DE662382C - Process for the production of acetone - Google Patents

Description

Process for the preparation of acetone It is known to eat acetone by passing glacial acetic acid over heated gene catalysts. the previous embodiments have several shortcomings. One shortcoming is that the process is very sensitive to temperature changes. depending on the applied In each case, the catalyst consists of legs for the cleavage of a certain optimal temperature. Once a temperature increase has occurred, it cannot be reversed. If the optimum temperature @ is exceeded, which can hardly be avoided in the company, so the catalyst loses its effectiveness in the original. Temperature. So you have to work closer to the critical temperature limit at which Decomposition occurs with formation of soot. More - overruns will result soon to a premature end of the catalytic effect. Another shortcoming of the previous one Litigation aimed at the fullest possible conversion of the sent Acetic acid was discontinued, the process was shown to be troublesome against fluctuations in: the speed of the acetic acid vapor. When exceeding The optimal speed occurred with the complete acetic acid conversion Disruptions that are difficult to rectify and that have a long-lasting effect - Catalyst cooling, overloading with vinegar, acid, decrease in effectiveness: des Catalyst, atoTs - on.

It has now been found that these difficulties can be eliminated and that at the same time, above all, the performance is significantly improved by the Measure that the acetic acid in s @ 0 rapid current over the to at least q.80 ° Heated gel catalysts conducts that a considerable part of the acetic acid remains unchanged remains and serves as a means of transport, whereby the unreacted Es: sigs, äure nach their separation from the reaction product is fed back to the reaction space.

Another, under certain circumstances particularly economical, embodiment consists in the fact that the unchanged part of the acetic acid, which serves as a transparent medium, is replaced by inert gas or steam and the vapor mixture is passed through the reaction chamber so quickly that a considerable part of the acetic acid remains unchanged under the same reaction conditions if the steam consisted only of acetic acid. As s, all means of transport come e.g. B. water vapor, carbonic acid, nitrogen into consideration. You can z. B. in the catalyst ralam acetic acid dam.pf and at the same time steam, z. B. exhaust steam: blow in; but one can also start from acetic acid mixed with an inert liquid. Of the in performing this procedure if necessary @required additional effort Warmth can be achieved by suitable warmth a *: ` Exchange in the interest of preheating tri-acetic acid, the acetron distillation and the like.

If you drive z. B. stands by a angebitzten at least 48o ° reaction furnace mixtures of 2o to 50 parts Essigsäurudampf with 8o to # 5o Teilren water vapor so rapidly that under identical reaction conditions einerheblicher of the acetic acid would remain unchanged when the vapor loading only from acetic acid With increased performance, the catalyst remains insensitive to the above-mentioned fluctuations in temperature and steam speed. A temperature can safely be brought up to the sooting temperature without the catalyst therefore losing its effectiveness at lower temperatures. The steam speed can be increased and decreased as desired without interference.

This surprising result could not be achieved through the usual variations in the test conditions. According to the state of the art, the starting point for such attempts was to send about as much of the diluted vinegar through the catalyst chamber per day as there was practically no residue under the same conditions of concentrated acid. able to implement. If the given initial throughput is increased to double or even quadruple, then, as described in the third paragraph of Example 2, the sensitivity of the catalyst to the inevitable fluctuations in the rate of passage and the temperature is in no way reduced. Rather, this sensitivity even increases in this area of the throughput magnifications. The protective effect according to the invention only occurs at very high speeds. Before this is reached, a vast area is traversed, in which the fluctuations in the speed of steam and that of the temperature have an even greater effect the more steam is driven through. The damage to this catalyst caused by the recurring disturbances also accumulates, the more rapidly the more rapidly the problem is prohibitive, the greater the amount of acid which is enforced daily and - with each disturbance, more moderately less decomposed into catalyst poisons " In the intermediate area of the increase in throughput, the reaction product was free from acid, and it could not be foreseen that the , @ n amounts of free acid are only insignificant @ '`.; grow when one increases in size ., POrder this throughput applies. 1 "## The increase in performance made possible by the above procedure leads to quite, extraordinary dimensions. This procedure gives the means to achieve a multiplication of production with existing manufacturing units. The following comparison experiment shows this in a noteworthy way Oxides, carbonates, acetates and the like of cerium can be used, especially cerium oxide. The fixing of the cerium catalysts on the support, such as charcoal, pumice stone and the like, can take place in the form of any ara-organic or organic compounds. Example in my reaction furnace of 1 content A stream of acetic acid vapor was passed over a catalyst consisting of cerium oxide and pumice stone at an initial temperature of q.80 ° C. so that no free acetic acid appeared in the condensate Acetone obtained. During the implementation, the difficulties already mentioned arose opportunities. The reaction was very sensitive to temperature changes. Inevitable increases in the temperature could no longer be reversed and ultimately led to the sooting of the catalyst and thus to the premature termination of the experiment.

