JP2016117800A - Method for producing lower olefin, apparatus for producing lower olefin and construction method of production equipment for lower olefin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a lower olefin that when producing ethylene and propylene from a light paraffinic hydrocarbon raw material such as light naphtha or the like, can easily change the production ratio of the ethylene and the propylene and permits a reduction in cost required for equipment, to provide an apparatus for producing a lower olefin and to provide a construction method of production equipment for a lower olefin.SOLUTION: The method for producing a lower olefin has a catalytic cracking reaction step S1 of producing ethylene and propylene from a light paraffinic hydrocarbon raw material by a catalytic cracking reaction using a zeolite catalyst, and when a component for re-cracking separated from a cracked mixture through the catalytic cracking reaction step S1 so as not to include ethylene and propylene and separated so as to include an unreacted component in the catalytic cracking reaction is supplied, has a steam cracking step S4 of producing ethylene and propylene from the component for re-cracking by a steam cracking.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a lower olefin production method for producing a lower olefin from a light paraffinic hydrocarbon feedstock, a lower olefin production apparatus and a lower olefin production facility construction method.

  The petrochemical industry uses light naphtha from a refinery as a raw material to produce lower olefins such as ethylene and propylene by steam cracking. These lower olefins are important basic raw materials for various chemical products such as fibers and plastics (synthetic resins). In steam cracking using light naphtha as a raw material, light naphtha and steam are mixed at a certain ratio, and lower olefins are produced by pyrolysis under conditions of high temperature and no catalyst above 800 ° C. The production ratio is about 2: 1 and is a simple pyrolysis reaction, so it is difficult to change this ratio.

  In recent years, the rise of so-called ethane lacquer, which separates ethane from unconventional gas such as associated gas and shale gas discharged from oil fields and produces ethylene in a high yield, has become a low-grade product using naphtha as a raw material. In the production of olefins, an increase in the production amount of propylene has become one issue.

As a solution to this problem, Olefin Conversion Technology (OCT) using a metathesis reaction has been devised. Commercial equipment using the OCT process (hereinafter referred to as the OCT process) is moving.
The OCT process can produce 2 moles of propylene from 1 mole of ethylene and 1 mole of butene using a special catalyst. OCT Pros commercial equipment is used in combination with light naphtha steam cracking to produce propylene using ethylene and butene produced by steam cracking.

  In this case, since the production amount of propylene is governed by the production amount of butene produced by steam cracking, for example, the production ratio of ethylene and propylene in the facility in which the commercial equipment of the OCT process is installed in the facility of the steam cracker is About 1: 1 is the limit.

Propylene is selectively produced from light naphtha in high yield by catalytic cracking reaction using zeolite catalyst as a method that can increase the production ratio of propylene compared to the conventional production of ethylene and propylene as described above. A method has been developed (for example, see Patent Documents 1 to 3). In the catalytic cracking reaction of light naphtha by the zeolite catalyst as shown in these patent documents 1 to 3, the reaction can proceed at a temperature lower by 200 ° C. to 300 ° C. than steam cracking. It will be advantageous.
In addition, in the catalytic cracking reaction using a zeolite catalyst, the production ratio of ethylene and propylene is about 1: 1.5 to 1: 3 depending on the reaction conditions, which is more than in the case of steam cracking or combining the OCT process with steam cracking. Propylene production ratio can be dramatically increased.

JP 2014-24005 A JP 2014-24006 A JP 2014-24007 A

  By the way, in the production of ethylene and propylene using the above-mentioned zeolite catalyst, the production ratio of propylene to ethylene can be dramatically increased. For example, for the primary increase in demand for ethylene and the decrease in demand for propylene. Correspondingly, it is difficult to adjust the production ratio of ethylene to propylene to be high. Therefore, for example, when a facility for catalytic cracking reaction using a zeolite catalyst is provided instead of the existing steam cracker facility, the production amount of propylene and the energy efficiency can be improved. It is difficult to change the production ratio, and it is impossible to cope with the rapid increase in demand for ethylene.

  In addition to existing steam crackers, when installing equipment for catalytic cracking reaction using zeolite catalyst, in addition to the cost of newly installing equipment for catalytic cracking reaction, the cost of dismantling steam crackers and the waste generated at the time of dismantling The cost for processing the object is required. Therefore, there is a problem that the initial investment for providing the equipment for catalytic cracking reaction becomes large.

  The present invention has been made in view of the above circumstances, and when ethylene and propylene are produced from a light paraffinic hydrocarbon raw material such as light naphtha, the production ratio of these ethylene and propylene can be easily changed, and An object of the present invention is to provide a method for producing a lower olefin, a production apparatus for a lower olefin, and a method for constructing a production facility for a lower olefin, which can reduce the cost of the equipment.

In order to solve the above problems, the method for producing a lower olefin of the present invention is a method for producing a lower olefin, which produces ethylene and propylene as a lower olefin from a light paraffin hydrocarbon raw material,
A catalytic cracking reaction step of producing the ethylene and propylene from the light paraffinic hydrocarbon raw material by a catalytic cracking reaction using a zeolite catalyst; and a cracked mixture (reaction mixture) obtained through the catalytic cracking reaction step from the ethylene and the propylene When the re-cracking component separated so as to contain no unreacted raw material in the catalytic cracking reaction is supplied, the ethylene and the propylene are removed from the re-cracking component by steam cracking. And a steam cracking process to be manufactured.

  According to such a configuration, ethylene and propylene are produced from a light paraffinic hydrocarbon raw material by a catalytic cracking reaction using a zeolite catalyst, and from the cracked mixture after the light paraffinic hydrocarbon raw material is catalytically cracked. While being separated so as not to contain ethylene and propylene, ethylene and propylene are produced by steam cracking from the re-decomposition component separated so as to contain paraffin which is an unreacted raw material. In addition, what is manufactured in this invention is not restricted to ethylene and propylene, For example, a butadiene may be included and you may make it possible to isolate | separate and utilize another useful component.

  In such a case, in the catalytic cracking reaction using a zeolite catalyst, the production ratio (weight) of propylene / ethylene can be adjusted from about 1.5 to about 3.0 by appropriately setting the reaction conditions. Propylene production can be increased. On the other hand, in steam cracking, the production ratio (weight) of propylene / ethylene is about 0.5, and the production amount of ethylene is higher than the production amount of propylene.

  In the current supply-demand relationship, it is required to increase the production of propylene over ethylene. However, in the production of propylene by steam cracking, it is difficult to increase the production ratio of propylene to ethylene beyond the current level. Thus, by combining ethylene and propylene production by steam cracking with ethylene and propylene production by catalytic cracking reaction, the production ratio of propylene to ethylene can be made higher than in the case of steam cracking alone.

  In addition, it is possible to provide a facility for catalytic cracking reaction using a zeolite catalyst in an existing steam cracker (steam cracking facility) that is present in a relatively large amount, and the existing steam cracker can be used effectively. . For example, compared with the case where the equipment for steam cracking is discarded and the equipment for the catalytic cracking reaction is newly provided, the cost for constructing the equipment can be reduced.

  In addition, compared to steam cracking, the catalytic cracking reaction has a lower reaction temperature and better energy efficiency, so combining steam cracking with catalytic cracking reaction improves energy efficiency compared to steam cracking alone. Can be planned. Since both steam cracking and catalytic cracking reaction in the present invention produce ethylene and propylene from the same raw material, the same equipment can be used for the separation (separation and purification) of ethylene and propylene, When the equipment for catalytic cracking reaction is installed in the steam cracking equipment, it becomes possible to effectively utilize the existing separation and purification equipment for steam cracking for the separation and purification of ethylene and propylene after the catalytic cracking reaction. The construction cost can be reduced.

  The light paraffinic hydrocarbon raw material is, for example, a paraffin having about 7 carbon atoms (C7) or less as a main component. For example, a light naphtha having a C4 to C7 paraffin as a main component is preferable. Used. Light naphtha is a fraction containing a large amount of paraffins of about C5 and C6 when crude oil is separated by distillation, but the raw material is not limited to petroleum, and may be shale oil, condensate, or the like. The light paraffin hydrocarbon raw material is not limited to light naphtha, and may be basically a hydrocarbon raw material having a high content of paraffins of about C4 to C7. For example, naphtha including heavy naphtha may be used. However, when considering the production efficiency and the catalyst life in the catalytic cracking reaction, for example, a hydrocarbon material having a high C4-C7 paraffin content and a higher carbon number than that, particularly a hydrocarbon material having a low heavy content. preferable.

  In the configuration of the present invention, it is preferable that the re-decomposition component can be returned to the catalytic decomposition reaction step.

  According to such a configuration, not all the components for re-decomposition including unreacted paraffin are supplied to the steam cracking process, but a part of the components for re-decomposition is sent to the steam cracking and the rest is returned to the catalytic cracking reaction. As a result, it is possible to increase the production ratio of propylene and improve the energy efficiency.

