A process for the production of propylene by methylation of ethylene

Abstract

The application discloses a method for producing propylene by ethylene methylation, and belongs to the technical field of propylene preparation. The method provided by the application comprises the following steps: reacting a mixture containing raw gas and a catalyst to obtain propylene; the raw gas comprises ethylene and a methylation reagent; and the catalyst comprises an acidic BIK molecular sieve and / or a modified MOR molecular sieve. The method has the advantages of high propylene selectivity, good catalyst stability, mild reaction conditions, simple process and the like, and can be applied to adjusting the olefin product structure of a methanol-to-olefins (MTO) process, a fluidized catalytic cracking (FCC) process and the like, and has a wide application prospect.

Description

Technical Field

[0001] This application belongs to the field of propylene preparation technology, and particularly relates to a method for producing propylene by ethylene methylation. Background Technology

[0002] Propylene is an important basic organic chemical raw material, currently mainly produced through processes such as naphtha steam cracking, methanol-to-olefins (MTO), and propane dehydrogenation. Industrially, MTO and FCC processes simultaneously produce ethylene and propylene, but some downstream industries have only a demand for propylene, requiring the targeted conversion of ethylene into propylene. Ethylene methylation to propylene provides an ideal technical route, and developing such technology is of practical significance. In addition, ethylene methylation can convert C1 methylating agents such as methanol, dimethyl ether, and halomethanes into propylene, providing an important conversion pathway for the high-value utilization of C1 methylating agents.

[0003] Patent WO2005 / 056504A1 discloses a method for preparing propylene from methanol and / or dimethyl ether and ethylene. Methanol and / or dimethyl ether and ethylene are reacted in the presence of a catalyst to produce propylene, with a yield of propylene exceeding 40 mol%.

[0004] CN101130470A discloses a method for producing propylene using alkylation. A feed gas containing ethylene and a methylating agent (methanol, dimethyl ether, monohaloalkane) is contacted with a SAPO-34 or ZSM-5 molecular sieve catalyst containing micropores with a pore size of 0.3–0.5 nm to generate a propylene-containing product, wherein the propylene product selectivity can reach over 65%.

[0005] The catalysts for ethylene methylation are acidic molecular sieve catalysts. Besides methylation, these catalysts are also prone to ethylene polymerization and MTH reactions under the catalysis of the acid centers in the molecular sieves, leading to low propylene selectivity and catalyst deactivation due to carbon buildup. Therefore, the production of propylene from ethylene via methylation presents significant technical challenges. Developing suitable molecular sieve-confined catalytic systems, utilizing the spatially confined nature of the acid centers in molecular sieves, to inhibit ethylene polymerization and MTH reactions is a key breakthrough for achieving highly selective propylene production from ethylene via methylation. Summary of the Invention

[0006] To address the aforementioned technical problems, this application provides a method for producing propylene by ethylene methylation. The method uses a methylating agent and ethylene as raw materials to generate propylene over a catalyst containing an acidic molecular sieve. This method is carried out in a gas-solid phase and uses a non-precious metal catalyst. The process is simple, the catalyst is readily available and inexpensive, and it has significant potential for industrial application.

[0007] To achieve the above-mentioned objectives, this application provides the following technical solution:

[0008] On the one hand, this application provides a method for producing propylene by methylation of ethylene, comprising the following steps:

[0009] A mixture containing feed gas and catalyst is reacted to produce propylene;

[0010] The feed gas includes ethylene and a methylating agent;

[0011] The catalyst comprises acidic BIK molecular sieves and / or modified MOR molecular sieves.

[0012] Optionally, the molar ratio of ethylene to the methylating agent is 0.05 to 100:1.

[0013] Optionally, the molar ratio of ethylene to the methylating agent is independently selected from any value or a range between 0.05:1, 1:1, 10:1, 20:1, 40:1, 60:1, 80:1, and 100:1.

[0014] Optionally, the Si / Al ratio of the acidic BIK molecular sieve and the modified MOR molecular sieve is independently 6 to 30.

[0015] Optionally, when the catalyst is an acidic BIK molecular sieve and a modified MOR molecular sieve, the mass ratio of the acidic BIK molecular sieve to the modified MOR molecular sieve is 0.01 to 100:1.

