Method for adsorbing and separating n-alkanes in C10-C25 distillate oil

Abstract

The invention relates to a method for adsorption separation of n-alkanes in C10-C25 distillate oil, and the method comprises the following steps: S1, carrying out first contact on the C10-C25 distillate oil and an adsorbent to obtain a to-be-desorbed material containing the C10-C25 n-alkanes and the adsorbent, and a raffinate containing C10-C25 isoparaffin, C10-C25 cycloparaffin, C10-C25 aromatic hydrocarbons and a desorption agent; s2, a desorption agent and the material to be desorbed are subjected to second contact, and an extract containing C10-C25 n-alkanes and the desorption agent is obtained; the C10-C25 distillate oil comprises n-alkanes of C10-C25, isoparaffin of C10-C25, cycloalkanes of C10-C25 and aromatic hydrocarbons of C10-C25, and the aromatic hydrocarbons of C10-C25 are used as raw materials; the desorption agent is prepared from n-alkanes of C5-C8, aromatic hydrocarbons of C6-C8 and optional isoalkanes of C5-C8; the particle size of the adsorbent is 0.3-0.6 mm, the adsorbent comprises a 5A molecular sieve, and the grain size of the 5A molecular sieve is 0.2-0.8 [mu] m; according to the method, the yield of the n-alkanes of C14 or above can be remarkably increased, and the content of aromatic hydrocarbons in the n-alkanes is reduced.

Description

Technical Field

[0001] The present disclosure relates to the field of adsorption separation, and in particular to a method for adsorption separation of normal alkanes in C10-C25 fraction oil. Background Art

[0002] C10-C13 normal alkanes are mainly found in kerosene fractions, while C14-C25 normal alkanes are mainly found in diesel fractions. C10-C13 normal alkanes are the main components of light liquid wax, which are mainly used to produce linear alkylbenzenes and fatty alcohols. C14-C20 normal alkanes are the main components of heavy liquid wax, which can be used to produce high value-added products such as petroleum grease plasticizers, chlorinated paraffins, higher fatty alcohols, beauty cosmetics, and synthetic petroleum proteins. Normal alkanes above C20 are the main components of solid paraffin wax. Paraffin wax with high purity normal alkanes can be used as latent heat storage materials and is widely used in various fields such as aviation, aerospace, microelectronics and other high-tech systems, as well as house energy conservation. The dewaxed oil remaining after separating normal alkanes can be used as kerosene or diesel with a low freezing point. Therefore, the separation of normal alkanes and non-normal alkanes in kerosene and diesel fractions has important practical significance.

[0003] Kerosene and diesel have a wide distillation range, and the boiling point difference between isomers is very small, so it is impossible to separate the liquid wax by distillation. The effective pore size of 5A molecular sieve is about 0.51nm, and normal alkanes with a diameter less than 0.50nm can enter, while isoalkanes, cycloalkanes and aromatics with a diameter greater than 0.51nm are excluded from the pores. Therefore, adsorption separation of 5A molecular sieve is an effective method for extracting liquid wax.

[0004] The Chinese industry standard NB / SH / T 0417-2013 stipulates that the aromatic content in light liquid wax is less than 0.4% by mass and the purity of normal alkanes is greater than 98.5% by mass. Aromatic molecules have a large diameter and will not enter the micropores of the 5A molecular sieve, but due to the strong polarity of aromatics, a small amount of adsorption will occur on the surface of the adsorbent, which makes it difficult to reduce the aromatic content of normal alkanes. With the improvement of environmental protection requirements, the restrictions on aromatics in normal alkanes products may become more stringent in the future.

[0005] Normal alkanes with different carbon numbers can be adsorbed by 5A molecular sieve. However, as the carbon number increases to more than 11, the mass transfer rate of normal alkanes has a significant downward trend, which makes it difficult to improve the recovery rate of high carbon number normal alkanes.

[0006] CN91101507.8 discloses a method for improving the yield of long-chain normal alkanes, which uses 5A molecular sieve adsorbent, C5-C8 normal alkanes as desorbents, and liquid phase simulated moving bed technology to perform adsorption separation on C10-C35 normal alkanes. The method is characterized in that low-carbon non-linear hydrocarbons are injected before or when the raw materials are fed to reduce the concentration of the desorbent in the adsorbent bed, thereby reducing the competitive adsorption between the desorbent and the long-chain normal alkanes in the raw materials and improving the yield of the latter. The low-carbon non-linear hydrocarbon flow introduced by the invention requires the addition of a fractionation device for recycling, which will increase investment and energy consumption.

[0007] CN201610825766.2 provides a method for adsorbing and separating normal alkanes from C8-C22 normal alkanes and isoalkanes, wherein the raw materials are subjected to adsorption separation at one time through the first adsorption separation zone, the second adsorption separation zone and the third adsorption separation zone, wherein the first adsorption separation zone is filled with 5A molecular sieves, which mainly adsorb C8-C14 normal alkanes, the second adsorption separation zone is filled with HY molecular sieves, which mainly adsorb C15-C18 normal alkanes, and the third separation zone is filled with 13X molecular sieves, which mainly adsorb C19-C22 normal alkanes. The adsorption strength of HY molecular sieves and 13X molecular sieves for aromatics is much greater than that for alkanes, so this method is not suitable for separating raw materials containing aromatics. Summary of the invention

[0008] The purpose of the present disclosure is to provide a method for separating normal alkanes in C10-C25 distillate oil by adsorptive separation, which method can separate normal alkanes in C10-C25 distillate oil, can significantly improve the yield of normal alkanes above C14, and can reduce the content of aromatics in normal alkanes.

[0009] In order to achieve the above object, the present disclosure provides a method for adsorbing and separating normal alkanes in C10-C25 distillate oil, the method comprising the following steps:

[0010] S1, contacting the C10-C25 fraction oil with an adsorbent for the first time to obtain a material to be desorbed comprising C10-C25 normal alkanes and the adsorbent, and a raffinate comprising C10-C25 isoalkanes, C10-C25 cycloalkanes, C10-C25 aromatics and a desorbent;

[0011] S2, bringing the desorbent into second contact with the material to be desorbed to obtain an extract containing C10-C25 normal alkanes and the desorbent;

[0012] The C10-C25 distillate oil includes C10-C25 normal alkanes, C10-C25 isoalkanes, C10-C25 cycloalkanes and C10-C25 aromatics;

[0013] The desorbent includes C5-C8 normal alkanes, C6-C8 aromatic hydrocarbons and optionally C5-C8 isoalkanes;

[0014] The particle size of the adsorbent is 0.3-0.6 mm. The adsorbent includes 5A molecular sieve, and the grain size of the 5A molecular sieve is 0.2-0.8 μm.

