EA007979B1 - Low pressure separation of dimethyl ether from an olefin stream - Google Patents

Abstract

Disclosed is a method of removing dimethyl ether from an ethylene and/or propylene containing stream. Dimethyl ether is removed at a low pressure preferably in a distillation column. The low pressure separation has the benefit of providing a relatively low temperature separation, while allowing for recovery of a highly concentrated ethylene and/or propylene stream.

Description

FIELD OF THE INVENTION

The present invention relates to a method for removing oxygen-containing contaminants from an olefin stream. Thus, in particular, the present invention relates to a method for removing dimethyl ether from a stream comprising ethylene and / or propylene.

BACKGROUND OF THE INVENTION

There is a need for olefins, especially C ₂ - and C ₃ olefins, as a source of raw materials for derivative products, such as oligomers, for example higher olefins, and polymers, such as polyethylene and polypropylene. Olefin feedstocks are traditionally obtained by cracking petrochemical feedstocks.

I8 No. 5090977 describes a method for producing olefins by steam cracking. This method involves the separation of the olefin product into streams of methane, hydrogen, ethane, ethylene, propylene and C ₅ + compounds. As a result of the described separation, mainly propylene is obtained and no streams of propane, butane, butene or butadiene are obtained.

However, oxygen-containing starting materials become an alternative to petrochemical raw materials for the production of olefins, in particular large quantities of ethylene and propylene, in order to obtain higher olefins and plastics. Typically, olefins are prepared by contacting oxygen containing components with a molecular sieve catalyst to catalyze the conversion of oxygen containing substances to olefins.

So, for example, in IZ No. 4499327 describes a method for producing olefins from methanol using any of a variety of silicoaluminophosphate (KAFO) catalysts based on molecular sieves. This method is carried out at a temperature in the range of 300 and 500 ° C, under pressure in the range from 0.1 to 100 atm and at a mass hourly speed (MES) in the range of 0.1 and 40 h ^-1 . This method is highly selective in the production of ethylene and propylene.

IZ No. 6121504 also describes a method for producing an olefin product from an oxygen-containing starting material using molecular sieve catalysts. Water and other undesirable by-products from the olefin product are removed by contacting with a cooling medium. After contacting with the cooling medium, a light fraction of the product is obtained that includes the target olefins, but also includes dimethyl ether, methane, CO, CO2, ethane, propane and other small components such as water and unreacted oxygen-containing starting material.

For the subsequent processing of olefins, it is often necessary to reduce or remove unwanted by-products that are contained in the olefin composition. Thus, in particular, patent FROM No. 4474647 states that dimethyl ether can adversely affect the oligomerization of certain olefins. This patent describes a method for removing dimethyl ether from a stream of C4 and / or C5 olefins using distillation. This stream is distilled and separated into streams of overhead and bottoms. The overhead stream includes dimethyl ether, water and various hydrocarbons, and the bottoms stream includes refined olefins.

IZ No. 5914433 describes a method for producing an olefin composition and a system for removing neolefin by-products such as CO2. The dehydrated olefin composition is washed with caustic soda to remove CO2 and the washed olefin composition is dried to reduce the amount of water added as a result of washing with caustic soda.

IZ No. 5720929 describes a process that involves producing isobutylene from isobutane. Isobutylene is cooled and water is evaporated from the product. An additional amount of water is removed by washing the product with methanol.

Eid et al. In 1p1sdg1yup оГ 1ее υΟΡ / ΗΎΏΚΟ МТО Ртосезз ίηΐο Е1йу1епе Р1аи18, 101Н Е1йу1ее Рпобисетз 'СопГегепсе, 1998, describe a block diagram of the preparation of an olefin composition from methanol. This flow chart shows that methanol and dimethyl ether are squeezed out of an olefin product and returned to a reactor to convert methanol to olefins, ethylene and propylene being recovered.

EP-B1 0060103 describes a method for extracting dimethyl ether from a steam stream comprising ethylene and propylene using a methanol washing system. During the washing with methanol, a substantial amount of dimethyl ether is removed, but a significant amount of ethylene and propylene are also removed.

There is a need for other methods for removing undesired components from olefin streams. Thus, in particular, a search is underway for the removal of oxygen-containing hydrocarbons, in particular dimethyl ether, as well as CO2 and water, to reduce their concentration in olefin product streams to expressed in parts per million without removing significant amounts of olefin.

Summary of the invention

In carrying out the present invention, dimethyl ether is isolated from a stream of olefins, including ethylene and / or propylene, using low pressure separation, preferably low pressure distillation. In one embodiment, the invention provides a method for separating dimethyl ether from an olefin stream, which comprises producing an olefin stream comprising ethylene, ethane, propylene, propane and dimethyl ether. The resulting stream is divided into the first fraction

- 1 007979 and a second fraction under gauge pressure below 200 psi. The first fraction comprises at least a major portion of the ethylene and propylene contained in the olefin stream, and the second fraction comprises at least a major portion of the dimethyl ether contained in the olefin stream. In another embodiment, the resulting olefin stream further includes water in an amount of not more than about 15,000 parts by weight per million.

The invention is particularly effective for olefin streams that comprise at least about 500 parts by weight of dimethyl ether. In a preferred embodiment, the olefin stream comprises not more than about 50 wt.% Dimethyl ether.

In one embodiment, the separation is carried out in such a way that the first fraction comprises at least a majority of the propane contained in the olefin stream, and preferably not more than about 100 parts by weight of dimethyl ether. The separation can be carried out in such a way that the main part of the propane contained in the olefin stream can be either in the first or in the second fraction. The separation can also be carried out in such a way that the main part of propadiene, which may also be contained in the olefin stream, can be either in the first or in the second fraction. In order to obtain very high purity propylene streams from the olefin stream, in the preferred embodiment with the second fraction, it is necessary to isolate the bulk of the total mass of propadiene and propane contained in the olefin feed.

In another embodiment, the olefin stream in the distillation column is separated into a first fraction and a second fraction. In a preferred embodiment, a water absorber is added to this distillation column. The water absorber can be added to the distillation column at a molar ratio between the water absorber and the total olefin stream to be separated, from about 4: 1 to about 1: 5000.

However, in another embodiment, the first fraction is treated to remove acid gas. Subsequently, after treating the acid gas, the stream can be washed with water and brought into contact with solid adsorbent material.

Due to the high quality of the emitted streams, ethylene and propylene isolated from the olefin stream can be used in any process for producing derivatives of ethylene or propylene. Preferred options include polymerization to produce polyethylene and polypropylene.

In another embodiment, the invention provides a method for separating dimethyl ether from an olefin stream, which comprises contacting an oxygenate with a molecular sieve catalyst to produce an olefin stream, wherein the olefin stream includes ethylene, ethane, propylene, propane and dimethyl ether. The olefin stream is separated into a first fraction and a second fraction under gauge pressure below 1380 kPa (200 psi). The first fraction includes at least a major portion of the ethylene and propylene contained in the olefin stream, and the second fraction comprises at least a major portion of the dimethyl ether in the olefin stream.

In one embodiment, the olefin stream resulting from the introduction of an oxygen-containing substance into contact with a molecular sieve catalyst is contacted with a water scavenger prior to separation into the first and second fractions. It is necessary that the water absorber is in contact with the olefin stream with a molar ratio between the water absorber and the total weight of olefins from about 1: 2 to about 1: 200. In a preferred embodiment, the olefin stream in contact with the water absorber comprises water in an amount of not more than about 15,000 parts by weight per million.

The invention further provides a process for separating dimethyl ether from an olefin stream, which comprises contacting an oxygenate with a molecular sieve catalyst to produce an olefin stream, wherein the olefin stream includes ethylene, ethane, propylene, propane, dimethyl ether and water. Next, the water from the olefin stream is removed so that the olefin stream includes no more than about 15,000 parts by weight per million of water. Then, the olefin stream, comprising not more than about 15,000 parts by weight per million water, at a gauge pressure below 1380 kPa (200 psi) is divided into a first fraction and a second fraction, where the first fraction comprises at least a major portion ethylene and propylene contained in the stream of olefins, and the second fraction includes at least the bulk of the dimethyl ether in the stream of olefins.

In addition, the present invention provides a method for separating dimethyl ether from an olefin stream, which comprises producing an olefin stream comprising ethylene, ethane, propylene, propane, propadiene and dimethyl ether. The olefin stream is divided into a first fraction comprising at least a major portion of ethylene and propylene contained in the olefin stream, and a second fraction comprising at least a major portion of dimethyl ether and propadiene in the olefin stream. The separation is carried out at a gauge pressure below 1380 kPa (200 psi) and so that the average temperature of the second fraction is not higher than about 99 ° C (210 ° E).

