Catalyst for preparing isobutene by converting acetic acid as well as preparation method and application of catalyst

Abstract

The invention belongs to the technical field of molecular sieve catalysts, and discloses a catalyst for preparing isobutene through acetic acid conversion and a preparation method and application thereof.The preparation method comprises the steps that firstly, an HBeta molecular sieve is treated with concentrated nitric acid to prepare a dealuminated Beta molecular sieve; then zirconium oxynitrate and yttrium nitrate are loaded in the dealuminated Beta molecular sieve through an impregnation method, and a Y-Zr / Beta catalyst is obtained; the catalyst is a dual-Lewis acid catalyst, shows excellent catalytic activity and selectivity in a reaction for preparing isobutene by converting acetic acid, and can obtain higher isobutene yield; the catalyst carrier and the metal precursor salt are cheap and easy to obtain, and the preparation process is simple; therefore, a new effective way is provided for production of isobutene, and the situation that isobutene mainly depends on traditional energy at present is effectively relieved.

Description

Technical Field

[0001] The invention belongs to the technical field of molecular sieve catalysts, and in particular relates to a catalyst for converting acetic acid into isobutylene, and a preparation method and application thereof. Background Art

[0002] Isobutylene is an important chemical raw material, widely used in the production of important chemicals such as butyl rubber, polyisobutylene, methyl tert-butyl ether and organic glass. At present, the main route for producing isobutylene is to rely on the further production of petroleum processing products, such as isobutane dehydrogenation, isobutanol dehydration, methyl tert-butyl ether cracking and other methods. With the proposal of the dual-carbon strategy, the preparation of isobutylene from renewable resources has been favored by scientific researchers. For example, acetic acid is an important biomass platform molecule and the most abundant organic acid, accounting for 12% of the bio-oil content. Untreated bio-oil will corrode metal engines and promote the occurrence of side reactions such as polymerization reactions, thereby further affecting performance. Therefore, the conversion of acetic acid to prepare isobutylene has important economic and environmental value.

[0003] Patent CN108097300A applied by the inventor mainly introduces active centers into the molecular sieve by impregnation method, thereby obtaining excellent activity. However, there is still room for improving the activity of this reaction. Based on the previous patent for the conversion of acetic acid to prepare isobutylene, this application further optimizes the catalyst to improve the conversion rate and selectivity of the reaction. Summary of the invention

[0004] The present invention provides a new method for preparing a catalyst for the reaction of preparing isobutylene from acetic acid. The obtained catalyst is innovatively applied to the reaction of preparing isobutylene from acetic acid for the first time, and a higher isobutylene yield can be obtained.

[0005] In order to solve the above technical problems, the present invention is implemented by the following technical solutions:

[0006] According to a first aspect of the present invention, there is provided a catalyst for converting acetic acid to isobutylene, which is obtained by the following preparation method:

[0007] S1. Treating HBeta molecular sieve with concentrated nitric acid to prepare dealuminated Beta molecular sieve;

[0008] S2. After the zirconium oxynitrate and yttrium nitrate water are mixed and stirred, a small amount of concentrated nitric acid is added to dissolve the slightly turbid solution into a clear solution, and the sample obtained in step (1) is added. After sufficient stirring, the mixture is heated and stirred at 80-100° C. and evaporated to dryness; the sample obtained by evaporation is dried and calcined at 400-600° C. for 4-8 hours to obtain a Y-Zr / Beta catalyst.

[0009] According to a second aspect of the present invention, there is provided a method for preparing a catalyst for converting acetic acid to isobutylene, comprising:

[0010] S1. Treating HBeta molecular sieve with concentrated nitric acid to prepare dealuminated Beta molecular sieve;

[0011] S2. After the zirconium oxynitrate and yttrium nitrate water are mixed and stirred, a small amount of concentrated nitric acid is added to dissolve the slightly turbid solution into a clear solution, and the sample obtained in step (1) is added. After sufficient stirring, the mixture is heated and stirred at 80-100° C. and evaporated to dryness; the sample obtained by evaporation is dried and calcined at 400-600° C. for 4-8 hours to obtain a Y-Zr / Beta catalyst.