  Further, in the configuration of the present invention, the re-decomposition component is divided into a forward flow portion to be sent to the steam cracking step and a reflux portion to be returned to the catalytic cracking reaction step, and the forward flow portion and the It is preferable that the distribution ratio with respect to the reflux component can be adjusted.

  According to such a configuration, for example, by increasing the distribution ratio of the reflux component returned to the catalytic cracking reaction step among the components for re-decomposition, the production ratio of propylene can be increased, or cracking can be performed among the components for re-decomposition. By increasing the distribution ratio of the forward flow sent to the process, the ethylene production ratio can be increased. Each demand for ethylene and propylene changes with the passage of time, and there is a possibility that demand for ethylene will increase in the short term and demand for propylene will increase. In response to changes in demand and demand for propylene, the production ratio of ethylene and propylene can be changed relatively easily.

  Further, in the configuration of the present invention, a separation step for catalytic cracking for separating the ethylene, the propylene, and the re-cracking component from the cracked mixture after the catalytic cracking reaction step, and a cracked mixture after the steam cracking step, respectively. It is preferable to provide a thermal decomposition separation step for separating at least the ethylene and the propylene.

  According to such a configuration, after producing ethylene and propylene produced by a catalytic cracking reaction from a light paraffinic hydrocarbon raw material, these are separated, and a re-cracking component containing unreacted paraffin is separated, This re-decomposition component can be supplied to the steam cracking process. Further, ethylene and propylene generated by steam cracking can be separated.

  Moreover, in the said structure of this invention, in the said separation process for catalytic cracking, the lower paraffin component which has lighter (C1-C3) paraffin lighter than C4 as a main component is isolate | separated, and the said lower paraffin component is supplied to the said steam cracking process. It is preferable.

  According to such a configuration, paraffin that is lighter than C4 (C1 to C3) can be processed by steam cracking and used as a raw material for ethylene or propyne, for example. In the catalytic cracking reaction, for example, it is difficult to change ethane or propane to ethylene or propylene as lighter (C1 to C3) paraffin than C4. That is, even if these ethanes and propanes are returned to the catalytic cracking reaction, the cracking is difficult. In particular, ethane is difficult to be decomposed by the catalytic cracking reaction, and if ethane is returned to the catalytic cracking reaction, the content of unreacted ethane increases, so that it is necessary to remove ethane. By using the catalytic cracking reaction and steam cracking in combination, ethane can be effectively used.

  Further, in the above configuration of the present invention, a lower hydrocarbon that separates a lower hydrocarbon component comprising the ethylene and the propylene and mainly comprising a lower hydrocarbon having 4 or less carbon atoms from the cracked mixture that has undergone the catalytic cracking reaction step. It is preferable to provide a residue obtained by removing the lower hydrocarbon component from the decomposition mixture that has been provided with a separation step and has undergone the catalytic cracking reaction step.

  According to such a configuration, the cracked mixture that has undergone the catalytic cracking reaction is separated into a lower hydrocarbon component containing ethylene and propylene and a re-cracking component containing unreacted paraffin by a lower hydrocarbon separation step, The re-decomposition component is sent to the steam cracking process. In the lower hydrocarbon separation step, ethylene, propylene and other components are not separated, but basically only the lower hydrocarbon component and the re-cracking component are separated. For example, a distillation column used for separation is used. It is possible to simplify the equipment such as the above, and to send the components for re-decomposition to the steam cracking process.

  Moreover, the said structure of this invention WHEREIN: It is preferable to provide the common separation process which isolate | separates the said ethylene and the said propylene from the said lower hydrocarbon component and the decomposition mixture which passed through the said steam cracking process.

  According to such a configuration, ethylene and propylene produced by the catalytic cracking reaction and ethylene and propylene produced by the steam cracking can be separated in the same shared separation step. That is, both the separation of ethylene and propylene produced by the catalytic cracking reaction and the separation of ethylene and propylene produced by the steam cracking can be performed using the same separation and purification equipment. In this case, when the equipment for catalytic cracking reaction is provided in the existing steam cracking equipment, the separation and purification equipment in the steam cracking equipment is also used for the catalytic cracking reaction without providing the separation and purification equipment for the catalytic cracking reaction. It is possible to reduce the construction cost of the equipment, reduce the equipment cost, and improve the space efficiency of the equipment.

  Moreover, in the said structure of this invention, in the said shared separation process, the lower paraffin component which has lighter (C1-C3) paraffin lighter than C4 as a main component is isolate | separated, and the said lower paraffin component is returned to the said steam cracking process. preferable.

  According to such a configuration, in the catalytic cracking reaction as described above, it is difficult to decompose paraffin that is lighter than C4 (C1 to C3), and in particular, when re-decomposing components including unreacted paraffin are circulated. If the ethane is contained in the re-decomposition component, the problem that ethane is accumulated can be solved by sending a lower paraffin component containing paraffins lighter than C4 (C1-C3) to the steam cracking process. . In the steam cracking step, ethylene or propylene can be produced from paraffins that are lighter than C4 (C1-C3).

    Moreover, in the said structure of this invention, it is preferable that the zeolite in the said zeolite catalyst used at the said catalytic cracking reaction process is a crystalline aluminosilicate of MFI type containing iron or iron and gallium.

  According to such a configuration, in the catalytic cracking reaction, the amount of propylene produced in the catalytic cracking reaction is increased by using a zeolite catalyst containing zeolite that is MFI type crystalline aluminosilicate containing iron or iron and gallium. When combined with the production of ethylene and propylene by steam cracking, the production ratio of propylene can be further increased.

The lower olefin production apparatus of the present invention is a lower olefin production apparatus for producing ethylene and propylene as a lower olefin from a light paraffinic hydrocarbon raw material,
A catalytic cracking means comprising a reactor for producing the ethylene and the propylene from a light paraffinic hydrocarbon raw material by a catalytic cracking reaction using a zeolite catalyst; and the ethylene and the propylene from a cracked mixture discharged from the reactor The ethylene and the propylene are produced by steam cracking from the re-decomposition component when the re-decomposition component separated so as to contain the unreacted component in the catalytic decomposition reaction is supplied. And a thermal decomposition means including a decomposition furnace.

  According to such a configuration, as in the above-described method for producing lower olefins, by combining ethylene and propylene production by steam cracking with ethylene and propylene production by catalytic cracking reaction, steam cracking alone can be achieved. The production ratio of propylene to ethylene can be increased. In addition, it is possible to provide a facility for catalytic cracking reaction using a zeolite catalyst in an existing steam cracker (steam cracking facility) that is present in a relatively large amount, and the existing steam cracker can be used effectively. . Further, energy efficiency can be improved as compared with the case of steam cracking alone. In addition, when the catalytic cracking equipment is installed in the steam cracking equipment, it becomes possible to effectively utilize the existing steam cracking equipment for the separation and purification of ethylene and propylene after the catalytic cracking reaction. Further, the construction cost of the equipment can be further reduced.

In the configuration of the present invention, the re-cracking component separated from the cracked mixture flowing out of the reactor can be returned to the reactor,
Distributing means capable of distributing the re-cracking component into a forward flow portion to be sent to the cracking furnace and a reflux portion to be returned to the reactor, and adjusting a distribution ratio between the forward flow portion and the reflux portion at the time of the distribution. It is preferable to provide.

  According to such a configuration, the propylene production ratio is increased by increasing the distribution ratio of the reflux component of the re-cracking component in the same manner as the above-described method for producing lower olefins. The production ratio of ethylene can be increased by increasing the distribution ratio of the forward flow.

  Further, in the above configuration of the present invention, a catalytic cracking separation and purification means for separating the ethylene, propylene and the recracking component from the cracked mixture flowing out from the reactor, and a cracked mixture flowing out from the cracking furnace. It is preferable to provide thermal decomposition separation and purification means for separating at least the ethylene and the propylene.

  According to such a configuration, as in the above-described method for producing lower olefins, ethylene and propylene produced by a catalytic cracking reaction are produced from a light paraffinic hydrocarbon raw material and then separated from each other, and unreacted paraffin is produced. Can be separated and supplied to the steam cracking process. Further, ethylene and propylene generated by steam cracking can be separated.

Further, in the above configuration of the present invention, the lower hydrocarbon separation which separates the lower hydrocarbon component mainly comprising lower hydrocarbons having 4 or less carbon atoms, including the ethylene and the propylene, from the cracked mixture flowing out from the reactor. Means for removing the lower hydrocarbon component from the cracked mixture flowing out of the reactor as the recracking component,
It is preferable to provide a common separation and purification means for separating the ethylene and the propylene from the lower hydrocarbon component and the cracked mixture flowing out from the cracking furnace.

  According to such a configuration, ethylene and propylene produced by the catalytic cracking reaction and ethylene and propylene produced by the steam cracking can be separated in the same shared separation step, as in the above-described method for producing a lower olefin. Therefore, when the equipment for catalytic cracking reaction is installed in the existing steam cracking equipment, the separation and purification equipment in the steam cracking equipment is also used for the catalytic cracking reaction without providing the separation and purification equipment for the catalytic cracking reaction. Therefore, the construction cost of the equipment can be reduced, the equipment cost can be reduced, and the space efficiency in the equipment can be improved.