[0015] Optionally, the crystal size of the 5A molecular sieve is 0.2-0.7 μm;

[0016] Optionally, the water content of the adsorbent is less than 3 wt %.

[0017] Optionally, relative to the total volume of the desorbent, the content of the C5-C8 normal alkanes is 50-95% by volume, the content of the C6-C8 aromatics is 5-20% by volume, and the content of the C5-C8 isoalkanes is 0-30% by volume.

[0018] Optionally, the temperature of the first contact and the second contact are 185-230° C., and the pressure are 1.0-2.5 MPa, respectively.

[0019] Optionally, a liquid phase simulated moving bed process is used to adsorb and separate normal alkanes in the C10-C25 fraction oil, and the simulated moving bed comprises 12-24 adsorbent beds;

[0020] Step S1 comprises: subjecting the C10-C25 fraction oil to the first contact with the adsorbent bed to obtain a raffinate containing the C10-C25 isoalkanes, the C10-C25 cycloalkanes, the C10-C25 aromatics and a desorbent, and the adsorbent bed adsorbing the C10-C25 normal alkanes as the material to be desorbed;

[0021] Step S2 includes: bringing the desorbent into contact with the material to be desorbed for the second time to obtain the extract.

[0022] Optionally, the method further comprises:

[0023] Separating the extracted liquid to obtain the C10-C25 normal alkanes and the desorbent;

[0024] The raffinate is separated to obtain the C10-C25 isoalkanes, the C10-C25 cycloalkanes, the C10-C25 aromatics and the desorbent.

[0025] Optionally, the method further comprises: contacting the material containing the C10-C25 normal alkanes obtained by separating the extract with an X-type molecular sieve adsorbent and / or a Y-type molecular sieve adsorbent for a third time;

[0026] The temperature of the third contact is 100-120°C, the pressure is 0.5-1.5 MPa, and the volume space velocity is 0.5-5.0 h -1 ;

[0027] The water contents of the X-type molecular sieve adsorbent and the Y-type molecular sieve adsorbent are respectively less than 5% by weight.

[0028] Optionally, the method for preparing the adsorbent comprises the following steps:

[0029] (1) mixing a molecular sieve raw material, a binder and an auxiliary agent and performing a molding process to obtain a first product;

[0030] (2) heat treating the first product to obtain a second product;

[0031] (3) contacting the second product with an alkaline solution to obtain a third product;

[0032] (4) contacting the third product with a solution containing a calcium source to perform an ion exchange reaction to obtain a fourth product;

[0033] (5) subjecting the fourth product to an activation treatment;

[0034] The crystal size of the molecular sieve raw material is 0.2-0.8 μm, and the molecular sieve raw material includes NaA molecular sieve raw powder.

[0035] Optionally, in step (1), the binder includes one or more of a clay binder, silica sol and alumina sol;

[0036] The clay binder includes one or more of kaolin, halloysite and attapulgite;

[0037] The auxiliary agent comprises one or more of lignin, sesbania powder, corn starch, bayberry tannin and methyl cellulose.

[0038] Optionally, in step (1), on a dry basis, the weight ratio of the molecular sieve raw material to the binder is (85-95):(5-15);

[0039] On a dry basis, the amount of the auxiliary agent used is 1-6% by weight relative to the total weight of the molecular sieve raw material and the binder.

[0040] Optionally, step (1) further comprises: forming the product of the molding process into particles with a particle size of 0.30-0.60 mm, and performing a first drying process on the particles to obtain the first product;

[0041] The conditions of the first drying treatment include: temperature of 80-200° C. and time of 1-4 hours.

[0042] Optionally, in step (2), the heat treatment conditions include: temperature of 500-740°C and time of 1-4h.

[0043] Optionally, in step (3), the contacting conditions include: temperature of 80-99° C., time of 1-5 h;

[0044] The alkaline solution includes sodium hydroxide solution and / or potassium hydroxide solution;

[0045] The concentration of the alkaline solution is 0.5-2 mol / L, and the volume ratio of the second product to the alkaline solution is 1:(1-5);

[0046] Optionally, step (3) further comprises: washing the solid obtained by the contact until the pH value of the washing liquid is below 10.0, to obtain the third product.

[0047] Optionally, in step (4), the conditions of the ion exchange reaction include: time of 1-4h, temperature of 10-99°C;

[0048] The calcium source includes calcium chloride and / or calcium nitrate;

[0049] The volume ratio of the third product to the solution is 1:(2-6);

[0050] In the solution, the concentration of the calcium source is 0.1-2.0 mol / L;

[0051] Step (4) further comprises: subjecting the solid product obtained by the ion exchange reaction to a second drying treatment to obtain the fourth product;

[0052] The conditions of the second drying treatment include: time of 1-4 hours and temperature of 80-200°C.

[0053] Optionally, in step (5), the conditions of the activation reaction include: time of 1-4h and temperature of 250-350°C.

[0054] Through the above technical scheme, the present application effectively adsorbs and separates normal alkanes in C10-C25 fraction oil by using an adsorbent containing a 5A molecular sieve with specific properties and a specific desorbent. The method disclosed in the present invention has simple steps and can significantly improve the yield of normal alkanes above C14. Aromatic hydrocarbons with low carbon number and low boiling point are added to the desorbent used for adsorption separation, and the aromatic hydrocarbon content in the normal alkane product can be significantly reduced.

[0055] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0057] Figure 1 It is a schematic diagram of a process for separating normal alkanes in C10-C25 fraction oil by adsorptive separation using a liquid phase simulated moving bed process according to an embodiment of the present disclosure.

[0058] Description of Reference Numerals

[0059] 101-112 adsorption column DETAILED DESCRIPTION

[0060] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0061] The present disclosure provides a method for adsorbing and separating normal alkanes in C10-C25 distillate oil, the method comprising the following steps:

[0062] S1, contacting the C10-C25 fraction oil with an adsorbent for the first time to obtain a material to be desorbed comprising C10-C25 normal alkanes and the adsorbent, and a raffinate comprising C10-C25 isoalkanes, C10-C25 cycloalkanes, C10-C25 aromatics and a desorbent;

[0063] S2, bringing the desorbent into second contact with the material to be desorbed to obtain an extract containing C10-C25 normal alkanes and the desorbent;

[0064] The C10-C25 distillate oil includes C10-C25 normal alkanes, C10-C25 isoalkanes, C10-C25 cycloalkanes and C10-C25 aromatics;

[0065] The desorbent includes C5-C8 normal alkanes, C6-C8 aromatic hydrocarbons and optionally C5-C8 isoalkanes;

[0066] The particle size of the adsorbent is 0.3-0.6 mm. The adsorbent includes 5A molecular sieve, and the grain size of the 5A molecular sieve is 0.2-0.8 μm.

