Method for preparing aromatic hydrocarbon from methanol

Abstract

The invention relates to a method for preparing aromatic hydrocarbon from methanol and belongs to the technical field of preparation of aromatic hydrocarbon from methanol. According to the method, two inorganic acids (selenic acid and boric acid) and two metal salts (magnesium salt and bismuth salt) are selected to modify the HZSM-5 molecular sieve subjected to ammonia water alkalization treatment, so that the conversion rate of methanol aromatization reaction, the yield of BTX, the yield of trimethylbenzene and the yield of total aromatic hydrocarbon can be effectively improved.

Description

Technical Field

[0001] The invention relates to a method for preparing aromatics from methanol, and belongs to the technical field of preparing aromatics from methanol. Background Art

[0002] Aromatic hydrocarbons are organic compounds containing benzene rings. Aromatic hydrocarbons were originally derived from crude benzene and coal tar in the coal coking industry, but were later replaced by petroleum catalytic reforming and gasoline cracking, and currently account for more than 90% of all aromatic hydrocarbon sources. However, my country's oil and natural gas resources are very scarce, but coal resources are relatively abundant. Therefore, the process of using methanol to prepare aromatic hydrocarbons has become a research hotspot. The conversion process of methanol to aromatic hydrocarbons is as follows: first, methanol is dehydrated to form dimethyl ether; then, methanol / dimethyl ether is catalytically converted into low-carbon olefins on the acid center of the catalyst; finally, low-carbon olefins are converted into a mixture of long-chain olefins, alkanes, aromatic hydrocarbons, etc. through dehydrogenation, cyclization, hydrogen transfer and other reactions.

[0003] Due to its optimal acidity and appropriate pore size, ZSM-5 molecular sieve is widely used as a catalyst for methanol to aromatics. However, the conversion rate and aromatics yield of methanol to aromatics using conventional ZSM-5 molecular sieve are currently low. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing aromatics from methanol to solve the problem of low conversion rate and low aromatics yield in the current method for preparing aromatics from methanol.

[0005] The invention provides a method for preparing aromatic hydrocarbons from methanol, comprising the following steps: performing an aromatization reaction on methanol by using a catalyst, wherein the preparation method of the catalyst is as follows: immersing HZSM-5 molecular sieve raw powder in ammonia water with a concentration of 0.8-1.2 mol / L for a mixing reaction, and then immersing in an ammonium nitrate solution for a replacement reaction to obtain an alkali-treated molecular sieve powder; then adsorbing a modifier solution on the alkali-treated molecular sieve powder, drying, and calcining to obtain a catalyst, wherein the modifier solution consists of selenic acid, boric acid, magnesium nitrate, bismuth nitrate and water, and the ratio of the mass of the alkali-treated molecular sieve powder, the mass of the selenium element in the selenic acid, the mass of the boron element in the boric acid, the mass of the magnesium element in the magnesium nitrate and the mass of the bismuth element in the bismuth nitrate is 100: (0.4-0.6): (0.8-1): (0.9-1.2): (0.7-0.9).

[0006] Preferably, the volume of ammonia water used for every 10 g of HZSM-5 molecular sieve raw powder is 120-150 mL.

[0007] Preferably, the molar ratio of SiO2 to Al2O3 in the HZSM-5 molecular sieve raw powder is 38-60, and the specific surface area is 350-355m 2 / g.

[0008] Preferably, the temperature of the mixed reaction is 60-70° C., and the time is 1-1.5 h.

[0009] Preferably, after the mixing reaction is completed, the solid-liquid separation is performed, the solid obtained by the solid-liquid separation is washed, dried and immersed in an ammonium nitrate solution for a replacement reaction, and after the replacement reaction is completed, the solid-liquid separation is performed, the solid obtained by the solid-liquid separation is washed and dried to obtain the alkali-treated molecular sieve powder.

[0010] Preferably, the replacement reaction includes a first replacement reaction and a second replacement reaction; the temperature of the first replacement reaction is 80-90° C. and the time is 4-6 hours; the temperature of the second replacement reaction is 80-90° C. and the time is 4-6 hours.

