JPH0627080B2 - Hydrocarbon oxidation method and apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for oxidizing a liquid phase hydrocarbon utilizing oxygen-containing gas, which achieves improved selectivity of reaction and high oxygen utilization efficiency.

[Prior Art and Problems to be Solved by the Invention] Oxidation of hydrocarbons in the liquid phase is a method commonly used in the chemical industry. The method includes, for example, a method of oxidizing cyclohexane to cyclohexanol, cyclohexanone, isopropylbenzene to isopropylbenzene hydroperoxide, toluene to benzoic acid, and p-xylene to terephthalanol acid. From the viewpoint of achieving a high degree of selectivity, the cyclohexane oxidation method has a very large problem. The target substances-cyclohexanol and cyclohexanone-are more easily oxidized than cyclohexane itself to form by-products, mainly mono- and dicarboxylic acids.

Apart from the method of limiting the conversion, the improved selectivity of the known hydrocarbon oxidation processes avoids so-called backmixing by carrying out the successive reaction steps in separate steps. The method of introducing the oxidizing gas into the reaction solution is an important factor in the process of oxidizing hydrocarbons. The method of introducing the oxidizing gas should ensure a suitable expansion of the interface and a suitable turbulence of the liquid phase, preventing local differences in concentration and / or temperature.

For this reason, the oxidizing gas is introduced into the bottom layer of the reaction solution. The oxidizing gas is introduced in the form of bubbles, and the bubbles are
It is produced using a perforated bottom, a porous distributor made of ceramic or sintered metal, or a distribution pipe made of suitable perforated tubes. For example, in the case of a pipe distribution pipe in the form of a horizontally arranged frame, the oxidizing gas flows uniformly over all planes of the distributor, just as when using a perforated bottom and a porous distribution pipe, and the reaction The tubes are placed and perforated so that they flow at a uniform rate through the liquid. As a result, an upward flow of the total volume of liquid occurs over the entire surface of the distributor, and this downward flow of liquid is only possible beyond the edge of the distributor frame surface close to the reactor wall. Such a condition is that the rising liquid must pass a long distance before reaching the falling zone (along with the reactor wall or along the transverse partition if the wall partitions the reactor). It must prevent mixing in separate compartments of the reactor. Such a method of introducing oxidizing gas may consume all of the dissolved oxygen, which is deficient in dissolved oxygen and causes the upper zone of the column of liquid in contact with the oxidizing gas (where the oxygen consumption rate is The fact that it is no longer dissolved (in the high) results in a large volume in which no reaction takes place in the particular compartment. Since the amount of the oxidizing gas introduced into each compartment of the reactor is constant, the presence of the compartment volume not used in the reaction causes excess of the oxidant in the other part, which leads to peroxidation, that is, from the target substance to the by-product. Allows oxidation. In larger diameter reactors, a down zone also occurs on or parallel to the axis of the horizontal drum reactor.

Known devices for the oxidation of hydrocarbons include several separate tank reactors, reactors connected by a series of pipe systems, or one reactor consisting of several series of connected reaction sections. It is one of the form. For example, the reactor disclosed in Polish Patent Specification No. 6449 is a horizontal tubular body, which is divided into pairs of adjacent vertical partition walls, one of which is a reaction liquid. Overflow baffles for, others block vapor spaces in adjacent compartments. Perforated dispersion tubes are present in these compartments, for example in the shape of a frame, through which the oxidizing gas is introduced into the reaction liquid.

The reactor according to Polish Patent No. 136028 is a modification of this example. The reactor has an enlarged frame structure of a distribution pipe and consists of several arms bent in a manner similar to the curve of the bottom of the reactor. The arms are located in the direction intersecting the axis of the reactor and are parallel to the axis of the reaction. Are bound to. The improvement lies in the hole in the distribution pipe arm, in which the orifice is arranged at a higher distance in the uppermost portion than in the lower central portion. This method allows a constant outflow of oxidising gas along the distribution arm, while at the same time avoiding an excessively strong flow of gas at the end of the arm and incomplete absorption of oxygen. This example is achieved not only by the reactor or reaction compartment walls, but also by the unperforated compartments by leaving some unperforated parts of the distribution pipe, for example on the longitudinal axis of the reactor. It leaves the possibility of creating a vertical liquid descent zone.