[0067] In the present disclosure, in step S1, the desorbent in the raffinate does not originate from the first contact, but from the upstream of the simulated moving bed, and may also originate from the desorbent in the downstream adsorbent bed.

[0068] In the present disclosure, an adsorbent comprising a 5A molecular sieve having specific properties is used to perform adsorption separation of normal alkanes in C10-C25 fraction oil. The 5A molecular sieve has a relatively small crystal size, which can significantly increase the intracrystalline diffusion rate of long-chain normal alkanes. The adsorbent also has a relatively small particle size, which can significantly increase the external diffusion rate of long-chain normal alkanes, thereby improving the adsorption efficiency.

[0069] In order to further improve the mass transfer rate of high carbon number normal alkanes, according to one embodiment of the present disclosure, the grain size of the 5A molecular sieve is 0.2-0.7 μm, and the above grain size can increase the intracrystalline diffusion rate of normal alkanes.

[0070] According to one embodiment of the present disclosure, before adsorption separation, the C10-C25 fraction oil is hydrotreated to saturate the olefins therein to convert them into alkanes, and the sulfur-containing compounds and nitrogen-containing compounds therein need to be removed to avoid poisoning the adsorbent.

[0071] According to one embodiment of the present disclosure, the water content of the adsorbent is less than 3 weight %, wherein "the water content of the adsorbent" refers to the content of water relative to the total weight of the adsorbent; when the water content of the adsorbent is within the range of the present disclosure, a higher adsorption amount of normal alkanes can be obtained.

[0072] According to one embodiment of the present disclosure, in the 5A molecular sieve, Ca 2+ The exchange degree is 67-97%, which means that Ca 2+ The percentage of exchangeable cation sites in the molecular sieve occupied by ions. The specific measurement method includes: using X-ray fluorescence spectrometry (XRF) to analyze the mass fraction of Na2O and CaO in the adsorbent, recorded as m N and m C , then Ca 2+ Degree of ion exchange = m C / M C / (m C / M C +m N / M N ). N and M C are the molar masses of Na2O and CaO respectively.

[0073] In the present disclosure, the C5-C8 normal alkanes in the desorbent can have a better desorption effect on the C10-C25 normal alkanes in the C10-C25 distillate oil, especially the C14-C25 normal alkanes, and can not affect the adsorption of C10-C25 normal alkanes. Using it as a desorbent can obtain a higher recovery rate of normal alkanes; and C6-C8 aromatic hydrocarbons are also added to the desorbent of the present disclosure, which can effectively elute the C10-C25 aromatic hydrocarbons adsorbed on the surface of the adsorbent and improve the product purity; C5-C8 isoparaffins can adjust the adsorption strength and desorption capacity of the desorbent.

[0074] According to one embodiment of the present disclosure, relative to the total volume of the desorbent, the content of normal alkanes of C5-C8 is 50-95% by volume, the content of aromatic hydrocarbons of C6-C8 is 5-20% by volume, and the content of isoalkanes of C5-C8 is 0-30% by volume; wherein, the normal alkanes of C5-C8 may include, for example, normal hexane (nC6), normal heptane (nC7), etc., the isoalkanes of C5-C8 may include, for example, isooctane (iC8), etc., and the aromatic hydrocarbons of C6-C8 may include, for example, benzene, toluene, ethylbenzene, xylene, etc.

[0075] In order to take into account both high adsorption capacity and mass transfer diffusion of long-chain normal alkanes, according to one embodiment of the present disclosure, the temperatures of the first contact and the second contact are 185-230°C, and the pressures are 1.0-2.5MPa, respectively. The above-mentioned condition range can ensure that the logistics is in liquid phase at the adsorption temperature and can ensure the mass transfer diffusion of long-chain normal alkanes.

[0076] According to one embodiment of the present disclosure, a liquid phase simulated moving bed process is used to adsorb and separate normal alkanes in C10-C25 distillate oil, and the simulated moving bed comprises 12-24 adsorbent beds;

[0077] Step S1 comprises: contacting the C10-C25 fraction oil with the adsorbent bed in the first step to obtain a raffinate containing C10-C25 isoalkanes, C10-C25 cycloalkanes, C10-C25 aromatics and a desorbent, and an adsorbent bed adsorbing C10-C25 normal alkanes as a material to be desorbed;

[0078] Step S2 includes: bringing the desorbent into contact with the material to be desorbed in the second step to obtain an extract.

[0079] According to one embodiment of the present disclosure, the method further includes: separating the extract to obtain C10-C25 normal alkanes and a desorbent; the separation method is conventional in the art, such as fractional distillation, and the separated desorbent can be recycled, and in the material containing C10-C25 normal alkanes obtained by fractionation, the content of C10-C25 normal alkanes is more than 99.5% by weight, and the content of aromatics is less than 0.1% by weight.

[0080] In order to further reduce the aromatic content in the normal alkane product, according to one embodiment of the present disclosure, the method comprises: subjecting the material containing C10-C25 normal alkanes obtained by separation of the extract to a third contact with an X-type molecular sieve and / or a Y-type molecular sieve; the temperature of the third contact is 100-120°C, the pressure is 0.5-1.5MPa, and the volume space velocity is 0.5-5h -1 The water content of the X-type molecular sieve and the Y-type molecular sieve is less than 5% by weight, respectively. There are at least two adsorption towers for the above treatment, including adsorption and regeneration, which are used alternately. After the third treatment, the aromatic content of C10-C25 in the normal alkane product is less than 0.01% by weight.

[0081] According to one embodiment of the present disclosure, the method further comprises: separating the raffinate to obtain C10-C25 isoalkanes, C10-C25 cycloalkanes, C10-C25 aromatics and a desorbent, wherein the separated desorbent can be recycled; the separation method is conventional in the art, such as fractional distillation.