[0011] Preferably, the drying temperature is 80-90°C.

[0012] Preferably, the calcination temperature is 580-620° C. and the calcination time is 4-6 hours.

[0013] Preferably, the particle size of the catalyst is 60-80 mesh.

[0014] Preferably, the temperature for the aromatization reaction of methanol is 340-500° C. and the pressure is 0.02-0.06 MPa.

[0015] The beneficial effects of the present invention are as follows:

[0016] (1) The present invention uses ammonia water of appropriate concentration to alkalize the HZSM-5 molecular sieve, thereby increasing the mesoporous channels of the HZSM-5 molecular sieve, which is beneficial to the subsequent loading and fixation of metal and non-metal ions and the aromatization reaction of methanol, thereby improving the conversion rate of methanol, the yield of BTX, the yield of trimethylbenzene and the yield of total aromatics.

[0017] (2) The present invention uses selenic acid and boric acid in combination, which can improve the conversion rate of methanol aromatization reaction, the yield of BTX, the yield of trimethylbenzene and the yield of total aromatics more than the combination of either of the two with phosphoric acid.

[0018] (3) The present invention uses magnesium salt and bismuth salt to modify the HZSM-5 molecular sieve, which can work together with selenic acid and boric acid to improve the conversion rate of methanol aromatization reaction, the yield of BTX, the yield of trimethylbenzene and the yield of total aromatics.

[0019] (4) The present invention selects two inorganic acids (selenic acid and boric acid) and two metal salts (magnesium salt and bismuth salt) to modify the HZSM-5 molecular sieve after the ammonia alkalization treatment, so that each step can play a synergistic role and effectively improve the conversion rate of the methanol aromatization reaction, the yield of BTX, the yield of trimethylbenzene and the yield of total aromatics. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the comparison results of the average value of methanol conversion rate, the average value of BTX (benzene, toluene and xylene) yield, the average value of trimethylbenzene yield and the average value of total aromatic hydrocarbon yield in the preparation methods of various embodiments and comparative examples of the present invention. DETAILED DESCRIPTION

[0021] The following examples are intended to further illustrate the present invention rather than to limit the scope of protection of the present invention.

[0022] Example 1

[0023] The method for preparing aromatics from methanol in this embodiment comprises the following steps:

[0024] (1) 10 g of HZSM-5 molecular sieve powder (molar ratio of SiO2 to Al2O3 is 38, specific surface area is 352 m 2 / g) was added into 120mL of 0.8mol / L ammonia water, stirred evenly, then heated to 60°C, stirred and refluxed for 1h, cooled to room temperature, filtered, and the filter cake was first rinsed with dilute hydrochloric acid to neutralize the weak alkaline solution on the surface of the molecular sieve, then washed with distilled water until neutral, and then placed in a forced air drying oven at 100°C for 12h to obtain an alkaline molecular sieve.

[0025] (2) placing the alkaline molecular sieve obtained in step (1) in 200 mL of 1 mol / L ammonium nitrate solution, stirring evenly, heating to 80°C, stirring and reflux for 4 h, filtering, and then placing the filter cake in 300 mL of 1 mol / L ammonium nitrate solution, stirring evenly, heating to 80°C, stirring and reflux for 4 h, filtering, and placing the filter cake in a forced air drying oven at 100°C for 12 h to obtain an alkali-treated molecular sieve powder.

[0026] (3) According to the equal volume impregnation method, the modifier solution is uniformly added to the alkali-treated molecular sieve powder, and the mass of water in the modifier solution is equal to the saturated adsorbed water of the alkali-treated molecular sieve; the modifier solution is prepared by mixing selenic acid, boric acid, magnesium nitrate, bismuth nitrate and water, and the ratio of the mass of the alkali-treated molecular sieve, the mass of the selenium element in selenic acid, the mass of the boron element in boric acid, the mass of the magnesium element in magnesium nitrate and the mass of the bismuth element in bismuth nitrate is 100:0.4:0.8:0.9:0.7; then the molecular sieve powder adsorbed with the modifier solution is placed in an ultrasonic cleaning machine for ultrasonication to uniformly disperse the modifier solution in the molecular sieve powder; then the molecular sieve powder adsorbed with the modifier solution is dried at 80°C for 12h, and finally the dried solid is ground and placed in a muffle furnace, calcined at 580°C for 4h, and cooled to room temperature to obtain a modified HZSM-5 molecular sieve. The modified HZSM-5 molecular sieve is tableted, ground, sieved, and particles with a particle size of 60 to 80 mesh are collected to obtain a catalyst.