Regardless of the technology and equipment used, known examples include the selectivity and oxygen utilization of the hydrocarbon oxidation process,
That is, the possibility of improving the decrease in the concentration in the consumed gas cannot be eliminated.

[Means for Solving the Problems] The method of the present invention is for oxidation in the form of a bubbly flow in the form of a continuous flat trickle so as to be transverse to the direction of liquid flow through an aerated reactor or reaction zone. In a method of oxidizing a hydrocarbon in a liquid phase using a gas containing oxygen by aeration of a gas, an adjoining flow of a bubbling stream of an oxidizing gas is separated by a gas-free area. Is a method for oxidizing hydrocarbons.

In the process according to the invention, the reaction liquid moves from the inside to the outside of the compartment and is lifted up by a bubbling flow of the oxidizing gas transverse to the direction of flow of this liquid. The liquid then falls downward in the lateral, gas-free areas between the bubbly streams. At the bottom, the reaction liquid again contacts the bubbles and is lifted again. That is, in the process of going from the inside to the outside of the reaction zone, the liquid rises and falls several degrees. This results in a strong multi-step reaction liquid circulation around a plane perpendicular to the direction of liquid flow. In the downflow zone of the liquor, no fresh oxidizing gas is supplied and the oxygen already dissolved in cyclohexane is exhausted to the reaction, the reaction takes place at a low oxygen efficiency, which leads to high selectivity. It is advantageous to The circulating flow of the reaction liquid around the plane perpendicular to the direction of the flow of the reaction liquid is used alone or together with the known circulating flow around the plane parallel to the direction of the flow of the liquid.

The liquid phase hydrocarbon oxidizer of the present invention is a horizontal cylindrical drum, divided into a series of compartments and equipped with an oxidizing gas distributor. The distribution pipe consists of several porous arms that are perpendicular to the direction of liquid flow, and the arms of the individual distribution pipes are spaced from each other to prevent mixing of gas bubbles from adjacent arms. Located at a distance of 4 above
It is at least 00 mm. To increase circulation, a circulation barrier can be used, which is fixed between the individual arms, parallel to the arms. These barriers are submerged below the liquid level, leaving empty passages on the bottom of the reactor. Such shields are installed in pairs between adjacent arms;
Then, the shielding plate forms separate areas of the liquid rising (upper arm) and the descending area (between the shielding plates).

They can also be installed as a shield between two adjacent arms. : In that case, the rising and falling areas of the liquid are not separated, but the circulation areas belonging to the individual arms of the distributor are separated separately.

The present invention and its embodiments are as follows.

1. Oxygen is vented to the reaction liquid in the reactor by bubbling an oxidizing gas in the form of a bubbly flow in the form of a continuous flat stream in a direction transverse to the direction of liquid flow through the reactor or reaction compartment. A process for oxidizing hydrocarbons in a liquid phase using a containing gas, characterized in that adjacent streams are separated by gas-free zones.

2. In a liquid-phase hydrocarbon oxidizer comprising a horizontal tubular body divided into several compartments provided with distribution pipes for oxidizing gas, and including several perforated arms perpendicular to the direction of liquid flow, A hydrocarbon oxidizer, characterized in that the separate arms of the distribution pipe are separated from each other by a distance such that bubbles from adjacent arms do not mix, the distance being 400 mm or more.

3. Apparatus according to claim 2, characterized in that there is a circulation shield between the individual arms, which is submerged below the surface of the water, leaving an empty passage above the bottom of the reactor.

4. 3 characterized by two shields between the arms
The device according to the item.

5. 3 characterized by one shield between the arms
The device according to the item.

The method and apparatus of the present invention are shown more specifically in the schematic drawing. FIG. 1 is a horizontal longitudinal sectional view of a section of a reactor. FIG. 2 is a vertical sectional view of the compartment.

Example The oxidation method of cyclohexane using air is a continuous method,
Performed at pressure, 0.9 MPa and temperature 160 ° C. In this method, 130 cu.m / h of cyclohexane, 1 ppm of cobalt in the form of cobalt naphthenate as a catalyst are added and a total volume of air of 5800 cu.m / h is used. The individual compartments of the reactor are separated by an outer wall 1 and a partition wall 2 and filled with the reaction liquid to a height of 3, jetting air in the form of bubbles to form a flat flow, which is transverse to the liquid flow, It is divided into areas that are out of air. In the flow zone, the reaction liquid becomes an ascending flow together with air bubbles, but in a region where air is not communicated, it separates from the previous region and becomes a descending flow of the liquid. Therefore, a strong circulating flow occurs in the container containing the oxidizing agent.