[0082] The method disclosed in the present invention can be used for both intermittent operation and continuous operation. According to one embodiment of the present invention, a liquid phase simulated moving bed process is used to adsorb and separate normal alkanes in C10-C25 distillate oil, and the simulated moving bed contains 12-24 adsorbent beds. In order to realize the continuous operation of the industrial separation device, the adsorption separation process is carried out in a simulated moving bed device having multiple adsorbent beds. The adsorbent is loaded in a column container in the form of a fixed bed. The adsorbent bed can be multiple adsorption columns connected in series, or it can be divided into multiple adsorbent beds by a screen or grid inside an adsorption tower. The liquid flow flows from top to bottom between the adsorbent beds. The several logistics entering or leaving the adsorbent bed divide the adsorbent into at least four areas: adsorption zone, purification zone, desorption zone and isolation zone for adsorption separation operation. The normal alkanes in C10-C25 distillate oil undergo adsorption, purification and desorption processes in different areas. Figure 1As shown, in the liquid phase simulated moving bed device, the adsorbent bed between the raw material to be separated entering the simulated moving bed adsorption tower and the raffinate flow leaving the adsorption tower is the adsorption zone, the raw material flow to be separated containing normal alkanes enters the adsorption chamber from the upstream of the adsorption zone, contacts with the adsorbent, and the C10-C25 normal alkanes therein are adsorbed into the crystal pores of the 5A molecular sieve, and the isoalkanes, cycloalkanes and aromatics that are not adsorbed flow out of the adsorbent bed from the downstream of the adsorption zone together with part of the desorbent to form the raffinate flow; the area between the extracted liquid flow leaving the adsorption tower and the raw material flow to be separated entering the adsorption tower is called the purification zone, the logistics from top to bottom in this zone flushes the non-normal alkanes outside the adsorbent micropores to the downstream, and the extracted liquid flow rich in C10-C25 normal alkanes and containing the desorbent at the upstream of this zone leaves the adsorption bed. The area between the desorbent flow entering the adsorption tower and the extracted liquid flow leaving the adsorption tower is called the desorption zone. The desorbent enters from the upstream of this zone to displace the normal alkanes in the micropores of the adsorbent so that the adsorbent can be reused. There is also an isolation zone between the desorbent flow and the residual liquid flow. The purpose of this zone is to prevent non-normal alkanes in the adsorption zone from entering the desorption zone and contaminating the extracted liquid. Each adsorption column or adsorbent bed is connected to at least one logistics pipeline to transport several logistics entering or leaving the adsorption separation device. The positions of these logistics entering or leaving the adsorbent bed are periodically changed from top to bottom, so as to achieve the effect of the relative countercurrent simulation movement of the liquid and solid phases in the adsorbent with the liquid flowing downward and the adsorbent moving upward, wherein the step time is 50-300s. For a small test device, the position of the inlet and outlet materials remains unchanged, and the effect of the relative countercurrent simulation movement of the liquid and solid phases can also be achieved by moving the adsorbent bed. The extracted liquid flow and the residual liquid flow leaving the adsorption tower enter the fractionation tower respectively to separate the products and recycle the desorbent.

[0083] In the present disclosure, the adsorbent containing 5A molecular sieve used can be formed by 4A molecular sieve, binder and auxiliary agent, and then the molded body is obtained by calcination, binder crystallization, Ca exchange and activation. The molding process can be carried out according to various techniques well known to those skilled in the art, such as mixing the molecular sieve, binder and auxiliary agent, and then agglomerating and molding by methods such as extrusion, tableting, rolling into balls, etc. The molding is often carried out with silicon aluminum oxide binders without adsorption capacity. In order to increase the adsorption capacity of the adsorbent, it is necessary to crystallize this type of binder to obtain a binder-free 4A molecular sieve molded body; the unit cell composition of the 5A molecular sieve disclosed in the present disclosure is Ca4Na4[Al 12 Si 12 O 48 ]·20H2O. The micropores in the 5A molecular sieve can selectively adsorb C10-C25 normal alkanes.

[0084] According to one embodiment of the present disclosure, the method for preparing the adsorbent comprises the following steps:

[0085] (1) mixing a molecular sieve raw material, a binder and an auxiliary agent and performing a molding process to obtain a first product;

[0086] (2) heat treating the first product to obtain a second product;

[0087] (3) contacting the second product with an alkaline solution to obtain a third product;

[0088] (4) contacting the third product with a solution containing a calcium source to perform an ion exchange reaction to obtain a fourth product;

[0089] (5) subjecting the fourth product to an activation treatment;

[0090] The crystal grain size of the molecular sieve raw material is 0.2-0.8 μm, and the molecular sieve raw material includes NaA molecular sieve raw powder.

[0091] According to one embodiment of the present disclosure, the crystal size of the molecular sieve raw material is 0.2-0.7 μm.

[0092] According to one embodiment of the present disclosure, in step (1), the binder includes one or more of a clay binder, silica sol and alumina sol; the clay binder includes one or more of kaolin, halloysite and attapulgite; the auxiliary agent includes one or more of lignin, sesbania powder, corn starch, bayberry tannin and methyl cellulose; when the types of binders or auxiliary agents are more than two, the present disclosure does not impose specific restrictions on their ratio.

[0093] According to one embodiment of the present disclosure, in step (1), on a dry basis, the weight ratio of the molecular sieve raw material to the binder is (85-95): (5-15), preferably (90-95): (5-10). When the weight ratio of the molecular sieve raw material to the binder is within the above range, the problems of high bulk density of the adsorbent due to excessively high binder content, decreased active component content, and poor adsorbent strength due to too low a binder content can be avoided.

[0094] According to one embodiment of the present disclosure, in step (1), the amount of the auxiliary agent used is 1-6 wt %, preferably 2-4 wt %, relative to the total weight of the molecular sieve raw material and the binder, calculated on a dry basis.

[0095] In the present disclosure, the molding process may be, for example, rolling ball molding, extrusion molding or tablet molding, and the molding process may be performed in a high-speed granulator, sugar coating machine, disc granulator, extruder, tablet press, etc. For example, rolling ball molding may be performed by placing the mixed powder into a rolling ball device, adding water to the material in the form of spraying while rolling, and adding the mixed powder into the material in the form of throwing, so that the fine powder agglomerates, becomes round, and forms small balls, and then throwing to obtain spherical particles; extrusion molding may be performed by placing the mixed powder into an extrusion device, first kneading by adding a certain amount of water, and then extruding to obtain strips, and drying, crushing and sieving the strips to obtain particles; tablet molding may be performed by placing the mixed powder into a tablet pressing device, pressing and molding, and then crushing and sieving to obtain particles.