The acetic acid flow was increased from 2.4 kg in 24 hours to 33.3 kg in 24 hours in the same reaction furnace with the same catalyst filling and at the same temperature. In the process, 60,000 of the acetic acid was converted into acetone. The acetic acid freed from the acetone and water formed was circulated: the output in this case was ten times as high; namely in 24 hours io; 6 kg Aoetön. The experiment was also much easier and more convenient to carry out under these speed conditions. Changes in temperature and speed no longer acted as sources of interference. EXAMPLE 2 1 8.7 kg of acetic acid vapor, mixed with 56.1 kg of steam, were driven through the reaction oven described above with the same catalyst filling and at the same temperature. This ratio was adjusted so that the flow of acetic acid was increased with a constant flow of steam until just traces of free acid began to appear in the reaction product. The output in this case was 9 kg of acetone in 24 hours. The output was increased eightfold through the control - the transport speed of the acetic acid vapor.

If, on the other hand, according to the previous state of the art, according to which the aim was to achieve practically complete freedom from acid of this reaction product, especially with strong water dilution, only 2 to 3 kg of the steam containing 250/0 acetic acid and -5% water per day through the reaction furnace, so you initially get a daily output of o.23 to o.34 kg aoeton. This performance can only be maintained, however, by increasing the reaction temperature each time the conversion decreases, which frequently occurs under these conditions. Since in this procedure this; intentionally caused and the frequently occurring increases in temperature can be reverses overall otherwise inevitable not, she soon lead to fouling of the catalyst and the pre-contemporaneous failure of this experiment.

If one then tries a systematic increase in throughput, one likewise does not achieve the goal. The initial powers increase according to the doubled or quadrupled throughput, for example, but the sensitivity of the catalyst to fluctuations in the steam speed and temperature and the speed at which it slows down is increased to this extent as the throughput increases. In addition, when the throughput is quadrupled, i.e. about 2 kg of acetic acid vapor and 6 kg of water vapor per day, quite noticeable traces of converted acetic acid are noticeable in the reaction product.

Example 3 5 In the experiment described in Example 2 Paragraph i all other things being equal, the 56.1 kg of water vapor were passed through 44 kg of nitrogen .replaces, giving the same result.

Claims (4)

PATEN TANSPRÜCIIr; i. Process for the production of acetone by Passing acetic acid over heated gel catalysts, characterized in that that the acetic acid vapor sio quickly through the to temperatures of at least 48o ° heated reaction chamber is passed, d @ ate a considerable part of the acetic acid remains unchanged and serves as a means of transport, with the unreacted acetic acid is fed back to the reaction rates after their separation from the reaction product. 2. The method according to claim i, characterized in that the unchanged, as Part of the acetic acid serving as a means of transport by inert gas or steam replaced and the vapor mixture is passed so quickly through the reaction chamber that under the same reaction conditions a considerable part of the acetic acid remained unchanged would remain if the steam consisted only of acetic acid. 3. The method according to claim i and 2, characterized in that the vapors or ILGasy are removed before they enter preheated in the reaction chamber. 4. The method according to claim i to 3, characterized in that that one works using heat exchange.