The system and method of catalytic conversion

 

(57) Abstract:

The invention relates to a system for catalytic conversion and the method of carrying out exothermic reactions between, for example, propylene and hydropredict ethylbenzene to obtain propylene oxide using a solid heterogeneous catalyst. The reactor is divided into a number of separate zones, and each zone contains a solid catalyst for the epoxidation. Conditions of carrying out exothermic reactions support so that all the reactor was kept liquid phase without substantial vaporization. Served in the reactor cold input stream, which is pre-heated to the reaction temperature by a separate indirect heat exchange with the reaction liquid of different specific zones of the reactor. The reaction liquid from the last reaction zone is subjected to pressure reduction for the formation of a gas-liquid mixture at low temperature, and this gas-liquid mixture is heated by indirect heat exchange with the reaction liquid from at least one of the individual zones of the reactor. The proposed system is able to achieve a considerable reduction of costs associated with construction and to operate the camping propylene is 99%. 2 S. and 2 C.p. f-crystals, 1 tab., 1 Il.

The scope of the invention

The invention relates to a system catalytic Converter and method of carrying out highly exothermic reaction between propylene and hydropredict ethylbenzene to obtain propylene oxide using a solid heterogeneous catalyst.

The known technical solutions

When carrying out highly exothermic reactions involving temperature-sensitive reagents and/or products have significant difficulties. For example, liquid-phase catalytic reaction of propylene with an organic hydropredict to obtain propylene oxide is highly exothermic, and the reaction selectivity for the target product is strongly dependent on temperature. Thus, the exothermic heat of reaction to prevent excessive temperature rise is a serious problem.

Conventional reactors for exothermic reactions are of two types:

reactors with intermediate input of cold stream, consisting of the set of fixed layers, in which the cold flow of the original mixture is injected between the layers;

tubular reactors in which the catalyst is placed in a pipe Vesta heat the reactor of the first type usually does not provide a sufficient heat sink. This disadvantage can be overcome by recyclization cold output stream from the reactor, but this creates disadvantages associated with reactor-back confusion.

The cost of the tubular reactor becomes excessively large, if you want to take up a large amount of heat through the surface of the heat exchanger operating at a low heat transfer coefficient. In addition, there is a temperature gradient between the center and the periphery of the pipe, which often has a negative impact on the process that requires approximately isothermal conditions.

In the European patent 0323663 described reactor with a fixed bed of catalyst and method of carrying out the epoxidation of an olefin by reaction with organic hydropredict under almost isothermal conditions. As described in this European patent, all of the heat released in the exothermic reaction, assign due to the evaporation of low-boiling component of the reaction mixture, in the case of propylene/organic Gidropress propylene. In the reactor enter the amount of propylene, sufficient to drain all izbytochnyye joint downward movement of the liquid and gas phases. It is argued that this method is a superior option compared to currently used methods, including mnogofaktornye system with intermediate cooling between stages.

The method and apparatus described in the European patent 0323663, have a number of significant drawbacks. If the excess heat of reaction away by evaporation of propylene, as required by the specified European patent in system, it is necessary to enter in liquid form excessive amounts of propylene. Indeed in the above-mentioned European patent, it is indicated that the reactor serves 16,67 moles of propylene per one mol of gidroperekisi benzene. If we assume that the epoxidation is almost equimolar reaction to propylene and gidroperekisi, the method described in the European patent, inevitably involves the regeneration and management of large amounts of propylene with significant costs.

In addition, although the European patent pressure at the reactor outlet is listed as 26 bar (about 377 psig or 26,4 kg/cm2), it seems to be incompatible with the vapor pressure of the liquid reaction mixture. It is more likely that the actual outlet pressure will be 150 lb is whether the re-compression of a significant amount of propylene return.

Another problem arising in connection with use of the system according to European patent 0323663, related to the low selectivity of the reaction, resulting in the concentration of propylene in the liquid phase in the lower part of the reactor will be low.

Brief description of the invention

In accordance with the invention provides a reactor and method, particularly useful in the production of oxirane compounds by reaction of the olefin, for example propylene, with organic hydropredict using a solid catalyst; the invention is characterized by the following features:

the reactor is divided into a number of separate zones, and each zone contains a solid catalyst for the epoxidation;

conditions support so that all the reactor was kept liquid phase without substantial vaporization;

served in the reactor cold input stream, which is pre-heated to the reaction temperature by a separate indirect heat exchange with the reaction liquid of different specific zones of the reactor;

the reaction liquid from the last reaction zone is subjected to pressure reduction for the formation of a gas-liquid mixture at low temperature, and this gatico the individual zones of the reactor.

Description of drawings

The accompanying drawing illustrates the invention.