In another embodiment, the invention provides a method of separating dimethyl ether from a stream of olefins, which includes obtaining a stream of olefins, including ethylene, ethane, propylene,

- 2 007979 propane and dimethyl ether. In this embodiment, the olefin stream in the distillation column is separated into a first fraction and a second fraction, the first fraction comprising at least a majority of the ethylene and propylene contained in the olefin stream. The second fraction includes at least the bulk of the dimethyl ether contained in the olefin stream. In a preferred embodiment, the resulting olefin stream comprises no more than about 15,000 parts by weight per million water, and the average temperature of the second fraction is not higher than about 99 ° C (210 ° P).

Brief Description of the Drawings

Various embodiments of the invention as a whole are shown by way of example in the accompanying drawings, where in FIG. 1 is a flowchart illustrating a reaction process involving methanol to produce olefins, the olefins being divided into a first fraction comprising ethylene and propylene, and a second fraction comprising dimethyl ether and C ₄ + hydrocarbon components; and in FIG. 2 is a flowchart illustrating the treatment of ethylene and propylene by washing with caustic soda, washing with water, and adsorption.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a method for removing oxygen-containing hydrocarbon components, such as dimethyl ether, from an olefin stream. Such components must be removed because they are capable of poisoning the catalysts that are used for further processing of olefins from the olefin stream. The invention is particularly effective in removing dimethyl ether from a stream of ethylene and / or propylene, whereby ethylene and / or propylene can be polymerized without poisoning the catalyst used in the polymerization reaction.

In carrying out the present invention, oxygen-containing contaminants, including, in particular, dimethyl ether, are removed from the resulting olefin stream under low pressure. The advantage of using low pressure separation is that during the separation process, heavier fractions can be isolated at low temperatures. The advantage of lower temperatures is that there are always fewer problems associated with equipment contamination. In addition, when carrying out such a process, less energy is consumed for the operation of the used technological equipment, such as boilers and refrigerators.

Another advantage of low pressure separation is that less energy is always required to maintain pressure in the separation system. This means that it is possible to use compressors with fewer stages with great success.

In general, the method of the present invention involves the production of an olefin stream that includes ethylene, ethane, propylene, propane and dimethyl ether, then isolating at least a major portion, i.e. more than 50% of dimethyl ether contained in the olefin stream. This olefin stream can be obtained from any conventional source. However, the present invention is particularly effective in the separation of dimethyl ether from olefin streams in the process of converting an oxygen-containing substance to olefins.

In one embodiment, the olefin stream that is produced comprises not more than about 50 wt.% Dimethyl ether, preferably not more than about 20 wt.% Dimethyl ether, more preferably not more than about 10 wt.% Dimethyl ether, and most preferably not more than about 5 wt.% dimethyl ether. In order to remove dimethyl ether from the olefin stream, it must, of course, be contained in some measurable amount. In a suitable embodiment, the resulting olefin stream typically includes at least about 100 parts by weight of dimethyl ether, preferably at least about 500 parts by weight of dimethyl ether, and more preferably at least about 1000 parts by weight / million dimethyl ether.

In another embodiment, the olefin stream that is produced comprises at least about 25 wt.% Ethylene. In a preferred embodiment, the resulting olefin stream comprises from about 25 to about 75 wt.% Ethylene, more preferably from about 30 to about 60 wt.%, And most preferably from about 35 to about 50 wt.% Propylene.

In yet another embodiment, the olefin stream that is produced also includes at least about 20% by weight of propylene. In a preferred embodiment, the resulting olefin stream comprises from about 20 to about 70 wt.% Propylene, more preferably from about 25 to about 50 wt.% Propylene, and most preferably from about 30 to about 40 wt.% Propylene.

It is necessary that the resulting olefin stream include ethane at a relatively low concentration, preferably include ethane at a lower concentration than propane. In a preferred embodiment, the olefin stream comprises not more than about 4 wt.% Ethane, more preferably not more than about 3 wt.% Ethane, and most preferably not more than about 2 wt.% Ethane.

It is also necessary that the resulting olefin stream include propane in a relatively low concentration. In a preferred embodiment, the olefin stream comprises not more than about 5 wt.% Propane, more preferably not more than about 4 wt.% Propane, and most preferably not more than about 3 wt.% Propane.

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In another embodiment, the resulting olefin stream comprises both ethylene and propylene. Suitably, the olefin stream comprises at least about 50% by weight of ethylene and propylene. In a preferred embodiment, the olefin stream comprises from about 50 to about 95 wt.% Ethylene and propylene, more preferably from about 55 to about 90 wt.% Ethylene and propylene, and most preferably from about 60 to about 85 wt.% Ethylene and propylene.

The resulting olefin vapor may also include some water. However, it is necessary that all the water in the olefin stream is contained in such a concentration that the formation of free water (i.e. the formation of a separate phase of water) or gas hydration is not a noticeable obstacle to the separation process. As a result of gas hydration, clathrate compounds are formed. Such compounds are solid particles, and these solid particles can cause significant technological problems in the separation process.

In order to prevent a separate phase of water from forming during the separation process, the water contained in the resulting olefin stream must be in a sufficiently low concentration. This is especially important when a distillation column equipped with trays is used to isolate dimethyl ether from olefins, since the separate phase of water formed on these trays usually interferes with mass transfer. At elevated concentrations of water, distillation columns equipped with a packing are preferred, since such columns are usually not prone to the accumulation of individual phases of water.

In carrying out the present invention, it is necessary that the resulting olefin stream comprise no more than about 15,000 parts by weight per million of water. In a preferred embodiment, the olefin stream comprises not more than about 10,000 parts by weight of water, more preferably not more than 5,000 parts by weight of water, and most preferably not more than about 1,000 parts by weight of water.

In carrying out the present invention, it is not necessary that the olefin stream be completely dry. In other words, the olefin stream may include some water. The benefit of a stream of olefins, including some water, is that there is no need for additional and / or sophisticated drying equipment prior to the isolation of dimethyl ether from the stream of olefins. In a preferred embodiment, the olefin stream comprises at least about 10 parts by weight of water, more preferably at least about 20 parts by weight of water, and most preferably at least about 25 parts by weight of water.

If the olefin stream includes water in an unacceptably high concentration, either before or during the isolation of dimethyl ether, a sufficient amount of water can be removed using a water absorber. Examples of water scavengers include alcohols, amines, amides, nitriles, heterocyclic nitrogen-containing compounds, and a combination of any of the above agents. Either monohydric alcohols or polyhydric alcohols can be used as an alcohol scavenger. Specific examples of scavengers include methanol, ethanol, propanol, ethylene glycol, diethylene glycol, triethylene glycol, ethanolamine, diethanolamine, triethanolamine, hindered cyclic amines, acetonitrile, Ν-methylpyrrolidone, dimethylformamide, and combinations thereof.

To achieve a significant degree of effectiveness, the water absorber must include components that are not very absorbent in water. So, for example, the water absorber should include at least about 75 wt.% Water absorbing components. Advantageously, the water absorber comprises at least about 90 wt.%, Preferably at least about 95 wt.%, And most preferably at least about 98 wt.% Of the water absorber.

When a water absorber is used in order to reduce the concentration of water in the olefin stream prior to the isolation of dimethyl ether, a flushing method using a flushing vessel may be used. The washing process is essentially a process in which a stream of olefins is brought into contact with a water absorber so as to remove, i.e. wash a substantial amount of water from the olefin stream. The amount of scavenger added to the washing vessel should be sufficient to substantially reduce the amount of free water that forms (i.e., the resulting separate liquid phase), especially in the vessel in which dimethyl ether is isolated from olefins. In this embodiment, it is necessary that the water absorber be added to the washing vessel at a molar ratio between the absorption compound and the total amount of olefin feed introduced into the washing vessel, from about 1: 2 to about 1: 200. In a preferred embodiment, the scavenger is added in a molar ratio of from about 1: 5 to about 1: 100, and more preferably from about 1:10 to about 1:50.

Although the source of the olefin stream can be any conventional source that includes dimethyl ether, the invention is particularly suitable for removing dimethyl ether from olefin streams obtained from the process of converting an oxygen-containing substance to olefins. In one embodiment of the present invention, an olefin stream comprising dimethyl ether is prepared by contacting an oxygen-containing starting material with a molecular sieve catalyst.

