DE2347062B2 - METHOD AND APPARATUS FOR THE PRODUCTION OF PHOSPHORUS PENTASULFIDE - Google Patents

Description

The present invention relates to a process for the production of phosphorus pentasulfide from phosphorus and Sulfur at an elevated temperature in a reaction zone, the walls of which are used for absorption and control the heat of reaction is in heat exchange with a substance that is responsible for cooling or heating the Has reaction mixture required temperature.

It is known to produce by reaction of molten phosphorus and sulfur at temperatures between about 280 and 515 ⁰ C P2S5. Various methods have already been developed for removing the heat of reaction released in this reaction in order to be able to keep the reaction temperature in the range mentioned.

For example, according to US Pat. No. 2,794,705, attempts have already been made Introduce phosphorus and sulfur into a P2Ss melt and the heat of reaction to distill off the new to use the resulting product. However, this procedure has the disadvantage that the distillation of P2S5 involves a lot of effort and many difficulties, particularly due to the ease of use Flammability of P2S5 in the molten and vapor state can be caused.

It is also known from US-PS 25 69 128, the implementation of phosphorus and sulfur in one Perform reactor, the side walls of which are given away with a cooling system. As a coolant were liquid, predominantly inert heat exchange materials are used here. Besides being liquid Coolant causes decomposition to a greater or lesser extent at the high temperatures that occur tend and lead to incrustations of the heat exchange surfaces, the maintenance of such is highly heated Coolants are not without problems.

For this reason, DT-PS

11 65 560 proposed to cool the side walls of the reactor with the help of an Oasstrom, which is guided along the walls. Although this process represents a significant improvement in P2S ₅ production compared to the other working methods, this process is also not without any drawbacks. In the non-cooled bottom zone of the reactor there is Oberhitzungen of the product and bumping, which are manifested in strong reaction shock and damage to the reactor parts and can cause bearing structure him.

Furthermore, the temperature differences occurring in the reactor make the product inhomogeneous and of poor quality.

Surprisingly, it has now been found that these disadvantages can be avoided if the heat exchange material is passed to the bottom of the reaction zone through a system which is separate and independent of the heat exchange system of the side walls of the reaction zone.

Depending on the desired throughput through the reaction zone, the mutually independent Heat exchange systems operate in different ways. Recommended for low throughput it is that the bottom of the reaction zone is cooled with air as heat exchange material and the side walls be heated with a heat exchanger, the side walls of the reaction zone, for example can be heated with hot combustion gases. On the other hand, it is with normal throughput advantageous if both the bottom and the side walls of the reaction zone are cooled with air will. However, if a large throughput is desired, it is better to use the bottom of the reaction zone Water and only the side walls to cool with air.

The measures according to the invention achieve a number of advantages.

The course of the reaction is calmed down and the reactor temperatures are equalized. The throughput line

The performance of the reactor can be increased significantly. The quality of the product so produced is related to its homogeneity and iron contamination are greatly improved.

While according to DT-PS 11 65 500 the impurities with iron could not _{be reduced below 6-8 ppm Fe in the P 2} S ₅ , after using the method according to the invention only 1-2 ppm Fe can be detected in the P2S5.

To carry out the method according to the invention, a device has proven to be advantageous, which is shown in Fig. 1 and which consists of a closed reactor 1, the side walls of which are surrounded by a jacket 2 provided with a heat exchange system, with 8 the reactor 1 a further heat exchange system 3 is attached and the reactor 1 with supply lines 4 and 5 for phosphorus and sulfur, an outlet 6 for the product produced, and an exhaust gas nozzle 7 Is provided. The bottom 8 of the reactor 1 is preferably flat and against the horizontal arranged inclined. It is recommended that the feed lines 4 and 5 for phosphorus and sulfur Reach down to close to the bottom 8 of the reactor t and that the outlet 6 is designed as an overflow. That Heat exchange system 3 for the floor 8 can, as shown in FIG. 2, either as a spray nozzle for cooling liquids or, as in FIG. 1 shown, be designed as a gas nozzle. Furthermore, inside the

Reactor 1 an agitator 9 may be attached.
example 1

With a reactor of 4001 content whose cooling jacket windings were cooled according to DT-PS 11 65 560 air per hour, with stirring, 620 kg P ₂ S ₅ generates the temperature at the bottom of the reactor 390-400 ⁰ C and above 365-375 ° C. The composition of the product was 28.1% P and 71.9% S. The Fe content was 7 ppm.

Example! 2

With the same reactor with a capacity of 400 liters, the cooling jacket and bottom of which were separately and independently cooled with air, it was possible to generate _{735 kg of P 2} S _{5 per hour with stirring.}

The temperature at the bottom of the reactor 375-390 ⁰ C, and above 37o-375 ° C. The composition of the product was 28.1% P and 71.9% S. The ίο Fe content was 1 ppm.

For this purpose 2 sheets of drawings

Claims (3)

Patent claims: 1. A process for the production of phosphorus pentasulfide from phosphorus and sulfur at elevated temperature in a reaction zone, the walls of which are in heat exchange with a substance which has the temperature required for cooling or heating the reaction mixture to absorb and control the heat of reaction, characterized thereby that the heat exchanger on. the bottom of the reaction zone is passed through a system "which is separate and independent of the heat exchange system of the side walls of the reaction zone 2. Apparatus for carrying out the method according to claim 1, characterized by a closed reactor (1), the side walls of which are surrounded by a jacket (2) provided with a heat exchange system, under the bottom of which a further heat exchange system (3) is attached, and with Supply lines (4, 5) for phosphorus and sulfur, an outlet (6) for the product produced and an exhaust gas nozzle (7) is equipped. 3. Apparatus according to claim 2, characterized in that the heat exchange system (3) for the Base (8) is designed as a spray nozzle (Fig. 2) for cooling liquids or as a gas nozzle (Fig. 1).