[0012] For the above-mentioned catalyst for converting acetic acid to isobutylene and its preparation method:

[0013] Furthermore, S1 includes: mixing HBeta molecular sieve with concentrated nitric acid and heating to react; after the reaction is completed, filtering and washing the product to neutrality, and then drying it for later use.

[0014] Preferably, in S1: the reaction temperature is 100-120° C., the reaction time is 20-30 hours; the feed ratio of HBeta molecular sieve to concentrated nitric acid is 1 g: 10-30 ml; the drying temperature is 80-120° C., and the drying time is 6-10 hours.

[0015] Preferably, in S2: the percentage of element Y in the catalyst is 3-7wt%, and the percentage of element Zr in the catalyst is 3-7wt%.

[0016] More preferably, in S2: the percentage of element Y in the catalyst is 5wt%, and the percentage of element Zr in the catalyst is 5wt%.

[0017] Preferably, in S2: the stirring time is 3-6 hours;

[0018] Preferably, in S2: the drying temperature is 100-120° C., and the drying time is 12-24 hours.

[0019] According to a third aspect of the present invention, there is provided an application of a catalyst for converting acetic acid to isobutylene, which is used in the reaction of converting acetic acid to isobutylene at a reaction temperature of 300-500°C.

[0020] Furthermore, the obtained catalyst is first pressed into tablets, and then placed in a reaction bed, and pretreated at a temperature of 400-500°C for 0.5-2 hours with a carrier gas flow rate of 20-50 ml / min; after the pretreatment, the reaction temperature is set, and acetic acid is fed into the reaction bed with an acetic acid flow rate of 0.1-1 ml / min.

[0021] The beneficial effects of the present invention are:

[0022] The present invention proposes a new catalyst preparation method for the reaction of preparing isobutylene from acetic acid. The Y-Zr / Beta catalyst prepared by the method is a double Lewis acid catalyst, and its activity is improved compared with the previous Y / Beta rare earth catalyst with only one Lewis acid. At the same time, the catalyst carrier and the metal precursor salt of the present invention are cheap and easy to obtain, and the preparation process of the catalyst is simple. The Y / Beta rare earth catalyst obviously shows excellent catalytic activity and selectivity, and the yield of isobutylene is further improved, so that the current situation that isobutylene mainly relies on traditional energy can be effectively alleviated. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 XRD spectra of three different catalysts and a comparative catalyst prepared in Example 1 of the present invention;

[0024] Figure 2 The activity test results of three different catalysts prepared in Example 1 of the present invention are shown in FIG.

[0025] Figure 3 This is a graph showing the activity test results of different catalysts prepared by using different proportions of Y and Zr in Example 2 of the present invention;

[0026] Figure 4 This is a graph showing the activity test results of three different catalysts prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0027] In some preferred embodiments of the present invention, a catalyst for converting acetone to isobutylene and a preparation method thereof are provided, which are carried out according to the following steps:

[0028] S1. Treating HBeta molecular sieve with concentrated nitric acid: mixing HBeta molecular sieve and concentrated nitric acid in a ratio of 1:10-30 (g / ml); stirring at 100-120°C for 20-30 hours; after the reaction is completed, washing it by suction filtration until it is neutral, and then drying it in an oven at 80-120°C for 6-10 hours for standby use to obtain a dealuminated Beta molecular sieve;

[0029] S2. Loading zirconium oxynitrate and yttrium nitrate into the sample obtained in S1 by impregnation to obtain a Y-Zr / Beta catalyst:

[0030] A certain amount of zirconium oxynitrate and yttrium nitrate precursors are weighed and added to a beaker containing 20-60 ml of water, a small amount of concentrated nitric acid is added to dissolve the slightly suspended solution into a clear solution, and then a certain amount of the sample obtained by S1 is added, and the mixture is fully stirred for 3-6 hours, and then heated and stirred at 80-100°C to evaporate to dryness, and the evaporated sample is placed in a 100-120°C oven for drying for 12-24 hours, and then placed in a muffle furnace for calcination for 4-8 hours at a calcination temperature of 400-600°C to obtain a Y-Zr / Beta (Xwt%-Ywt%) catalyst, where X and Y represent the mass percentages of elements Y and Zr in the catalyst, respectively.