[0027] (4) 7 g of the catalyst and 3 g of the inert carrier quartz sand were mixed evenly and then loaded into the middle constant temperature section of a stainless steel reactor with an inner diameter of 10 mm and a length of 900 mm. Then, the inert carrier quartz sand was filled at the upper and lower ends of the reactor respectively. Nitrogen was introduced into the reactor at a flow rate of 30 mL / min. At the same time, the reactor was heated to the reaction temperature and purged for 2 h. Then, raw methanol was pumped into the reactor with a double-plunger micropump to allow the methanol to contact and react with the catalyst in the reactor. The reaction temperature was 340°C, the reaction pressure was 0.02 MPa, and the methanol mass space velocity was 0.8 / h.

[0028] Example 2

[0029] The method for preparing aromatics from methanol in this embodiment comprises the following steps:

[0030] (1) 10 g of HZSM-5 molecular sieve powder (molar ratio of SiO2 to Al2O3 is 46, specific surface area is 355 m 2 / g) was added into 130mL of 1mol / L ammonia water, stirred evenly, then heated to 65°C, stirred and refluxed for 1.2h, cooled to room temperature, filtered, and the filter cake was first rinsed with dilute hydrochloric acid to neutralize the weak alkaline solution on the surface of the molecular sieve, then washed with distilled water until neutral, and then placed in a forced air drying oven at 100°C for 12h to obtain an alkaline molecular sieve.

[0031] (2) placing the alkaline molecular sieve obtained in step (1) in 200 mL of 1 mol / L ammonium nitrate solution, stirring evenly, heating to 85°C, stirring and reflux for 5 h, filtering, and then placing the filter cake in 300 mL of 1 mol / L ammonium nitrate solution, stirring evenly, heating to 85°C, stirring and reflux for 5 h, filtering, and placing the filter cake in a forced air drying oven at 100°C for 12 h to obtain an alkali-treated molecular sieve powder.

[0032] (3) According to the equal volume impregnation method, the modifier solution is uniformly added to the alkali-treated molecular sieve powder, and the mass of water in the modifier solution is equal to the saturated adsorbed water of the alkali-treated molecular sieve; the modifier solution is prepared by mixing selenic acid, boric acid, magnesium nitrate, bismuth nitrate and water, and the ratio of the mass of the alkali-treated molecular sieve, the mass of the selenium element in selenic acid, the mass of the boron element in boric acid, the mass of the magnesium element in magnesium nitrate and the mass of the bismuth element in bismuth nitrate is 100:0.5:0.9:1:0.8; then the molecular sieve powder adsorbed with the modifier solution is placed in an ultrasonic cleaning machine for ultrasonication to uniformly disperse the modifier solution in the molecular sieve powder; then the molecular sieve powder adsorbed with the modifier solution is dried at 85°C for 12h, and finally the dried solid is ground and placed in a muffle furnace, calcined at 600°C for 5h, and cooled to room temperature to obtain a modified HZSM-5 molecular sieve. The modified HZSM-5 molecular sieve is tableted, ground, sieved, and particles with a particle size of 60 to 80 mesh are collected to obtain a catalyst.

[0033] (4) 7 g of the catalyst and 3 g of the inert carrier quartz sand were mixed evenly and then loaded into the middle constant temperature section of a stainless steel reactor with an inner diameter of 10 mm and a length of 900 mm. Then, the inert carrier quartz sand was filled at the upper and lower ends of the reactor respectively. Nitrogen was introduced into the reactor at a flow rate of 30 mL / min. At the same time, the reactor was heated to the reaction temperature and purged for 2 h. Then, raw methanol was pumped into the reactor with a double-plunger micropump to allow the methanol to contact and react with the catalyst in the reactor. The reaction temperature was 400°C, the reaction pressure was 0.04 MPa, and the methanol mass space velocity was 1 / h.

