A method for purifying a pentane feedstock

Abstract

The application discloses a method for removing impurities from a pentane raw material. The method comprises the following steps: (1) contacting the pentane raw material with a pretreatment agent to perform pretreatment; the impurities contained in the pentane raw material include at least one of chlorine, nitrogen and colloid; (2) contacting the stream pretreated in the step (1) with a refining agent to perform reaction, and separating to obtain a refined pentane product. The method has the advantages of stable production, long operation period, good effect of removing impurities and olefins, and can be used in actual production on a large scale.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of alkane production, in particular to a method for removing impurities from pentane raw material to produce ultra-low impurity pentane. BACKGROUND

[0002] Pentane raw material is mainly derived from oil refineries. There are mainly two routes, one is direct distillation of oil field light hydrocarbon, and the other is by-product C5 in the process of petroleum refining, such as ethylene cracking or cracking to produce gasoline products. Pentane products are widely used as foaming agents, solvents, chemical raw materials, etc. The downstream of pentane industry is relatively concentrated, mainly used as foaming agent for producing polyurethane products, EPS (polystyrene foam) foaming agent and linear low density polyethylene solvent. In recent years, it is also used as a substitute for freon as a refrigerant for air conditioning and refrigeration, and as a tobacco expansion agent to reduce the amount of tar and nicotine.

[0003] With the continuous progress of polyethylene production technology, the requirements for pentane and other products, especially solvent isopentane, are increasing, and the limit of olefin content is also increasing, which is reduced to below 30 ppm or even higher.

[0004] There are two ways to purify carbon five alkanes: one is through the refining method of hydrogenation, and the other is through the molecular sieve refining technology. The production of ultra-low olefin content pentane by using hydrogenation saturation reaction combined with molecular sieve adsorption refining method is to use two-stage hydrogenation process. After removing diene and alkyne in the carbon five raw material by one-stage hydrogenation, saturated alkanes are produced by two-stage hydrogenation. If one-stage saturated hydrogenation process is used, a saturated hydrogenation catalyst with high hydrogenation activity and good hydrogenation depth is needed. After hydrogenation, carbon five alkanes are treated by purification, which generally uses molecular sieve adsorption of olefins, or uses further purification of carbon five alkanes by clay, and the olefin content in the product is more than 1000 ppm, which cannot obtain a product with olefin content less than 30 ppm.

[0005] Zhang Deshun et al. reported in the development of isopentane production technology (Shandong Chemical Industry, 2013, (42), 33) that higher purity pentane was distilled and then treated by molecular sieve adsorption method to reduce the olefin content to about 50 ppm. The molecular sieve refining agent needs to be regenerated in a short time.

[0006] In the above methods for removing olefins, the molecular sieve adsorption removal method has the technical problems of short service life and large molecular sieve consumption, and the hydrogenation technology has the technical problems of high cost, high operation difficulty and high impurity content. SUMMARY

[0007] The technical problem solved by the present application is that in the production process of pentane purification in the prior art, the current method of adsorbing and separating impurities has high requirements for raw materials, especially olefin impurities, and also has the problems of small scale and unstable production, which is difficult to achieve large-scale production, and the service life of the molecular sieve adsorbent is short, and the purification effect is poor. A method for removing impurities from pentane raw materials is provided. The method of the present application has the advantages of stable production, long running period, good effect of removing impurities and olefins, and can be used in large-scale actual production.

[0008] The first aspect of the present application provides a method for removing impurities from pentane raw materials, comprising:

[0009] (1) The pentane raw material is contacted with a pretreatment agent for pretreatment; the impurities contained in the pentane raw material include at least one of chlorine, nitrogen and gum;

[0010] (2) The stream after pretreatment in step (1) is contacted with a refining agent for reaction, and a refined pentane product is obtained by separation.

[0011] Further, in the pentane raw material of step (1), the mass content of pentane is more than 40%, preferably more than 60%, the mass content of pentene is 30-2000ppm, preferably 50-1000ppm, further preferably 100-700ppm, and further preferably 200-700ppm. The impurities contained in the pentane raw material include at least one of chlorine, nitrogen and gum, wherein the mass content of chlorine is 0-50ppm, further 1-50ppm, and more further 3-50ppm, the mass content of nitrogen is 0-50ppm, further 1-50ppm, and more further 2-50ppm, and the mass content of gum is 0-20mg / 100ml, further 1-20mg / 100ml, and more further 2-20mg / 100ml.

[0012] Further, the pretreatment agent of step (1) is an adsorbent for removing chlorine, nitrogen and gum impurities in the pentane raw material. The adsorbent for removing nitrogen and / or gum is selected from at least one of white clay, alumina and molecular sieve. The molecular sieve is one or more of SAPO-40, SAPO-44, X type, Y type, beta, MOR, ZSM-5 type molecular sieve, preferably at least one of USY type molecular sieve and SAPO-44 molecular sieve. The adsorbent for removing chlorine is selected from one or more of magnesium oxide, zinc oxide, nickel oxide, copper oxide, platinum oxide, alumina, iron oxide or copper oxide, preferably one or more of alumina, magnesium oxide and iron oxide. The above adsorbents are selected according to the types of impurities in the pentane raw material.

