SU116689A1 - Method for removing dissolved cobalt compounds from oxo-synthesis products - Google Patents

Description

It is known that the reaction of oxo synthesis is carried out in high-pressure furnaces with a catalyst containing cobalt in the form of a metal or one of its salts or oxides on a solid support, for example pumice or alumina. An appropriate double bond hydrocarbon and gas mixture is passed through this furnace at elevated temperature and elevated pressure.

In this case, the cobalt under the influence of the gas mixture is converted into an active catalyst, which dissolves in the initial hydrocarbon, as a result of which the reaction occurs.

Further, from the solution with the reaction product, the cobalt is regenerated, and the cycle is repeated.

The cobalt is isolated in a furnace filled with porous material at elevated temperature and pressure by treating the reaction product with gases that do not contain carbon monoxide. At the same time, cobalt is released and deposited on the carrier.

Thus, the cobalt in the oxo synthesis furnace is freed from the carrier, and in the regeneration furnace it is again applied to the carrier.

After a certain period of operation, the duration of which depends on the amount of cobalt on the carrier, both furnaces are switched.

To increase the service life of furnaces without switching them, the concentration of cobalt on the carrier is increased to 30-40% of the carrier material. However, this is associated with a number of difficulties, since the release of cobalt must occur in such a way as to ensure a uniform distribution of the process along the entire length of the furnace in order to avoid local obstructions. It is also necessary that all the cobalt from the reaction product be isolated in order to avoid its loss and the possibility of using it.

No. 116689

reaction product in other processes where the presence of cobalt may interfere.

In order to evenly release cobalt, it was suggested to introduce a product containing cobalt in several places in the furnace. But such an event requires the distribution of the product into several streams and their separate regulation, which is much worse: false installation.

The described method makes it possible to simply and effectively isolate cobalt from oxo-synthesis products by operating the furnace at a temperature that increases from the entrance of the furnace to the exit of the furnace.

The inlet temperature is adjusted so that it is not sufficient to immediately release the cobalt, but only cause such. With a uniform increase in temperature, cobalt is uniformly released along the entire length of the furnace. The transmission of an inert gas contributes to the thermal decomposition of dissolved cobalt compounds.

Example

a) before applying the invention

As a reaction furnace, a tube for high pressure, 8 m long, filled with 50 liters of catalyst, consisting of approximately 30% cobalt on pumice, is used. The catalyst grain is about 6 mm. This pipe has a high pressure casing that can be heated with steam or superheated water. At a pressure of 200 atm and a uniform temperature of 180 ° along the entire length of the tube, 25 l / h of product was introduced from the bottom, containing dissolved cobalt compounds resulting from the reaction of the exchange decomposition of olefins with CO and P2 in the presence of cobalt.

The product contains cobalt 0.14 g / l. At the same time, 6 gas consisting of 90% of hydrogen and containing only traces of carbon monoxide is passed through the furnace.

After three days of operation, clogging phenomena are noticeable, and the furnace must be stopped. After removing the kata, the pore in the lower third of the pipe, a large deposit of metallic cobalt is found. No significant cobalt precipitation occurs in the upper third of the furnace.

b) Using the described method

The same experiment was performed a second time with a change in oven temperature.

Using slowly circulating superheated water, the temperature was adjusted so that it stood at the top at the exit of the pipe 180 °, and then evenly decreased along the length of the pipe so that it reached only 105 ° at the entrance to the furnace.

Even after operation for 14 days, no precipitation was observed, and product introduction was not a problem; The pressure difference in the furnace was approximately 3 atm, which was obtained due to the natural resistance of the catalyst.

After the aforementioned time had elapsed, it turned out that a uniform distribution of the released cobalt on the vessel wall and pumice grains occurred over the entire length of the pipe. Only a small part of cobalt accumulated in a loose form in part of the furnace, but did not clog it.