[0031] In some preferred embodiments of the present invention, the content of element Y in the catalyst is 3-7 wt %, most preferably 5 wt %.

[0032] In some preferred embodiments of the present invention, the content of element Zr in the catalyst is 3-7 wt %, most preferably 5 wt %.

[0033] The Y-Zr / Beta catalyst of the present invention is used for the reaction of converting acetic acid to isobutylene: firstly, the obtained catalyst is tableted, a certain amount of catalyst (0.1-0.3 g) of 20-40 mesh is sieved out with a sieve, and then the catalyst is placed in a fixed bed for pretreatment for 0.5-2 hours, the pretreatment temperature is 400-500°C, and the carrier gas flow rate is 20-50 ml / min; after the pretreatment is completed, the temperature is set to a specified temperature, acetic acid is sent into the fixed bed with an injection pump, the acetic acid flow rate is 0.2 ml / min, and the reaction temperature is 300-500°C.

[0034] The following is a more detailed description of the specific implementation of the present invention in conjunction with the accompanying drawings and embodiments, so as to better understand the scheme of the present invention and its advantages in various aspects. It should be noted that the specific implementation methods and embodiments described below are only for the purpose of illustration, and are not intended to limit the present invention.

[0035] Example 1

[0036] In this embodiment, HBeta catalyst is used as raw powder, and the silicon-to-aluminum ratio used is 28.

[0037] Preparation of dealuminated Beta molecular sieve: 200 ml of concentrated nitric acid and 10 g of HBeta raw powder were placed in a three-necked flask and mixed, and then placed in a 100°C oil bath for heating and reflux for 20 hours; after the mixture was filtered, washed until neutral, and dried in an oven at 80°C for 24 hours.

[0038] Preparation of Y / Beta (10 wt%), Y-Zr / Beta (5 wt%-5 wt%) and Zr / Beta (10 wt%) catalysts:

[0039] Weigh a certain amount of yttrium nitrate into a beaker, add 40 ml of water, stir for 30 minutes, then add 1 g of the above-mentioned dealuminated Beta molecular sieve, stir for 4 hours, evaporate to dryness in an 80°C water bath, dry in an oven at 100°C for 24 hours, and finally place in a muffle furnace at 550°C and calcine for 6 hours to obtain Y / Beta (10wt%).

[0040] Weigh a certain amount of yttrium nitrate and zirconium oxynitrate into a beaker, add 40 ml of water, stir for 30 minutes, add a small amount of concentrated nitric acid to dissolve the slightly turbid solution into a clear solution, then add 1 g of the above-mentioned dealuminated Beta molecular sieve, stir for 4 hours, stir and evaporate to dryness in a 80°C water bath, dry in an oven at 100°C for 24 hours, and finally calcine in a 550°C muffle furnace for 6 hours to obtain Y-Zr / Beta (5wt%-5wt%).

[0041] Weigh a certain amount of zirconium oxynitrate into a beaker, add 40 ml of water, stir for 30 minutes, add a small amount of concentrated nitric acid to dissolve the slightly turbid solution into a clear solution, then add 1 g of the above-mentioned dealuminated Beta molecular sieve, stir for 4 hours, stir and evaporate to dryness in a 80°C water bath, dry in an oven at 100°C for 24 hours, and finally calcine in a 550°C muffle furnace for 6 hours to obtain Zr / Beta (10wt%).

[0042] The above three catalysts were evaluated in the reaction of acetic acid conversion to isobutylene:

[0043] The evaluation method is consistent with the previously applied patent for preparing isobutylene by conversion of acetic acid (publication number: CN108097300A). First, tablets are pressed and sieved with a 20-40 mesh sieve. 0.16 g of the sample is weighed and then placed in a fixed bed quartz reaction tube and pretreated with nitrogen at 450°C for 1 hour with a nitrogen flow rate of 20 ml / min. After the pretreatment, acetic acid is introduced through a syringe pump with a mass space velocity of 1 / h. Finally, the reaction product enters the gas chromatograph through a six-way valve for online analysis, and the following is obtained: Figure 1 The XRD spectra of the four catalysts are shown in Figure 2. Figure 1 It can be seen that dealumination and loading of metals on the molecular sieve do not affect the BEA structure of the molecular sieve.