  In the configuration of the present invention, the zeolite in the zeolite catalyst used in the reactor is preferably MFI type crystalline aluminosilicate containing iron or iron and gallium.

  According to such a configuration, by using a zeolite catalyst containing zeolite that is MFI type crystalline aluminosilicate containing iron or iron and gallium in the catalytic cracking reaction as in the above-described method for producing lower olefins, The amount of propylene produced in the catalytic cracking reaction can be increased, and the production ratio of propylene can be further increased when combined with the production of ethylene and propylene by steam cracking.

The construction method of the lower olefin production facility of the present invention is a construction method of a lower olefin production facility for producing ethylene and propylene as a lower olefin from a light paraffinic hydrocarbon raw material,
From a light paraffin hydrocarbon raw material to a zeolite catalyst, an existing steam cracking facility comprising a cracking furnace for producing the ethylene and propylene by steam cracking and a separation and purification facility for separating and purifying the cracked mixture flowing out of the cracking furnace A catalytic cracking reaction facility equipped with a reactor for producing the ethylene and the propylene by a catalytic cracking reaction using
A re-cracking component separated from the cracked mixture flowing out from the reactor so as not to contain ethylene and propylene and separated to contain unreacted components in the catalytic cracking reaction can be supplied to the cracking furnace. It is characterized by doing.

  According to such a configuration, by installing a catalytic cracking reaction facility using a zeolite catalyst in an existing steam cracking facility, the production ratio of propylene in the production of ethylene and propylene combined with these facilities is determined by the steam cracking facility alone. Can be higher than in the case of. In the construction of the equipment in this case, compared with the case where the steam cracking equipment is discarded and the catalytic cracking equipment is provided, the cost for disposal of the steam cracking equipment is not required, and the cost can be reduced. . In addition, post-process equipment for steam cracking can be used as post-process equipment up to separation and purification after catalytic cracking reaction. The construction cost can be reduced.

  According to the present invention, by producing both ethylene and propylene by using steam cracking and catalytic cracking reaction using a zeolite catalyst together, the production ratio of propylene can be increased as compared with the case of producing ethylene and propylene by steam cracking alone. Energy efficiency.

It is process drawing for demonstrating the catalytic cracking reaction in the manufacturing method of the lower olefin of the 1st Embodiment of this invention. It is process drawing corresponding to Example 1 which shows the manufacturing method of a lower olefin similarly. It is process drawing corresponding to Example 2 which shows the manufacturing method of a lower olefin similarly. It is process drawing corresponding to Example 3 which shows the manufacturing method of a lower olefin similarly. It is process drawing corresponding to Example 4 which shows the manufacturing method of a lower olefin similarly. It is a block diagram which shows the outline of the manufacturing apparatus of a lower olefin same as the above. It is process drawing corresponding to Example 5 which shows the manufacturing method of the lower olefin of the 2nd Embodiment of this invention. It is process drawing corresponding to Example 6 which shows the manufacturing method of a lower olefin similarly. It is process drawing corresponding to Example 7 which shows the manufacturing method of a lower olefin similarly. It is process drawing corresponding to Example 8 which shows the manufacturing method of a lower olefin similarly. It is a block diagram which shows the outline of the manufacturing apparatus of a lower olefin same as the above. It is a figure for demonstrating the experimental result of manufacture of a lower olefin by a catalytic cracking reaction, and the calculation result based on it. It is a figure which shows the experimental result by the simulation (calculation) of Example 1- Example 4. FIG. It is a figure which shows the experimental result by the simulation (calculation) of Example 5-8.

Hereinafter, a first embodiment of the present invention will be described.
In this embodiment, a light olefin, which is a light paraffinic hydrocarbon raw material, is used as a hydrocarbon raw material, and a lower olefin production method, a lower olefin production apparatus, and a lower olefin production facility that mainly produce ethylene and propylene. The construction method of is described.

  In the method for producing a lower olefin of the present embodiment, ethylene and propylene are produced by combining production of ethylene and propylene by a catalytic cracking reaction using a zeolite catalyst and production of ethylene and propylene by steam cracking. This is because the production ratio of ethylene and propylene by the catalytic cracking reaction of the present embodiment is about 1: 1.5 to 3.0 depending on various conditions, whereas in the case of steam cracking, the production ratio of ethylene and propylene is Since it becomes about 2: 1, the production ratio of ethylene and propylene can be adjusted by combining these production methods.

Next, before explaining the manufacturing method of the lower olefin which combined catalytic cracking reaction and steam cracking, the manufacturing method of the lower olefin by catalytic cracking reaction is demonstrated.
As shown in FIG. 1, in the production of lower olefins by catalytic cracking reaction, light naphtha is supplied into a reactor (reaction vessel) in which a zeolite catalyst is fixed in a fixed bed system, and light naphtha is brought into contact with the zeolite catalyst. The catalytic cracking reaction step S1 is performed. Next, as a subsequent step of the catalytic cracking reaction step S1, a quench / gas pressure increasing / dehydrating step (post catalytic cracking treatment step) S2 is performed. Next, ethylene and propylene are obtained by performing a separation and purification step (separation step for catalytic cracking) S3 on the cracked mixture that has been catalytically cracked in the catalytic cracking reaction step S1 and has undergone the quench, gas pressurization, and dehydration step S2.

  In the catalytic cracking reaction step S1, a composite catalyst containing gallium (Ga) and iron (Fe) or a crystalline aluminosilicate containing iron and silicon dioxide functioning as a binder for molding is used. The binder may be alumina (aluminum oxide), but silicon dioxide is preferred.

  The zeolite that is a crystalline aluminosilicate has, for example, an MFI type skeleton structure. The framework structure of zeolite has been made into a database by the International Zeolite Society, and a structure code consisting of three capital letters is given. The MFI type is one of the structure codes.

  Further, Fe contained in the zeolite catalyst has a function of suppressing the acid strength at the acid sites of the zeolite. Further, Ga has a function of promoting alkane dehydrogenation. The zeolite catalyst of the present embodiment is a composite catalyst obtained by molding and firing with a binder (binder) added, and silicon dioxide is used as the binder.

  In a zeolite that is an MFI type crystalline aluminosilicate containing an iron element (not containing a gallium element), the elemental molar composition ratio (Fe / (Fe + Al)) of the iron element is 0.4 to 0.7. Furthermore, it is more preferable that it is 0.4-0.6.

  In addition, in zeolite that is an MFI type crystalline aluminosilicate containing an iron element (not containing a gallium element), the acid density (molar composition ratio defined as Si / (Fe + Al)) is 75.0 to 200. It is preferably 0, and more preferably 80.0 to 200.0. The element ratio is a composition ratio based on the number of moles of each element described above.

  In addition, in the zeolite which is an MFI type crystalline aluminosilicate containing an iron element and a gallium element, the elemental molar composition ratio (Fe / (Fe + Ga + Al)) of the iron element is preferably 0.2 to 0.6. Furthermore, it is more preferable that it is 0.3-0.5.

  Further, in the zeolite which is an MFI type crystalline aluminosilicate containing an iron element and a gallium element, the elemental molar composition ratio (Ga / (Fe + Ga + Al)) of the gallium element is preferably 0.1 to 0.4. Furthermore, it is more preferable that it is 0.2-0.4.

  Further, in the MFI type zeolite catalyst containing iron element and gallium element, the acid density (molar composition ratio defined as Si / (Fe + Ga + Al)) is preferably 75.0 to 200.0, and 80 More preferably, it is 0 to 200.0.

  As described above, by using the zeolite of this embodiment which is an MFI type crystalline aluminosilicate containing an iron element, the acid strength can be adjusted from the content of the iron element and the acid density. By adding gallium element, the promoting action of dehydrogenation of alkane can be improved. At the acid point of the zeolite, the alkane is divided and a carbon double bond is generated by the decarbonization reaction, resulting in a lower olefin. For example, if the acid strength at the acid point is too strong, However, the reaction proceeds further without leaving the acid point, and cyclized and dehydrogenated to produce aromatic hydrocarbons, and the amount of aromatic hydrocarbons generated increases, so the amount of coke deposited increases and the composite This will shorten the life of the body catalyst. Therefore, adjustment of acid strength is important in reducing the amount of coke deposited.

  By making the composition ratio of the number of moles of the iron element, the composition ratio of the number of moles of the gallium element, and the acid density within the above-mentioned ranges, the yield of propylene can be further improved and the fragrance that causes the generation of the cake. The generation of group carbon can be further suppressed.