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In a preferred embodiment of the method of the invention, the oxygen-containing starting material comprises one or more oxygen-containing substances, more particularly one or more organic compounds containing at least one oxygen atom. In a most preferred embodiment of the method of the invention, the oxygenate in the starting material comprises one or more alcohols, preferably aliphatic alcohols, where the aliphatic alcohol (s) residue contains from 1 to 20 carbon atoms, preferably from 1 to 10 carbon atoms, and most preferably from 1 up to 4 carbon atoms. Alcohols that can be used as starting material in the process of the invention include lower straight chain and branched aliphatic alcohols and their unsaturated analogs. Non-limiting examples of oxygenates include methanol, ethanol, n-propanol, isopropanol, methyl ethyl ether, dimethyl ether, diethyl ether, diisopropyl ether, formaldehyde, dimethyl carbonate, dimethyl ketone, acetic acid, and mixtures thereof. In a most preferred embodiment, the starting material is selected from one or more products such as methanol, ethanol, dimethyl ether, diethyl ether and a combination thereof, more preferably methanol and dimethyl ether, and most preferably methanol.

In one embodiment, the starting material includes one or more diluents, typically used to reduce the concentration of the starting material, and are usually non-reactive with the starting material or molecular sieve catalyst composition. Non-limiting examples of diluents include helium, argon, nitrogen, carbon monoxide, carbon dioxide, water, substantially non-reactive paraffins (mainly alkanes such as methane, ethane and propane), substantially non-reactive aromatic compounds and mixtures thereof. The most preferred diluents are water and nitrogen, with water being particularly preferred.

The diluent is either added directly to the starting material entering the reactor, either added directly to the reactor, or added together with the molecular sieve catalyst composition. In one embodiment, the amount of diluent in the starting material is in the range of from about 1 to about 99 mol%, based on the total number of moles of the starting material and diluent, preferably from about 1 to 80, more preferably from about 5 to about 50, most preferably from about 5 to about 25 mol%. In one embodiment, other hydrocarbons are added directly or indirectly to the starting material, which include olefin (olefins), paraffin (paraffins), aromatic compound (s) (for the addition of aromatic compounds see, for example, I8 No. 4677242) and mixtures thereof , preferably propylene, butylene, pentylene and other hydrocarbons comprising 4 or more carbon atoms, or mixtures thereof.

Molecular sieves capable of converting an oxygen-containing substance into an olefinic compound include zeolitic as well as non-zeolitic molecular sieves and are materials of types with large, medium or small pores. Non-limiting examples of these molecular sieves are small pore molecular sieves, ΑΕΙ, LRT, APC, ΑΤΝ, ATT, ATU, Λ \ ν \ ν. ΒΙΚ, CA8, CHA, CH1, PAS, EEV, ΕΌΙ, ΕΒΙ, LLC, ΚΕΙ, LEE, LOW, LTA, РА, RAI, ΡΗΙ, VNO, VOS, TNO and their substituted forms; medium pore molecular sieves, AEO, AEB, EIO, NEI, REV, MEI, ΜΕΙ, MTT, MTT, ΤΟN and their substituted forms; and molecular sieves with large pores, EMT, EAI and their substituted forms. Other molecular sieves include ΑNΑ, BEA, CH, CbO, EOH ΟΙ8, Lb, MEB, MOB, Μ \ ν \ ν, and 8OP. Non-limiting examples of preferred molecular sieves, in particular for converting a starting material comprising oxygenates to olefin (s), include AEB, AGC, BEA, CHA, E1) E EAI, EEB, ΟΙ8, LTA, LET, MEB, MN, MOB , MTT, MTT, TAM and TOC In one preferred embodiment, the molecular sieve of the invention has an ΑΕI topology or a CHA topology, or a combination thereof, most preferably a CHA topology.

All materials of molecular sieves have a three-dimensional four-bound framework structure located in the corner of the common tetrahedron TO4, where T denotes any tetrahedrally coordinated cation. These molecular sieves are typically described in terms of the size of the ring, which determines the pore, and this size is based on the number T of atoms in the ring. Other frame-type characteristics include the placement of the rings that make up the cavity, and if any, the size of the channels and the distance between the cavities (see the work of Uap Vekkit et al. , pp. 1-67, Ekeuet 8s1epse, V.U., AtDetbat, No. 1yet1apb (2001)).

Molecular sieves with small, medium and large pores have frame types with rings of 4 to 12 membered or larger. In a preferred embodiment, the molecular sieves have 8-, 10-, or 12-membered or larger ring structures, and the average pore size is in the range of about 3 to 15 A. In the most preferred embodiment, the molecular sieves in the invention, preferably silicoaluminophosphate molecular sieves, have 8 membered rings and an average pore size of less than about 5 A, preferably in the range from 3 to about 5 A, more preferably from 3 to about 4.5 A, and most preferably from 3.5 to about 4.2 A.

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Preferred molecular sieves, especially zeolite and zeolite type molecular sieves, have a molecular skeleton with one, preferably two or more common angled tetrahedral units [TO ₄ ], more preferably two or more tetrahedral units [8ίΘ ₄ ], [A1O ₄ ] and / or [PO _4], and most preferably tetrahedral units [8ίΘ _4], [A1O _4] and [PO _4]. These molecular sieves on a silicon, aluminum and phosphorus basis and metal-containing molecular sieves on a silicon, aluminum and phosphorus basis are described in detail in numerous publications, including, for example, I8 No. 4567029 (MeAPO, where Me means Md, Mn, Ζη or Co), I8 No. 4440871 (8APO), EP-A 0159624 (EBAR8O, where E1 denotes Az, Be, B, Cr, Co, Ca, Ce, Her, S, Md, Mn, Mn or Ζη), I8 No. 4554143 (HerARO), I8 No. 4822478, 4683217, 4744885 (EAYAR8O), EP-A 0158975 and I8 No. 4935216 (2pAR8O), EP-A 0161489 (CoAP8O), EP-A 0158976 (EAPO, where E represents Co, Her, Md, Mn, Τι or Ζη), I8 № 4,310,440 (A1RO _4), EP-A 0158350 (8EYAR8O) I8 4973460 (S1AR8O), I8 No. 4789535 (LARO), I8 No. 4992250 (CeAR8O), I8 No. 4888167 (CeARO), I8 No. 5057295 (VAR8O), I8 No. 4738837 (STAR8O), I8 No. 4759919 and SАОРОО) (48А106) I8 No. 4758419, 4882038, 5434326 and 5478787 (MdAR8O), I8 No. 4554143 (EYAARO), I8 No. 4894213 (AgAR8O), I8 No. 4913888 (AzARO), I8 No. 4686092, 4846956 and 4793833 (MpAR8O, No. 5345011 and 6156931 (MpARO), I8 No. 4737353 (BeARO), I8 No. 4940570 (BeARO), I8 No. 4801309, 4684617 and 4880520 (Т1АР8О), I8 No. 4500651, 4551236 and 4605492 (Т1АРО) 4824554, 4744970 (СоАР8О), И8 No. 4735806 (СаАР8О), ЕР-А 0293937 (ОАРЗО, where О denotes a frame oxide unit of YuO ₂ ]), as well as И8 No. 4567029, 4686093, 4781814, 4793984, 4801364, 485376, 4983876, 4953177, 485376. , 4952384, 4956164.4956165, 4973785, 5241093, 5493066 and 5675050, and all they are fully incorporated into the present description by reference.

Other molecular sieves include those presented in EP-B1 0888187 (microporous crystalline metal phosphates, 8APO ₄ (UI-6)), I8 No. 6004898 (molecular sieve and alkaline earth metal), patent application I8 serial No. 09/511943, filed 24 February 2000 (combined cocatalyst for hydrocarbons), PCT application UO 01/64340 published on September 7, 2001 (thorium-containing molecular sieve) and in B.8x51ac. For example, Wo Wo Wo Wo wk W e w O w e w e W e w O w e w e w e w W e w e w W e w e w W e w W e w O w (W) (1992), all of which are hereby incorporated by reference in their entirety.

More preferred silicon, aluminum, and / or phosphorus-containing molecular sieves and aluminum, phosphorus, and optionally silicon-containing molecular sieves include aluminophosphate (ALO) molecular sieves and silicoaluminophosphate (8APO) molecular sieves, as well as substituted, preferably metal-substituted, ALO and 8APO sieves. The most preferred molecular sieves are 8APO molecular sieves and metal-substituted 8APO molecular sieves. In one embodiment, the metal is an alkali metal of group 1A of the Periodic table of elements, alkaline earth metal of group IIA of the Periodic table of elements, rare earth metal of group BW, including lanthanides (lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium , holmium, erbium, thulium, ytterbium and lutetium), scandium and yttrium of the Periodic table of elements, transition metals of groups 1УВ, УВ, УТВ, UPВ, УШВ and 1В of the Periodic table of elements and mixtures of any of these metals. In one preferred embodiment, the metal is selected from the group consisting of Co, Cr, Cu, Eg, Ca, Ce, Md, Mn, N1, 8n, Τι, Ζπ, Ζτ and mixtures thereof. In another preferred embodiment, the metal atoms discussed above are introduced into the molecular sieve frame through a tetrahedral unit, such as [MeO ₂ ], they carry a full charge, depending on the valence state of the metal substituent. So, for example, in one embodiment, when the valence state of the metal substituent is +2, +3, +4, +5 or +6, the total charge of the tetrahedral unit is in the range of -2 and +2.

