CS263577B1 - It causes an increase in the selectivity of cyclohexane oxidation to cyclohexanol and cyclohexanone - Google Patents

Abstract

The purpose of the solution is to increase the useful conversion of the cyclohexane oxidation process in the liquid phase to a mixture containing cyclohexanol and cyclohexanone. The stated purpose is achieved by the fact that, due to the appropriate distribution of the dosed oxidation catalyst before the oxidation reactor and to a convenient location in the oxidation reactor, its improved dispersion into the liquid phase occurs, which favorably affects the cyclohexane oxidation process to the desired products, i.e. cyclohexanone and cyclohexanol.

Description

263S77

SUMMARY OF THE INVENTION The present invention provides a method for increasing the selectivity of the oxidation of cyclohexane to cyclohexanol and cyclohexanone in a liquid phase with an oxygen-containing gas.

The cyclohexane oxidation reaction is an inter-reaction where subsequent re-actions often take place. In order to maintain a high selectivity of the reaction, it is operated with almost complete oxygen conversion and low cyclohexane conversion. Attempting to shift the mode to the kinetic area results in a deliberate reduction of the reaction rate and this prefers the reactors with a large liquid retention. From the point of view of both performance and selectivity, it is expedient to select the cascade of reactors with a bubbled layer, preferably a ventricular reactor with a suitable gas dispersion dispersion in the liquid to provide a large specific interfacial surface.

Although the aforementioned requirements of the process for the oxidation of cyclohexane on an industrial scale are satisfactorily achieved by the formation of considerable amounts of introduced and / or sequential products, they are organic mono and dicarboxylic acids, hydroxy acids, aldehydes, ketones, alcohols, esters , cyclic and linear angular thanks. They lead, through esterification, etherification, condensation, polyesterification, polyetherification, polycondensation and polymerization reactions, to the formation of other organic compounds which, together with these, form undesirable waste from the production of cyclohexanone. These reactions also partially result in high molecular weight compounds which cause clogging of the steno-reactor and subsequent reaction-separation devices, especially in poorly-fed sites. Various methods of cyclohexane oxidation have been developed in order to achieve the desired conversion and / or selectivity. It is known to add cyclohexane and an oxygen-containing gas to each chamber at a constant volume ratio, with the added amount of cyclohexane being proportional to the heat released (SU 503 843). CS-AO No. 256 583 protects the process, whereby oxygen-containing gas is bubbled through the liquid in an amount of 0.89 to 1.5 km / h per 1 m 3 of fluffed liquid.

A process is also known in which the oxygen concentration in the off-gas is limited to a maximum of 2% by volume (BE 827 835) and to a process of maintaining the effective height of the liquid and the liquid to be spaced from 1 to 2 meters (PL 241914). .

Concentration and temperature homogeneity ensuring high selectivity of the reactor 4 to 8 chamber reactor (PL 64 449) formed by a horizontally mounted cylindrical shell, overflow baffles and baffles preventing contact between the two components of the individual chambers, which may be provided with an additional baffle to more effectively prevent poor flow between the plaques (PL 94 062), whose sheathing distance is 1 to 400 mm (PL 134 291).

The improvement of the gas dispersion in the bubbled liquid is solved by a method characterized by an average linear velocity of the oxidation gas flow through the apertures accurately defined in relation to the positioning hole on the bubbler (PL241111) or by using a gas distributor with unevenly spaced openings in the horizontal reactor cross section perpendicular to the flow direction of the reaction mixture. It is also known to provide a high degree of oxygen utilization by the advantageous spaced apart partitioning divisions by different distances and diameters of the openings from the vertical axis of the bubbling device (PL136 028). In the course of the experiments, the process of oxidizing cyclohexane to cyclohexanol and cyclohexanone in multi-stage reactors has proven to be very important to effectively disperse the oxidation catalyst into the gas-containing cyclohexane containing oxygen. The above mentioned procedures and methods enhance the attention to this issue, or more precisely. The catalyst feed is most commonly solved under the cyclohexane level in the individual stages of the oxidation reactor and through a suitable tube, with a substantial portion of the catalyst being dosed to the first stage since it is a starting stage. A further increase in the co-concentration homogeneity of the dispersed oxidation catalyst in the liquid phase of the individual stages of the oxidation reactor allows the process of the present invention to be carried out.

SUMMARY OF THE INVENTION The present invention provides a method for increasing the selectivity of cyclohexane acyclohexanone oxidation in a liquid phase with an oxygen-containing gas in the presence of a catalyst in a multistage barbotage reactor. It is characterized in that more than 30 wt. from the amount of catalyst needed to oxidize the cyclohexane, the cyclohexane feed system is injected at the beginning of the reaction system, at a site prior to at least one local resistance at the inlet of the reactor, allowing partial homogenization of the cyclohexane catalyst to enter the reactor. The dosing is carried out through a system of two to six distribution elements which can be directed in the pipeline in the direction or against the direction of the cyclohexane flow.

The remaining portion of the total amount of catalyst is injected into the at least one oxidation reactor chamber and the overflow and hydraulic overflow of the liquid from the chamber to the chamber, most preferably from the n-3-chamber oxidation reactor in the cyclohexane flow direction,

Claims (2)

SUBJECT A process for increasing the selectivity of oxidation of cyclohexane to cyclohexanol and cyclohexanone in a liquid phase by an oxygen-containing gas, in the presence of a catalyst, in a multi-stage barbotage-type reactor, characterized in that more than 30 wt. from the amount of catalyst required for the oxidation of cyclohexane to the start of the reaction system in the inlet cyclohexane at a point prior to at least one local resistance at the other inlet to the reactor, through a system of two to six, preferably three flow direction of cyclohexane to the reactor, the remaining portion of the total catalyst feed being injected into at least one transition between the overflow and the hydraulic baffle from the chamber to the reactor chamber, preferably from the n-3th chamber of the oxidation reactor in the cyclohexane flow direction; n is the number of chambers in the oxidation reactor.