CS239600B1 - Concentration method of mercury catalytic solutions by acetylene hydration and apparatus for its realising - Google Patents

Description

SUMMARY OF THE INVENTION The present invention provides a process for concentrating the ortho-catalysts used to produce acetaldehyde by hydrating acetylene and an apparatus for carrying out this process.

At present, on an industrial scale, the hydration of acetylene to acetaldehyde in a contact solution is an aqueous solution of mercury sulphate, ferrous sulphate and ferric sulphate in dilute sulfuric acid in a plant whose main cell is a reactor filled with this solution, fed at temperatures of 95 to 105 ° C acetylene. The emerging pan gas mixture containing acetaldehyde, water, reaction by-products, mercury and unreacted acetylene exiting the reactor is partially cooled most often in three consecutive apparatuses. the purpose of condensation of the mercury vapor is that. keeps coming back with. often with condensate into the fresh regenerated catalyst branch and with it to enter the reactor at its bottom. The mixture thus treated is then further treated with water, where the acetaldehyde is separated off and this is worked up by known methods into the finished product. Unreacted acetylene is further reclaimed by known methods and is reused in the process. To ensure sustained activity of the catalytic solution in the reactor, a portion of it is withdrawn and returned to the reactor inlet, along with the streams in the above partial process after recovery. condensation of the exiting reaction mixture. It is necessary to control the temperature in the first heat exchanger within a limited range, in which the condensation of some of the mercury vapor, water and the higher-boiling fractions is predominant.

More intensive cooling is unsuitable, since product condensation would also occur and this would, together with the regenerated catalyst stream, penetrate into the reactor inlet, which is inappropriate. The research leading to the discovery of the hydration reaction was initiated by Ku.čerov in 1875 and he published his first works in this field six years later. However, industrial use has long been prevented by pitch formation and rapid catalyst deactivation. Only the principle of using an excess of acetylene according to Grunstein (German Pat. Nos. 250,356, U.S. Pat. Nos. 1,044,169 and 1,107,019, Fr. Pat. 455,370) enabled the full industrial utilization of acetylene hydration based on Kučerová's reaction. Further improvements in industrial applications have been introduced by IG Farben by the continuous regeneration of the trivalent iron catalyst, which reached its peak in thirty years and is used in practice to date. The principle of hydration is as follows. The reactor, enters 2800 ^m3 / h _and acetylene, to which. is added 1.5 m ³ / h of steam. The mixture enters the bottom of the reactor and barbots through the catalyst solution. The catalyst solution contains 4 grams of Fe2 (CO4) 3 per liter and 180 g of SO4 ⁺² , including free H2SO4, and the catalyst solution contains a large amount of metallic Hg suspended in the solution, and later the acetaldehyde production was directed to raw materials other than acetylene. It is based on petrochemical raw materials, which are more economical if the process does not need to use expensive and toxic mercury.

Because the mechanism of the hydration reaction of acetylene nio is now reliably elucidated, in natural gas-based acetylene plants, the catalytic solution activity decreases, resulting in a decrease in product formation and consequently reduced reaction heat, due to various, precisely unidentified and analytically imperceptible causes. as a result, the reactor temperature and acetylene conversion dropped and the catalyst began to be diluted. The diluted catalyst has, of course, a lower activity and the whole process has a progressively declining performance until production has to be interrupted and a suitable contact is prepared.

The aforementioned drawbacks are overcome by the method of thickening the mercury catalysts of acetylene hydration according to the invention, in which water vapor in amounts of 0.3 to 3 m ^{3 of} steam per m ^{3 of} acetylene is also fed to the hydration reactor together with the acetylene entering.

The condensate obtained by partial cooling from the exiting steam-gas mixture reactor is led directly back to the reactor together with the regenerated catalyst, or via a mercury separator to the sewage, or simultaneously to both the reactor and the sewage. An apparatus 11a for carrying out the process, comprising a cylindrical vessel with a conical bottom 1 connected by an upper part to the lower opening 2 of the heat exchanger 3, the vessel 1 being fitted with an assembly 4 and its conical bottom being via a valve 5 connected to the inlet pipe of the regenerated catalyst 7. The conduit 7 is further connected to the lower part of the hydration reactor 8 above the acetylene S supply conduit to which water vapor is connected through the conduit 10 and the upper part of the reactor 8 is connected via conduit 11 to the lower part 2 of the heat exchanger 3. the bottom part is connected with its upper part via a line 13 with a valve 14 to a mercury separator 15, which is connected via a line 16 to the sewer. By using an increased amount of steam, without subsequent dilution of the catalyst, the conditions in the barbotage reactor are significantly improved at lower amounts of reacted acetylene with impurity admixture.