In one embodiment, the molecular sieve, as described in many of the aforementioned I8 patents, is represented by the empirical formula (on an anhydrous basis):

shK: (M _x A1 _at P ₂ ) O ₂ in which K represents at least one structural directing agent, preferably an organic structural directing agent; t represents the number of moles of K per mole (M _x A1 _at P ₂ ) O ₂ and the value of t is from 0 to 1, preferably from 0 to 0.5, and most preferably from 0 to 0.3; each of x, y and ζ denotes the molar fraction of elements A1, P and M in the form of tetrahedral oxides, where M denotes a metal atom selected from one of the groups 1A, II A, 1B, 111B, 1UV, UV, UTV, UT1V, UShV and lanthanides of the Periodic Table of the Elements, with M being preferred from one of the groups including Co, Cr, Cu, Ei, Ca, Ce, Md, Mn, N1, 8n, Τι, Ζη and Ζτ. In one embodiment, the value of m is greater than or equal to 0.2, and the values of x, y, and ζ are greater than or equal to 0.01.

In another embodiment, t means from more than 0.1 to about 1, x means from more than 0 to about 0.25, the value of y is in the range from 0.4 to 0.5, and the value of ζ is in the range from 0.25 to 0.5, a more preferred value of t is from 0.15 to 0.7, x means from 0.01 to 0.2, y means from 0.4 to 0.5, and ζ means from 0.3 to 0, 5.

Non-limiting examples of 8APO and APO molecular sieves used in the invention include one or a combination of 8APO-5, 8APO-8, 8APO-11, 8APO-16, 8APO-17, 8APO-18, 8APO-20, 8 ARO-31 sieves , 8ARO-34, 8ARO-35, 8ARO-36, 8ARO-37, 8ARO-40, 8ARO-41, 8ARO-42, 8ARO-44 (I8 No.

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6162415), 8LRO-47, 8LRO-56, ALRO-5, LRO-11, LRO-18, LRO-31, LRO-34, LRO-36, LRO-37, ALRO-46 and metal-containing variants of these molecular sieves. More preferred zeolite type molecular sieves include one or a combination of 8LRO-18, 8LRO-34, 8LRO-35, 8LRO-44, 8LRO-56, LRO-18 and LRO-34 sieves, even more preferably one or a combination of 8LRO-18 sieves, 8LRO-34, LRO-34 and LRO-18, as well as their metal-containing molecular sieves, and most preferably one or a combination of sieves 8LRO-34 and LRO-18, as well as metal-containing variants of these molecular sieves.

In one embodiment, the molecular sieve is an intergrowth material having two or more distinct phases of crystalline structures within a single molecular sieve composition. So, in particular, fused molecular sieves are described in patent application I8 serial No. 09/924016, filed on August 7, 2001, and PCT application UO 98/15496, published on April 16, 1998, both of which are fully included in the present description is by reference. In another embodiment, the molecular sieve comprises at least one intergrown phase of the frameworks of types LE1 and CHA. So, for example, 8LRO-18, LRO-18 and Pb \ U-18 have a frame like LE1, and 8LRO-34 has a frame like CHA.

In one embodiment, the molecular sieves used in the invention are combined with one or more other molecular sieves. In another embodiment, preferred silicoaluminophosphate or aluminophosphate molecular sieves or a combination thereof are combined with another molecular sieve of the following non-limiting examples described in the following sources: beta zeolite (in I8 No. 3308069), Ζ8Μ-5 (in I8 No. 3702886, 4797267 and 5783321), Ζ8Μ-11 (in I8 No. 3709979), Ζ8Μ-12 (in I8 No. 3832449), Ζ8Μ-12 and Ζ8Μ-38 (in I8 No. 3948758), Ζ8Μ-22 (in I8 No. 5336478), Ζ8Μ-23 (in I8 No. 4076842), Ζ8Μ-34 (in I8 No. 4086186), Ζ8Μ-35 (in I8 No. 4016245), Ζ8Μ-48 (in I8 No. 4397827), Ζ8Μ-58 (in I8 No. 4698217), MSM-1 (in I8 No. 4639358), MSM-2 (in I8 No. 4673559), MSM-3 (in I8 No. 4632811), MSM-4 (in I8 No. 4664897), MSM-5 (in I8 No. 4639357), MSM-9 (in I8 No. 4880611), MSM -10 (in I8 No. 4623527), MSM-14 (in I8 No. 4619818), MSM-22 (in I8 No. 4954325), MSM-41 (in I8 No. 5098684), Μ-418 (in I8 No. 5102643), MSM -48 (in I8 No. 5198203), MSM-49 (in I8 No. 5236575), MSM-56 (in I8 No. 5362697), LRO-11 (in I8 No. 4310440), titanium aluminum silicates (TL8O), TL8O-45 (EP- L 0229295), borosilicates (in I8 No. 4254297), titanium aluminum phosphates (TARO) (in I8 No. 4500651), a mixture of materials Ζ8Μ-5 and Ζ8Μ-11 (in I8 No. 4229424), ESK-18 (in I8 No. 5278345), LRO -5, bound by 8LRO-34 (in I8 No. 5972203), PCT application XV O 98/57743, published December 23, 1988 (molecular sieve and Fischer Tropsch catalyst), I8 No. 6300535 (zeolites bound by ΜΡΙ) and mesoporous molecular sieves (in I8 № 6284696, 5098684, 5102643 and 5108725), all of which are fully incorporated herein by reference.

Based on molecular sieves, catalysts are prepared or made by combining the synthesized molecular sieves with a binder and / or matrix material to form a molecular sieve catalyst composition or a molecular sieve catalyst composition. This molecular sieve catalyst composition is formed to form particles of effective shape and size by conventional methods such as spray drying, granulation, extrusion, etc.

There are many different binders that can be used to form a molecular sieve catalyst composition. Non-limiting examples of binders that can be used alone or in combination include hydrated alumina, silica, and / or various types of inorganic oxide sols. One preferred sol-containing alumina is aluminochlorhydrol. Inorganic oxide sol acts like an adhesive that binds synthesized molecular sieves and other materials, such as a matrix, to one another, especially after heat treatment. When heated, an inorganic oxide sol, preferably having a low viscosity, is converted into an inorganic oxide matrix component. Thus, for example, an alumina sol is usually converted into an alumina matrix as a result of heat treatment.

Alumochlorohydrol, a hydroxylated aluminum sol containing a chloride counterion, corresponds to the general formula A1 _t Oη (ОΗ) _ο С1ρ · x (Η ₂ О), in which m denotes a number from 1 to 20, n denotes a number from 1 to 8, o denotes a number from 5 to 40, p denotes a number from 2 to 15, and x denotes a number from 0 to 30. In one embodiment, the binder is a product of L (zodoposhchsb-P ^ O) described in the work Ο.Μ.ΧνοΙΙοηηαη and al., 81ib.8sht.8s1. Apb Ca1a1 .. 76, ss. 105144 (1993), which is incorporated herein by reference. In another embodiment, one or more binders are combined with one or more other alumina materials, non-limiting examples of which include, but are not limited to, aluminum oxyhydroxide, γ alumina, boehmite, diasporas, and transition aluminas such as α-alumina, β-alumina , γ-alumina, δ-alumina, ε-alumina, κ-alumina and ρ-alumina, aluminum trihydroxide such as gibbsite, bayerite, nordstrandit, doyelite and mixtures thereof.

- 7 007979

In another embodiment, the binders are alumina sols, including mainly alumina, optionally containing a certain amount of silicon. However, in yet another embodiment, the binders are peptized alumina obtained by treating alumina hydrates such as pseudoboehmite with an acid, preferably an acid that does not contain halogen, resulting in the formation of sols or aluminum ion solutions. Non-limiting examples of technically available colloidal alumina sols include products No. 11eo 8676, available from No. 11eo ΟΊιοιηίοαΙ Co., Naperville, Illinois, and Νναοοί. available at TNE RO Sogrogayoi, Valley Forge, PA.

In a preferred embodiment, the molecular sieve is combined with one or more matrix materials. Matrix materials, as a rule, effectively reduce the total cost of the catalyst, act as heat sinks, promoting thermal protection of the catalytic composition, for example during recovery, densifying the catalytic composition, increasing the strength of the catalyst, in particular crush resistance and abrasion resistance, and controlling the conversion rate in a particular process.