  Further, the content of silicon dioxide (silica) as a binder in the composite catalyst is preferably 5 to 50 wt% (wt%), more preferably 5 to 40 wt%. . In order to increase the yield of lower olefins, it is preferable to reduce the content of silicon dioxide to increase the content of zeolite, and to suppress the production of aromatic hydrocarbons, increase the content of silicon dioxide. Is preferred. Further, it is presumed that silicon dioxide as a binder has a stronger action to coat and inactivate acid sites on the outer surface of zeolite than aluminum oxide (alumina) as a binder.

  By covering and inactivating the acid sites on the outer surface of the zeolite, this suppresses the formation of aromatic hydrocarbons at the acid sites on the outer surface of the zeolite and suppresses carbon deposition on the outer surface of the zeolite. Thus, it seems that it is possible to maintain the catalytic ability of the conversion of alkanes into lower olefins in the pores of the zeolite for a long period of time.

  The above-mentioned zeolite composition is suitable when, for example, silicon dioxide is used as the binder.

  For example, as a production method for producing a lower olefin from light naphtha using such a composite catalyst, a raw material gas such as light naphtha is supplied to a reactor in which a zeolite catalyst is arranged in a fixed bed system. That is, light naphtha is reacted with the composite catalyst. Note that the raw material gas may contain, for example, steam or nitrogen gas as a diluent. In this case, the gas supplied to the composite catalyst preferably contains 15 wt% or more of light naphtha. More preferably, it is contained in an amount of 50 wt% or more. A method is used in which the composite catalyst described above is arranged as a fixed bed in the reactor, and the raw material gas supplied into the reactor is passed while contacting the composite catalyst. At this time, the reaction is allowed to proceed in a mild temperature range of 530 ° C. to 650 ° C., more preferably 550 ° C. to 640 ° C., to produce ethylene and propylene.

  The lower olefin hydrocarbon feedstock is, for example, light paraffinic hydrocarbon feedstock (low-boiling hydrocarbon feedstock) such as light naphtha, but naphtha (full-range naphtha) is separated by distillation of crude oil using an atmospheric distillation unit. The product obtained in this way has a boiling range of about 35 to 180 (200) ° C. Among these naphtha, those having a boiling range of about 35-80 (100) ° C. are called light (light) naphtha, and those having a boiling range of about 80 (100) -180 (200) ° C. are called heavy (heavy) naphtha. . Light naphtha corresponds to a fraction mainly composed of pentane having 5 carbon atoms and hexane having 6 carbon atoms. C4 or C7 may be included. Light naphtha can be obtained not only by distillation of crude oil but also by distillation from shale oil or condensate.

  In other words, the raw material may be other than naphtha distilled from crude oil. For example, shale oil other than petroleum, condensate, and other hydrocarbon raw materials that basically use a fraction equivalent to light naphtha. Can do. Further, by-products and the like when various products are produced from petroleum and natural gas can be used as the hydrocarbon raw material, and basically a hydrocarbon having a low boiling point can be used as the raw material. Further, in the present embodiment, the lower olefin includes, for example, ethylene, propylene, butene, or an olefin having a higher carbon number (for example, 5 to 8 carbon atoms) as the olefin having a lower carbon number. In this case, the lower olefin includes ethylene having 2 carbon atoms and propylene having 3 carbon atoms. Further, butadiene may be included in the lower olefin.

In the reaction for producing the lower olefin, the contact time as the reciprocal of LHSV (Liquid Hourly Space Velocity) of the raw material hydrocarbon in the composite catalyst of the present embodiment is 0.08 to 1.0 h. It is preferable to set it to 0.08 to 0.4 h. The LHSV, preferably in the 1.0～12.5H ^-1, further, it is more preferable that the 2.5~12.5h ^-1. Here, LHSV is the speed at which the raw material hydrocarbon is supplied as a liquid to the composite catalyst, and the contact time is the time for the raw material hydrocarbon to pass through the composite catalyst as a liquid (composite catalyst). When the raw material is supplied to the reactor, the raw material is gasified from the liquid as described above, but here, the space velocity of the raw material as the liquid before gasification supplied to the reactor is used) . In addition, the space velocity (GHSV) of source gas (gas) may be used as the space velocity, or the space velocity (WHSV) of weight (weight) may be used.

  In the production of lower olefins, the higher the reaction temperature, the higher the conversion rate of the hydrocarbon raw material, the higher the amount of lower olefins produced and the greater the amount of aromatic hydrocarbons produced. It is necessary to determine the reaction temperature in consideration of the efficiency, the production amount of lower olefins, and the life of the composite catalyst due to the increase in aromatic hydrocarbons. By setting the above range, the long life of the composite catalyst can be increased. As well as ensuring stable production of lower olefins.

  In the production of lower olefins, the longer the contact time, the higher the conversion rate of the hydrocarbon raw material, the more lower olefins are produced, and the more aromatic hydrocarbons are produced. It is necessary to determine the contact time in consideration of the production amount and the life of the composite catalyst due to the increase in aromatic hydrocarbons. By setting the above range, it is possible to ensure a long life of the composite catalyst and Stable production can be ensured.

  Next, in the quench / gas pressurization / dehydration step S2, for example, the gas flowing out from the catalytic cracking reaction step S1 is quenched (stopped by cooling (rapid cooling)) in a quench tower that is a heat exchanger. At this time, the liquefied heavy component is separated, and further the liquefied water is separated. In addition, when a catalytic cracking reaction is performed using light naphtha as a raw material, there is basically almost no heavy component and little moisture. However, steam may be added as a diluent to light naphtha in the catalytic cracking reaction. In this case, steam is liquefied and separated by cooling.

  In the separation / purification step S3, the gas supplied after being pressurized from the quench / gas pressurization / dehydration step S2 is cooled and liquefied, and separated from low-boiling substances by a plurality of distillation columns. In the present embodiment, in the separation and purification step S3, the undecomposed component (unreacted component) of light naphtha as a raw material is separated as a component for re-decomposition. For example, undecomposed components in the case of night naphtha are mainly composed of C5 (carbon number 5) and C6 (carbon number 6) paraffins. For example, in each distillation column, the boiling point is higher than that of C5 and C6 paraffins. By separating low substances, finally, an undecomposed component mainly composed of C5 and C6 paraffins is separated as a re-decomposing component (undegraded component: undegraded light naphtha). The re-decomposition component has an undecomposed component as a main component, ethylene and propylene are separated, and hardly contains ethylene and propylene.

The separated undecomposed component (redecomposition component) is returned to the catalytic cracking reaction step S1, and again catalytically cracked using a zeolite catalyst. The undecomposed components returned from the separation and purification step S3 to the catalytic cracking reaction step S1 are mainly C5 and C6 paraffins. Moreover, the weight per time of each substance shown by FIG. 1 describes the result of the experiment and simulation which are demonstrated in the below-mentioned Example. In FIG. 1 and the like, C6 paraffins are described as undecomposed naphtha. In the experiment in the examples, n-hexane (n is a representative component of light naphtha that is a light paraffinic hydrocarbon raw material. -C ₆ H ₁₄ ) is used, and the undecomposed component is C6 paraffins, but when light naphtha is used as a raw material, C5 and C6 paraffins are undecomposed components.

  As shown in FIG. 1, in the separation and purification step S3 of the present embodiment, hydrogen, methane, ethane, and propane, which are lighter (C1-C3) lower paraffin components than hydrogen and C4, are separated. . Also, ethylene is separated and propylene is separated. Also, C4 (4 carbon atoms) is separated. An aromatic component (for example, BTX made of benzene, toluene, xylene). Further, there is Others as the remainder after separating them. In addition, if there is a necessary substance other than ethylene and propylene, it may be separated even if it is other than the above-described substances, and may be separated from the above-described separation method.

  In the present embodiment, for example, as shown in the process charts of FIGS. 2 to 5, the light naphtha catalytic cracking reaction using the zeolite catalyst shown in FIG. 1 and the thermal cracking reaction by steam cracking are combined. The production ratio of ethylene and propylene can be changed by adjusting the feed rate of the raw materials for the catalytic cracking reaction and the thermal cracking reaction. The raw material for the thermal decomposition reaction is mainly an undecomposed component in the catalytic decomposition reaction.

  That is, in this embodiment, the catalytic cracking reaction step S1 is performed prior to the steam cracking step S4, and undecomposed components (mainly C5 and C6 paraffins) in the cracked mixture flowing out from the catalytic cracking reaction step S1. The entire amount is not returned to the catalytic cracking reaction step S1 as shown in FIG. 1, but undecomposed components are supplied to the steam cracking step S4 as shown in FIG.

  Note that what is supplied to the steam cracking step S4 is not limited to undecomposed components, and is not particularly limited to C5 and C6 paraffins, and may include C2 to C4 hydrocarbons. . In the present embodiment, ethane and propane as lower paraffin of C3 or less separated in the separation and purification step S3 are supplied to the steam cracking step S4.

