DE752746C - Process for the production of acetone from acetylene - Google Patents

Description

Process for the production of acetone from acetylene Es; it is known to use zinc oxide as a catalyst for the production of acetone from acetylene and steam. A large number of catalysts have also been described which contain zinc oxide as the basic substance and also other substances such as aluminum oxide, oxides of manganese and iron. Even with dilute acetylene (8 to 10%) at temperatures of 350 to 50 ° and residence times of about 1 second, these substances lead to an almost complete conversion of the acetylene. For the technical implementation of the process, it is of crucial importance that the catalyst retains its activity for as long as possible. This is particularly important when using dilute acetylene, which was obtained by thermal treatment of hydrocarbons, since such acetylene usually still contains impurities, such as ethylene and higher acetylenes, which easily lead to contamination and inactivation of the catalyst. It is true that such contaminated catalysts can be revived by treatment with oxygen-containing gases, but it is essential for technical implementation that such a revitalization is not necessary too often and that the catalyst can withstand a sufficient number of such treatments . It is known that the mechanical durability of a catalyst can be increased by the fact that the ka.talvtisch wirh: on the substance on a firm basis, z. B. any carrier applies. However, such an improvement in the mechanical properties often worsens the catalytic properties such as efficiency and efficiency.

It has now been found that zinc oxide catalysts of excellent mechanical and catalytic properties are obtained even without the use of carriers and activating additives if the zinc oxide is produced by roasting basic tin carbonate. It has proven to be useful to roast between .25o and 50o '. The basic tin carbonate is obtained by precipitation from zinc salt solutions with carbonate ion in the presence of ammonium ions. You can dab; First ammonia is added to the zinc salt solution, a mixture of zinc hydroxide and zinc oxide precipitating out, and this mixture is converted into the desired product by introducing carbon dioxide. y -You can continue to introduce ammonia and carbon dioxide together into the zinc salt solution or z. J. a solution of ammonium carbonate or ammoninin bicarbonate flow in. @ N let. Finally, solid ammonium bicarbonate or ammonium carbonate can also be introduced into the zinc salt solution with stirring; the precipitation then proceeds to the extent and with the speed with which the ammonium salt dissolves. It is advisable to exclude small amounts of solid alkali from the precipitation. The precipitates precipitated in this way are dried in the heat, expediently at 60 to 150 °, and then best roasted at 250 to 450 °. For the purpose of obtaining a mechanically solid catalyst from the zinc oxide powder thus produced, the zinc oxide can be mixed with organic binders, e.g. B. De #> trin, starch or gelatin. Paste, dry and roast the organic matter. Instead of this, you can knead the zinc oxide with a small amount of nitric acid and then dry it and roast it. Through this final line of zinc oxide powder one has it in the hand, the strength and the 1, za.talvtisclien proper; connections to b-kin flows.

The following Peispi-el.z describe some of them special manufacturing methods; in connection the use of the catalyst is gates to Acetonliersteiling described. Example i A solution of 3.5 kg of zinc nitrate in 5 1 Water: r is under ice cooling with 63; o cm3 added ioprozeritigen ammonia and iri hours while stirring with charcoal saturated dioxide. The gained here Precipitation product is filtered and washed, then dried at iio = and at 250 ' toasted. iooo g of the thus obtained Tin oxide powder is mixed with 20 g of dextrin and pasted with the necessary amount of water and in a kneading machine to a tough one Porridge through gelznetet. This pulp is on a Aluminum sheet painted to cubes of 8 mm edge length grooved. These will be i io #l; dried. Last is the dextrin hot 40o 'roasted in a stream of air. -With the catalyst produced in this way a reaction furnace is charged. Through this Oi.:n one conducts at temperatures between 360 and 170 'from below through thermal mixed decomposition of methane with acid gas mixture obtained from the substance, which in addition to Carbon oxide and hydrogen in total 8% Contains acetylenic hydrocarbons that lead to co0f'o consist of pure acetylene. This Gas is used without further purification. At the same time one leads per cubic meter Dry gas, calculated to o 'and 76o mm Pressure, 0.81-z water vapor through. the \ "extended time of the reaction mixture in the settlement furnace is 1 second. You get in this way during (, -months of operating lasting an average yield of 940/0 Acetone, calculated on the acetylene used len; contain the gases leaving the furnace only about 0.25 % acetylene. In each case after about 4 to 5 weeks the catalyst becomes through one to four days of treatment with air diluted by nitrogen animates. He keeps his physical Forin. Used in place of the above described a catalyst produced those made from ordinary zinc carbonate with an activating addition of iron hydroxyd was produced, one has to use the The catalyst is restored every 1 hour. animate; its total life is only i @ days and the average yield Acetone only about 860/0. Example e A three-fold molar zinc nitrate solution is mixed with a hot, saturated solution of technical ammonium carbonate at g0 'until nothing more precipitates in a filtrate sample. The precipitate is filtered off, washed out, dried at 10 ° and roasted at 45 °.