[0016] Optionally, when the catalyst is an acidic BIK molecular sieve and a modified MOR molecular sieve, the mass ratio of the acidic BIK molecular sieve and the modified MOR molecular sieve is independently selected from any value among 0.01:1, 1:1, 10:1, 20:1, 40:1, 60:1, 80:1, 100:1 or any range between the two.

[0017] Optionally, the particle size of the acidic BIK molecular sieve is 0.3 to 0.5 nm.

[0018] Optionally, the modified MOR molecular sieve is obtained by modifying H-MOR acidic molecular sieve with a modifier.

[0019] Optionally, the preparation method of the acidic BIK molecular sieve or H-MOR acidic molecular sieve is as follows:

[0020] The calcined molecular sieve is placed in a 0.5–1 mol / L NH4NO3 aqueous solution and subjected to ion exchange at room temperature (90°C) for 0.5–10 h. After washing with deionized water, the above steps are repeated 1–3 times. The sieve is then dried at 80–150°C and calcined at 500–600°C to obtain the acidic BIK molecular sieve or H-MOR acidic molecular sieve.

[0021] Optionally, the modifier includes at least one of pyridine, pyridine derivatives, pyridine salts, and quaternary ammonium salts.

[0022] Optionally, the pyridine derivative is selected from at least one of compounds having the structural formula shown in Formula I:

[0023]

[0024] In this process, one or two of R1, R2, R3, R4, and R5 are independently selected from any one of C1 to C4 alkyl groups, and the rest are H atoms.

[0025] Preferably, the pyridine derivative is selected from at least one of 3-methylpyridine, 2,6-dimethylpyridine, and 2-ethylpyridine.

[0026] Optionally, the pyridine salt is selected from at least one of compounds having the structural formula shown in Formula II:

[0027]

[0028] Wherein, R1 and R2 are independently H-, F-, Br-, CH3O-, CH3-, CH3CH2-, and CH3(CH2). n Any one of CH2-, (CH3)2CH-, and (CH3)2CHCH2-, where 0 < n ≤ 2; R3 is any one of H-, CH3-, CH3CH2-, CH3CH2CH2-, and CH3CH2CH2CH2-; X is -F, -Cl, -Br, -I, -COOCH3, or -SO4. 2- Any one of -NO3.

[0029] Preferably, the pyridine salt is selected from at least one of pyridine hydrochloride, pyridine hydrogen bromide, pyridine hydrofluoride, methylpyridine hydrochloride, methylpyridine hydrogen bromide, methylpyridine hydrofluoride, pyridine sulfate, pyridine acetate, and pyridine nitrate.

[0030] Optionally, the quaternary ammonium salt is selected from at least one of compounds having the structural formula shown in Formula III:

[0031]

[0032] Among them, R1, R2, and R3 are independently CH3-, CH3CH2-, and CH3(CH2), respectively. n Any one of CH2-, (CH3)2CH-, and (CH3)2CHCH2-, where 0 < n ≤ 2; R4 is H-, CH3-, CH3CH2-, or CH3(CH2). nAny one of CH2-, (CH3)2CH-, (CH3)2CHCH2-, C6H5-, CH3C6H4-, (CH3)2C6H3-, and C6H5CH2-, where 0 < n ≤ 2; X is any one of -Cl, -Br, and -F.

[0033] Preferably, the quaternary ammonium salt is selected from at least one of methylammonium chloride (bromide), tetraethylammonium chloride (bromide), tetrapropylammonium chloride (bromide), ethyltrimethylammonium chloride (bromide), diethyldimethylammonium chloride (bromide), triethylmethylammonium chloride (bromide), phenyltrimethylammonium chloride (bromide), and benzyltrimethylammonium chloride (bromide).

[0034] Optionally, the modification method includes adsorption pretreatment or ion exchange treatment.

[0035] Preferably, the pyridine and pyridine derivatives are subjected to adsorption pretreatment, and the pyridine salt and quaternary ammonium salt are subjected to ion exchange treatment.

[0036] Optionally, the adsorption pretreatment method involves a carrier gas carrying pyridine or a pyridine derivative through an H-MOR acidic molecular sieve.