  In the method for producing a lower olefin of the present embodiment, the catalytic cracking reaction step S1, the quench gas pressurization / dehydration step S2, and the separation and purification step (catalytic cracking separation step) S3 for catalytic cracking reaction are performed. The steam cracking step S4 is performed. After pyrolysis in the steam cracking step S4, quench, gas pressurization, acid gas removal, dehydration step (post-thermal decomposition treatment step) S5, and separation and purification step (thermal decomposition separation step) S6 after the thermal decomposition reaction are performed. Is called.

In the steam cracking step S4, steam and raw materials are supplied to the cracking furnace and heated to 800 ° C. or higher, and the raw materials are pyrolyzed in the presence of steam to produce ethylene and propylene.
In quenching, gas pressurization, acid gas removal, dehydration step (thermal decomposition post-processing step) S5, quenching is performed to cool the gaseous decomposition mixture (reaction mixture) flowing out from the decomposition furnace and stop the thermal decomposition reaction. Is called. In the quench, heavy components that are liquefied by cooling are separated, and liquefied water is separated from steam. Next, in order to liquefy the gas that has flowed out of the cracking furnace in the separation / purification step S6, the gas is pressurized to compress the gas.

  At this time, the acidic gas is removed. The acid gas is mainly hydrogen sulfide. In the steam cracking step S4, DMDS (dimethyl disulphide) is added in order to suppress the adhesion of coke (carbon) to the tube or the like in the cracking furnace. DMDS becomes hydrogen sulfide in the thermal decomposition reaction and prevents the adhesion of coke, but hydrogen sulfide is included as an acidic gas in the outflow gas. In the quench, gas pressurization, acidic gas removal, dehydration step S5, Hydrogen sulfide gas is removed as an acid gas. In the separation and purification step S6, the temperature is lowered to separate methane and the like. As a result, the water may freeze and the pipes may be clogged. Therefore, it is necessary to sufficiently remove the water.

  The separation / purification step S6 is basically performed by a method substantially the same as the separation / purification step S3 after the catalytic cracking reaction. In the separation and purification steps S3 and S6, the gas pressurized in the previous step is first cooled in order to liquefy the gas. The compressor of this cooler is generated using the heat of the cracking furnace. It is designed to work with the steam generated. Also in the separation and purification step S6, ethane and propane are separated and returned to the steam cracking step S4 as lighter (C1 to C3) lower paraffin than C4. In a general steam cracker facility, ethane and propane returned from the separation and purification step S6 are not returned to the main cracking furnace, but a small sub-cracking furnace is provided for the main cracking furnace, and the cracking is performed. Lighter (C1-C3) lower paraffins such as ethane, propane and the like returned from the furnace are decomposed. Also in the present embodiment, ethane and propane separated in the separation / purification step S3 as the catalytic cracking separation step and the separation / purification step S6 as the thermal cracking / separation step are supplied to the sub-cracking furnace.

  Therefore, even if the forward flow of the undecomposed component supplied to the steam cracking step S4 is 0%, it is preferable that the sub-decomposition furnace is activated to thermally decompose ethane, propane, and the like. In this case, it is preferable to operate the process after the steam cracking process S4. The lower paraffin that is lighter (C1 to C3) than C4 separated in the separation and purification step S3 and supplied to the steam cracking step S4 may be returned to the main cracking furnace. Also, when the forward flow of undecomposed components is 0%, lower paraffin that is lighter than C4 (C1 to C3) is stored and supplied to the main cracking furnace when the main cracking furnace is activated It is good.

  From the above, in the method for producing a lower olefin, ethylene and propylene are produced by a catalytic cracking reaction using a zeolite catalyst. The undecomposed component in the catalytic cracking reaction is divided into a reflux component that returns to the reactor that performs the catalytic cracking reaction, and a forward flow component that is sent to the cracking furnace that performs steam cracking. Produces ethylene and propylene by steam cracking from the forward flow.

  The ratio of the reflux portion of the undecomposed component to the forward flow portion can be changed, for example, from 0% to 100% of the reflux portion of the undecomposed component, and the ratio of the forward flow portion corresponding to that can be set to 100. It can be changed from% to 0%. In the case shown in FIG. 2, the reflux component of the undecomposed component (redecomposition component) is 0%, the forward flow component is 100%, and in the case shown in FIG. 3, the reflux component is 50%, and the forward flow component is 50%. In the case shown in FIG. 4, the reflux component is 80% and the forward flow component is 20%. In the case shown in FIG. 5, the reflux component is 100% and the forward flow component is 0%.

  The production amount of ethylene, propylene, etc. in a state where the ratio of the forward flow component and the reflux component is changed will be described as a result of experiments and simulations in the examples described later. As shown in FIG. 5, when 100% of the undecomposed component in the catalytic cracking reaction is returned to the catalytic cracking reaction as a reflux component, steam cracking is not performed. In this case, the steam for operating the compressor of the refrigerating machine in the separation and purification step S3 cannot be supplied from the operating cracking furnace, but the steam cracking equipment is in a state where the temperature of the cracking furnace has not yet been raised at the start of operation. A start-up boiler that supplies steam to the cracking furnace is provided, and steam can be supplied from the start-up boiler to the compressor of the cooler.

  As described above, in the catalytic cracking reaction, the production ratio of propylene is higher than that of ethylene, and in the steam cracking, the production ratio of ethylene is higher than that of propylene. By combining the thermal decomposition reaction by steam cracking, the production ratio of propylene can be improved and the production amount of propylene can be improved. Similarly, the catalytic cracking reaction requires a lower temperature than the thermal cracking reaction, and energy efficiency is achieved by combining the catalytic cracking reaction and the thermal cracking reaction by steam cracking rather than producing ethylene and propylene by steam cracking alone. And energy saving is possible.

Next, a lower olefin production apparatus (production equipment) for producing a lower olefin by the above-described method for producing a lower olefin will be described.
As shown in FIG. 6, the lower olefin production apparatus includes a catalytic cracking means (catalytic cracking reaction facility) 10 for performing the above-described catalytic cracking reaction step S <b> 1, and the above-described quench gas pressurization / dehydration step (after catalytic cracking). Treatment Step) The catalytic cracking post-treatment means 20 for performing S2, the separation and purification means 30 for catalytic cracking for carrying out the separation and purification step S3, and the undecomposed component separated in the separation and purification step S3 as the above reflux component Distributing means 35 for separating the flow into the forward flow and adjusting the distribution ratio of the reflux flow and the forward flow, the thermal decomposition means 40 for performing the above-described steam cracking step S4, and the above-described quench / gas pressure increase / acid gas removal / dehydration step (Post-pyrolysis treatment step) The post-pyrolysis treatment means 50 for performing S5 and the pyrolysis separation and purification means 60 for carrying out the separation and purification step S6 described above are provided.

The catalytic cracking means 10 includes a reactor filled with the above-mentioned zeolite catalyst in a fixed bed system, and a heating device for heating the reactor to the above-mentioned predetermined temperature.
The catalytic cracking post-treatment means 20 includes a quenching quenching device (quenching tower), a gas booster, a dehydrating device, and the like. In addition, although water is separated at the time of quenching quenching, it is preferable to have a dehydrating device that further removes moisture. In the case of catalytic cracking, water is hardly contained in the cracked mixture after the catalytic cracking treatment unless steam is added.

  The catalytic cracking separation and purification means 30 includes the above-described refrigerator, and a plurality of distillation columns for separation of methane, hydrogen, etc., separation of ethane and ethylene, separation of propane and propylene, and the like. For example, a plurality of distillation columns such as a distillation column for separating ethane and ethylene together as a C2 hydrocarbon and a distillation column for separating ethane and ethylene separated separately are provided.

  The distribution means 35 distributes undecomposed components (redecomposition components) mainly composed of C5 and C6 paraffin, and is composed of a pipe, a pump, a valve, and the like. It separates into minutes. In addition, the distribution ratio between the forward flow portion and the reflux portion can be adjusted.

The thermal decomposition means 40 includes the above-described main cracking furnace for steam cracking, a sub-decomposing furnace, a startup boiler, and the like.
The thermal decomposition post-treatment means 50 includes a quenching quenching device (quenching tower), a gas pressure raising device, a dehydration device, an acid gas removal device, and the like. It has the structure which added the removal apparatus.
The pyrolysis separation / purification means 60 basically includes a cooling device and various distillation towers in the same manner as the catalytic cracking separation / purification means 30.

With such a lower olefin production apparatus, a lower olefin can be produced by the above-described production method of lower olefin.
In the production apparatus for lower olefins, the catalytic cracking separation / purification means 30 and the thermal cracking separation / purification means 60 are separately provided. The decomposition mixture flowing out from the thermal decomposition post-treatment means 50 may be combined and separated and purified by the separation and purification means. In this case, the undecomposed component separated from the separation and purification means is separated into a forward flow component and a reflux component by the distribution means 35.

