The acetylene is to be supplied according to the consumption. During the development of the catalyst, a partial stream from the gas space of the reactor is replaced by a gas

Discharge flowing off gas amount is to be regulated so that the COO content in the exhaust gas does not exceed 80 % . By means of a metering pump, a sufficient amount of 5% strength sodium hydroxide solution is metered in at the beginning of the introduction of acetylene in order to maintain a pH value of the suspension of 18 initially, and then to return to a value of 7 as the seeding progresses. The temperature to set during, Sntwicklungsphase for a period of 2-4 hours, a at 65 ⁰ C. During this time, the CX) _o -bonding decays, the -Acetylenaufnahme increases. Before raising the temperature to the desired Bndwert of 85 ⁰ G to adjust the COp concentration in the exhaust gas by increased Acetylenangebot to a value of 'less than 5 % . The course of the seeding can be controlled by monitoring the acetylene uptake and the formaldehyde concentration in the suspension. After a reaction time of 9 b. the formaldehyde concentration reaches a value of 0.75 %. · The reaction is interrupted by cooling the reactor with acetylene gassing.

In the follow-up tests, in which each of the reaction solutions had been replaced by 8 liters of fresh 30% formalin solution, the formaldehyde content could be reduced to 0.5% within 7.5 l at a continuous reaction temperature of 85 °. be lowered.

With the catalyst prepared from the regenerated copper chloride solution, the same results were obtained as with catalysts prepared from pure copper nitrate original solutions.

The developed catalyst is colored deep black and has a particle size distribution in the range of 5-10 μm identical to the precursor. finest particles

- 232715 2

with a diameter of 0.5 - 1 pm _t a characteristic appearance of spent catalysts, missing completely · The sedimentation and PiItrationseigenschaften the developed catalyst are correspondingly favorable.

Claims (2)

1. A process for the regeneration of a suspension catalyst, in particular a finely divided copper acetyl idhalt igen catalyst, which is obtained from a slurry of malachite by simultaneous action of formaldehyde and acetylene and required for the production of 1,4-butynediol after the Athinilierungsverfahren, characterized in that a) the exhausted catalyst discharged from the reaction system washed with water, resuspended in water and decomposed after addition of HCl in a molar ratio of <2 at boiling temperature under "tubes until complete expulsion of acetylenes that b) during cooling, an air stream is passed through the suspension until the acidity is lowered to a value of 1.5 g Ή01 / 1, that c) is prepared from the separated Cu-II-GhIoridlösung in a continuous process at a pH of 7-9 and a temperature of 70-SO ⁰ C by reaction with soda-J3in Hohmalachit, the d) is exhaustively oxidized while maintaining the precipitation temperature and the pH with sodium hypochlorite solution and after separation, washing and Resuspendieruhg ^ in concentrated Jmalmaldehydlösung in a known manner under the action of acetylene with gradual increase in the Sektionstemperatur converted into the active form and that e) the catalyst formation is increasingly in the Ithinilierungsreaktion passes. 232715 2 2. The method according to item 1, characterized in that the copper poor Bückstand the decomposition process at £? 9Λιπίϊ eni.p β.? is re-suspended at uv in excess Wissfis'pr HOl and the separated hydrochloric acid Cu-II-Ghloridlösung is used again in the Zeraetsungsproseß after item 1.