[0044] Figure 2 The reaction activities of three different catalysts prepared in Example 1 are as follows: Figure 2 It is obvious that the Y and Zr bimetallic species loaded on the molecular sieve have better activity than the Y / Beta catalyst in the prior application.

[0045] Example 2

[0046] In this embodiment, HBeta catalyst is used as raw powder, and the silicon-to-aluminum ratio used is 28.

[0047] Preparation of dealuminated Beta molecular sieve: 200 ml of concentrated nitric acid and 10 g of HBeta raw powder were placed in a three-necked flask and mixed, and then placed in a 100°C oil bath for heating and reflux for 20 hours; after the mixture was filtered, washed until neutral, and dried in an oven at 80°C for 24 hours.

[0048] Weigh different mass contents of zirconium oxynitrate and yttrium nitrate into a beaker, the mass content ratios are Y:Zr=10:0, 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8, 1:9, 0:10 respectively; then add 40 ml of water, stir for 30 minutes, add a few drops of concentrated nitric acid to promote dissolution, then add 1 g of the above-mentioned dealuminated Beta molecular sieve, stir for 4 hours, evaporate to dryness with stirring in an 80°C water bath, dry in a 100°C oven for 24 hours, and finally put it into a 550°C muffle furnace for calcination for 6 hours to obtain catalysts with different yttrium and zirconium ratios.

[0049] The catalysts with different ratios of yttrium to zirconium were evaluated in the reaction of acetic acid conversion to isobutylene:

[0050] The evaluation method is consistent with the previously applied patent for preparing isobutylene by conversion of acetic acid (publication number: CN108097300A). First, tablets are pressed and sieved with a 20-40 mesh sieve, 0.16 g of the sample is weighed, and then placed in a fixed bed quartz reaction tube and pretreated with nitrogen at 450°C for 1 hour with a nitrogen flow rate of 20 ml / min. After the pretreatment, acetic acid is introduced through a syringe pump with a mass space velocity of 1 / h. Finally, the reaction product enters the gas chromatograph through a six-way valve for online analysis.

[0051] Figure 3 The activity of different ratios of Y and Zr loaded on the molecular sieve at a temperature of 450°C. It can be seen that the activity is best when the mass content ratio of Y to Zr is 5:5.

[0052] Example 3

[0053] In this embodiment, HBeta catalyst is used as raw powder, and the silicon-to-aluminum ratio used is 28.

[0054] Preparation of dealuminated Beta molecular sieve: 200 ml of concentrated nitric acid and 10 g of HBeta raw powder were placed in a three-necked flask and mixed, and then placed in a 100°C oil bath for heating and reflux for 20 hours; after the mixture was filtered, washed until neutral, and dried in an oven at 80°C for 24 hours.

[0055] Preparation of Y-Zr / Beta (5wt%-5wt%), Y-Zr / Silicalite-1 (5wt%-5wt%) and Y-Zr / SiO2 (5wt%-5wt%) catalysts:

[0056] Weigh a certain amount of yttrium nitrate and zirconium oxynitrate into a beaker, add 40 ml of water, stir for 30 minutes, add a small amount of concentrated nitric acid to dissolve the slightly turbid solution into a clear solution, then add 1 g of the above-mentioned dealuminated Beta molecular sieve, stir for 4 hours, stir and evaporate to dryness in a 80°C water bath, dry in an oven at 100°C for 24 hours, and finally calcine in a 550°C muffle furnace for 6 hours to obtain Y-Zr / Beta (5wt%-5wt%).