[0034] Example 3

[0035] The method for preparing aromatics from methanol in this embodiment comprises the following steps:

[0036] (1) 10 g of HZSM-5 molecular sieve powder (molar ratio of SiO2 to Al2O3 is 60, specific surface area is 350 m 2 / g) was added into 150mL of 1.2mol / L ammonia water, stirred evenly, then heated to 70°C, stirred and refluxed for 1.5h, cooled to room temperature, filtered, and the filter cake was first rinsed with dilute hydrochloric acid to neutralize the weak alkaline solution on the surface of the molecular sieve, then washed with distilled water until neutral, and then placed in a forced air drying oven at 100°C for 12h to obtain an alkaline molecular sieve.

[0037] (2) placing the alkaline molecular sieve obtained in step (1) in 200 mL of 1 mol / L ammonium nitrate solution, stirring evenly, heating to 90°C, stirring and reflux for 6 h, filtering, and then placing the filter cake in 300 mL of 1 mol / L ammonium nitrate solution, stirring evenly, heating to 90°C, stirring and reflux for 6 h, filtering, and placing the filter cake in a forced air drying oven at 100°C for 12 h to obtain an alkali-treated molecular sieve powder.

[0038] (3) According to the equal volume impregnation method, the modifier solution is uniformly added to the alkali-treated molecular sieve powder, and the mass of water in the modifier solution is equal to the saturated adsorbed water of the alkali-treated molecular sieve; the modifier solution is prepared by mixing selenic acid, boric acid, magnesium nitrate, bismuth nitrate and water, and the ratio of the mass of the alkali-treated molecular sieve, the mass of the selenium element in selenic acid, the mass of the boron element in boric acid, the mass of the magnesium element in magnesium nitrate and the mass of the bismuth element in bismuth nitrate is 100:0.6:1:1.2:0.9; then the molecular sieve powder adsorbed with the modifier solution is placed in an ultrasonic cleaning machine for ultrasonication to uniformly disperse the modifier solution in the molecular sieve powder; then the molecular sieve powder adsorbed with the modifier solution is dried at 90°C for 12h, and finally the dried solid is ground and placed in a muffle furnace, calcined at 620°C for 6h, and cooled to room temperature to obtain a modified HZSM-5 molecular sieve. The modified HZSM-5 molecular sieve is tableted, ground, sieved, and particles with a particle size of 60 to 80 mesh are collected to obtain a catalyst.

[0039] (4) 7 g of the catalyst and 3 g of the inert carrier quartz sand were mixed evenly and then loaded into the middle constant temperature section of a stainless steel reactor with an inner diameter of 10 mm and a length of 900 mm. Then, the inert carrier quartz sand was filled at the upper and lower ends of the reactor respectively. Nitrogen was introduced into the reactor at a flow rate of 30 mL / min. At the same time, the reactor was heated to the reaction temperature and purged for 2 h. Then, raw methanol was pumped into the reactor with a double-plunger micropump to allow the methanol to contact and react with the catalyst in the reactor. The reaction temperature was 500°C, the reaction pressure was 0.06 MPa, and the methanol mass space velocity was 1.5 / h.

[0040] Comparative Example 1

[0041] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example, magnesium nitrate is replaced by aluminum nitrate.

[0042] Comparative Example 2

[0043] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example, magnesium nitrate is replaced by ferric nitrate.

[0044] Comparative Example 3

[0045] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that magnesium nitrate is replaced by potassium nitrate in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example.

[0046] Comparative Example 4

[0047] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example, magnesium nitrate is replaced by zinc nitrate.

[0048] Comparative Example 5

[0049] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that magnesium nitrate is replaced by cadmium nitrate in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example.

[0050] Comparative Example 6

[0051] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that magnesium nitrate is replaced by lanthanum nitrate in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example.

[0052] Comparative Example 7

[0053] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example, magnesium nitrate is replaced by cobalt nitrate.