[0037] The volume fraction of pyridine or pyridine derivative in the mixed gas is 0.1% to 10%.

[0038] The carrier gas includes at least one of nitrogen, helium, CO2, and argon;

[0039] The gas volume hourly space velocity (VHSV) of the adsorption pretreatment is 300–5000 mL·g. -1 ·h -1 .

[0040] The temperature of the adsorption pretreatment is 150–350°C;

[0041] The adsorption pretreatment time is 0.5 to 4 hours.

[0042] Optionally, the specific method of the ion exchange treatment is as follows:

[0043] (a) H-MOR acidic molecular sieves were added to a solution containing pyridine salt or quaternary ammonium salt at a certain solid-liquid mass ratio, and the mixture was exchanged at 30-100℃ for 1-8 hours, and the product was collected.

[0044] (b) The resulting product is washed, filtered, and dried sequentially;

[0045] (c) Repeat the above steps 2 to 5 times to obtain the modified MOR molecular sieve;

[0046] In step (a), the solid-liquid mass ratio is 1 / 10 to 1 / 100, and the concentration of the pyridine salt or quaternary ammonium salt solution is 0.05 to 2 mol / L.

[0047] Optionally, the raw material gas further includes gas I;

[0048] The volume fraction of gas I in the raw material gas is x, where 0% < x ≤ 95%;

[0049] Gas I includes at least one of hydrogen, nitrogen, helium, and argon.

[0050] Optionally, the methylating agent includes at least one selected from dimethyl ether, methanol, chloromethane, bromomethane, and iodomethane.

[0051] Optionally, the mass hourly space velocity (HHSV) of the methylating agent is 0.01–20 h⁻¹. -1 .

[0052] Optionally, the mass hourly space velocity (MSV) of the methylating agent is independently selected from 0.01 h⁻¹. -1 1h -1 5h -1 10h -1 15h -1 20h -1 Any value in the range or any value between the two.

[0053] Optionally, the reaction temperature is 100–300°C;

[0054] The reaction pressure is 0.1–2 MPa.

[0055] Optionally, the temperature of the reaction is independently selected from any value of 100°C, 150°C, 200°C, 250°C, 300°C, or a range between any two.

[0056] Optionally, the pressure of the reaction is independently selected from any value of 0.1 MPa, 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, or a range between any two.

[0057] Optionally, the reaction is carried out in a reactor;

[0058] The reactor includes at least one of a fixed-bed reactor, a fluidized-bed reactor, and a moving-bed reactor.

[0059] Compared with the prior art, this application has the following advantages:

[0060] This application provides a method for producing propylene by methylation of ethylene. The method utilizes the shape-selective catalytic ability of molecular sieves to directionally couple ethylene and methylating reagents to generate propylene. The method has advantages such as high propylene selectivity, good catalyst stability, mild reaction conditions, and simple process. It can be applied to adjust the olefin product structure in processes such as methanol-to-olefins (MTO) and fluidized catalytic cracking (FCC), and has broad application prospects. Attached Figure Description

[0061] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0062] Figure 1 The FTIR characterization spectra of acidic MOR molecular sieve sample H-3# and partially modified acidic MOR molecular sieve samples H-11#, H-23#, and H-28# are shown in this application. Detailed Implementation

[0063] The present application is further illustrated below with reference to specific embodiments. The following descriptions are merely a few embodiments of the present application and are not intended to limit the present application in any way. Although the present application discloses preferred embodiments as follows, they are not intended to limit the present application. Any modifications or variations made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

[0064] Unless otherwise specified, the raw materials used in the embodiments of this application are all purchased commercially and used directly without any special treatment.

[0065] Unless otherwise specified, the analytical methods in the embodiments all adopt conventional instrument or equipment settings and conventional analytical methods.

[0066] In the embodiments of this application, the elemental composition of H-MOR acidic molecular sieve before and after modification was determined using a Philips Magix 2424X-ray fluorescence analyzer (XRF). The silica-alumina ratio of mordenite did not change before and after modification.

[0067] In the embodiments of this application, the acidity of the molecular sieve was tested on a Bruker Vertex 70 instrument, with each spectrum obtained through 64 scans at a resolution of 4 cm⁻¹. -1 The spectral range is 4000–1000 cm⁻¹ -1 All spectra were recorded at room temperature.