[0057] The preparation methods of the two catalysts Y-Zr / Silicalite-1 (5wt%-5wt%) and Y-Zr / SiO2 (5wt%-5wt%) are as above, the only difference is that Silicalite-1 and SiO2 are used instead of the dealuminated Beta molecular sieve respectively.

[0058] The above three catalysts were evaluated in the reaction of acetic acid conversion to isobutylene:

[0059] The evaluation method is consistent with the previously applied patent for preparing isobutylene by conversion of acetic acid (publication number: CN108097300A). First, tablets are pressed and sieved with a 20-40 mesh sieve, 0.16 g of the sample is weighed, and then placed in a fixed bed quartz reaction tube and pretreated with nitrogen at 450°C for 1 hour with a nitrogen flow rate of 20 ml / min. After the pretreatment, acetic acid is introduced through a syringe pump with a mass space velocity of 1 / h. Finally, the reaction product enters the gas chromatograph through a six-way valve for online analysis.

[0060] Figure 4 The reaction activities of three different catalysts prepared in Example 3 at a temperature of 450°C. It can be seen that the activity is best when Y and Zr are loaded on the dealuminated Beta molecular sieve.

[0061] Although the preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments, which are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms of specific changes without departing from the scope of protection of the invention and the claims, all of which fall within the scope of protection of the present invention.

Claims

1. A method for preparing a catalyst for converting acetic acid to isobutylene, characterized in that: include: S1. Treating HBeta molecular sieve with concentrated nitric acid to prepare dealuminated Beta molecular sieve; S2. After the zirconium oxynitrate and yttrium nitrate water are mixed and stirred, a small amount of concentrated nitric acid is added to dissolve the slightly turbid solution into a clear solution, and the sample obtained in step (1) is added. After sufficient stirring, the mixture is heated and stirred at 80-100° C. and evaporated to dryness; the sample obtained by evaporation is dried and calcined at 400-600° C. for 4-8 hours to obtain a Y-Zr / Beta catalyst.

2. The method for preparing a catalyst for converting acetic acid to isobutylene according to claim 1, characterized in that: S1 includes: The HBeta molecular sieve is mixed with concentrated nitric acid and heated to react; after the reaction is completed, the product is filtered and washed to neutrality, and then dried for later use.

3. The method for preparing a catalyst for converting acetic acid to isobutylene according to claim 2, characterized in that: In S1, the reaction temperature is 100-120° C., and the reaction time is 20-30 hours; the feed ratio of HBeta molecular sieve to concentrated nitric acid is 1 g:10-30 ml; the drying temperature is 80-120° C., and the drying time is 6-10 hours.

4. The method for preparing a catalyst for converting acetic acid to isobutylene according to claim 1, characterized in that: In S2: the percentage of element Y in the catalyst is 3-7wt%, and the percentage of element Zr in the catalyst is 3-7wt%.

5. The method for preparing a catalyst for converting acetic acid to isobutylene according to claim 1, characterized in that: In S2: the percentage of element Y in the catalyst is 5wt%, and the percentage of element Zr in the catalyst is 5wt%.

6. The method for preparing a catalyst for converting acetic acid to isobutylene according to claim 1, characterized in that: In S2: the stirring time is 3-6 hours.

7. The method for preparing a catalyst for converting acetic acid to isobutylene according to claim 1, characterized in that: In S2: the drying temperature is 100-120°C, and the drying time is 12-24 hours.

8. A catalyst for converting acetic acid to isobutylene, characterized in that: Obtained by the preparation method according to any one of claims 1 to 7.

9. Use of the catalyst for converting acetic acid to isobutylene as claimed in claim 8, characterized in that: Used in the reaction of acetic acid to isobutylene, the reaction temperature is 300-500℃.

10. Use of the catalyst for converting acetic acid to isobutylene as claimed in claim 9, characterized in that: First, the obtained catalyst is pressed into tablets, and then placed in a reaction bed, and pretreated at a temperature of 400-500°C for 0.5-2 hours with a carrier gas flow rate of 20-50ml / min; after the pretreatment, the reaction temperature is set, and acetic acid is fed into the reaction bed with an acetic acid flow rate of 0.1-1ml / min.

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