[0013] Further, the pretreatment conditions in step (1) are as follows: temperature 60–280℃, pressure 0.5–6.0 MPa, and mass hourly space velocity 2–20 h⁻¹. -1 .

[0014] Furthermore, the purification conditions described in step (2) are as follows: temperature 80–200°C, pressure 0.5–6.0 MPa, and mass hourly space velocity (MHV) 1–5 h⁻¹. -1 .

[0015] Furthermore, the mass hourly space velocity used in the pretreatment in step (1) is more than twice that used in the refining in step (2), and more specifically, 2 to 10 times, and more specifically, 5 to 8 times.

[0016] Further, the refining agent described in step (2) comprises: a molecular sieve and a rare earth metal component, wherein the micropore volume of the molecular sieve accounts for 10% to 40% of the total pore volume. In this invention, the micropore refers to a pore with a diameter of less than 2 nm.

[0017] Further, in the refined formulation, the molecular sieve is selected from one or more of ten-membered ring, twelve-membered ring silica-alumina molecular sieves, and silica-alumina-phosphorus molecular sieves, preferably from one or more of needle zeolite, potassium pyroxene zeolite, L zeolite, VPI-5, Y zeolite, X zeolite, ω zeolite, β zeolite, MOR molecular sieve, ZSM-3, ZSM-4, ZSM-18, ZSM-20, SAPO-5, SAPO-34, SAPO-11, MCM-22, ZSM-5, ZSM-11, ZSM-12, MCM-22, silica zeolite-1, and silica zeolite-2. More preferably, at least one of MOR, β zeolite, ZSM-5, SAPO-11, SAPO-34, USY molecular sieve, and MCM-22 is selected.

[0018] Furthermore, in the refining agent, the rare earth metal is selected from one or more of La, Ce, Pr, Lu, Nd, and Dy.

[0019] Further, based on the weight of the refined preparation, the content includes: molecular sieve content of 35% to 95%, further of 50% to 95%, and rare earth metal content of 0.01% to 15%, further of 0.1% to 10%, and even further of 0.1% to 6%.

[0020] Furthermore, the refined preparation also contains a binder component selected from one or more of silica and alumina. Based on the weight of the refined preparation, the binder component content is 1% to 50%, more specifically 3% to 45%.

[0021] Furthermore, the refined preparation can be prepared by the following method: kneading molecular sieves and binder precursors together, followed by drying and calcination to obtain the refined preparation; wherein rare earth metal components are introduced into the refined preparation before kneading, during kneading, or after calcination.

[0022] Furthermore, in the preparation method of the refined agent, the molecular sieve is an ammonium-type or hydrogen-type molecular sieve. The binder precursor is one or more of an alumina precursor (such as boehmite) or a silica precursor (silica sol).

[0023] Furthermore, in the preparation method of the refining agent, the rare earth metal source before the rare earth metal component is introduced into the refining agent is one or more of nitrates, halides, and sulfates.

[0024] Furthermore, in the preparation method of the refined product, the rare earth metal component can be introduced into the refined product before kneading and molding by ion exchange with molecular sieves. The rare earth metal component can be introduced into the refined product after molding and calcination by impregnation, such as by equal-volume impregnation. The specific introduction method can be carried out according to conventional procedures.

[0025] Furthermore, in the preparation method of the refined preparation, conventional molding aids, such as lubricants, pore-forming agents, and pectinic acids, can be added during the kneading process. These can be selected from one or more of guar gum powder, polyethylene glycol, and cellulose. The drying conditions after molding are as follows: 20–200℃, drying time 0.5–50 hours. The calcination conditions are as follows: calcination temperature 350–700℃, calcination time 0.1–20 hours.

[0026] Furthermore, the pretreatment in step (1) and the purification in step (2) can be carried out in one apparatus or in one or more apparatuses respectively.

[0027] Furthermore, part of the heat from the pentane feedstock comes from the reaction products of step (2), which can be obtained through heat exchange.

[0028] Furthermore, some of the heat from the pentane feedstock can also be obtained by using other hot materials as a heat exchange source.

[0029] Furthermore, the pentane product, by mass fraction, has a total olefin removal rate of 30% or more for the pentane feedstock containing C5 olefins and other olefins, preferably 85% or more, and even more preferably 95% or more.

[0030] Furthermore, in the pentane product, the mass content of C5 olefins is 1 to 200 ppm, preferably, the mass content of C5 olefins is below 30 ppm, more preferably, the mass content of C5 olefins is below 20 ppm, and even more preferably, the mass content of C5 olefins is below 15 ppm.

[0031] Furthermore, the number of days in which the mass content of C5 olefins in the pentane product is below 30 ppm (preferably below 20 ppm, more preferably below 15 ppm) reaches more than 30 days, more preferably more than 100 days, and even more preferably more than 12 months.