The process is carried out in a horizontal tubular reactor with a total volume of 110
cu.m. It is divided into 6 reaction compartments. Except for the sixth compartment where decomposition of cyclohexyl hydroperoxide is expected, all the remaining compartments have a frame-shaped oxidizing gas distribution pipe consisting of a perforated pipe arm 4 and a vertical pipe connecting member 5 which crosses the reaction axis. is doing. The arms 4 are installed apart from each other so that bubbles generated by the adjacent arms do not mix, and the distance is 450 mm. A pair of shield plates 6 are provided between the individual arms 4, which sink below the liquid surface and have an empty passage on the bottom surface of the reactor. The oxidizing gas is supplied to the distribution pipe through the vertical introduction pipe 7. Based on the analysis results of the liquid product from the reactor, the obtained reaction selectivity was changed to cyclohexanol, cyclohexanone and cyclohexyl hydroperoxide, and reached 85%.

During the oxidation reaction of cyclohexane, air is introduced by the conventional method in the form of air bubbles, and all reagents are added under the same pressure, temperature and total reaction reagent conditions, and then introduced into a reactor with the same total volume and the same number of compartments . The reaction selectivity obtained reaches 82.5%.

[Brief description of drawings]

FIG. 1 is a horizontal longitudinal sectional view of a section of a reactor. Second
The figure is a vertical sectional view of a section. In FIG. 1 and FIG. 2, 1 ... Outer wall 2 ... Partition wall 4 ... Perforated tube arm 3 ... Reaction liquid level 5 ... Connecting member 6 ... Shielding plate 7 ... Introducing tube.

Continuation of the front page (72) Inventor Antoni Janusz Gzba Tarnow, Poland, Ulitsa Lornicya 5a / 14 (72) Inventor Arena Janitz Warsaw, Poland, Ulitza Fabrichuna 2/139 (72) Inventor Anjujay Kashnia Tarnow, Poland, Uritsa Zabazykiego 6/73 (72) Inventor, Josef Kumiech, Denitsa, Poland Śrica Vierekopolska 61 (72) Inventor, Boichech Rubieva-Bielejski, Warsaw, Poland , Ulitsa Batu Tei 7 Tse / 401 (72) Inventor Jan Mathuga Tarnow, Poland, Urica Burtniza 4/8 (72) Inventor Marek Pohibarskiy Pwavy, Poland Ulitzka Schier Chebskiego 12/6 Number (72) Inventor Rishi Luto Pokhorez Warsaw, Poland, Uritsa-Narenchobuska 47/68 (72) Inventor Stanislaw Ryger, Tarnow, Poland Uritsa Remonta 31/22 (72) Inventor Yuzev Spursky, Taruz, Poland・ Mieszka I 5 (72) Inventor Alexander Udinsky Ki Pwaby, Poland, Ulica Partei Zantube 7A / 24 (72) Inventor Dadeus Wiebeger, Warsaw Poland, Ulyza Bronieb Skiego 6/123 (72) Inventor Mihau Zilbershteyan Ulitsa Mikulashev Skiego 14/58, Warsaw, Poland

Claims (3)

[Claims] 1. A reaction liquid in the reactor is bubbled with an oxidizing gas in the form of a bubbly flow in the form of a flat, flat stream which is continuous transversely to the direction of liquid flow through the reactor or reaction compartment. The method for oxidizing hydrocarbons in a liquid phase using a gas containing oxygen is characterized in that adjacent streams of a bubbling stream of oxidizing gas are separated by gas-free zones. , Hydrocarbon oxidation method. 2. A liquid hydrocarbon comprising a horizontal cylinder divided into several compartments having a distribution pipe for an oxidizing gas and comprising several perforated arms perpendicular to the direction of liquid flow. In the oxidizer of claim 1, the separate arms of the distribution pipe are separated from each other by a distance that does not mix bubbles from adjacent arms, and the distance is 400 mm or more. 3. Apparatus according to claim 2, characterized in that there is a circulation shield between the individual arms, which is submerged below the surface of the liquid, leaving an empty passage above the bottom of the reactor.