Detailed description

The practice of the present invention is particularly suitable for highly exothermic reactions, for example, the reaction between the olefin, for example propylene, and organic hydropredict, such as hydropredict ethylbenzene, and can be described best with reference to the accompanying drawing.

According to the drawing, the reactor 1 is a vertical cylindrical reactor containing five individual layers 2, 3, 4, 5, and 6 solid heterogeneous catalyst for the epoxidation. Provided by the locking device (not shown in the drawing) that supports the solid catalyst in place, but allowing passage of fluid through it.

The liquid reaction mixture containing propylene and Gidropress ethylbenzene, preheated to the reaction temperature, is fed via line 7 to the lower zone 8 of the reactor. As shown in the drawing, the flow of the reaction mixture in the reactor is directed from the bottom up, but leaking fluid down the well as possible.

The reaction mixture from zone 8 to pass through the layer 2 catalyst, which produce propylene oxide in re leraut thus, to provide a moderate increase in temperature, for example, 10-50oF(5-28oC) the heat of reaction in the layer 2.

The reaction mixture from the layer 2 catalyst enters the zone 9; in this zone it away from reactor 1 via line 10 and is served in an indirect heat exchanger 11.

Relatively cool, for example 80 -120oF(27-49oC), the propylene feedstock and the product of oxidation of ethylbenzene containing Gidropress ethylbenzene, is fed into the system via lines 12 and 13 respectively, and then in mixed flow in line 14. Part of this cold stream flows through the pipe 15 into the heat exchanger 11 where it is heated by indirect heat transfer to the reaction temperature. The cooled reaction mixture, which allocated exothermic heat of reaction is supplied through pipe 16 into the zone 17 of the reactor 1, while preheated source flows into zone 8 of the reactor 1 through lines 18 and 7.

From the zone 17 of the liquid reaction mixture passes through the layer 3 catalyst, where there is a further reaction of propylene with hydropredict ethylbenzene with the formation of propylene oxide. Conditions are again adjusted to provide moderate povysheniya a mixture of layer 3 catalyst enters the zone 19; in this zone it away from reactor 1 via line 20 and serves in an indirect heat exchanger 21.

The second part of the relatively cold source stream is fed via line 22 to the heat exchanger 21 where it is heated by indirect heat transfer to the reaction temperature. The cooled reaction mixture, which allocated exothermic heat of reaction is supplied through pipe 23 into the zone 24 of the reactor 1, while preheated source flows into zone 8 of the reactor 1 through lines 25 and 7.

From the zone 24 of the liquid reaction mixture passes through the catalyst layer 4, where there is a further reaction of propylene with hydropredict ethylbenzene with the formation of propylene oxide. Conditions are adjusted to provide a moderate increase in temperature, for example, 10-50oF(5-28oC) the heat of reaction in the layer 4.

The reaction mixture from the layer 4 of catalyst enters the zone 26; in this zone it away from reactor 1 via line 27 and serves in an indirect heat exchanger 28.

The remainder of the relatively cold source stream flows through the pipe 44 into the heat exchanger 28 where it is heated by indirect heat exchange to a temperature R is the wire 29 zone 30 of the reactor 1, while preheated source flows into zone 8 of the reactor 1 through lines 31 and 7.

From the zone 30 of the liquid reaction mixture passes through the catalyst layer 5, where further reaction of propylene with hydropredict ethylbenzene with the formation of propylene oxide. Conditions are adjusted to provide a moderate increase in temperature, for example, 10-50oF(5-28oC) the heat of reaction in the layer 5.

The reaction mixture from layer 5 of the catalyst enters the zone 32; in this zone it away from reactor 1 via line 33 and serves in an indirect heat exchanger 34.

In the heat exchanger 34, the reaction mixture from the layer 5 is cooled, the heat of the exothermic reaction is removed by indirect heat exchange, and the cooled reaction mixture flows through the pipe 35 into the zone 36 of the reactor 1.

From the zone 36, the reaction mixture passes through the catalyst layer 6, where the completed reaction of propylene with hydropredict ethylbenzene with the formation of propylene oxide. Throughout the reactor 1 support increased pressure to prevent substantial evaporation of components of the reaction mixture. To illustrate the pressure maintained in the reactor 1, sostavlyayuschej temperature, for example, 10-50oF(5-28oC) the heat of reaction in the layer 6.

The reaction mixture passes through the catalyst layer 6 in the area 37 and away from reactor 1 via line 38. Derived mixture, which is basically the fluid passes through the device for reducing pressure, where the pressure is reduced to the value at which the evaporation of the lighter components, such as propylene, and reduction of temperature by evaporation to a level significantly lower, for example 30-60oF(16-33oC), compared with the temperature of the reaction mixture withdrawn from zone 32 through the pipe 33. As shown in the drawing, to perform a reduction of pressure in the pipe 40 is formed by a mixed phase, can be applied to the control valve 39. As a rule, in order to achieve evaporation and lowering the temperature, the pressure is reduced from that which is supported in the reactor 1, to approximately 250-350 psig (17,5-24,5 kg/cm2).