[0032] Furthermore, the separation described in step (2) is carried out using a conventional pentane distillation column. Generally, the operating conditions are as follows: 30-150℃ and pressure of 0.1-2.0MPa.

[0033] Furthermore, the purification reaction products and part of the pentane distillation column bottoms are heat-exchanged in the distillation column reboiler, and the heated pentane distillation column bottoms are recycled back to the distillation column.

[0034] Compared with existing adsorption technologies for obtaining high-purity pentane products, this invention has the following advantages:

[0035] 1. This invention can be used to prepare polystyrene foaming agents, and can also be used for pentane products that meet the quality requirements of refrigerants in the refrigeration industry.

[0036] 2. The method of the present invention first uses pretreatment to effectively remove impurities such as nitrogen, chlorine, and colloids from pentane raw materials, and then uses refining to remove olefin impurities. This greatly broadens the source of raw materials and reduces the cost of producing high-purity pentane.

[0037] 3. The inventors discovered through research that refining and removing olefins from C5 alkane feedstocks with low olefin content is extremely difficult. It is generally challenging to maintain a C5 olefin content below 50 ppm while ensuring a long service life of the refining agent (over one month). Further research revealed that using molecular sieves with a specific micropore volume ratio in combination with rare earth metals, while extending the service life of the refining agent, yields excellent refining results for C5 alkanes with low olefin content. This led to the completion of this invention. This invention uses molecular sieves with a micropore volume ratio of 10%–40% in combination with rare earth metals for the refining and olefin removal of C5 alkanes. It can handle feedstocks with low olefin content, achieving a long service life for the refining agent, and reducing the mass content of C5 olefins in the refined C5 alkanes to below 20 ppm, and further, below 15 ppm.

[0038] 4. The method of the present invention only requires one heat-exchangeable external heat source to meet the feed temperature requirements of pentane feedstock. The reaction control is simple, the heat utilization rate is high, which effectively reduces the energy consumption of pentane production and the operation is simple. Attached Figure Description

[0039] Figure 1 A schematic diagram of a process flow for removing impurities from pentane;

[0040] The annotations in the attached figures are explained as follows:

[0041] 1-Pentane feedstock, 2-Pentane feedstock after heat exchange in the first heat exchanger 21, 3-Pentane feedstock after heat exchange in the second heat exchanger 22, 4-Feed to the first refiner, 5-Feed to the second refiner, 6-Reaction product of the second refiner, 7-Reaction product of the third refiner, 8-Product of the first refiner, 9-Reaction product before heat exchange in the third heat exchanger, 10-Reaction product after heat exchange in the third heat exchanger, 11-Reaction product after cooling in the first heat exchanger, 12-Pentane product, 13-Bottom of the distillation column, 14-Bottom of the circulating refiner, 15-Bottom of the discharged distillation column, 16-Heating source, 17-Heating source cooled by the second heat exchanger, 21-First heat exchanger, 22-Second heat exchanger, 23-Pre-processor, 24-First refiner, 25-Second refiner, 26-Third heat exchanger (reboiler at the bottom of the distillation column), 27-Distillation column. Detailed Implementation

[0042] The present invention will be described in detail below with reference to the embodiments, but the scope of protection of the present invention is not limited to the embodiments.

[0043] This invention provides a process flow diagram of a method for removing impurities from pentane (e.g.) Figure 1The method for removing impurities from pentane according to the present invention includes: pentane feedstock 1 is heat-exchanged with reaction product 10 after heat exchange in a first heat exchanger 21 and a third heat exchanger 26 to obtain pentane feedstock 2 after heat exchange in the first heat exchanger and reaction product 11 after cooling in the first heat exchanger; pentane feedstock 2 after heat exchange in the first heat exchanger is heat-exchanged with a heating source 16 in a second heat exchanger 22 to obtain pentane feedstock 3 after heat exchange in the second heat exchanger and a heating source 17 after cooling in the second heat exchanger; pentane feedstock 3 after heat exchange in the second heat exchanger enters a first purifier 23 for pre-purification. The product 8 obtained from the first purifier is used as feed 4 to the second purifier 24 or feed 5 to the third purifier 25. The first purifier 24 and the second purifier 25 are switched during operation. The reaction product 6 from the second purifier or the reaction product 7 from the third purifier is used as reaction product 9 and exchanges heat with the bottom material 14 of the circulating purifier 27 via the third heat exchanger 26, resulting in reaction product 10 after heat exchange via the third heat exchanger 26 and circulating purifier bottom material after heating via the third heat exchanger 26. The circulating purifier bottom material after heating via the third heat exchanger 26 is recycled back to the purifier. The reaction product 11, cooled by the first heat exchanger 21, enters the purifier 27 for distillation, yielding pentane product 12 and purifier bottom material 13, part of which is used as circulating purifier bottom material 14 and part as effluent purifier bottom material 15.