[0068] In the embodiments of this application, the reaction raw materials for preparing propylene and the resulting product were analyzed online using an Agilent 7890A gas chromatograph (column: HP-PLOT-Q capillary column; detector: FID).

[0069] In the embodiments of this application, the conversion rate of the methylating agent and the selectivity of propylene are calculated based on the number of carbon moles of the methylating agent:

[0070] Methylation reagent conversion rate = [(number of carbon moles of methylation reagent in feed gas) - (number of carbon moles of methylation reagent in product)] ÷ (number of carbon moles of methylation reagent in feed gas) × (100%);

[0071] Propylene selectivity = (1 / 3) × (number of carbon moles of propylene in the product) ÷ [(number of carbon moles of methylating agent in the feed gas) - (number of carbon moles of methylating agent in the product)] × (100%).

[0072] The sources of different catalysts and their silicon and aluminum ratios in the following examples are shown in Table 1.

[0073] Table 1. Sources and silicon-to-aluminum ratios of different catalysts

[0074]

[0075]

[0076] Example 1

[0077] Preparation of hydrogen-form molecular sieves:

[0078] The calcined molecular sieves from Table 1 were added to a pre-prepared 1 mol / L NH4NO3 aqueous solution at a solid-liquid mass ratio of 1:10. The mixture was subjected to an exchange reaction at 80°C for 2 hours with stirring. The mixture was then vacuum filtered and washed with water. After three consecutive exchange reactions, the mixture was dried overnight at 120°C and calcined at 550°C for 4 hours to obtain the hydrogen-form molecular sieve sample. Sample numbers are shown in Table 2.

[0079] Table 2 Sample Numbers of Hydrogen-Form Molecular Sieves

[0080] serial number Sample Name Molecular sieve Si / Al ratio H-1# H-EU-7 13 H-2# H-MOR 6 H-3# H-MOR 16 H-4# H-MOR 30 H-5# H-SSZ-13 16 H-6# HY 15 H-7# H-SAPO-34 0.15 H-8# H-Beta 20 H-9# H-ZSM-5 20

[0081] Example 2

[0082] Preparation of pyridine salt-modified MOR molecular sieves by ion exchange:

[0083] Acidic molecular sieve samples H-2#, H-3#, and H-4# were placed in an ion exchange solution and subjected to ion exchange under specific conditions. After filtration, washing, and drying, the above steps were repeated several times to obtain the final samples. The specific preparation conditions for each sample are shown in Table 3.

[0084] Table 3. Ion exchange sample number, composition, and preparation conditions

[0085]

[0086]

[0087] Note: a indicates that samples H-10# to H-22# were prepared using pyridine hydrochloride, and samples H-23# to H-26# were prepared using methylpyridine hydrochloride, ethylpyridine hydrochloride, tetramethylammonium bromide, and tetraethylammonium chloride, respectively.

[0088] Example 3

[0089] MOR molecular sieves modified with pyridine or its derivatives were prepared by an adsorption pretreatment method:

[0090] Acidic zeolite molecular sieve samples H-2#, H-3#, and H-4# were loaded into reaction tubes and heated to 550℃ under a nitrogen atmosphere at a rate of 100 mL / min, held for 4 h, and then treated with pyridine or its derivatives using nitrogen gas to obtain pyridine-substituted acidic zeolite molecular sieves. The specific preparation conditions for each sample are shown in Table 4.

[0091] Table 4. Sample number, composition, and preparation conditions for pretreatment

[0092]

[0093]

[0094] Note: 'a' indicates that pyridine was used for the pretreatment of samples H-27# to H-40#, and 3-methylpyridine, 2,6-dimethylpyridine, and 2-ethylpyridine were used for the pretreatment of samples H-41# to H-43#, respectively.