[0096] According to one embodiment of the present disclosure, step (1) further includes: forming the product of the molding process into particles with a particle size of 0.30-0.60 mm, and performing a first drying process on the particles to obtain the first product; the particles may be, for example, spherical particles, which have good fluidity, are easy to load evenly, and have good fluid distribution uniformity; the conditions of the first drying process include: a temperature of 80-200°C and a time of 1-4 hours. The method of the first drying process is conventional in the art and is not specifically required; the above drying process can remove water in the macropores inside the particles.

[0097] According to an embodiment of the present disclosure, in step (2), the conditions for heat treatment include: a temperature of 500-740° C. and a time of 1-4 h. The heat treatment method may be, for example, calcination.

[0098] According to one embodiment of the present disclosure, in step (3), the contact conditions include: temperature of 80-99° C., time of 1-5 h; the alkaline solution includes sodium hydroxide solution and / or potassium hydroxide solution; the concentration of the alkaline solution is 0.5-2 mol / L, and the volume ratio of the second product to the alkaline solution is 1:(1-5).

[0099] According to one embodiment of the present disclosure, step (3) further comprises: washing the solid obtained by the contact until the pH value of the washing liquid is below 10.0, to obtain a third product.

[0100] According to one embodiment of the present disclosure, in step (4), the conditions of the ion exchange reaction include: time of 1-4h, temperature of 10-99°C; the calcium source includes a soluble compound of calcium, preferably calcium chloride and / or calcium nitrate. When the calcium source includes more than two types, there is no specific restriction on their ratio, that is, any ratio can realize the technology of the present disclosure; the volume ratio of the third product to the solution is 1:(2-6); in the solution, the concentration of the calcium source is 0.1-2.0 mol / L.

[0101] According to one embodiment of the present disclosure, step (4) also includes: subjecting the solid product obtained by the ion exchange reaction to a second drying treatment to obtain the fourth product; the conditions of the second drying treatment include: time of 1-4h, temperature of 80-200°C; the method of the second drying treatment is conventional in the art and no specific requirements are made.

[0102] In the present disclosure, pH values ​​are all measured values ​​under the conditions of 25° C. and standard atmospheric pressure.

[0103] In the present disclosure, the ion exchange reaction may be carried out by, for example, immersing the third product in a solution containing a calcium source.

[0104] According to one embodiment of the present disclosure, the temperature of the activation treatment is 250-350°C, preferably 270-320°C; the time of the activation treatment is 1-4h, preferably 2-3h; the activation treatment can be carried out in a dry air atmosphere, or under vacuum conditions, or in a nitrogen atmosphere to reduce the degree of hydrothermal damage of the molecular sieve at higher temperatures; the methods and steps of the activation treatment are conventional in the art.

[0105] In the present disclosure, 98% of the binder is converted into the molecular sieve during the preparation process, that is, the adsorbent contains almost no binder.

[0106] The following examples use Figure 1 The small-scale simulated moving bed apparatus shown was tested to verify the effect of the present disclosure.

[0107] The small-scale simulated moving bed device with continuous countercurrent is used to test and verify the effect of the present invention. The small-scale simulated moving bed device comprises 12 adsorption columns connected in series, each column is 195 millimeters long, the column inner diameter is 30 millimeters, and the total loading amount of adsorbent is 1650 milliliters. The ends of the 12 columns connected in series are connected with a circulating pump to form a closed loop, and the raw material to be separated, the desorbent, the extracted liquid, and the residual liquid are four inlet and outlet materials, and the 12 adsorption columns are divided into four districts, that is, the 3 adsorption columns between the raw material flow to be separated and the residual liquid flow are the adsorption district, the 4 adsorption columns between the extracted liquid flow and the raw material flow to be separated are the purification district, the 3 adsorption columns between the desorbent flow and the extracted liquid flow are the desorption district, and the 2 adsorption columns between the residual liquid flow and the desorbent flow are the isolation district.

[0108] During the operation, a micro pump is used to continuously inject a desorbent flow and an adsorption feed flow into the simulated moving bed device. The extracted liquid flows out of the device at a continuous flow rate through the micro pump, and the residual liquid flows out of the device through pressure control. The flow rate of each area is adjusted by setting the circulation pump flow rate and the four inlet and outlet streams. An adsorption column is moved in the opposite direction of the liquid flow at regular intervals to realize the principle of continuous countercurrent chromatography of the adsorbent and the fluid. The composition of the extracted liquid and the residual liquid is analyzed by chromatography, and the purity and yield of the extract are calculated in combination with the flow rates of each stream.

[0109] Unless otherwise specified, the reagents used in the examples and comparative examples are commercially available.

[0110] Gas chromatography instrument model and test conditions: Agilent 7890 gas chromatograph was used to test the composition of the liquid sample, HP-5 chromatographic column, injection volume 0.3 μL, injection temperature 290°C, split ratio 45:1, column flow 3.9 mL / min, FID detection, detection temperature 290°C, H2 flow 35 mL / min, air flow 350 mL / min, N2 flow 20 mL / min, initial column temperature was 50°C, maintained for 3 min, heated to 150°C at a rate of 2°C / min, and maintained for 6 min.

[0111] Particle size testing method: Use the US standard sieve to select particles of 0.3-0.6 mm.

[0112] Testing method for water content: The sample is calcined at 600℃ for more than 2h, and the percentage of mass reduction is the water content.

[0113] Grain size testing method: The morphology of the molecular sieve was observed using a Hitachi S4800 scanning electron microscope, and the grain size was measured using SMile View software.

[0114] Exchange degree test method: X-ray fluorescence spectrometry (XRF) is used to analyze the mass fractions of Na2O and CaO in the adsorbent, which are recorded as m N and m C , then Ca 2+ Degree of ion exchange = m C / M C / (m C / M C +m N / M N ). N and M Care the molar masses of Na2O and CaO respectively; the XRF instrument model and test conditions are: 3013 X-ray fluorescence spectrometer (XRF) produced by Nippon Mechanics Co., Ltd. After drying at 100-120℃, the sample to be tested is ground into a powder of about 200 meshes, poured into a tablet pressing mold, and pressed into an ingot on a hydraulic press. The applied pressure is generally above 30MPa and maintained for 5 seconds. The size of the pressed ingot is Φ30mm.