  As a method for constructing the production apparatus (manufacturing equipment) for the lower olefin as described above, there are currently many steam crackers (steam cracking equipment: cracking furnace (pyrolysis means 40), pyrolysis separation and purification means 60). Therefore, it is preferable that a catalytic cracking reaction means (reactor: catalytic cracking reaction facility) 10 using a zeolite catalyst is additionally provided in an existing steam cracker. For example, the catalytic cracking means 10, the catalytic cracking post-processing means 20, the catalytic cracking separation and purification means 30, and the distributing means 35 are provided in the site of the steam cracker or adjacent or close to the site, as described above. Are provided with facilities such as a pump, piping and valves for sending C3 or lower lower paraffin from the catalytic cracking separation and purification means 30 to the thermal cracking means 40.

  The steam cracker is a product whose main products are the above-mentioned ethylene and propylene. However, there is a problem that the production amount of propylene is low and the energy efficiency is low as described above. In the future, for example, There is a possibility that the production facility for ethylene and propylene by the catalytic cracking reaction using the zeolite catalyst as described above or the production facility for ethylene or propylene by other methods may be replaced. However, ethylene and propylene are currently produced by steam crackers, and in the current situation, it is costly to dispose of equipment and to construct new equipment to break down the steam cracking equipment. There is.

  Therefore, by attaching the equipment for catalytic cracking reaction to the existing steam cracker as described above, the cost for disposal of equipment is not required, and part of the existing equipment can be used for the production of lower olefins by catalytic cracking reaction. By diverting, etc., it is possible to increase the production amount of propylene and improve the energy efficiency while suppressing the construction cost.

  In addition, both steam cracking and catalytic cracking reactions can basically produce ethylene and propylene from the same raw material, and the production and separation methods after decomposition are similar, and separation and purification of ethylene and propylene using substantially the same equipment. Therefore, if the separation and purification equipment can be used together by remodeling a part of the separation and purification equipment, the construction cost can be further reduced and the space efficiency can be increased.

Next, a second embodiment of the present invention will be described.
In the second embodiment, in the first embodiment, after the decomposition mixture after catalytic cracking is post-treated, at least ethylene and propylene are separated and purified, and undecomposed components are separated during the separation and purification. As described above, it was divided into a forward flow portion and a reflux portion.

  On the other hand, in the second embodiment, after catalytic cracking, only quenching is basically performed, the reaction is stopped by cooling after catalytic cracking, and then the cooled cracked mixture mainly contains ethylene and propylene. The lower hydrocarbon component is separated into a residue containing mainly undecomposed components (C5, C6 paraffin), and the lower hydrocarbon components are sent to the post-pyrolysis treatment and heated using a separation and purification facility for thermal decomposition. It is processed with the decomposition mixture after decomposition, and ethylene and propylene are separated. The residue is distributed as a re-decomposition component into the above-mentioned forward flow and reflux components, and is used to produce ethylene and propylene by catalytic cracking reaction or thermal cracking reaction.

  The method for producing a lower olefin according to the present embodiment is a catalytic cracking reaction / quenching step in which a catalytic cracking reaction using a zeolite catalyst similar to that of the first embodiment and a quenching of the cracked mixture through the catalytic cracking reaction are performed. (Catalytic cracking reaction step) S11 and a lower hydrocarbon separation step S12 for separating the cooled cracked cracked mixture into the above-mentioned lower hydrocarbon component and a re-cracking component (residual component) containing an undecomposed component; A steam cracking step S14 in which the components for re-cracking including the undecomposed components separated in the lower hydrocarbon separation step S12 are supplied to produce ethylene and propylene by steam cracking (pyrolysis), and a cracked mixture after pyrolysis, Quench, gas pressurization, acid gas removal, dehydration step (thermal decomposition post-treatment step) S15 for performing post-treatment on the lower hydrocarbon component; Decomposition mixture after decomposition and ethylene from lower hydrocarbon components, shared isolation purification step of separating the propylene or the like and a (common separation step) S16.

  The catalytic cracking reaction in the catalytic cracking reaction / quenching step S11 is performed by the same method as in the first embodiment. The quench is performed in the same manner as the quench described in the first embodiment for the decomposition mixture after the catalytic decomposition reaction. In quenching, heavy components and moisture liquefied from the decomposition mixture after catalytic decomposition are removed.

In the lower hydrocarbon separation step S12, basically, a distillation column is used to separate a lower hydrocarbon component of C4 or lower and a residual component mainly containing undecomposed components of C5 and C6. At this time, for example, an aromatic compound (for example, BTX) generated during the catalytic decomposition reaction is removed as a heavy component or the like.
The lower hydrocarbon component includes hydrogen, methane, C2, C3, and C4 olefins and paraffin, as shown in FIG. In FIG. 7 and the like, in the lower hydrocarbon component at the upper right end, the symbol 0 indicates paraffin, and the symbol = indicates olefin. Specifically, for example, ethane, propane, butane as paraffin, and ethylene, propylene, butene, butadiene, etc. as olefins.

  The steam cracking process S14 is the same process as the steam cracking process S4 of the first embodiment. The quenching / gas boosting / acid gas removal / dehydration step S15 is the same as the quenching / gas boosting / acid gas removal / dehydration step S5 of the first embodiment, but in this embodiment, after the thermal decomposition, In addition to the cracked mixture, the above-mentioned lower hydrocarbon component is treated.

  In this case, the future reaction product after pyrolysis and the lower hydrocarbon component may be mixed and supplied to the quench, gas pressurization, acid gas removal, dehydration step S15, or the lower hydrocarbon component may be Since the quenching previously performed in the gas pressurization / acid gas removal / dehydration step S15 has been completed, the lower hydrocarbon component may be introduced after the quench in the quench / gas pressurization / acid gas removal / dehydration step S15. Good.

  The common separation / purification step S16 is basically the same as the separation / purification step S3 for catalytic cracking and the separation / purification step S6 for thermal cracking according to the first embodiment. -Ethylene and propylene are isolate | separated from the decomposition mixture after the thermal decomposition which passed through spin-drying | dehydration process S15, and the mixture of a lower hydrocarbon component.

  According to such a method for producing a lower olefin of the second embodiment, not only can the same effects as those of the first embodiment be obtained, but also after catalytic cracking reaction and thermal cracking reaction. It is possible to perform the post-treatment process (for example, quenching, gas pressurization, acid gas removal, dehydration process S15) and separation and purification process S16 in the thermal decomposition reaction and the catalytic decomposition reaction using the same equipment. Costs related to the equipment can be reduced. In particular, when the equipment for catalytic cracking reaction is attached to the existing steam cracking equipment, the existing steam cracking equipment is used as post-treatment equipment after the catalytic cracking (quenching device, gas booster, dehydrator). In addition, existing steam cracking equipment (such as various distillation towers) can be used for separation and purification of the cracked mixture after catalytic cracking.

  Therefore, it is possible to reduce the construction cost of the lower olefin production facility (production device) of the present embodiment, reduce the facility cost, improve the space efficiency of the facility, and the like.

  The lower olefin production apparatus (production equipment) for producing the lower olefin by the lower olefin production method of the second embodiment performs the catalytic cracking reaction / quenching step S11 as shown in FIG. Catalytic cracking cooling means (catalytic cracking means) 110 for separating the lower hydrocarbon component from the cracked mixture produced by the catalytic cracking reaction and separating the re-cracking component including the undecomposed component from the lower hydrocarbon separation step S12 The lower hydrocarbon separation means 120 for performing the separation and the separated undecomposed component (residual component: component for re-decomposition) are separated into the above-mentioned reflux component and the forward flow component, and the distribution ratio of the reflux component and the forward flow component is adjusted. Distributing means 130, thermal cracking means 140 for performing the above-described steam cracking step S14, and the cracked mixture and lower hydrocarbon components after pyrolysis The common post-treatment means 150 for performing the quench, gas pressurization, acid gas removal, dehydration step (common post-treatment step) S5, and the above-described separation and purification step S16 for the pyrolysis decomposition mixture and lower hydrocarbon component And a common separation and purification means 160 for performing.

  The catalytic cracking cooling means 110 includes the quenching quenching device (quenching tower) described above in addition to the catalytic cracking means 10 including the reactor of the first embodiment. After the cracked mixture after the catalytic cracking reaction flowing out from the reactor is quenched, it is supplied to the lower hydrocarbon separation means 120. In addition, when supplying steam to a reactor, water is removed by quenching.

  The lower hydrocarbon separation means 120 removes aromatic hydrocarbons such as BTX as heavy components from the cracked mixture by using, for example, about two distillation columns, and then regenerates C4 or lower hydrocarbon components and C5 or higher recycle components. Fractionated into components for decomposition (undecomposed components). It becomes a simple installation with respect to the installation provided with many distillation columns corresponding to each component isolate | separated like the above-mentioned separation and purification means 30 for catalytic cracking.

  Similar to the distribution unit 35 of the first embodiment, the distribution unit 130 distributes the re-decomposition component to the above-mentioned forward flow component and the reflux component and can adjust the distribution ratio, and the forward flow component is catalytically decomposed. The cooling unit 110 is supplied to the reactor, and the forward flow is supplied to the cracking furnace of the thermal decomposition unit 140.