iooo g of so. zinc oxide obtained. be with a solution of 12.4 g concentrated nitric acid in 428 cm3 water and put in the kneading machine kneaded into a firm dough. This dough is pressed through an extruder, dried at 100 ° and finally roasted the nitric acid at 400 to 500 °.

If a catalyst prepared in this way is used to obtain acetone. as in example i, similarly good yields are obtained as there. The catalyst only needs to be revived to% every 6 to 7 weeks. Example 3 3780 g of zinc nitrate, dissolved in about 71% of water, are mixed with 2750 g of ammonium bicarbonate in small pieces at 80 ° to 90 ° with stirring. The temperature is kept at 80 °. After the evolution of carbon dioxide has ended, the mixture is stirred for a further 10 minutes at this temperature, then filtered, washed, dried at 10 ° and roasted at 300 °. The zinc oxide powder obtained in this way is processed into the catalyst in the same way as in Example 1 and this is used to produce acetone. The results are as good as in the previous examples.

Example 4. A 20 ° warm solution of 10 moles of zinc nitrate in 5 liters of water 167o g of ground ammonium bicarbonate are added with stirring, the temperature being increased decreases to -io '°. After stirring for a further hour, it is filtered and washed and dried in the heat. The zinc oxide powder roasted at 300 ° is processed as in Example i processed into a catalytic converter.

The catalyst produced in this way is as in the example i used to convert a dilute acetylene (acetylene content about 81/0), which was obtained by thermal conversion of methane with oxygen and one contains a small proportion of higher acetylene hydrocarbons. The catalytic Implementation can be carried out for 7 to 8 months and longer. During this time the Catalyst revived several times by treatment with gases containing oxygen. A definitive decline in activity cannot be determined during this time will. The yield of acetone is between 90 and 95 throughout the period % calculated on acetylene used. Example 5 A 2o ° 'warm solution of io Moles of zinc nitrate in 5 l of water are mixed with 1670 g of ground ammonium bicarbonate while stirring and a solution of 0.05 moles of sodium hydroxide in water. The precipitation will happen until. washed to freedom from alkali and further processed as indicated in Example 4. The catalyst prepared from him according to the information in Example 4 has an approximately just as good service life and delivers a practically just as good yield of about 90 o / o acetone like the catalyst used there.

For comparison, a zinc oxide was used as a catalyst, which can be washed out well by precipitating zinc nitrate solution with sodium hydroxide solution; Drying at 135 ° and solidification with 21 / o dextrin was made. Using the same gas mixture, average yields of only 70 to 80 o / o acetone were obtained with this catalyst. The catalyst had to be revived after just 14 days; a second resuscitation was required after a further 8 days. About half of the catalyst crumbled in the process.

Claims (2)

PATENT CLAIMS: i. Process for the production of acetone from acetylene on zinc oxide catalysts, characterized in that the catalyst used is a zinc oxide used, which is made by roasting basic zinc carbonate, wherein the basic zinc carbonate by precipitation from zinc salt solutions with carbonate ions is obtained in the presence of ammonium ions. 2. The method according to claim i, characterized characterized in that the precipitation is carried out in the absence of fixed alkali.