[0115] In the examples and comparative examples, the crystal size of the molecular sieve is the same as that of the original molecular sieve powder.

[0116] Example 1

[0117] Adsorbent X-1 was prepared by the following steps and used for adsorption separation of normal alkanes in C10-C25 fraction oil:

[0118] 50kg of NaA molecular sieve raw powder, 3kg of halloysite (all on dry basis) and 1kg of corn starch were mixed evenly to form a mixed powder, wherein the grain size of the NaA molecular sieve was 0.8μm. The mixed powder was rolled into small balls with a diameter of 0.3-0.6mm in a sugar coating pan, and then dried at 85℃ for 4h and roasted at 550℃ for 4h. 40L of the above roasted small balls were soaked in 80L of 1.0mol / L NaOH aqueous solution at 97℃ for 4h, and then washed with deionized water until the pH value was below 10.0 to obtain NaA small balls. 40L of NaA beads were immersed in 200L of 1.0mol / L CaCl2 aqueous solution for ion exchange, the exchange liquid temperature was maintained at 95°C, the exchange time was 4h, then washed with deionized water, dried (time was 4h, temperature was 150°C), and then programmed to 280°C in a dry air atmosphere for activation for 2h to obtain 5A bead adsorbent X-1. The parameters are listed in Table 1.

[0119] use Figure 1 The small simulated moving bed shown in the figure was tested, and the above-mentioned adsorbent was filled in 12 adsorption columns. The composition of C10-C25 distillate oil is shown in Table 2, and the desorbent is 80% by volume of nC7 and 20% by volume of toluene. There are 3 columns in the adsorption zone, 4 columns in the purification zone, 3 columns in the desorption zone, and 2 columns in the isolation zone. Adsorption separation was carried out under the conditions of temperature 235°C, pressure 2.5MPa, feed flow rate 1158mL / h, desorbent flow rate 1734mL / h, extract flow rate 1015mL / h, residual liquid flow rate 1877mL / h, and step time 150s. The composition of the extract and residual liquid was obtained by chromatographic analysis, and the content of normal alkanes in the extract (excluding the desorbent) was calculated to be 99.6% by weight, the content of aromatics was 0.07% by weight, and the yield of nC10-nC25 normal alkanes was shown in Table 3.

[0120] Example 2

[0121] Adsorbent X-2 was prepared by the steps of Example 1, except that the grain size of the original NaA molecular sieve powder was 0.3 μm, the activation temperature after ion exchange drying was 300° C., and the water content of the adsorbent was 1.5% by weight. The parameters of adsorbent X-2 are listed in Table 1.

[0122] The small-scale simulated moving bed test was carried out according to the method of Example 1, except that the desorbent was 60% by volume of nC6, 20% by volume of iC8 and 20% by volume of benzene, and adsorption separation was carried out under the conditions of temperature 200°C, pressure 2.5MPa, feed flow rate 1158mL / h, desorbent flow rate 2000mL / h, extract flow rate 1381mL / h, raffinate flow rate 1777mL / h, and step time 150s. The composition of the extract and the raffinate was obtained by chromatographic analysis, and the content of normal alkanes in the extract (excluding the desorbent) was calculated to be 99.6% by weight, the content of aromatics was 0.05% by weight, and the yield of nC10-nC25 normal alkanes was shown in Table 3.

[0123] Example 3

[0124] Adsorbent X-1 was used to separate normal alkanes from C10-C25 fraction by adsorption in a manner similar to that of Example 1;

[0125] A small-scale simulated moving bed test was carried out according to the method of Example 1, except that the desorbent was 60% by volume of nC5, 20% by volume of iC8 and 20% by volume of benzene, and adsorption separation was carried out under the conditions of temperature 185°C, pressure 2.5MPa, feed flow rate 1158mL / h, desorbent flow rate 1891mL / h, extract flow rate 1172mL / h, raffinate flow rate 1877mL / h, and step time 150s. The composition of the extract and the raffinate was obtained by chromatographic analysis, and the content of normal alkanes in the extract (excluding the desorbent) was calculated to be 99.5% by weight, the content of aromatics was 0.06% by weight, and the yield of nC10-nC25 normal alkanes was shown in Table 3.

[0126] Example 4

[0127] Adsorbent X-1 was used to separate normal alkanes from C10-C25 fraction by adsorption in a manner similar to that of Example 1;

[0128] A small-scale simulated moving bed test was carried out according to the method of Example 1, except that the desorbent was 95% by volume of nC7 and 5% by volume of toluene, and adsorption separation was carried out under the conditions of temperature 235°C, pressure 2.5MPa, feed flow rate 1158mL / h, desorbent flow rate 1734mL / h, extract flow rate 1015mL / h, raffinate flow rate 1877mL / h, and step time 150s. The composition of the extract and the raffinate was obtained by chromatographic analysis, and the content of normal alkanes in the extract (excluding the desorbent) was calculated to be 99.5% by weight, the content of aromatics was 0.1% by weight, and the yield of nC10-nC25 normal alkanes is shown in Table 3.

[0129] Example 5

[0130] The method of Example 4 was used to perform adsorption separation of normal alkanes in the C10-C25 fraction. 13000 mL of the obtained nC10-nC25 normal alkanes product was injected into an adsorption column filled with 1000 mL of NaX molecular sieve adsorbent (water content of 3 wt%) at a temperature of 100° C., a pressure of normal pressure, and a volume space velocity of 5 h -1 The aromatic content detected at the outflow port was 0.01 wt%.

[0131] Example 6

[0132] Adsorbent X-6 was prepared by the following steps and used for adsorption separation of normal alkanes in C10-C25 fraction oil:

[0133] 58 kg of NaA molecular sieve powder, 10 kg of kaolin (all on dry basis), and 2 kg of sesbania powder were uniformly mixed to form a mixed powder, wherein the grain size of the NaA molecular sieve was 0.2 μm. The mixed powder was rolled into small balls with a diameter of 0.3-0.6 mm in a sugar coating pan, and then dried at 150°C for 3 hours and calcined at 600°C for 4 hours. 40 L of the above-mentioned calcined small balls were soaked in 60 L of 2 mol / L NaOH aqueous solution at 90°C for 5 hours, then washed with deionized water until the pH value was below 10.0, and dried (time was 2 hours, temperature was 200°C) to obtain NaA small balls. 30L of NaA beads were immersed in 150L of 1.5mol / L CaCl2 aqueous solution for ion exchange, the exchange liquid temperature was maintained at 80°C, the exchange time was 3h, then washed with deionized water, dried (time was 2h, temperature was 200°C), and then programmed to 290°C in a dry air atmosphere for activation for 2h to obtain 5A bead adsorbent X-6. The parameters are listed in Table 1.