The advantages of the proposed method are, in particular, that it allows the prescribed density and catalyst composition to be maintained even with fluctuating impurities in the treated acetylene due to changes in the composition of the treated natural gas, disturbances in the acetylene production system or scrubbing section. Uneven quality of acetylene also occurs during start-ups. As a result of the use of a higher amount of steam in the hydration reactor without subsequent dilution of the catalyst, the impurities coming in from the acetylene feedstock but also in the process itself are removed from the reaction medium. The advantages undoubtedly include simplicity in terms of operation of the equipment and low investment. The process and apparatus have been successfully verified on acetaldehyde production as shown in the following examples.

EXAMPLE

A catalyst with a density of 1120 kg / m ³ was used in the manufacturing process after modifications of the apparatus according to the invention. In the course of 24 hours of hydration with the addition of 2 m ³ / h of water vapor per 1 m ^{3 of} acetylene entering and alternating drainage of the condensate through the mercury separator both into the sewer and the reactor, the catalyst density increased to 1210 kg / m ³ .

Example 2

At a steady state of hydration and a catalyst density of 1241 kg / m ³ , the reactor was charged with acetylene and water vapor at a rate of 0.635 m ^{3 of} steam per meter of cubic acetylene. Within 2 hours the volume of unreacted acetylene downstream of the reactor increased to twice the initial value, and the catalyst density, measured at hourly intervals, decreased to 1,206 kg / m ³ . Based on these data, the amount of steam added was adjusted to 1 m ³ per m ^{3 of} acetylene and over the next three hours the condensate obtained in the first condenser downstream of the reactor at 85 ° C was discharged equally back to the reactor and through the mercury separator to the sewer. After this time, the catalyst density was 1,250 kg / m ³ and the amount of unreacted acetylene downstream of the reactor dropped to its original value, the acetylene / water vapor feed mixture was again adjusted to 0.635 m ³ vapor per m ³ acetylene, and production continued at the favorable parameters of the contact solution.

Example 1 and d 3

During the 3-month production run using the method and apparatus of the invention, the density was consistently maintained. of a contact solution in the range of 1200 to 239600

230 kg / m ^3, as against the use of said wiring density was about 1050 kg / m ^3, which was added to the reactor according to the needs of from 0.4 to 2.9 m ³ per m ³ of steam entering the acetylene.

The application of the invention falls within the field of acetaldehyde production by hydrating acetylene using mercury catalysts.

Claims (2)

SUBJECT 1. A process for the concentration of mercury catalyst solutions of hydration of acetylene consisting of a solution of mercury, ferrous and ferric sulphate in dilute sulfuric acid, characterized in that water vapor in amounts of 0.3 to 3 m ^{3 of} steam is fed to the hydration reactor. 1 m ^{3 of} acetylene, whereby the condensate obtained by partial cooling from the exiting steam-gas mixture reactor is led directly back to the reactor together with the regenerated catalyst or via a mercury separator into the sewage or into both the reactor and the sewage. 2. Apparatus for carrying out the method according to claim 1, characterized in that it comprises a cylindrical vessel with a conical bottom (1). BACKGROUND OF THE INVENTION connected by an upper portion to a lower opening (2) of the heat exchanger (3), wherein the vessel (1) is provided with a built-in (4) and a conical bottom thereof. it is a pipe (5). via a valve (6) connected to the feed line of the regenerated catalyst (7), which is further connected to the bottom of the hydration reactor (8) above the feed line of acetylene (9), to which water steam and the top of the reactor (10) are connected 8) is connected via a conduit (11i) to the lower part (2) of the heat exchanger (3), wherein the inter-tube space (12) of the conical bottom vessel (1) is connected with its upper part via a pipe (13) to the valve (14) a mercury separator (15) which is connected via a pipe (16) to the sewer.