[0054] Comparative Example 8

[0055] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that bismuth nitrate is replaced by aluminum nitrate in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example.

[0056] Comparative Example 9

[0057] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that bismuth nitrate is replaced by ferric nitrate in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example.

[0058] Comparative Example 10

[0059] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that bismuth nitrate is replaced by potassium nitrate in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example.

[0060] Comparative Example 11

[0061] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example, bismuth nitrate is replaced by zinc nitrate.

[0062] Comparative Example 12

[0063] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that bismuth nitrate is replaced by cadmium nitrate in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example.

[0064] Comparative Example 13

[0065] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that bismuth nitrate is replaced by lanthanum nitrate in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example.

[0066] Comparative Example 14

[0067] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that bismuth nitrate is replaced by cobalt nitrate in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example.

[0068] Comparative Example 15

[0069] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example, boric acid is replaced by phosphoric acid.

[0070] Comparative Example 16

[0071] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that selenic acid is replaced by phosphoric acid in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example.

[0072] Comparative Example 17

[0073] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that the concentration of aqueous ammonia used in step (1) of the method for preparing aromatic hydrocarbons from methanol in this comparative example is 0.6 mol / L.

[0074] Comparative Example 18

[0075] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that the concentration of aqueous ammonia used in step (1) of the method for preparing aromatic hydrocarbons from methanol in this comparative example is 1.4 mol / L.

[0076] Comparative Example 19

[0077] The difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that in step (1) of the method for preparing aromatic hydrocarbons from methanol in this comparative example, aqueous ammonia is replaced by a tetramethylammonium hydroxide solution of equal concentration.

[0078] Comparative Example 20

[0079] The difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that in step (1) of the method for preparing aromatic hydrocarbons from methanol in this comparative example, aqueous ammonia is replaced by a sodium hydroxide solution of equal concentration.

[0080] Comparative Example 21

[0081] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example, the modifier solution is prepared by mixing selenic acid, boric acid, magnesium nitrate and water, and the ratio of the mass of the alkali-treated molecular sieve, the mass of the selenium element in the selenic acid, the mass of the boron element in the boric acid and the mass of the magnesium element in the magnesium nitrate is 100:0.6:1:2.1.

[0082] Comparative Example 22

[0083] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example, the modifier solution is prepared by mixing selenic acid, boric acid, bismuth nitrate and water, and the ratio of the mass of the alkali-treated molecular sieve, the mass of the selenium element in the selenic acid, the mass of the boron element in the boric acid and the mass of the bismuth element in the bismuth nitrate is 100:0.6:1:2.1.

[0084] Comparative Example 23

[0085] The difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example, the modifier solution is prepared by mixing selenic acid, magnesium nitrate, bismuth nitrate and water, and the ratio of the mass of the alkali-treated molecular sieve, the mass of the selenium element in selenic acid, the mass of the magnesium element in magnesium nitrate and the mass of the bismuth element in bismuth nitrate is 100:1.6:1.2:0.9.

[0086] Comparative Example 24

[0087] The only difference between the method for preparing aromatic hydrocarbons from methanol in this comparative example and the method for preparing aromatic hydrocarbons from methanol in Example 1 is that in step (3) of the method for preparing aromatic hydrocarbons from methanol in this comparative example, the modifier solution is prepared by mixing boric acid, magnesium nitrate, bismuth nitrate and water, and the ratio of the mass of the alkali-treated molecular sieve, the mass of the boron element in the boric acid, the mass of the magnesium element in the magnesium nitrate and the mass of the bismuth element in the bismuth nitrate is 100:1.6:1.2:0.9.

[0088] The reaction products of the embodiments and comparative examples at three sampling times of 1 h, 2 h and 3 h were subjected to chromatographic analysis. The methanol conversion rate, the yield of BTX (benzene, toluene and xylene), the yield of trimethylbenzene and the yield of total aromatics at each sampling time were calculated according to the analysis results. The average values ​​of the methanol conversion rate, the average values ​​of the yield of BTX (benzene, toluene and xylene), the average values ​​of the yield of trimethylbenzene and the average values ​​of the yield of total aromatics at the three sampling times were calculated. The results are shown in Tables 1 and Figure 1 shown.