[0044] In this invention, pore volume and pore distribution were determined using a liquid nitrogen adsorption-desorption apparatus. The determination method is as follows: the test was conducted at the liquid nitrogen saturation temperature (77K), and N2 isothermal adsorption-desorption curves were obtained by different relative pressures. The pore volume and pore distribution were then calculated. The relative pressure during the experiment ranged from 0.001 to 0.995.

[0045] Example 1

[0046] Take 100g of H-type MOR molecular sieve (SiO2 / Al2O3 molar ratio of 30, micropore volume accounting for 31% of total pore volume), 65g of pseudoboehmite (containing 67wt% alumina), 12g of guar gum powder, 2.0g of lanthanum nitrate, 6.0g of 65wt% nitric acid, and an appropriate amount of water, knead them into a mold, dry at 120℃ for 12 hours, and calcine at 550℃ for 3 hours to obtain the purified product of the second or third purifier.

[0047] Adopting such Figure 1 The process involves a pentane feedstock (containing 80 parts pentane and 20 parts hexane by mass) with olefin impurities of 300 ppm (270 ppm pentene, 30 ppm hexene, 3 ppm nitrogen compounds, less than 1 ppm chlorine, and less than 1 mg / 100 ml gum content). This feedstock is heated to 150°C and 3.0 MPa via a first and second heat exchanger, and then discharged at a mass hourly space velocity (MHSV) of 8 h⁻¹. 1The liquid phase enters the first purifier and contacts with a USY molecular sieve pretreatment agent (SiO2 / Al2O3 molar ratio of 4.1). The product from the first purifier enters the second purifier and is purified for 2 hours. -1 After contacting the above-mentioned refining agent at 150℃ and 3.2MPa to remove olefins, the resulting reaction product (containing 15ppm olefins) was cooled to 80℃ and then fed into a pentane distillation column. The top of the column yielded pentane (containing 18ppm olefins and less than 1ppm nitrogen compounds). Part of the material discharged from the bottom of the column was used as bottom recirculation material and exchanged heat with the olefin removal reaction product in the reboiler of the distillation column. After 100 days of operation, the pentane product at the top of the column contained 20ppm olefins and less than 1ppm nitrogen compounds.

[0048] Example 2

[0049] Take 100g of H-type ZSM-5 molecular sieve (SiO2 / Al2O3 molar ratio of 30, micropore volume accounting for 39.1% of total pore volume), 65g of pseudoboehmite (containing 67wt% alumina), 12g of guar gum powder, 2.0g of lanthanum nitrate, 6.0g of 65wt% nitric acid, and an appropriate amount of water, knead them into a mold, dry at 120℃ for 12 hours, and calcine at 550℃ for 3 hours to obtain the refined product of the second or third purifier.

[0050] Adopting such Figure 1 The process involves a C5 alkane feedstock (by mass fraction) containing 5 ppm chlorine, 60% pentane, 630 ppm pentene, 2 ppm nitrogen compounds, less than 1 mg / 100 ml of colloids, 35% hexane, more than 4% hexane, and the remainder being less than butane. This feedstock is heated to 150°C, 3.0 MPa, and maintained for 1.0 h after passing through a first and second heat exchanger. -1 The liquid phase is then contacted with a magnesium oxide pretreatment agent (20% magnesium oxide, 10% copper oxide, and the remainder aluminum oxide by mass), and then subjected to a 5-hour incubation period. -1 After undergoing the above-mentioned refining agent reaction at 2.9 MPa and 150 °C to remove olefins, the resulting reaction product (olefin content 10.2 ppm) is cooled and fed into a pentane distillation column. The top of the column yields pentane (olefin content 15 ppm, chlorine content less than 1 ppm, nitrogen compounds less than 1 ppm, and gum content less than 1 mg / 100 ml), while the bottom is discharged through the material removal system. After 20 days of operation, the top of the column yields pentane with an olefin content of 16 ppm, nitrogen compounds less than 1 ppm, chlorine content less than 1 ppm, and gum content less than 1 mg / 100 ml. After 100 days of operation, the top of the column yields pentane with an olefin content of 18 ppm, nitrogen compounds less than 1 ppm, chlorine content less than 1 ppm, and gum content less than 1 mg / 100 ml.

[0051] Example 3

[0052] Take 100g of H-type β-zeolite (SiO2 / Al2O3 molar ratio of 21, micropore volume accounting for 11% of total pore volume), 45g of pseudoboehmite (containing 67wt% alumina), 3.0g of cerium nitrate, 6g of 65wt% nitric acid, and an appropriate amount of water, knead them into a mold, dry at 120℃ for 12 hours, and calcine at 650℃ for 0.5 hours to obtain the refined product of the second or third purifier.