Non-limiting examples of matrix materials include one or more of the following: rare earth metals, metal oxides including titanium dioxide, zirconia, magnesium oxide, thorium dioxide, beryllium oxide, quartz, silicon dioxide or sols, and mixtures thereof, for example silicon dioxide / magnesium oxide , silica / zirconia, silica / titanium dioxide, silica / alumina and silica / alumina / thorium. In one embodiment, matrix clays are natural clays, such as clays from the montmorillonite and kaolin families. These natural clays include subbentonites and those kaolins that are known, for example, as Όίχίο, MeM-cpss, Ceogd1a and Popba clays. Non-limiting examples of other matrix materials include halloysite, kaolinite, dicit, nakrit and anoxite. In one embodiment, the matrix material, preferably any of the clays, is treated using well-known modification methods, such as calcination and / or acid treatment, and / or chemical treatment.

In one preferred embodiment, the matrix material is clay or a clay type composition, preferably clay or a clay type composition having a low content of iron or titanium dioxide, and the most preferred matrix material is kaolin. Kaolin has been found to form pumpable sludge with a high solids content, it has a low fresh surface area, and due to its lamellar structure it is easily compacted. A preferred average particle size of the matrix material, most preferably kaolin, is from about 0.1 to about 0.6 μm with a particle size distribution of Ό90 less than about 1 μm.

In another embodiment, the mass ratio between the binder and the matrix material used to prepare the molecular sieve catalyst composition is from 0: 1 to 1:15, preferably from 1:15 to 1: 5, more preferably from 1:10 to 1 : 4, and most preferably from 1: 6 to 1: 5. It was found that with a high sieve content and a lower matrix content, the operational properties of the molecular sieve catalyst composition are improved, however, with a reduced sieve content and a high content of matrix material, the abrasion resistance of the composition increases.

In another embodiment, the prepared molecular sieve catalyst composition comprises from about 1 to about 99 wt.%, More preferably from about 5 to about 90 wt.%, And most preferably from about 10 to about 80 wt.%, The molecular sieve in terms of on the total weight of the molecular sieve catalyst composition.

In yet another embodiment, the weight percent of the binder in the spray dried molecular sieve catalyst composition based on the total weight of the binder, molecular sieve and matrix material is from about 2 to about 30 wt.%, Preferably from about 5 to about 20 wt. %, and more preferably from about 7 to about 15 wt.%.

After molding the molecular sieve catalyst composition in a substantially dry or dried state to further solidify and / or activate this molded catalyst composition, a heat treatment, such as calcining at elevated temperature, is usually carried out. The usual medium for calcination is air, which typically includes a small amount of water vapor. Typical calcination temperatures range from about 400 to about 1000 ° C, preferably from about 500 to about 800 ° C, and most preferably from about 550 to about 700 ° C, preferably in a calcination medium such as air, nitrogen, helium , flue gas (combustion product with a lack of oxygen) or any combination thereof.

The process of converting the starting material, primarily the starting material including one or more oxygen-containing substances, in the presence of a molecular sieve catalyst composition according to the invention is carried out in the form of a reaction process in a reactor, this process being a fixed-bed process, a fluidized-bed process (including - 8 007979 tea process with a turbulent bed), preferably a continuous process with a fluidized bed, and most preferably a continuous process with a fluidized bed thin layer and high flow rate.

Such reaction processes can be carried out in a variety of catalytic reactors, such as hybrid reactors, in which there are reaction zones with a dense bed or a fixed bed and / or reaction zones with a fluidized bed and a high flow rate, combined with each other, circulating fluidized bed reactors, vertical pipe reactors, etc. Acceptable conventional types of reactors are described, for example, in patents I8 No. 4076796 and I8 No. 6287522 (double vertical pipe) and R1shb12ayoi Epshpssgsch. Κ.Κιιηίί and O. Leuey8r1e1, Koje E. Kpsdsg Ri1kksd Sotraiu, No. \ ν Wogk, No. \ ν Wogk 1977, all of which are fully incorporated into this description by reference.

Reactors of the preferred type are vertical tube reactors, generally described in Ketket Keaslot, Ish ^ ayoi apb P1shb-Rayyu Zuietk, ss. 48-59, Ε.Ά ^ ηζ and O.R.O1kto, Keshkoy RiUkshd Sotrogakoi, No. \ ν Wogk, 1960, in patent I8 No. 6166282 (reactor with a fluidized bed and a high flow rate) and patent application I8 serial No. 09 / 564613, filed May 4, 2000 (reactor with many vertical pipes), all of which are fully incorporated into this description by reference.

In a preferred embodiment, the process line of a fluidized bed process or a fluidized bed process with a high flow rate includes a reactor system, a recovery system, and a recovery system. A preferred reactor system is a fluidized bed reactor system comprising a first reaction zone inside one or more vertical pipe reactors and a second reaction zone inside at least one separation vessel, preferably including one or more cyclones. In one embodiment, one or more vertical pipe reactors and a separation vessel are contained within a single reaction vessel. Fresh starting material, preferably comprising one or more oxygen-containing substances, optionally with one or more diluents, is sent to one or more vertical pipe reactors into which a zeolite or a zeolite type molecular sieve catalyst composition or a heat-treated version thereof is introduced. In one embodiment, the molecular sieve catalyst composition or its heat-treated version is brought into contact with a liquid or gas, or a combination thereof, before being introduced into a vertical pipe reactor (s), the preferred liquid being water or methanol, and the gas being an inert gas such like nitrogen.

In one embodiment, the amount of fresh starting material sent to the reactor system separately or together with the vaporous starting material is in the range from 0.1 to about 85 wt.%, Preferably from about 1 to about 75 wt.%, More preferably from about 5 to about 65 wt.%, Calculated on the total weight of the starting material, including all the diluent contained therein. In a preferred embodiment, the liquid and vaporous starting materials are characterized by the same composition or include varying proportions of the same or different starting materials with the same or different diluent.

In a preferred embodiment, the feed to the reactor system in the first reactor zone is partially or completely converted to a gaseous effluent that enters the separation vessel together with the heat-treated molecular sieve catalyst composition. Preferably, the cyclone (s) inside the separation vessel is designed so that the molecular sieve catalyst composition, preferably the heat-treated molecular sieve catalyst composition, is separated from the gaseous effluent comprising one or more olefins within the separation zone. Cyclones are preferred, however, gravitational effects within the separation vessel also allow separation of the catalyst compositions from the gaseous effluent. Other methods for separating the catalyst compositions from the gaseous effluent include the use of plates, caps, elbows, etc.

In one embodiment of the separation system, this separation system includes a separation vessel, wherein the lower part of the separation vessel is typically a stripping zone. In this stripping zone, the heat-treated molecular sieve catalyst composition is contacted with a gas, preferably one of the following components, or a combination of water vapor, methane, carbon dioxide, carbon monoxide, hydrogen or an inert gas such as argon, preferably water vapor, to separate adsorbed hydrocarbons from the heat-treated molecular sieve catalyst composition, which is then introduced into the reduction system. In another embodiment, the stripping zone is located in a vessel separated from the separation vessel, and gas is passed at an hourly average gas flow rate (LHG) of from 1 to about 20,000 h ^-1 , calculated on the volume of gas relative to the volume of the heat-treated molecular sieve catalyst composition, preferably elevated temperature, from 250 to about 750 ° C, before

- 9 007979 respectfully from about 350 to 650 ° C., over a heat-treated molecular sieve catalyst composition.

The conversion temperature at which the conversion process is carried out, specifically within the reactor system, is in the range of from about 200 to about 1000 ° C, preferably from about 250 to about 800 ° C, more preferably from about 250 to about 750 ° C, even more preferably from from about 300 to about 650 ° C and, nevertheless, more preferably from about 350 to about 600 ° C, and most preferably from about 350 to about 550 ° C.

The pressure during the conversion, under which the conversion process is carried out, specifically inside the reactor system, is not critical. The pressure during the conversion is due to the partial pressure of the starting material, excluding all diluent contained in it. The absolute pressure under which the conversion process is carried out is typically in the range of from about 0.1 to about 5 MPa, preferably from about 5 to about 1 MPa, and most preferably from about 20 to about 500 kPa.

Mass hourly velocity (MES), in particular during the conversion of the starting material, including one or more oxygen-containing substances, in the presence of a molecular sieve catalyst composition inside the reaction zone, is defined as the total mass of the starting material, excluding all diluents supplied to the reaction zone per hour by weight of the molecular sieve in the molecular sieve catalyst composition in the reaction zone. The Ministry of Emergencies is maintained at a level sufficient to maintain the catalyst composition inside the reactor in a fluidized state.