The mixture of vaporous and liquid products of the reaction flows through the pipe 40 into the heat exchanger 34, where by indirect heat transfer the mixture is heated with heat of an exothermic reaction in the layer 5. Reaktionen above.

In the indirect heat exchange in heat exchanger 34 from the reaction mixture from zone 32 to the liquid-vapor mixture in the pipe 40 is transferred to the heat required to separate components3such as propylene, from the heavier components by subsequent conventional distillation operation. In the absence of the described reducing pressure through the device 39 and the accompanying lowering of the temperature of the corresponding heat transfer could not take place.

The heated mixture of vaporous and liquid reaction products from the heat exchanger 34 is fed via a pipe 41 in the device for separating the various components in accordance with known methods.

The epoxidation reaction of the present invention is carried out in accordance with known conditions. See, for example, U.S. patent 3351635, the content of which is incorporated into this description by reference.

Typically, the reaction temperature lies in the range from 150 to 250oF(65-120oS), usually from 180 to 225oF(82-107oC) and pressure sufficient to maintain in the reactor 1 of the liquid phase and are, for example, from 500 to 800 pounds per square inch (35 to 56 kg/cm2).

As a rule, higher temperaturethan high selectivity of the reaction. As a rule, it is advisable to cool the reaction mixture from each zone to approximately the temperature of the flow at the inlet of the reactor in order to achieve isothermal reaction conditions.

Apply known solid heterogeneous catalysts. In this respect, reference is made to the description of the European patent 0323663, patent Valoriani 1249079, U.S. patent 4367342, 3829392, 3923843 and 4021454, the contents of which are incorporated into this description by reference.

The invention is applicable, in particular, for the epoxidation of alpha-olefins containing from 3 to 5 carbon atoms, hydropredict of alkylaryl.

The following example illustrates a particularly preferred variant of the invention, described with reference to the accompanying drawing.

According to the drawing, propylene feedstock to a temperature of about 100oF(38oC) and pressure of about 700 psi (49 kg/cm2served on the pipe 13 with the mass rate of about 794072 pounds per hour (359715 kg/h). The product of oxidation of ethylbenzene is also under 100oF and 700 pounds per square inch (38oWith, 49 kg/cm2) served by pipeline 12 with the mass at about the 560,000 pounds per hour (253680 kg/h). The original threads are joined in the pipeline (214688 kg/h) flows through the pipe 15 into the heat exchanger 11, where it is heated to approximately 195oF(90oC) by indirect heat exchange with the reaction mixture from zone 9 of the reactor 1.

About 473926 pounds per hour (214688 kg/h) flows through the pipe 22 into the heat exchanger 21 where it is heated to approximately 195oF(90oC) by indirect heat exchange with the reaction mixture from zone 19 of the reactor 1.

The remainder of the original thread in the amount of 406221 pounds per hour (184018 kg/h) flows through the pipe 44 into the heat exchanger 28 where it is heated to approximately 195oF(90oC) by indirect heat exchange with the reaction mixture from zone 26 of the reactor 1.

Heated source flows again unite and serves on line 7 zone 8 of the reactor 1 at a temperature of 195oF(90oC) and a pressure of 570 pounds per square inch (40 kg/cm2).

The reactor 1 is a vertical cylindrical reactor having five separate zones containing individual layers 2, 3, 4, 5, and 6 solid heterogeneous epoxidation catalyst, prepared in accordance with Example VII patents Netherlands 145233.

The source liquid stream is introduced into zone 8 where it passes through the layer 2 catalyst is exothermic and re is the CIO through the layer 2 in zone 9, where the mixture with a temperature of 224.8oF(107,0oC) and a pressure of 700 psi (49 kg/cm2) flows through the pipe 10 into the heat exchanger 11, where by indirect heat exchange occurs, the heating of the source stream, as described above.

The reaction mixture from which allocated the excess heat of reaction in the layer 2, with a temperature of about 197,6oF(92oC) and a pressure of 700 psi (49 kg/cm2) flows through the pipe 16 into the zone 17 of the reactor 1. From the zone 17, the reaction mixture passes through the layer 3 catalyst, where a further exothermic reaction gidroperekisi ethyl benzene with propylene with the formation of propylene oxide. From a layer 3 catalyst, the reaction mixture enters the area 19 where temperature 225,3oF(103,4oC) and a pressure of 675 pounds per square inch (47 kg/cm2) on the pipe 20 enters the heat exchanger 21. In the heat exchanger 21 of the source stream is heated to the reaction temperature, as described above, by indirect heat exchange with the reaction mixture.