[0134] A small-scale simulated moving bed test was carried out according to the method of Example 1. The compositions of the extract and the raffinate were obtained by chromatographic analysis. The content of normal alkanes in the extract (excluding the desorbent) was calculated to be 99.5% by weight, the content of aromatics was 0.08% by weight, and the yield of nC10-nC25 normal alkanes is shown in Table 3.

[0135] Comparative Example 1

[0136] Adsorbent Y-1 was prepared by the following steps and used for adsorption separation of normal alkanes in C10-C25 fraction oil:

[0137] 50kg of NaA molecular sieve raw powder, 3kg of halloysite (all on dry basis) and 1kg of corn starch were mixed evenly to form a mixed powder, wherein the grain size of the NaA molecular sieve was 2.5μm. The mixed powder was rolled into small balls with a diameter of 0.3-0.6mm in a sugar coating pan, and then dried at 85℃ for 8h and roasted at 550℃ for 4h. 40L of the above roasted small balls were soaked in 80L of 1.0mol / L NaOH aqueous solution at 97℃ for 4h, then washed with deionized water until the pH value was below 10.0, and dried to obtain NaA small balls. 40L of NaA beads were immersed in 200L of 1.0mol / L CaCl2 aqueous solution for ion exchange, the exchange liquid temperature was maintained at 95°C, the exchange time was 4h, then washed with deionized water, dried (time was 4h, temperature was 150°C), and then programmed to 500°C in a dry air atmosphere for activation for 2h to obtain 5A bead adsorbent Y-1. The parameters are listed in Table 1.

[0138] use Figure 1 The small simulated moving bed shown in the figure was tested, and the above-mentioned adsorbent was filled in 12 adsorption columns. The composition of the adsorption raw materials is shown in Table 2, and the desorbent is 80% by volume of nC7 and 20% by volume of toluene. There are 3 columns in the adsorption zone, 4 columns in the purification zone, 3 columns in the desorption zone, and 2 columns in the isolation zone. Adsorption separation was carried out under the conditions of column temperature 235°C, pressure 2.5MPa, feed flow rate 1158mL / h, desorbent flow rate 1734mL / h, extract flow rate 1015mL / h, residual liquid flow rate 1877mL / h, and step time 150s. The composition of the extract and residual liquid was obtained by chromatographic analysis, and the content of normal alkanes in the extract (excluding the desorbent) was calculated to be 99.6% by weight, the content of aromatics was 0.07% by weight, and the yield of nC10-nC25 normal alkanes was shown in Table 3.

[0139] Comparative Example 2

[0140] Adsorbent Y-2 was prepared by the steps of Example 1, except that the particle size of the 5A molecular sieve adsorbent was 0.9-1.0 mm. The parameters of adsorbent Y-2 are listed in Table 1.

[0141] use Figure 1 The small simulated moving bed shown in the figure was tested, and the above-mentioned adsorbent was filled in 12 adsorption columns. The composition of the adsorption raw materials is shown in Table 2, and the desorbent is 80% by volume of nC7 and 20% by volume of toluene. There are 3 columns in the adsorption zone, 4 columns in the purification zone, 3 columns in the desorption zone, and 2 columns in the isolation zone. Adsorption separation was carried out under the conditions of column temperature 235°C, pressure 2.5MPa, feed flow rate 1158mL / h, desorbent flow rate 1734mL / h, extract flow rate 1015mL / h, residual liquid flow rate 1877mL / h, and step time 150s. The composition of the extract and residual liquid was obtained by chromatographic analysis, and the content of normal alkanes in the extract (excluding the desorbent) was calculated to be 99.6% by weight, the content of aromatics was 0.07% by weight, and the yield of nC10-nC25 normal alkanes was shown in Table 3.

[0142] Comparative Example 3

[0143] Adsorbent X-1 is used to perform adsorption separation of normal alkanes in C10-C25 fraction oil;

[0144] The above adsorbent was filled in 12 adsorption columns, and a small simulated moving bed test was carried out according to Example 1, except that the desorbent was 80% by volume of n-heptane and 20% by volume of isooctane, and adsorption separation was carried out under the conditions of temperature 200°C, pressure 2.5MPa, feed flow rate 1158mL / h, desorbent flow rate 2000mL / h, extract flow rate 1381mL / h, raffinate flow rate 1777mL / h, and step time 150s. The compositions of the extract and the raffinate were obtained by chromatographic analysis, and the content of normal alkanes in the extract (excluding the desorbent) was calculated to be 99.2% by weight, and the content of aromatics was 0.5% by weight.

[0145] Comparative Example 4

[0146] Adsorbent X-1 is used to perform adsorption separation of normal alkanes in C10-C25 fraction oil;

[0147] According to Example 3, a small simulated moving bed test was carried out, except that the desorbent was 60% by volume of nC5 and 40% by volume of iC8, and adsorption separation was carried out under the conditions of temperature 185°C, pressure 2.5MPa, feed flow rate 1158mL / h, desorbent flow rate 1891mL / h, extract flow rate 1172mL / h, raffinate flow rate 1877mL / h, and step time 150s. The compositions of the extract and raffinate were obtained by chromatographic analysis, and the content of normal alkanes in the extract (excluding the desorbent) was calculated to be 99.1% by weight, and the content of aromatics was 0.5% by weight.

[0148] Comparative Example 5

[0149] Adsorbent Y-3 was prepared by the method of Example 1, except that the grain size of the original NaA molecular sieve powder was 1.2 μm. The parameters of adsorbent Y-3 are listed in Table 1.

[0150] According to the method of Example 1, Figure 1 The small simulated moving bed shown in the figure was tested, and the above-mentioned adsorbent was filled in 12 adsorption columns. The composition of C10-C25 distillate oil is shown in Table 2, and the desorbent is 80% by volume of nC7 and 20% by volume of toluene. There are 3 columns in the adsorption zone, 4 columns in the purification zone, 3 columns in the desorption zone, and 2 columns in the isolation zone. Adsorption separation was carried out under the conditions of temperature 235°C, pressure 2.5MPa, feed flow rate 1158mL / h, desorbent flow rate 1734mL / h, extract flow rate 1015mL / h, residual liquid flow rate 1877mL / h, and step time 150s. The composition of the extract and residual liquid was obtained by chromatographic analysis, and the content of normal alkanes in the extract (excluding the desorbent) was calculated to be 99.5% by weight, the content of aromatics was 0.08% by weight, and the yield of nC10-nC25 normal alkanes was shown in Table 3.