The values of the MOE, as a rule, are in the range from about 1 to about 5000 h ^-1 , preferably from about 2 to about 3000 h ^-1 , more preferably from about 5 to about 1500 h ^-1 , and most preferably from about 10 to about 1000 h ^-1 . In one preferred embodiment, the MOE is greater than 20 h ⁻¹ , and the preferred value of the MOE for the conversion of the starting material including methanol and dimethyl ether is in the range of from about 20 to about 300 h ⁻¹ .

In a preferred embodiment, the gas flow per unit cross-section of the stream (RHP) of the starting material, including diluent and reaction products, inside the reactor system is sufficient to fluidize the molecular sieve catalyst composition inside the reaction zone in the reactor. RGP during the process, specifically inside the reactor system, more specifically inside the vertical pipe reactor (s), is at least 0.1 m / s (meter / second), preferably more than 0.5 m / s, more preferably more than 1 m / s, even more preferably more than 2 m / s, however, even more preferably more than 3 m / s, and most preferably more than 4 m / s (see, for example, patent application I8 serial No. 09/708753, filed 8 November 2000, which is incorporated herein by reference).

In one preferred embodiment of the process for converting an oxygenate to olefin (s) using a molecular sieve silica-alumina phosphate catalyst composition, this process is carried out at an MOE of at least 20 h ⁻¹ and a temperature-adjusted normalized methane selectivity (STSM) of less than 0.016, preferably less than or equal to 0.01 (see, for example, patent I8 No. 5952538, which is fully incorporated into this description by reference).

In another embodiment of the methods for converting an oxygen-containing substance, such as methanol, into one or more olefins using a molecular sieve catalyst composition, the MES value is from 0.01 to about 100 h ⁻¹ at a temperature of from about 350 to 550 ° C. and the molar ratio between silicon dioxide and Me ₂ About ₃ (Me denotes an element of group ΙΙΙΑ or VIII of the Periodic table of elements) from 300 to 2500 (see, for example, application EP-B1 0642485, which is fully incorporated into the present description by ss trees).

Other methods for converting an oxygen-containing substance, such as methanol, into one or more olefins using a molecular sieve catalyst composition are described in PCT application νΟ 01/23500, published April 5, 2001 (reduction in the amount of propane with the average exposure of the catalyst to the starting material according to at least 1.0), which is incorporated herein by reference.

In accordance with one embodiment, the degree of conversion of the primary oxygenate, for example methanol, is from 90 to 98 wt.%. In another embodiment, the methanol conversion is from 92 to 98% by weight, preferably from 94 to 98% by weight.

In another embodiment, the degree of methanol conversion is from greater than 98 to less than 100% by weight. In another embodiment, the methanol conversion is from 98.1 to less than 100 wt.%, Preferably from 98.2 to 99.8 wt.%. In another embodiment, the degree of methanol conversion is from 98.2 to less than 99.5 wt.%, Preferably from 98.2 to 99 wt.%.

In the process of producing olefins from an oxygen-containing material, a significant amount of water is formed as a by-product. Large amounts of water can be removed chilled.

- 10 007979 by lowering the olefin stream leaving the oxygen-containing reactor to a temperature below the condensation temperature of the water in the stream. In a preferred embodiment, the temperature of the product stream is reduced to a level below the condensation temperature of the oxygen-containing substance sent to the process of converting the oxygen-containing substance into olefins. In some embodiments, the product stream needs to be cooled below a condensation temperature of methanol.

One type of equipment that is effective in cooling a stream of olefins from a reaction process for converting an oxygen-containing substance to olefins is a cooling tower. In the cooling column, the cooling fluid comes into direct contact with the olefin stream, cooling the stream to a target condensation temperature. As a result of condensation, a stream comprising condensed water is formed, which usually leaves the cooling tower in the form of a bottoms stream. Olefins usually come out of such a column as a stream of overhead. It is this overhead stream that includes dimethyl ether, which is to be isolated in accordance with the present invention. If a high concentration of water is still maintained in the head chase, then to further reduce the concentration of water, the absorbers described above can be used.

In one particular embodiment, the cooled olefin stream is further processed by compression, preferably multi-stage compression. Two, three, four or more steps may be provided, with two or three steps being preferred.

During or after multi-stage compression, the olefin stream may optionally be washed using a water absorber as described above. Such flushing using a water absorber makes it possible to reduce problems associated with gas hydration and / or the formation of a separate phase of water. In a preferred embodiment, between stages, preferably multi-stage compression with washing with a water absorber. Then, dimethyl ether and C ₄ + hydrocarbon components are isolated from the olefin stream.

In one embodiment of the present invention, the olefin stream is separated into a first fraction and a second fraction, the main part of ethylene and / or propylene being isolated with the first fraction, and the main part of dimethyl ether is isolated with the second fraction. In a suitable embodiment, the separation is carried out at a gauge pressure below 200 psi (absolute pressure: 1480 kPa). In a preferred embodiment, the separation is carried out at a gauge pressure of from about 100 psi (absolute pressure 791 kPa) to about 200 psi (absolute pressure 1480 kPa), more preferably from about 120 psi (absolute pressure 929 kPa) to about 180 psi (absolute pressure 1342 kPa).

In another embodiment, the separation process is carried out in a distillation column such that the first stream or overhead stream is diverted at a temperature not exceeding about 30 ° E (-1.1 ° C). In a preferred embodiment, the first stream or overhead stream is diverted at a temperature of from about 0 ° E (-17.8 ° C) to about 30 ° E (-1.1 ° C), more preferably from about 10 ° E (-12, 2 ° C) to about 25 ° E (-3.9 ° C).

In carrying out the present invention, the temperature of the second fraction or fraction of bottoms of the distillation column must be maintained at a level that can reduce pollution problems. In one embodiment, the average temperature of the second fraction is not higher than about 210 ° E (99 ° C), preferably not higher than about 200 ° E (93 ° C), and more preferably not higher than about 190 ° E (88 ° C).

In addition, when carrying out the present invention, it is necessary to add a water absorber, which is presented above, to the vessel in which the process of separating oxygen-containing contaminants from the resulting olefin stream is carried out. An additional advantage of adding a water absorber directly to the separation vessel can be a reduction in the amount of free water and / or clathrates formed in the vessel.

In one embodiment of the invention, a water scavenger is added to the vessel to isolate the oxygenate in an amount sufficient to substantially reduce the concentration of the oxygenate (eg, dimethyl ether) or the amount of clathrates formed. In a preferred embodiment, the water absorber should be added to the vessel at a molar ratio between the water absorber and the total weight of the olefin feed entering the separation vessel from about 4: 1 to about 1: 5000. To reduce the amount of oxygenate, higher molar ratios are required between the water scavenger and the total amount of olefin feed, preferably from about 4: 1 to about 1: 1, more preferably from about 3: 1 to about 1.2: 1, and most preferably from about 2.5: 1 to about 1.5: 1. To reduce the amount of clathrates formed, lower molar ratios are required between the water scavenger and the total amount of olefin feed, preferably from about 1: 1 to about 1: 5000, more preferably from about 1: 100 to about 1: 4000, and most preferably from about 1 : 500 to about 1: 3000.

In one embodiment of the present invention, the separation is carried out by conventional distillation. Distillation is carried out using a vessel or column equipped with an internal nozzle

- 11 007979 or plates that create a temperature difference in the direction from the top to the base of the column. The upper part of the column is the colder part, and the higher volatile components of the feed come out of the upper part of the column.

When carrying out the present invention from a stream of olefins, including dimethyl ether, it is necessary to obtain a high concentration of ethylene and propylene. In one embodiment, the dimethyl ether is separated from the ethylene and propylene olefins in the stream. In this embodiment, ethylene and propylene are isolated with the first fraction, and dimethyl ether is isolated with the second fraction. The first fraction, as a rule, is apparently the overhead or intermediate fraction of the distillation column, and the second fraction is apparently the fraction of bottoms or other intermediate fraction of the distillation column.

In one embodiment, the bulk of the ethylene and propylene of the resulting olefin stream is usually isolated with the first fraction, and the bulk of the dimethyl ether of the resulting olefin stream is usually isolated with the second fraction. In a preferred embodiment, the first fraction typically comprises at least about 75% ethylene and propylene of the resulting olefin stream, more preferably at least about 85%, and most preferably at least about 95%.

In another embodiment, at least about 75% of the dimethyl ether of the resulting olefin stream is usually isolated with a second fraction. In a preferred embodiment, at least about 85% of dimethyl ether of the resulting olefin stream is usually isolated with a second fraction, more preferably at least about 95%, and most preferably at least about 99%.