[0053] Adopting such Figure 1 The process involves a C5 alkane feedstock containing 8 ppm chlorine, 60% pentane, 350 ppm pentene, 3 ppm nitrogen compounds, 3 mg / 100 ml of colloids, 35% hexane, 4% or more of hexane, and the remainder being butane or less (by mass fraction). After heat exchange in the first and second heat exchangers, the feedstock is heated to 140°C, 3.0 MPa, and heated for 2 hours. -1 The liquid phase is then contacted with a pretreatment agent containing iron oxide (70% alumina, the remainder being iron oxide), and the effluent contains less than 1 ppm of chlorine. Then, after 3.0 hours... -1 After contact reaction with the above-mentioned refining agent at 2.5 MPa and 140 °C to remove olefins, the resulting reaction product (olefin content 3.9 ppm) is cooled and fed into a pentane distillation column. The top of the column yields pentane (olefin content 5.2 ppm, nitrogen content less than 1 ppm, chlorine content less than 1 ppm, and gum content less than 1 mg / 100 ml). The bottom of the column is then discharged through the material removal system. After 150 days of operation, the top of the column yields pentane with an olefin content of 10 ppm, nitrogen content less than 1 ppm, chlorine content less than 1 ppm, and gum content less than 1 mg / 100 ml.

[0054] Example 4

[0055] Take 100g of H-type MOR molecular sieve (SiO2 / Al2O3 molar ratio of 40, micropore volume accounting for 23% of total pore volume), 65g of pseudoboehmite (containing 67wt% alumina), 12g of guar gum powder, 3.0g of lanthanum nitrate, 6.0g of 65wt% nitric acid, and an appropriate amount of water, knead them into a mold, dry at 120℃ for 12 hours, and calcine at 550℃ for 3 hours to obtain the refined product of the second or third purifier.

[0056] Adopting such Figure 1 The process involves taking pentane feedstock (containing 80 parts pentane and 20 parts hexane by mass) with a nitrogen content of 5 ppm, olefin impurities of 300 ppm (pentene 270 ppm, hexene 30 ppm, chlorine content less than 1 ppm, and gum content 2 mg / 100 ml), and heating it to 130℃, 3.0 MPa, and 3 hours after heat exchange in the first and second heat exchangers. -1The liquid phase was contacted with a pretreatment agent containing USY molecular sieve (SiO2 / Al2O3 molar ratio of 4.1), and then subjected to a reaction for 2 hours. -1 After being reacted with the above-mentioned refining agent at 130℃ and 3.2MPa to remove olefins, the resulting reaction product (olefin content 9.0ppm) was cooled and fed into a pentane distillation column. Pentane was obtained at the top of the column (olefin content 14ppm, nitrogen content less than 1ppm, chlorine content less than 1ppm, and gum content less than 1mg / 100ml), and the material was discharged from the bottom of the column. After 300 days of operation, pentane was obtained at the top of the column, with an olefin content of 20ppm, nitrogen content less than 1ppm, chlorine content less than 1ppm, and gum content less than 1mg / 100ml.

[0057] Example 5

[0058] Take 100g of H-type MCM-22 molecular sieve (SiO2 / Al2O3 molar ratio of 25, micropore volume accounting for 32% of total pore volume), 55g of pseudoboehmite (containing 67wt% alumina), 12g of guar gum powder, 2.0g of lanthanum nitrate, 6.0g of 65wt% nitric acid, and an appropriate amount of water, knead them into a mold, dry at 120℃ for 12 hours, and calcine at 550℃ for 3 hours to obtain the refined product of the second or third purifier.

[0059] Adopting such Figure 1 The process involves heating a pentane feedstock (containing 80 parts pentane and 20 parts hexane by mass) with 5 mg / 100g of gum, 300 ppm of olefin impurities (270 ppm pentene, 30 ppm hexene, 3 ppm nitrogen compounds, less than 1 ppm chlorine, and 5 mg / 100ml of gum content) to 150℃, 3.0 MPa, and for 8 hours via heat exchange in a first and second heat exchanger. -1 The liquid phase was contacted with a pretreatment agent containing USY molecular sieve (SiO2 / Al2O3 molar ratio of 4.1), and then subjected to a reaction for 2 hours. -1 After being treated with the above-mentioned refining agent at 150℃ and 3.2MPa to remove olefins, the resulting reaction product (olefin content 3.0ppm) was cooled and fed into a pentane distillation column. Pentane (olefin content 11ppm) was obtained at the top of the column, and the bottom material discharge system was used. After 20 days of operation, pentane (olefin content 12ppm, nitrogen content less than 1ppm, chlorine content less than 1ppm, and gum content less than 1mg / 100ml) was obtained at the top of the column. After 12 months of operation, pentane (olefin content 20ppm, nitrogen content less than 1ppm, chlorine content less than 1ppm, and gum content less than 1mg / 100ml) was obtained at the top of the column.

[0060] Example 6

[0061] Take 150g of H-type SAPO-11 molecular sieve (SiO2 / P2O5 / Al2O3 = 0.8∶1∶1, molar ratio, micropore volume accounts for 19% of the total pore volume), 40g of pseudoboehmite (containing 67wt% alumina), 2.0g of lanthanum nitrate, 15g of guar gum powder, 6g of 65% nitric acid, and an appropriate amount of water, knead them into a mold, dry at 120℃ for 12 hours, and calcine at 680℃ for 0.5 hours to obtain the purified product of the second or third purifier.