[0151] Table 1

[0152]

[0153] Table 2

[0154]

[0155] Table 3

[0156]

[0157] According to the above data, the method disclosed in the present invention can absorb and separate normal alkanes in C10-C25 fraction oil. This method can significantly increase the yield of normal alkanes above C14 and reduce the content of aromatics in normal alkanes.

[0158] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0159] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0160] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for separating normal alkanes from C10-C25 distillate oil by adsorption, characterized in that: The method comprises the following steps: S1, contacting the C10-C25 fraction oil with an adsorbent for the first time to obtain a material to be desorbed comprising C10-C25 normal alkanes and the adsorbent, and a raffinate comprising C10-C25 isoalkanes, C10-C25 cycloalkanes, C10-C25 aromatics and a desorbent; S2, bringing the desorbent into second contact with the material to be desorbed to obtain an extract containing C10-C25 normal alkanes and the desorbent; The C10-C25 distillate oil includes C10-C25 normal alkanes, C10-C25 isoalkanes, C10-C25 cycloalkanes and C10-C25 aromatics; The desorbent includes C5-C8 normal alkanes, C6-C8 aromatic hydrocarbons and optionally C5-C8 isoalkanes; The particle size of the adsorbent is 0.3-0.6 mm. The adsorbent includes 5A molecular sieve, and the grain size of the 5A molecular sieve is 0.2-0.8 μm.

2. The method according to claim 1, wherein: The crystal size of the 5A molecular sieve is 0.2-0.7 μm; Optionally, the water content of the adsorbent is less than 3 wt %.

3. The method according to claim 1, wherein: Relative to the total volume of the desorbent, the content of the C5-C8 normal alkanes is 50-95% by volume, the content of the C6-C8 aromatics is 5-20% by volume, and the content of the C5-C8 isoalkanes is 0-30% by volume.

4. The method according to claim 1, wherein: The temperatures of the first contact and the second contact are 185-230° C., and the pressures are 1.0-2.5 MPa, respectively.

5. The method according to claim 1, wherein: The liquid phase simulated moving bed process is used to absorb and separate normal alkanes in C10-C25 distillate oil, and the simulated moving bed contains 12-24 adsorbent beds; Step S1 comprises: subjecting the C10-C25 fraction oil to the first contact with the adsorbent bed to obtain a raffinate containing the C10-C25 isoalkanes, the C10-C25 cycloalkanes, the C10-C25 aromatics and a desorbent, and the adsorbent bed adsorbing the C10-C25 normal alkanes as the material to be desorbed; Step S2 includes: bringing the desorbent into contact with the material to be desorbed for the second time to obtain the extract.

6. The method according to claim 1 or 5, wherein: The method further comprises: Separating the extracted liquid to obtain the C10-C25 normal alkanes and the desorbent; The raffinate is separated to obtain the C10-C25 isoalkanes, the C10-C25 cycloalkanes, the C10-C25 aromatics and the desorbent.

7. The method according to claim 6, wherein: The method further comprises: contacting the material containing the C10-C25 normal alkanes obtained by separation of the extract with an X-type molecular sieve adsorbent and / or a Y-type molecular sieve adsorbent for a third time; The temperature of the third contact is 100-120°C, the pressure is 0.5-1.5 MPa, and the volume space velocity is 0.5-5.0 h -1 ; The water contents of the X-type molecular sieve adsorbent and the Y-type molecular sieve adsorbent are respectively less than 5% by weight.

8. The method according to claim 1, wherein: The method for preparing the adsorbent comprises the following steps: (1) mixing a molecular sieve raw material, a binder and an auxiliary agent and performing a molding process to obtain a first product; (2) heat treating the first product to obtain a second product; (3) contacting the second product with an alkaline solution to obtain a third product; (4) contacting the third product with a solution containing a calcium source to perform an ion exchange reaction to obtain a fourth product; (5) subjecting the fourth product to an activation treatment; The crystal size of the molecular sieve raw material is 0.2-0.8 μm, and the molecular sieve raw material includes NaA molecular sieve raw powder.

9. The method according to claim 8, wherein: In step (1), the binder includes one or more of a clay binder, silica sol and alumina sol; The clay binder includes one or more of kaolin, halloysite and attapulgite; The auxiliary agent comprises one or more of lignin, sesbania powder, corn starch, bayberry tannin and methyl cellulose.

10. The method according to claim 8, wherein: In step (1), the weight ratio of the molecular sieve raw material to the binder is (85-95): (5-15) on a dry basis; On a dry basis, the amount of the auxiliary agent used is 1-6% by weight relative to the total weight of the molecular sieve raw material and the binder.

11. The method according to claim 8, wherein: Step (1) further includes: forming the product of the molding process into particles with a particle size of 0.30-0.60 mm, and performing a first drying process on the particles to obtain the first product; The conditions of the first drying treatment include: temperature of 80-200° C. and time of 1-4 hours.

12. The method according to claim 8, wherein: In step (2), the heat treatment conditions include: temperature of 500-740°C and time of 1-4h.

13. The method according to claim 8, wherein: In step (3), the contacting conditions include: temperature of 80-99° C. and time of 1-5 h; The alkaline solution includes sodium hydroxide solution and / or potassium hydroxide solution; The concentration of the alkaline solution is 0.5-2 mol / L, and the volume ratio of the second product to the alkaline solution is 1:(1-5); Optionally, step (3) further comprises: washing the solid obtained by the contact until the pH value of the washing liquid is below 10.0, to obtain the third product.

14. The method according to claim 8, wherein: In step (4), the conditions of the ion exchange reaction include: time of 1-4h, temperature of 10-99°C; The calcium source includes calcium chloride and / or calcium nitrate; The volume ratio of the third product to the solution is 1:(2-6); In the solution, the concentration of the calcium source is 0.1-2.0 mol / L; Step (4) further comprises: subjecting the solid product obtained by the ion exchange reaction to a second drying treatment to obtain the fourth product; The conditions of the second drying treatment include: time of 1-4 hours and temperature of 80-200°C.

15. The method according to claim 8, wherein: In step (5), the conditions of the activation reaction include: time of 1-4h and temperature of 250-350°C.

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