[0089] Table 1 Average values ​​of methanol conversion, BTX yield, trimethylbenzene yield and total aromatics yield in each embodiment and comparative example

[0090]

[0091] From Table 1 and Figure 1 It can be seen that, compared with other metal elements, modifying HZSM-5 molecular sieves with magnesium and bismuth elements together with selenic acid and boric acid can effectively improve the yield of BTX, the yield of trimethylbenzene and the yield of total aromatics when preparing aromatics from methanol; compared with phosphoric acid, modifying HZSM-5 molecular sieves with selenic acid and boric acid at the same time can effectively improve the yield of BTX, the yield of trimethylbenzene and the yield of total aromatics when preparing aromatics from methanol; by selecting an appropriate concentration of ammonia water, the mesoporous channels of HZSM-5 molecular sieves can be increased, which is beneficial to the loading and fixation of metal and non-metal ions and the aromatization reaction of methanol, thereby improving the conversion rate of methanol, the yield of BTX, the yield of trimethylbenzene and the yield of total aromatics.

Claims

1. A method for preparing aromatics from methanol, characterized in that: The following steps are involved: A catalyst is used to carry out aromatization reaction of methanol. The preparation method of the catalyst is as follows: immersing HZSM-5 molecular sieve raw powder in ammonia water with a concentration of 0.8-1.2 mol / L for mixing reaction, and then immersing it in ammonium nitrate solution for replacement reaction to obtain alkali-treated molecular sieve powder; then adsorbing a modifier solution on the alkali-treated molecular sieve powder, drying, and calcining to obtain a catalyst. The modifier solution consists of selenic acid, boric acid, magnesium nitrate, bismuth nitrate and water. The ratio of the mass of the alkali-treated molecular sieve powder, the mass of the selenium element in the selenic acid, the mass of the boron element in the boric acid, the mass of the magnesium element in the magnesium nitrate and the mass of the bismuth element in the bismuth nitrate is 100: (0.4-0.6): (0.8-1): (0.9-1.2): (0.7-0.9).

2. The method for preparing aromatics from methanol according to claim 1, characterized in that: The volume of ammonia water used for every 10 g of HZSM-5 molecular sieve raw powder is 120-150 mL.

3. The method for preparing aromatics from methanol according to claim 1 or 2, characterized in that: The molar ratio of SiO2 to Al2O3 in the HZSM-5 molecular sieve raw powder is 38-60, and the specific surface area is 350-355m 2 / g.

4. The method for preparing aromatics from methanol according to claim 1 or 2, characterized in that: The temperature of the mixed reaction is 60-70° C. and the time is 1-1.5 hours.

5. The method for preparing aromatics from methanol according to claim 1 or 2, characterized in that: After the mixed reaction is completed, the solid and liquid are separated, and the solid obtained by the solid-liquid separation is washed, dried, and immersed in an ammonium nitrate solution for a replacement reaction. After the replacement reaction is completed, the solid and liquid are separated, and the solid obtained by the solid-liquid separation is washed and dried to obtain the alkali-treated molecular sieve powder.

6. The method for preparing aromatics from methanol according to claim 1, characterized in that: The replacement reaction includes a first replacement reaction and a second replacement reaction; the temperature of the first replacement reaction is 80-90° C. and the time is 4-6 hours; the temperature of the second replacement reaction is 80-90° C. and the time is 4-6 hours.

7. The method for preparing aromatics from methanol according to claim 1, characterized in that: The drying temperature is 80-90°C.

8. The method for preparing aromatics from methanol according to claim 1 or 7, characterized in that: The calcination temperature is 580-620° C. and the calcination time is 4-6 hours.

9. The method for preparing aromatics from methanol according to claim 1, characterized in that: The particle size of the catalyst is 60-80 meshes.

10. The method for preparing aromatics from methanol according to claim 1, characterized in that: The temperature for aromatization of methanol is 340-500°C and the pressure is 0.02-0.06MPa.

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