[0062] Adopting such Figure 1 The process involves processing a C5 alkane feedstock (by mass fraction) containing 4 ppm nitrogen, 70% pentane, 930 ppm pentene, 25% hexane, more than 3% hexane, less than 1 ppm chlorine, 2 mg / 100 ml of gum, and the remainder being butane or less. The feedstock is then heated in a first and second heat exchanger to achieve a temperature of 180°C, 3.6 MPa, and a heating time of 8 hours. -1 The liquid phase was then contacted with a SAPO-44 molecular sieve pretreatment agent (molar ratio SiO2 / P2O5 / Al2O3 = 0.08:0.95:1), and then subjected to a reaction for 4 hours. -1 After being reacted with the above-mentioned refining agent at 180℃ and 3.5MPa to remove olefins, the resulting reaction product (olefin content 1.5ppm) was cooled and fed into a pentane distillation column. Pentane (olefin content 2.0ppm) was obtained at the top of the column, and the material at the bottom was discharged from the system. After 30 days of operation, pentane (olefin content 2.1ppm, nitrogen content less than 1ppm, chlorine content less than 1ppm, and gum content 1mg / 100ml) was obtained at the top of the column. After 12 months of operation, pentane (olefin content 8.0ppm, nitrogen content less than 1ppm, chlorine content less than 1ppm, and gum content 1mg / 100ml) was obtained at the top of the column.

[0063] Example 7

[0064] Take 150g of H-type SAPO-34 molecular sieve (SiO2 / P2O5 / Al2O3 = 0.05-0.08:0.96:1, molar ratio, micropore volume accounts for 21% of the total pore volume), 20g of silica sol (silica sol mass content 40%), 20g of alumina monohydrate (containing 67wt% alumina), 2.0g of lanthanum nitrate, 15g of guar gum powder, 6g of 65% nitric acid, and an appropriate amount of water, knead into a mold, dry at 120℃ for 12 hours, and calcine at 680℃ for 0.5 hours to obtain the purified product of the second or third purifier.

[0065] Adopting such Figure 1The process involves a raw material containing 2 mg / 100 ml of gum, 70% pentane, 1320 ppm pentene, 25% hexane, more than 3% hexane, less than 1 ppm nitrogen compounds, less than 1 ppm chlorine, and the remainder being butane or less (by mass fraction). This raw material is then subjected to heat exchange in a first and second heat exchanger to achieve a temperature of 170°C, 3.6 MPa, and a working time of 1.4 hours. -1 The liquid phase was then contacted with a pretreatment agent containing kaolin (NC-01 kaolin), and then for 3 hours... -1 After being reacted with the above-mentioned refining agent at 170℃ and 3.5MPa to remove olefins, the resulting reaction product (olefin content 5.0ppm) was cooled and fed into a pentane distillation column. Pentane (olefin content 8.5ppm) was obtained at the top of the column, and the material was discharged from the bottom. After 30 days of operation, pentane was obtained at the top of the column, with an olefin content of 8.7ppm, nitrogen compounds less than 1ppm, chlorine content less than 1ppm, and gum content of 1mg / 100ml. After 12 months of operation, pentane was obtained at the top of the column, with an olefin content of 13ppm, nitrogen compounds less than 1ppm, chlorine content less than 1ppm, and gum content of 1mg / 100ml.

[0066] Comparative Example 1

[0067] Take 100g of H-type ZSM-5 molecular sieve (SiO2 / Al2O3 molar ratio of 30, micropore volume accounting for 39.1% of total pore volume), 65g of pseudoboehmite (containing 67wt% alumina), 12g of guar gum powder, 2.0g of lanthanum nitrate, 6.0g of 65wt% nitric acid, and an appropriate amount of water, knead them into a mold, dry at 120℃ for 12 hours, and calcine at 550℃ for 3 hours to obtain the refined product of the second or third purifier.

[0068] Comparative Example 1 had no raw material pretreatment step. A C5 alkane raw material (by mass fraction) containing 5 ppm chlorine, 60% pentane, 630 ppm pentene, 2 ppm nitrogen compounds, less than 1 mg / 100 ml of gum, 35% hexane, more than 4% hexane, and the remainder being less than butane was passed through a first heat exchanger and a second heat exchanger to achieve a temperature of 150°C, 3.0 MPa, and a heat exchange duration of 1.0 h. -1 Below, the liquid phase is in 5h -1 After undergoing the above-mentioned refining agent reaction at 2.9 MPa and 150 °C to remove olefins, the resulting reaction product (olefin content 5.7 ppm) was cooled and fed into a pentane distillation column. The top of the column yielded pentane (olefin content 10 ppm, nitrogen content less than 1 ppm, chlorine content less than 1 ppm, and gum content less than 1 mg / 100 ml), while the bottom of the column was discharged through a material removal system. After 20 days of operation, the top of the column yielded pentane with an olefin content of 60 ppm, nitrogen content of 2 ppm, chlorine content of 4 ppm, and gum content less than 1 mg / 100 ml.