Most of the propane of the resulting olefin stream can be isolated with either the first or second fraction. If the main part of the propane is contained in the first fraction, then there is a need to isolate smaller amounts of heavier products with the second fraction. However, when the majority of the propane is in the first fraction, the concentration of dimethyl ether in this first fraction may be slightly higher. In this embodiment, the first fraction typically contains at least about 60% propane of the resulting olefin stream, preferably at least about 70%, and more preferably at least about 80%, and this first fraction usually comprises no more than about 50 weight parts ./mln, preferably not more than about 25 parts by weight per million, more preferably not more than about 10 parts by weight per million of dimethyl ether, and most preferably not more than about 5 parts by weight of dimethyl ether.

If the bulk of the propane of the resulting olefin stream is isolated with a second fraction, then the concentration of dimethyl ether in the first fraction is usually much lower. In this embodiment, at least about 60% of the propane of the resulting olefin stream, preferably at least about 70%, and more preferably at least about 80%, are usually in the second fraction, and this second fraction includes no more than about 25 parts by weight ./mln, preferably not more than about 15 parts by weight per million, more preferably not more than about 5 parts by weight per million of ether, and most preferably not more than about 1 parts by weight of dimethyl ether.

In another embodiment, the second fraction also typically includes certain hydrocarbon compounds containing four or more carbon atoms. These compounds are also known as C ₄ + components. The number of C ₄ + components in the second fraction can be varied, in particular depending on the amount of propane in the second fraction. So, for example, the second fraction may include from about 5 to about 90 wt.% Components With ₄ +. In a preferred embodiment, the second fraction comprises from about 25 to about 80 wt.% C ₄ + components, more preferably from about 35 to about 75 wt.% C ₄ + components.

An additional advantage in carrying out the present invention is that the process in the separation vessel is carried out at a temperature and under pressure, allowing to isolate at least the main part (i.e. at least 50%) of all propadiene from the resulting olefin stream, which may be contained. In this embodiment, propadiene would be preferable to separate with the second fraction together with dimethyl ether. In a preferred embodiment, it would be desirable to isolate at least about 75%, more preferably at least about 85%, and most preferably at least about 95% propadiene. When isolating all propadiene in this way, it would be necessary to include the isolation of a substantial portion of all methylacetylene, which may also be contained in the resulting olefin stream. This is because methyl acetylene under normal conditions has a lower boiling point than propadiene and dimethyl ether. Removing propadiene and methylacetylene from the resulting olefin stream would provide a substantial benefit in that the first fraction comprising ethylene and / or propylene would include monoolefin compounds in a very high concentration. Such a stream would require, if at all, a small hydrotreatment, which, as a rule, may be necessary to reduce the amount of diolefins or alkylene compounds released with the first fraction.

- 12 007979

The use of the present invention is particularly advantageous in the treatment of ethylene and propylene streams included in the first fraction to remove entrained acid gases, such as CO ₂ , which may also be contained in such a fraction. The benefit is that when performing the present invention, the separated ethylene and propylene streams typically include relatively few hydrocarbon components that cause pollution problems in such acid gas treatment systems.

In carrying out the present invention, systems for treating acid gases with solid or liquid substances can be used. In any system, acid gas is removed from the ethylene and / or propylene stream in the first fraction by contacting this first fraction with an acid gas absorbent or adsorbent. Examples of such absorbents or adsorbents include amines, potassium carbonate, caustic soda, alumina, molecular sieves and membranes, in particular membranes formed from polysulfone, polyimide, polyamide, glassy polymer and cellulose acetate. Solutions comprising amines and alkaline compounds are preferred, with alkaline compounds being more preferred.

Aqueous solutions of amines that can be used in carrying out the present invention may include any amine compound or compounds suitable for the absorption of acid gases. Examples include alkanolamines such as triethanolamine (TEA), methyldiethanolamine (MDEA), diethanolamine (DEA), monoethanolamine (MEA), diisopropanolamine (DIPA) and hydroxyaminoethyl ether (GAE). Effective concentrations may range from about 0.5 to about 8 moles of amine per liter of aqueous solution.

Piperazine and / or monomethylethanolamine (MMEA) can be added to aqueous amine solutions to increase their absorption capacity. These additives can be introduced into the aqueous solution at a concentration of from about 0.04 to about 2 moles per liter of aqueous solution.

Alkaline compounds that can be used in carrying out the present invention are alkaline compounds that effectively remove acid gas from the olefin stream. Examples of such alkaline compounds include sodium hydroxide and potassium hydroxide.

After acid gas treatment, to rinse the captured material from the treated ethylene and / or propylene, it is necessary to rinse with water. Conventional equipment can be used. However, in the future, the water added at the same time from the selected streams of ethylene and / or propylene must be removed.

In one embodiment of the invention, the ethylene and propylene in the first fraction are washed with water, i.e. brought into contact with a stream of water. Such contacting is particularly advantageous when a water absorber is added to a vessel for separating an oxygen-containing substance, since the water absorber can be passed into the first fraction or overhead. Then, to remove a substantial part of the bypassed water absorber, it is better to rinse with water before treating the acid gases.

The present invention further includes an optional drying option. In this embodiment, a solid or liquid drying system can be used to remove water and / or an additional amount of oxygen-containing hydrocarbon from the first fraction.

In a solid drying system, ethylene and / or propylene, separated with the first fraction and optionally treated to remove acid gas and washed with water, are brought into contact with a solid adsorbent to further remove water and an oxygen-containing hydrocarbon to very low concentrations. The adsorption process is usually carried out in one or more fixed layers, including an acceptable solid adsorbent.

Adsorption can be used to remove water and oxygen-containing hydrocarbons to very low concentrations and to remove those oxygen-containing hydrocarbons, which, as a rule, cannot be removed using other processing systems. In a preferred embodiment, the adsorbent system used as part of the present invention includes many adsorbent layers. The presence of multiple layers provides the possibility of continuous separation without the need to stop the process for the regeneration of solid adsorbent. So, for example, in a three-layer system, as a rule, one layer is in operation, one layer is regenerated outside the production line, and the third layer is in a ready state.

The adsorbent solid or substances specifically used in the adsorbent layers depends on the types of contaminants removed. Examples of solid adsorbents for removing water and various polar organic compounds, such as oxygen-containing hydrocarbons and absorbent liquids, include alumina, silica, 3A molecular sieves, 4A molecular sieves and aluminosilicates. To remove water, as well as many oxygen-containing hydrocarbons, you can use layers, including mixtures of these sieves, or multiple layers, including various adsorbent solids.

In carrying out the present invention, one or more adsorption layers can be arranged in series or in parallel.

- 13 007979

In one example of sequential placement, the first layer is used to remove substances with the smallest and largest polarity molecules that are the easiest to remove. Then in this row are subsequent layers to remove oxygen-containing substances with molecules of a larger size and less polarity. As a specific example of the placement of one type at first, water is selectively removed using a molecular sieve. This layer is then followed by one or more layers comprising one or more less selective adsorbents, such as a molecular sieve with larger pores, for example 13X, and / or active alumina with a high specific surface area, such as the product 8е1ехот SE (trademark A1coa firms).

In another embodiment, the first layer is a 3.6 A molecular sieve capable of selectively removing both water and methanol. Further, this layer may be followed by one or more layers of material 13X or active alumina, which are described above.

Depending on the need, the adsorbent layers can be used at room temperature or at an elevated temperature and with either countercurrent or flow outflow. The recovery process of adsorbent materials can be carried out by conventional methods, including the processing of a stream of dry inert gas, such as nitrogen, at elevated temperature.

In a liquid drying system, a water absorber is used to remove water from the first fraction. A water absorber can be any liquid that effectively removes water from a stream of olefins. In a preferred embodiment, the same as described above is used as a water absorber.

A preferred olefin from the adsorption layers comprises less than about 100 parts by weight per million, more preferably less than about 10 parts by weight, and most preferably less than 1 parts by weight. In a preferred embodiment, the stream leaving the adsorption beds contains less than about 10 parts by weight of dimethyl ether, more preferably less than about 5 parts by weight, and most preferably less than about 1 part by weight.

The materials of ethylene and propylene streams processed and separated in accordance with the present invention can be polymerized to produce plastic compositions, for example polyolefins, in particular polyethylene and polypropylene. You can use any conventional method for producing polyethylene or polypropylene. Catalytic methods are preferred. Catalytic systems with metallocenes, Ziegler-Natta catalysts, chromium oxide and acids are particularly preferred (see, for example, patents I8 No. 3258455, 3305538, 3364190, 5892079, 4659685,4076698, 3645992, 4302565 and 4243691, moreover, descriptions of catalysts and methods in each of these patents is expressly incorporated herein by reference). Typically, these methods include contacting the ethylene or propylene product with a polyolefin forming catalyst under pressure and at a temperature that are effective to produce the polyolefin product.