[0095] Example 4

[0096] Characterization of the prepared modified molecular sieves:

[0097] The samples prepared in Examples 1, 2, and 3 were characterized by FTIR. Specifically, the pressed sample sheets were placed in an in-situ quartz cell and pretreated at 400°C in a vacuum for 30 min. After pretreatment, the samples were cooled to room temperature, and their infrared spectra were acquired. The results are as follows: Figure 1 As shown. By Figure 1 It can be seen that all samples are within the range of 3650–3550 cm. -1 A distinct absorption signal appears in the 3650–3550 cm⁻¹ range, indicating the presence of acidic hydroxyl groups in the sample. Compared to the parent hydrogen-type molecular sieve, MOR molecular sieves modified with pyridine or its derivatives, pyridine salts, and quaternary ammonium salts show a higher absorption signal in the 3650–3550 cm⁻¹ range. -1The signal is weaker, indicating that the organic nitrogen-containing compound has entered the pores of the MOR molecular sieve, effectively modifying the acidity of the sample and occupying part of the pores.

[0098] Example 5

[0099] The conversion of ethylene and dimethyl ether to propylene using different catalysts:

[0100] 1g of the solid acid catalysts from Examples 1, 2, and 3 (where H-1#, H-10# to H-43# were experimental groups, and H-3#, H-5# to H-9# were control groups) were respectively loaded into fixed-bed reactors with an inner diameter of 10mm and lined with quartz tubes (quartz tube inner diameter 6mm). The temperature was increased to 350℃ at 1℃ / min under a nitrogen atmosphere and maintained for 4 hours, then decreased to the reaction temperature of 300℃ under a nitrogen atmosphere. In this example, all feed gas consisted of dimethyl ether and ethylene. The reactants were passed from top to bottom through the catalyst bed. The mass hourly space velocity (MSV) of the dimethyl ether feed was 0.1 h⁻¹. -1 The catalytic reaction was carried out at a molar ratio of ethylene to dimethyl ether of 10:1 and a reaction temperature of 300℃ for 5 hours. The reaction results (TOS = 5h) are shown in Tables 5 and 6.

[0101] Table 5. Reaction results on the catalyst in the experimental group.

[0102]

[0103]

[0104]

[0105] Table 6. Reaction results on the catalyst in the control group.

[0106] catalyst Dimethyl ether conversion rate (%) Propylene selectivity (%) Other options (%) H-3# 95.17 4.39 95.61 H-5# 86.75 49.38 50.62 H-6# 36.57 26.58 73.42 H-7# 62.31 58.11 41.89 H-8# 65.37 19.90 80.10 H-9# 73.53 0.50 99.5

[0107] Table 5 shows that using acidic zeolite molecular sieves with a BIK topology as catalysts, the reaction of dimethyl ether and ethylene to produce propylene can achieve a propylene production rate of 66%. Using modified acidic MOR molecular sieves as catalysts, the reaction of dimethyl ether and ethylene to produce highly selective propylene can achieve a propylene production rate of over 95% with high conversion.

[0108] Comparing the experimental data with the control group in Table 6, it can be seen that the selectivity of dimethyl ether and ethylene methylation to propylene produced by acidic BIK molecular sieve or modified acidic MOR molecular sieve as catalyst is much higher than that of other molecular sieves, and it has excellent catalytic effect.

[0109] Example 6

[0110] The effect of combined catalysts on the conversion of dimethyl ether and ethylene to propylene:

[0111] Taking catalysts H-1# and H-28# as examples, they were mixed in different mass ratios, with other reaction conditions the same as in Example 5. The results of the catalytic reaction after 5 hours are shown in Table 7.

[0112] Table 7. Reaction results with different catalyst mixing ratios

[0113] H-28# / H-1# mass ratio 0.01:1 0.02:1 1:1 10:1 50:1 100:1 Dimethyl ether conversion rate (%) 25.91 25.86. 25.64 25.56 24.92 25.32 Propylene selectivity (%) 67.03 70.12 82.88 90.29 96.07 97.24 Selectivity of other compounds (%) 32.97 29.88 17.22 9.71 3.93 2.76

[0114] Example 7

[0115] The conversion of dimethyl ether to propylene at different reaction temperatures:

[0116] The catalyst used was sample H-28#, and the reaction temperature ranged from 100 to 300°C. Other reaction conditions were the same as in Example 5. The results of the catalytic reaction after 5 hours are shown in Table 8.