[0069] Comparative Example 2

[0070] Take 100g of H-type MCM-22 molecular sieve (SiO2 / Al2O3 molar ratio of 25, micropore volume accounting for 32% of total pore volume), 55g of pseudoboehmite (containing 67wt% alumina), 12g of guar gum powder, 2.0g of lanthanum nitrate, 6.0g of 65wt% nitric acid, and an appropriate amount of water, knead them into a mold, dry at 120℃ for 12 hours, and calcine at 550℃ for 3 hours to obtain the refined product of the second or third purifier.

[0071] Comparative Example 2 did not have a raw material pretreatment step. A pentane feedstock (containing 80 parts pentane and 20 parts hexane by mass), with a gum content of 5 mg / 100g, olefin impurities of 300 ppm (including 270 ppm pentene, 30 ppm hexene, 3 ppm nitrogen compounds, less than 1 ppm chlorine, and a gum content of 5 mg / 100ml), was heated for 2 hours after passing through a first and second heat exchanger. -1 At 150℃ and 3.2MPa, the liquid phase reacts with the above-mentioned refining agent to remove olefins, and the resulting reaction product (olefin content of 3.0ppm) is then cooled and fed into a pentane distillation column. The top of the column yields pentane (olefin content of 12ppm, nitrogen content less than 1ppm, chlorine content less than 1ppm, and gum content of 2mg / 100ml). The bottom of the column is discharged. After 20 days of operation, the top of the column yields pentane (olefin content of 80ppm, nitrogen content of 2ppm, chlorine content less than 1ppm, and gum content of 4mg / 100ml).

[0072] Comparative Example 3

[0073] The feedstock consists of 5 ppm chlorine, 60% pentane, 630 ppm pentene, 35% hexane, 4% or more hexane, 2 ppm nitrogen compounds, less than 1 mg / 100 ml of colloids, and the remainder being C5 alkane (by mass fraction) containing less than butane. No heat exchange is required; the liquid phase is kept at 5 h. -1 After reacting with NC-01 clay as a refining agent at 2.9 MPa and 150℃ to remove olefins, the resulting reaction product (olefin content 200 ppm) was cooled and fed into a pentane distillation column. The top of the column yielded pentane (olefin content 100 ppm, chlorine content 3 ppm, nitrogen compounds less than 1 ppm, and gum content less than 1 mg / 100 ml). The bottom of the column was then discharged through a material removal system. After 10 days of operation, the top of the column yielded pentane with an olefin content of 600 ppm, chlorine content 3 ppm, nitrogen compounds 2 ppm, and gum content less than 1 mg / 100 ml.

[0074] Comparative Example 4

[0075] Take 100g of H-type β-zeolite (SiO2 / Al2O3 molar ratio of 21, micropore volume accounting for 70% of total pore volume), 45g of pseudoboehmite (containing 67wt% alumina), 3.0g of cerium nitrate, 6g of 65wt% nitric acid, and an appropriate amount of water, knead them into a mold, dry at 120℃ for 12 hours, and calcine at 650℃ for 0.5 hours to obtain the refined product of the second or third purifier.

[0076] Adopting such Figure 1 The process involves a C5 alkane feedstock containing 8 ppm chlorine, 60% pentane, 350 ppm pentene, 3 ppm nitrogen compounds, 3 mg / 100 ml of colloids, 35% hexane, 4% or more of hexane, and the remainder being butane or less (by mass fraction). After heat exchange in the first and second heat exchangers, the feedstock is heated to 140°C, 3.0 MPa, and heated for 2 hours. -1 The liquid phase is then contacted with a pretreatment agent containing iron oxide (70% alumina, the remainder being iron oxide), and the effluent contains less than 1 ppm of chlorine. Then, after 3.0 hours... -1 After contact reaction with the above-mentioned refining agent at 2.5 MPa and 140 °C to remove olefins, the resulting reaction product (olefin content 3.9 ppm) was cooled and fed into a pentane distillation column. The top of the column yielded pentane (olefin content 5.2 ppm, nitrogen content less than 1 ppm, chlorine content less than 1 ppm, and gum content less than 1 mg / 100 ml). The bottom of the column was then discharged through the material removal system. After 28 days of operation, the top of the column yielded pentane with an olefin content of 60 ppm, nitrogen content of 2 ppm, chlorine content less than 1 ppm, and gum content of 2 mg / 100 ml.

[0077] Comparative Example 5

[0078] Take 100g of H-type MCM-22 molecular sieve (SiO2 / Al2O3 molar ratio of 25, micropore volume accounting for 32% of total pore volume), 55g of pseudoboehmite (containing 67wt% alumina), 12g of guar gum powder, 6.0g of 65wt% nitric acid, and an appropriate amount of water, knead them into a mold, dry at 120℃ for 12 hours, and calcine at 550℃ for 3 hours to obtain the refined product of the second or third purifier.