In one embodiment of the present invention, the ethylene or propylene product is contacted with a metallocene catalyst to produce a polyolefin. In a suitable embodiment, the process for producing a polyolefin is carried out at a temperature in the range of about 50 and about 320 ° C. Such a reaction can be carried out under low, medium or high pressure, and it is always in the range from about 1 to about 3200 bar. An inert diluent can be used to carry out the process in solution. In a process of this type, it is necessary that the pressure is in the range from about 10 to about 150 bar, and preferably in the temperature range from about 120 to about 250 ° C. For gas phase processes, the preferred temperature is usually in the range of from about 60 to 120 ° C, and the operating pressure is from about 5 to about 50 bar.

In addition to polyolefins, numerous other olefin derivatives can be prepared from ethylene, propylene and C ₄ + olefins, in particular from butylene isolated in accordance with the present invention. Olefins isolated in accordance with the present invention can also be used to obtain compounds such as aldehydes, acids such as C ₂ Cl ₃ monocarboxylic acids, alcohols such as monohydric C ₂ -C _{1 2} alcohols, esters (derived from C ₂ -C ₁₂ monocarboxylic acids and monoatomic C ₂ -C ₁₂ alcohols), linear alpha olefins, vinyl acetate, ethylene dichloride and vinyl chloride, ethylbenzene, ethylene oxide, cumene, acrolein, allyl chloride, propylene oxide, acrylic acid, ethylene-propylene rubbers, and acryl also trimers and dimer ethylene and propylene. C4 + olefins, in particular butylene, are particularly suitable for the preparation of aldehydes, acids, alcohols, esters (derived from C ₅ -C _{3 3} monocarboxylic acids and C ₅ C 13 monohydric alcohols) and linear alpha olefins.

One example of the isolation of dimethyl ether from an olefin stream is shown in FIG. 1. This example illustrates one way to produce ethylene and propylene flux substantially depleted in dimethyl ether, as well as C4 + components. However, a common feature in carrying out the present invention is that dimethyl ether and C ₄ + components from the stream comprising ethylene and / or propylene are substantially removed before alkaline treatment. This means that both ethylene and propylene can be isolated in the first fraction, while dimethyl ether and C4 + components are isolated in the second fraction. Propane contained in the olefin stream may

- 14 007979 should be isolated either in the first or in the second stream, which depends on how low the required concentration of dimethyl ether in the first fraction is. Then, both ethylene and propylene can be isolated and further processed, for example, treated with alkaline washing or treated with water washing, processed separately or after separation.

In FIG. 1 shows one embodiment in which the olefin to be treated is produced in an oxygenate to olefin reaction system. In accordance with this drawing, methanol is sent via line 100 to a reactor 102 to convert an oxygen-containing substance to an olefin, where methanol is converted into an olefin stream including methane, ethylene, ethane, propylene, propane, dimethyl ether, C4 + components, water and other hydrocarbon components. The olefin stream through line 104 is directed to a cooling tower 106 where the olefin is cooled and water and other condensable components are condensed.

Condensed components, which include a substantial amount of water, are withdrawn from the cooling tower 106 through bottoms line 108 for bottoms. A certain portion of the condensed components via line 110 is returned to the top of the cooling tower 106. Line 110 includes a cooling system, such as a heat exchanger (not shown), to further cool the condensed components so as to obtain a cooling medium for subsequent cooling of the components in the cooling tower 106.

On line 112, olefin pairs exit from the top of the cooling tower 106. These olefin pairs in the compressor 114 are compressed and the compressed olefin is sent via line 116 to the water absorption column 118. In this embodiment, methanol is used as a water absorber, which is sent via line 120 to the upper part of the water absorption column 118. Methanol and trapped water, as well as some an oxygen-containing hydrocarbon is recovered via line 122 as a bottoms stream. Olefin is isolated via line 124. This olefin is optionally sent to an additional compressor (not shown), then introduced into distillation column 126.

In distillation column 126, ethylene and propylene, as well as low boiling components, are separated from dimethyl ether and higher boiling components, including C ₄ + components and methanol remaining after methanol washing. In order to reduce the formation of clathrates and / or free water in the distillation column 126, additional methanol is added to this distillation column via line 125. Line 128 leaves a distillation column 126 including ethylene and propylene, and higher boiling components, which include dimethyl ether and C4 + components, exit the distillation column 126 via line 130.

In FIG. 2 shows the subsequent processing and drying of a stream comprising ethylene and propylene. Ethylene and propylene flow through line 128 to an alkaline wash column 200. The alkaline solution is sent via line 202 to the top of the alkaline wash column 200 to remove CO2, which is also entrained in a stream including ethylene and propylene. Spent alkali leaves the alkaline wash column 200 along line 204.

The alkali-treated ethylene and propylene exit the alkaline wash column 200 via line 206 and enter the water wash column 208. Water enters the water wash column through line 210, and water and absorbed components exit the water wash column 208 from line 212. Water-washed ethylene and propylene leave the water wash column 208 from line 214 and pass through the dryer 216. Dry ethylene and propylene exit from the dryer 216 through line 218.

It is obvious that now having a complete description of the present invention, those skilled in the art are capable of carrying out the invention within the wide range of parameters encompassed by the claims, without departing from the spirit and scope of the invention.

Claims (21)

CLAIM 1. A method of separating dimethyl ether from an olefin stream, comprising the steps of: producing an olefin stream including ethylene, ethane, propylene, propane and dimethyl ether, and separating the olefin stream into a first fraction and a second fraction in a distillation column, where this first fraction includes, at least a major portion of ethylene and propylene contained in the olefin stream, and the second fraction comprises at least a major portion of dimethyl ether contained in the olefin stream. 2. The method according to claim 1, in which the olefin stream is obtained by introducing an oxygen-containing substance into contact with a molecular sieve catalyst. 3. The method according to claim 1 or 2, in which the olefin stream is divided into first and second fractions under pressure below 1480 kPa (absolute). 4. The method according to claim 2 or 3, further comprising contacting the olefin stream resulting from the introduction of an oxygen-containing substance in contact with a molecular sieve catalyst, with a water absorber before separation into the first and second fractions. - 15 007979 5. The method according to claim 4, in which the water absorber is brought into contact with the olefin stream at a molar ratio between the water absorber and the total amount of olefins from 1: 2 to 1: 200. 6. The method according to claim 4 or 5, in which the olefin stream in contact with the water absorber includes water in an amount of not more than 15,000 parts by weight per million. 7. The method according to claims 4, 5 or 6, in which the olefin stream in contact with the water absorber comprises at least 500 parts by weight of dimethyl ether. 8. The method according to one of claims 3 to 7, in which the pressure is from 791 to 1480 kPa, preferably from 929 to 1342 kPa. 9. The method according to one of the preceding paragraphs, in which the first fraction includes at least the main part of the propane contained in the olefin stream. 10. The method according to one of the preceding paragraphs, in which the first fraction includes not more than 100 parts by weight per million of dimethyl ether. 11. The method according to one of the preceding paragraphs, in which the second fraction includes at least the main part of the propane contained in the olefin stream. 12. The method according to one of the preceding paragraphs, in which the average temperature of the second fraction is not higher than 99 ° C, preferably not higher than 93 ° C, more preferably not higher than 88 ° C. 13. The method according to item 12, in which a water absorber is added to the distillation column. 14. The method according to item 13, in which the water absorber is added to the distillation column at a molar ratio between the water absorber and the total olefin stream, which must be divided, from 4: 1 to 1: 5000. 15. The method according to one of the preceding paragraphs, in which the olefin stream further comprises CO ₂ and the first fraction further comprises at least a majority of CO _{2 of the} resulting olefin stream. 16. The method according to clause 15, further comprising the step of contacting the first fraction containing acid gases with an adsorbent or absorbent. 17. The method according to one of the preceding paragraphs, in which the olefin stream further comprises C ₄ + hydrocarbon components and the second fraction further comprises at least a major portion of the C ₄ + hydrocarbon components of the resulting olefin stream. 18. The method according to one of the preceding paragraphs, further comprising the step of washing with water the first fraction. 19. The method of claim 18, further comprising the step of drying the first fraction. 20. The method according to one of the preceding paragraphs, further comprising separating ethylene and propylene of the first fraction and polymerizing ethylene. 21. The method according to one of the preceding paragraphs, further comprising separating ethylene and propylene of the first fraction and polymerizing propylene.