[0117] Table 8. Reaction results at different reaction temperatures

[0118] Reactor temperature (°C) 100 180 210 240 270 300 Dimethyl ether conversion rate (%) 0.21 0.71 1.41 3.91 10.92 25.32 Propylene selectivity (%) 28.44 32.92 72.88 90.19 96.17 97.34 Selectivity of other compounds (%) 71.56 67.08 27.12 9.81 3.83 2.66

[0119] Example 8

[0120] The conversion of dimethyl ether to propylene under different reaction pressures:

[0121] The catalyst used was sample H-28, and the reaction pressures were 0.1 MPa, 0.5 MPa, 1.0 MPa, and 2.0 MPa, respectively. Other conditions were the same as in Example 5. The results of the catalytic reaction running for 5 hours are shown in Table 9.

[0122] Table 9. Reaction results under different reaction pressures.

[0123] Reaction pressure (MPa) 0.1 0.5 1.0 2.0 Dimethyl ether conversion rate (%) 25.32 65.26 75.26 85.18 Propylene selectivity (%) 97.34 90.34 87.40 83.09 Selectivity of other compounds (%) 2.66 9.66 12.60 16.91

[0124] Example 9

[0125] Propylene production under different dimethyl ether mass hourly space velocities:

[0126] The catalyst used was sample H-28#, and the mass hourly space velocity (HHSV) of the dimethyl ether feed was 0.1 h⁻¹. -1 0.3h -1 0.5h -1 1.0h -1 10h -1 and 20h -1 Other conditions were the same as in Example 5. The reaction was run for 5 hours, and the results are shown in Table 10.

[0127] Table 10 Reaction results for different dimethyl ether mass hourly space velocities.

[0128]

[0129]

[0130] Example 10

[0131] Propylene production under different molar ratios of ethylene and dimethyl ether:

[0132] The catalyst used was sample H-28#, and the molar ratios of ethylene to dimethyl ether were 0:1, 3:1, 5:1, 8:1, 10:1, 50:1, and 100:1, respectively. Other conditions were the same as in Example 5. The reaction was run for 5 hours, and the results are shown in Table 11.

[0133] Table 11 Reaction results of ethylene and dimethyl ether at different molar ratios

[0134]

[0135] Example 11

[0136] Propylene was prepared by conversion using different methylating agents as raw materials:

[0137] When using sample H-28 as the catalyst and methanol, chloromethane, bromomethane, and iodomethane as the methylating agents, other conditions were the same as in Example 2. The reaction was run for 5 hours, and the results are shown in Table 12.

[0138] Table 12 Reaction results using different methylating agents as raw materials

[0139] Methylating agents Conversion rate (%) Propylene selectivity (%) Other options (%) methanol 17.04 97.31 2.69 Chloromethane 11.21 88.96 11.04 bromomethane 13.64 86.85 13.15 Iodomethane 15.41 84.69 15.31

[0140] Using catalyst H-5# as a control group, and with methanol, chloromethane, bromomethane, and iodomethane as the methylating agents, other conditions were the same as in Example 2. The reaction was run for 5 hours, and the results are shown in Table 13.

[0141] Table 13. Reaction results on the control group catalyst using different methylating agents as raw materials.

[0142] Methylating agents Conversion rate (%) Propylene selectivity (%) Other options (%) methanol 80.06 47.31 52.69 Chloromethane 50.23 35.69 64.31 bromomethane 55.69 37.33 62.67 Iodomethane 63.45 39.62 60.38

[0143] As can be seen from the comparison of Tables 12 and 13, the modified acidic MOR molecular sieve as a catalyst has higher selectivity for different methylating reagents and for the methylation of ethylene to propylene than other molecular sieves, demonstrating excellent catalytic performance.

[0144] Example 12

[0145] Propylene preparation by conversion of methylating agents in different reactors:

[0146] The catalyst used was sample H-28. The reaction was carried out in fixed bed, fluidized bed and moving bed, respectively, with other conditions the same as in Example 2. The reaction was run for 5 hours and the results are shown in Table 14.