[0079] Adopting such Figure 1 The process involves heating pentane feedstock (containing 80 parts pentane and 20 parts hexane by mass) with 5 mg / 100g of gum, 300 ppm of olefin impurities (270 ppm pentene, 30 ppm hexene, 3 ppm nitrogen compounds, less than 1 ppm chlorine, and 5 mg / 100ml of gum content) through a first and second heat exchanger to 150℃, 3.0 MPa, for 8 hours. -1The liquid phase was contacted with a pretreatment agent containing USY molecular sieve (SiO2 / Al2O3 molar ratio of 4.1), and then subjected to a reaction for 2 hours. -1 After being reacted with the above-mentioned refining agent at 150℃ and 3.2MPa to remove olefins, the resulting reaction product (olefin content 3.0ppm) was cooled and fed into a pentane distillation column. Pentane (olefin content 11ppm) was obtained at the top of the column, and the bottom material discharge system was used. After 20 days of operation, pentane (olefin content 12ppm, nitrogen content less than 1ppm, chlorine content less than 1ppm, and gum content less than 1mg / 100ml) was obtained at the top of the column. After 7 months of operation, pentane (olefin content 70ppm, nitrogen content 2ppm, chlorine content less than 1ppm, and gum content 2mg / 100ml) was obtained at the top of the column.

[0080] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for removing impurities from pentane feedstock, comprising: (1) The pentane feedstock is pretreated by contacting a pretreatment agent; the impurities contained in the pentane feedstock include at least one of chlorine, nitrogen and colloids; (2) The pretreated stream from step (1) reacts with the refined agent to obtain the purified pentane product; In step (1), the pentane raw material contains more than 40% pentane by mass and 30-2000 ppm C5 olefins by mass. The pretreatment agent mentioned in step (1) is an adsorbent used to remove the impurities from the pentane feedstock; The refining agent described in step (2) comprises: a molecular sieve and a rare earth metal component, wherein the micropore volume of the molecular sieve accounts for 10% to 40% of the total pore volume; the molecular sieve is selected from at least one of MOR, β-zeolite, ZSM-5, SAPO-11, USY molecular sieve, MCM-22, and SAPO-34; the rare earth metal is selected from one or more of La, Ce, Pr, Lu, Nd, and Dy; based on the weight of the refining agent, it comprises: a molecular sieve content of 35% to 95% and a rare earth metal content of 0.01% to 15%; The purification conditions in step (2) are as follows: temperature 80~200℃, pressure 0.5~6.0MPa, and mass hourly space velocity 1-5h. -1 .

2. The method according to claim 1, characterized in that, In step (1), the pentane raw material contains more than 60% pentane by mass and 50-1000 ppm C5 olefins by mass.

3. The method according to claim 1, characterized in that, In step (1), the pentane raw material contains 100-700 ppm of C5 olefins.

4. The method according to claim 1, characterized in that, In step (1), the pentane raw material contains 200-700 ppm of C5 olefins.

5. The method according to claim 1, characterized in that, In step (1), the pentane raw material contains 1 to 50 ppm of chlorine by mass; the pretreatment agent in step (1) includes a dechlorination adsorbent, which is selected from one or more of magnesium oxide, zinc oxide, nickel oxide, copper oxide, platinum oxide, aluminum oxide, iron oxide or copper oxide.

6. The method according to claim 5, characterized in that, In step (1), the pentane raw material contains 3 to 50 ppm of chlorine by mass; the dechlorination adsorbent in step (1) is selected from one or more of alumina, magnesium oxide, and iron oxide.

7. The method according to claim 1 or 5, characterized in that, In step (1), the nitrogen content in the pentane raw material is 1-50 ppm; and / or the colloid content is 1-20 mg / 100 ml; the pretreatment agent in step (1) includes a denitrifying and / or colloid adsorbent, which is selected from at least one of kaolin, alumina, and molecular sieve; the molecular sieve is one or more of SAPO-40, SAPO-44, X-type, Y-type, β, MOR, and ZSM-5 molecular sieves.

8. The method according to claim 7, characterized in that, In step (1), the nitrogen content in the pentane raw material is 2-50 ppm; and / or the colloid content is 2-20 mg / 100 ml; in the pretreatment agent in step (1), the adsorbent for denitrification and / or colloid is at least one of USY molecular sieve and SAPO-44 molecular sieve.

9. The method according to claim 1, characterized in that, The pretreatment conditions in step (1) are as follows: temperature 60~280℃, pressure 0.5~6.0MPa, and mass hourly space velocity 2~20h. -1 .

10. The method according to claim 1 or 9, characterized in that, The mass hourly space velocity used in the pretreatment in step (1) is more than twice the mass hourly space velocity used in the refining in step (2).

11. The method according to claim 10, characterized in that, The mass hourly space velocity used in the pretreatment in step (1) is 2 to 10 times that used in the refining in step (2).

12. The method according to claim 10, characterized in that, The mass hourly space velocity used in the pretreatment in step (1) is 5 to 8 times that used in the refining in step (2).

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