  The thermal decomposition means 140 is the same as the thermal decomposition means 40 of the first embodiment. The shared post-processing means 150 is the same as the thermal decomposition post-processing means 50 of the first embodiment, and the shared separation and purification means 160 is the thermal decomposition separation and purification means 60 of the first embodiment. Is the same. However, the common post-treatment means 150 and the common separation and purification means 160 are supplied with a lower hydrocarbon component in addition to the decomposition mixture after the thermal decomposition reaction.

  According to such a lower olefin production apparatus, instead of including the catalytic cracking post-treatment means 20 and the catalytic cracking separation and purification means 30 as in the first embodiment, the downstream side of the catalytic cracking reactor. Is equipped with a quenching quenching device, and a lower hydrocarbon separation means 120 is provided downstream thereof to simplify separation and purification after catalytic cracking, and only separates into a lower hydrocarbon component and a recracking component. Final separation of ethylene, propylene, and the like is performed by the shared separation and purification means 160 together with the decomposition mixture after thermal decomposition.

  This makes it possible to separate and purify lower hydrocarbon components including ethylene and propylene using the separation and purification equipment of the steam cracking equipment, and attach the catalytic cracking equipment using a zeolite catalyst to the existing steam cracking equipment. In this case, existing facilities can be used as post-processing facilities and separation / purification facilities, and the facility cost and facility construction cost can be reduced.

Such a low olefin production apparatus (manufacturing facility) is constructed by the above-described catalytic cracking cooling means 110 (catalytic cracking means: in a site adjacent to or adjacent to a steam cracker (cracking furnace: steam cracking facility)). Reactor, quench quenching device), lower hydrocarbon separation means 120, and distribution means 130.
Here, the common post-treatment means 150 and the common separation / purification means (separation purification equipment) 160 are not only post-treatment and separation / purification of the cracked mixture after pyrolysis, but also lower hydrocarbons separated from the cracked mixture after catalytic cracking. It will also be used for work-up of components and separation and purification.

  These shared post-processing means 150 and shared separation and purification means 160 are existing facilities of a steam cracker, and do not need to be newly provided when constructing the lower olefin production apparatus of the present embodiment. Although it may be necessary to change or replace some devices, the construction cost can be greatly reduced.

Next, examples of the present invention will be described.
First, with reference to FIG. 1 and FIG. 12, an experiment for producing ethylene and olefin from a light paraffinic hydrocarbon raw material by a catalytic cracking reaction using a zeolite catalyst combined with production of ethylene and propylene by steam cracking will be described.

In the production experiment of lower olefins by catalytic cracking reaction, n-hexane (n-C ₆ H ₁₄ ) was used as a representative component of light naphtha which is a light paraffinic hydrocarbon raw material. Further, as the zeolite of the zeolite catalyst, MFI type crystalline aluminosilicate containing iron and gallium was used.

  As a result of fluorescent X-ray measurement of the synthesized zeolite, as shown in FIG. 12, Si / (Fe + Ga + Al) = 16.4, Fe / (Fe + Ga + Al) = 0.31, Ga / ( Fe + Ga + Al) = 0.16 and Al / (Fe + Ga + Al) = 0.53.

The zeolite catalyst used is a composite catalyst obtained by molding the above zeolite powder with a binder, and silica (SiO ₂ ) was used as the binder. The mixing ratio of zeolite and silica, that is, the zeolite / SiO ₂ mixing ratio is 90 wt% / 10 wt%.

The reaction conditions for the catalytic cracking reaction were a reaction temperature of 565 ° C., a total pressure of 0.1 MPa, n-hexane LHSV of 6.0 h ⁻¹ , and a zeolite catalyst amount of 1.8 ml. In the experiment, the concentration of each product after one-pass reaction of n-hexane was measured by gas chromatography without returning unreacted n-hexane (re-decomposition component). The rate was determined. Moreover, based on this one-pass yield, the overall yield after separation and purification of each component obtained when unreacted n-hexane was refluxed and recycled as a reaction raw material was calculated. FIG. 12 shows the one-pass yield of each component as an experimental result and the calculation result (overall yield) when the unreacted raw material is refluxed and recycled.

In continuous operation using reflux and recycling of undecomposed components, the yield of ethylene (C ₂ H ₄ ) is 10.0 wt% and the yield of propylene (C ₃ H ₆ ) is 22.6 wt%. The production ratio was about 1: 2. The yield varies depending on the molar composition ratio of each element of the zeolite, the kind of the binder, the reaction conditions, and the like. For example, as reaction conditions, when the raw material is diluted by introducing steam in addition to the raw material during the catalytic cracking reaction, the yield of propylene may be increased by about 1.5 times, for example, depending on the amount of steam introduced. Is possible.

  When ethylene and propylene are produced only by steam cracking, the yield of ethylene is 31.1 wt% and the yield of propylene is 17.1 wt as shown in Comparative Example 1 in FIGS. %Met. Therefore, the production ratio of ethylene and propylene was about 1: 0.5. In addition, the comparative example 1 is the yield of ethylene and propylene in the existing steam cracker.

  Next, Examples 1 to 4 corresponding to the first embodiment will be described with reference to FIGS. 2 to 5 and FIG. 13. The yields of ethylene and propylene in the catalytic cracking reactions of Examples 1 to 4 are determined based on the experimental results (one-pass yield) in FIG. The calculation results are 0%, 50%, 80%, and 100%. Similarly, the yields of ethylene and propylene in the thermal decomposition reaction of each example are the undecomposed components (redecomposition components), ethane and propane yields in the above-described one-pass, and the undecomposed component yields. It was obtained by calculation based on the yield of Comparative Example 1 from the distribution amount (0%, 20%, 50%, 100%) of the reflux / recycled use.

  As shown in FIGS. 2 and 13, Example 1 has 100% of the re-decomposition component to be sent to the thermal decomposition reaction side and 0% of the reflux amount to be returned to the catalytic decomposition reaction side. In this case, the combined yield of the catalytic cracking reaction and the thermal cracking reaction was 25.4%, and the yield of propylene was 21.7%. The combined yield of these ethylene and propylene was 47. 1%.

  As shown in FIGS. 3 and 13, Example 2 has 50% of the re-decomposition component to be sent to the thermal decomposition reaction side and 50% of the reflux component to be returned to the catalytic decomposition reaction side. In this case, the combined yield of the catalytic cracking reaction and the thermal cracking reaction was 23.4%, and the yield of propylene was 23.3%, and the combined ratio of these ethylene and propylene was 46.6. %.

  In Example 3, as shown in FIGS. 4 and 13, 20% of the re-decomposition component is sent to the thermal decomposition reaction side, and 80% of the reflux component is returned to the catalytic decomposition reaction side. In this case, the combined yield of the catalytic cracking reaction and the thermal cracking reaction was 22.2%, and the yield of propylene was 24.2%. The combined yield of these ethylene and propylene was 46. 4%.

  As shown in FIGS. 5 and 13, Example 4 has 0% of the re-decomposition component to be sent to the thermal decomposition reaction side and 100% of the reflux amount to be returned to the catalytic decomposition reaction side. In this case, the combined yield of the catalytic cracking reaction and the thermal cracking reaction was 21.4%, and the yield of propylene was 24.9%. The combined yield of these ethylene and propylene was 46. 2%.

  In Comparative Example 1, since the yield of ethylene by steam cracking is high, the combined yield of ethylene and propylene is slightly higher than in Examples 1-4. It is possible to increase the combined yield of ethylene and propylene in the catalytic cracking reaction by changing the experimental conditions, for example, by introducing steam into the catalytic cracking reaction. Comparative Example 1 and Example 1 The difference in the combined yield of ethylene and propylene of ~ 4 is not so great as to be a problem.

The difference in the combined yield of ethylene and propylene in Examples 1 to 4 is an error level. And when the ratio of the re-decomposition component reflux is increased to 0%, 50%, 80%, and 100%, the yield of propylene increases from 21.7 wt% to 24.9 wt%. In this case, the yield of ethylene decreases to 25.4 wt% to 21.4 Wt%. That is, it is possible to adjust the production amounts of ethylene and propylene. The production ratio (weight) of propylene / ethylene can be adjusted from 0.85 to 1.16. Therefore, the production ratio of propylene can be increased as compared with the case where steam cracking and the OCT process are combined.
Even if the re-cracking component supplied to the steam cracking is 0%, ethane and propane separated from the cracked mixture after the catalytic cracking reaction are supplied to the steam cracking. The yield is not 0%.