The reaction mixture from which allocated the excess heat of reaction at layer 3, with a temperature of about 198,2oF(92,3oC) and a pressure of 675 pounds per square inch (47 kg/cm2post what happens further exothermic reaction gidroperekisi ethyl benzene with propylene with the formation of propylene oxide. From the layer 4 of catalyst, the reaction mixture enters the zone 26, and then through the pipeline 27 is supplied at a temperature of about 222,8oF(TO 106.0oC) and a pressure of 650 psig (45,5 kg/cm2in the heat exchanger 28. In the heat exchanger 28 of the source stream is heated to the reaction temperature, as described above, by indirect heat exchange with the reaction mixture.

The reaction mixture from which allocated the excess heat of reaction in the layer 4, with a temperature of about 199,6oF(BR93.1oC) and a pressure of 650 psig (45,5 kg/cm2) flows through the pipe 29 into the zone 30 of the reactor 1. From the zone 30, the reaction mixture passes through the catalyst layer 5, where a further exothermic reaction gidroperekisi ethyl benzene with propylene with the formation of propylene oxide. From layer 5 of the catalyst, the reaction mixture is fed into the zone 32, and then through pipe 33 enters with a temperature of about 221,6oF(TO 105.3oC) and a pressure of 650 psig (45,5 kg/cm2in the heat exchanger 34.

In the heat exchanger 34, the reaction mixture from zone 32 is cooled by indirect heat exchange with the final reaction mixture from zone 37, which, as will be described below, subject to reduction by talentamerica about 198,6oF(92,5oC) and a pressure of 650 psig (45,5 kg/cm2) flows through the pipe 35 into the zone 36 of the reactor 1. From the zone 36, the reaction mixture passes through the catalyst layer 6, where a further exothermic reaction gidroperekisi ethyl benzene with propylene with the formation of propylene oxide. From layer 6 of the catalyst liquid reaction mixture is fed into the zone 37, and then divert her from reactor 1 via line 38 at a temperature of about 223,9oF(106,6oC) and a pressure of 650 psig (45,5 kg/cm2).

The liquid reaction mixture in the pipe 38 enters the pressure reducing valve 39, the pressure is reduced from 650 (45,5 kg/cm2) to 320 psig (22,4 kg/cm2). There is a partial evaporation of the reaction mixture, and the resulting reduction of pressure and partial evaporation temperature of the liquid and vapor is reduced to approximately 170oF(77oC).

From the pressure reducing valve 39 a mixture of vapor and liquid at a temperature of about 170oF(77oC) and a pressure of 320 psig (22,4 kg/cm2) flows through the pipe 40 into the heat exchanger 34. This mixture contains about 354669 pounds per hour (160665 kg/h) vapor and about 999402 pounds per hour (452729 kg/h) liquid.

A heated mixture of products with a temperature of about 180,6oF(82,5oC) and a pressure of 320 psig (22,4 kg/cm2) served by pipeline 41 to the separation of components of a well-known manner.

The table below presents the composition (in mass percent) of the various process streams. The designation "stream" in the table means the process stream in the corresponding pipeline or area on the accompanying drawing.

In this example, the conversion of gidroperekisi is 98% and the selectivity of conversion of propylene to propylene oxide is 99%, which demonstrates the effectiveness of the invention. Costs associated with the construction and operation of the system, is substantially minimized.

1. The method of carrying out catalytic liquid-phase ekzotermicheskimi and Gidropress, under conditions of high temperature and pressure reaction, through a series of separate reaction zones, each of which contains a layer of solid epoxidation catalyst, removing the liquid reaction mixture from the last-mentioned separate reaction zones, the pressure reduction to provide a partial evaporation and lowering the temperature of the reaction mixture removed from the last of separate reaction zones, heating the partially vaporized mixture by indirect heat exchange with the reaction mixture from the first or intermediate reaction zone and heating the initial mixture containing the olefin and Gidropress by indirect heat exchange with the reaction mixture from the first or intermediate reaction zone.

2. The method according to p. 1, which carried out the reaction of propylene with hydropredict ethylbenzene with the formation of propylene oxide.

3. The method according to p. 1, in which the partially vaporized mixture is heated by indirect heat exchange with the reaction mixture from the previous reaction zone.

4. The reaction system for carrying out an exothermic reaction of the olefin with an organic hydropredict education oxiranes compounds containing a reactor having a number of separate zones, containing osmannoro heat transfer from the reaction liquid from each zone, except the last in the series, the device for reducing pressure and partial evaporation of the reaction mixture from the last single zone for heating by indirect heat exchange of the cold stream at the inlet of the reactor and partially vaporized mixture from the last separate zone by indirect heat exchange with the reaction mixture from each zone, except the last in the series.

 

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