[0147] Table 14 Reaction results evaluated using different reactors

[0148] Reactor type Conversion rate (%) Propylene selectivity (%) Other options (%) Fixed bed 25.32 97.34 2.66 fluidized bed 27.94 97.44 2.56 mobile bed 27.55 97.41 2.59

[0149] Example 13

[0150] Results of the reaction of dimethyl ether and ethylene to propylene at different reaction times:

[0151] The catalyst used was sample H-28. The temperature was increased to 350℃ at a rate of 1℃ / min under a nitrogen atmosphere and maintained for 4 hours. Then, the temperature was lowered to 300℃ under a nitrogen atmosphere. A feed gas with a composition of dimethyl ether:ethylene:N2 = 1:10:19 was introduced into the reactor. The reaction pressure was 0.1 MPa, and the dimethyl ether feed mass hourly space velocity was 0.08 h⁻¹. -1 The reactions were run for 5, 10, 20, 30, 50, 100 and 200 hours, respectively. The results at different catalytic reaction times are shown in Table 15.

[0152] Table 15 Reaction results at different catalytic reaction times

[0153] Reaction time (h) Conversion rate (%) Propylene selectivity (%) Other options (%) 5 25.32 97.34 2.66 10 25.27 97.44 2.56 20 25.17 97.49 2.51 30 24.71 97.47 2.53 50 24.75 97.36 2.64 100 24.59 97.25 2.75 200 23.55 97.07 2.93

[0154] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A method for producing propylene by methylation of ethylene, characterized in that, Includes the following steps: A mixture containing feed gas and catalyst is reacted to produce propylene; The feed gas includes ethylene and a methylating agent; The catalyst comprises acidic BIK molecular sieves and / or modified MOR molecular sieves; The reaction temperature is 100~300℃; The reaction pressure is 0.1~2 MPa; The Si / Al ratio of the acidic BIK molecular sieve and the modified MOR molecular sieve is independently 6~30; The particle size of the acidic BIK molecular sieve is 0.3~0.5 nm; The modified MOR molecular sieve is obtained by modifying H-MOR acidic molecular sieve with a modifier; The modifier includes at least one of pyridine, pyridine derivatives, pyridine salts, and quaternary ammonium salts; The modification methods include adsorption pretreatment or ion exchange treatment; The methylating agent includes at least one of dimethyl ether, methanol, chloromethane, bromomethane, and iodomethane; The pyridine derivative is selected from at least one of 3-methylpyridine, 2,6-dimethylpyridine, and 2-ethylpyridine; The pyridine salt is selected from at least one of pyridine hydrochloride, pyridine hydrogen bromide, pyridine hydrofluoride, methylpyridine hydrochloride, methylpyridine hydrogen bromide, methylpyridine hydrofluoride, pyridine sulfate, pyridine acetate, and pyridine nitrate. The quaternary ammonium salt is selected from at least one of methylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, ethyltrimethylammonium chloride, diethyldimethylammonium chloride, triethylmethylammonium chloride, phenyltrimethylammonium chloride, benzyltrimethylammonium chloride, methylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, ethyltrimethylammonium bromide, diethyldimethylammonium bromide, triethylmethylammonium bromide, phenyltrimethylammonium bromide, and benzyltrimethylammonium bromide.

2. The method for producing propylene by ethylene methylation according to claim 1, characterized in that, The molar ratio of ethylene to methylating agent is 0.05 to 100:

1.

3. The method for producing propylene by ethylene methylation according to claim 1, characterized in that, When the catalyst is an acidic BIK molecular sieve and a modified MOR molecular sieve, the mass ratio of the acidic BIK molecular sieve to the modified MOR molecular sieve is 0.01~100:

1.

4. The method for producing propylene by ethylene methylation according to claim 1, characterized in that, The raw material gas also includes gas I; The volume fraction of gas I in the raw material gas is x, where 0% < x ≤ 95%; Gas I includes at least one of hydrogen, nitrogen, helium, and argon.

5. The method for producing propylene by ethylene methylation according to claim 1, characterized in that, The mass hourly space velocity (MSV) of the methylating agent is 0.01–20 h⁻¹. -1 .

6. The method for producing propylene by ethylene methylation according to claim 1, characterized in that, The reaction is carried out in a reactor; The reactor includes at least one of a fixed-bed reactor, a fluidized-bed reactor, and a moving-bed reactor.

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