  Next, Examples 5 to 8 corresponding to the method for producing a lower olefin of the second embodiment will be described with reference to FIGS. 7 to 10 and FIG. In Examples 5 to 8, as in Examples 1 to 4, the yield was obtained by calculation based on the one-pass experimental result of the catalytic cracking reaction shown in FIG. That is, as shown in FIGS. 7 to 10, the concentration of each product of the cracked mixture after steam cracking and the lower hydrocarbon separated after the catalytic cracking reaction is not measured by gas chromatography or the like. The yields of ethylene and propylene are obtained by the same calculation as in Examples 1 to 4, and the distribution ratio of the forward flow and the reflux of the undecomposed component (redecomposition component) is the same. Then, the yields of ethylene and propylene are the same in Examples 1 to 4 and Examples 5 to 8.

  Therefore, the results of Examples 1 to 4 corresponding to the first embodiment shown in FIG. 13 and the results of Examples 5 to 8 corresponding to the second embodiment shown in FIG. 14 are the same. It has become. That is, in Example 5, as shown in FIGS. 7 and 14, the forward flow sent to the thermal decomposition reaction among the components for re-decomposition is 100%, and the reflux returned to the catalytic decomposition reaction is 0%. . In this case, the combined yield of the catalytic cracking reaction and the thermal cracking reaction was 25.4%, the yield of propylene was 21.7%, and the combined yield of ethylene and propylene was 47. .1%.

  In Example 6, as shown in FIGS. 8 and 13, the forward flow sent to the thermal decomposition reaction among the components for re-decomposition is 50%, and the reflux returned to the catalytic cracking reaction is 50%. In this case, the combined yield of the catalytic cracking reaction and the thermal cracking reaction was 23.4%, the yield of propylene was 23.3%, and the combined yield of these ethylene and propylene was 46. .6%.

  In Example 7, as shown in FIGS. 9 and 13, the forward flow sent to the thermal decomposition reaction among the components for re-decomposition is 20%, and the reflux returned to the catalytic cracking reaction is 80%. In this case, the combined yield of the catalytic cracking reaction and the thermal cracking reaction is 22.2%, the yield of propylene is 24.2%, and the combined yield of ethylene and propylene is 46. 4%.

  In Example 8, as shown in FIGS. 10 and 13, the forward flow sent to the thermal decomposition reaction among the components for re-decomposition is 0%, and the reflux returned to the catalytic decomposition reaction is 100%. In this case, the combined yield of the catalytic cracking reaction and the thermal cracking reaction was 21.4%, the yield of propylene was 24.9%, and the combined yield of ethylene and propylene was 46. .2%.

  Basically, the method for producing the lower olefin of the first embodiment and the method for producing the lower olefin of the second embodiment differ in the separation method of the components for re-cracking, but basically the same raw materials are used. Since the re-decomposition component can be distributed in the same manner, the yields of ethylene and propylene are likely to be substantially the same in the first embodiment and the second embodiment.

10 catalytic cracking means (reactor: catalytic cracking reactor)
30 Separation and purification means for catalytic cracking 35 Distributing means 40 Thermal decomposition means (cracking furnace, steam cracking equipment)
60 Separation and purification means for pyrolysis (separation and purification equipment: steam cracking equipment)
110 catalytic cracking cooling means (catalytic cracking means: reactor, quench quenching device)
120 Lower hydrocarbon separation means 130 Distribution means 140 Pyrolysis means (cracking furnace, steam cracking equipment)
160 Common separation and purification means (Separation and purification equipment: Steam cracking equipment)
S1 catalytic cracking reaction process S3 separation and purification process (separation process for catalytic cracking)
S4 Steam cracking process S6 Separation and purification process (Separation process for thermal decomposition)
S11 catalytic cracking reaction / quenching process (catalytic cracking reaction process)
S12 Lower hydrocarbon separation step S14 Steam cracking step S16 Separation and purification step (shared separation step)

Claims (15)

A method for producing a lower olefin, wherein ethylene and propylene are produced as a lower olefin from a light paraffin hydrocarbon raw material,
A catalytic cracking reaction step for producing the ethylene and propylene from the light paraffinic hydrocarbon raw material by a catalytic cracking reaction using a zeolite catalyst, and not including the ethylene and the propylene from the cracked mixture obtained through the catalytic cracking reaction step. Steam cracking for producing the ethylene and the propylene by steam cracking from the re-decomposition component when the re-decomposition component separated so as to contain the unreacted component in the catalytic cracking reaction is supplied A process for producing a lower olefin comprising the steps of:   The method for producing a lower olefin according to claim 1, wherein the re-cracking component can be returned to the catalytic cracking reaction step.   The re-decomposition component is distributed to the forward flow sent to the steam cracking process and the reflux returned to the catalytic cracking reaction process, and the distribution ratio of the forward flow and the reflux can be adjusted during the distribution. The method for producing a lower olefin according to claim 2, wherein:   A separation step for catalytic cracking for separating the ethylene, the propylene and the re-cracking component from the cracked mixture after the catalytic cracking reaction step, and at least the ethylene and the propylene from the cracked mixture after the steam cracking step. The method for producing a lower olefin according to any one of claims 1 to 3, further comprising a separation step for pyrolysis for separating each of them.   5. The lower part according to claim 4, wherein a lower paraffin component mainly comprising a paraffin having 3 or less carbon atoms is separated in the catalytic cracking separation step, and the lower paraffin component is supplied to the steam cracking step. Production method of olefin.   A lower hydrocarbon separation step of separating a lower hydrocarbon component comprising the ethylene and the propylene and mainly consisting of lower hydrocarbons having 4 or less carbon atoms from the cracked mixture that has undergone the catalytic cracking reaction step, the catalytic cracking reaction The method for producing a lower olefin according to any one of claims 1 to 3, wherein a residue obtained by removing the lower hydrocarbon component from the cracked mixture after the step is used as the re-cracking component. .   The method for producing a lower olefin according to claim 6, further comprising a common separation step of separating the ethylene and the propylene from the lower hydrocarbon component and the cracked mixture that has undergone the steam cracking step.   8. The lower olefin according to claim 7, wherein, in the common separation step, a lower paraffin component mainly comprising a paraffin having 3 or less carbon atoms is separated, and the lower paraffin component is returned to the steam cracking step. Production method.   The zeolite in the zeolite catalyst used in the catalytic cracking reaction step is MFI type crystalline aluminosilicate containing iron or iron and gallium, according to any one of claims 1 to 8. A process for producing a lower olefin. A lower olefin production apparatus for producing ethylene and propylene as a lower olefin from a light paraffinic hydrocarbon raw material,
A catalytic cracking means comprising a reactor for producing the ethylene and the propylene from a light paraffinic hydrocarbon raw material by a catalytic cracking reaction using a zeolite catalyst; and the ethylene and the propylene from a cracked mixture discharged from the reactor The ethylene and the propylene are produced by steam cracking from the re-decomposition component when the re-decomposition component separated so as to contain the unreacted component in the catalytic decomposition reaction is supplied. An apparatus for producing a lower olefin, comprising: a thermal decomposition means including a decomposition furnace. The re-cracking component separated from the cracked mixture flowing out of the reactor can be returned to the reactor;
Distributing means capable of distributing the re-cracking component into a forward flow portion to be sent to the cracking furnace and a reflux portion to be returned to the reactor, and adjusting a distribution ratio between the forward flow portion and the reflux portion at the time of the distribution. The apparatus for producing a lower olefin according to claim 10, comprising:   Separation and purification means for catalytic cracking for separating the ethylene, propylene and the re-cracking component from the cracked mixture flowing out from the reactor, and at least the ethylene and propylene from the cracked mixture flowing out from the cracking furnace. The apparatus for producing lower olefin according to claim 10 or 11, further comprising a separation and purification means for thermal decomposition for separating each of them. A lower hydrocarbon separation means for separating the lower hydrocarbon component comprising the ethylene and the propylene and mainly comprising lower hydrocarbons having 4 or less carbon atoms from the cracked mixture flowing out from the reactor; The residue obtained by removing the lower hydrocarbon component from the cracking mixture is used as the re-cracking component,
The production of a lower olefin according to claim 10 or 11, further comprising a common separation and purification means for separating the ethylene and the propylene from the lower hydrocarbon component and a cracked mixture flowing out from the cracking furnace. apparatus.   The lower zeolite according to any one of claims 10 to 13, wherein the zeolite in the zeolite catalyst used in the reactor is MFI type crystalline aluminosilicate containing iron or iron and gallium. Olefin production equipment. A method for constructing a lower olefin production facility for producing ethylene and propylene as a lower olefin from a light paraffinic hydrocarbon raw material,
From a light paraffin hydrocarbon raw material to a zeolite catalyst, an existing steam cracking facility comprising a cracking furnace for producing the ethylene and propylene by steam cracking and a separation and purification facility for separating and purifying the cracked mixture flowing out of the cracking furnace A catalytic cracking reaction facility equipped with a reactor for producing the ethylene and the propylene by a catalytic cracking reaction using
A re-cracking component separated from the cracked mixture flowing out from the reactor so as not to contain ethylene and propylene and separated to contain unreacted components in the catalytic cracking reaction can be supplied to the cracking furnace. A method for constructing a production facility for a lower olefin, which comprises:

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