CN108503503B - Method for preparing isobutene by catalytic dehydrogenation of isobutane - Google Patents

Method for preparing isobutene by catalytic dehydrogenation of isobutane Download PDF

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CN108503503B
CN108503503B CN201710110557.4A CN201710110557A CN108503503B CN 108503503 B CN108503503 B CN 108503503B CN 201710110557 A CN201710110557 A CN 201710110557A CN 108503503 B CN108503503 B CN 108503503B
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attapulgite
catalyst
isobutane
hydrogen
modified carrier
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CN108503503A (en
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季静
纪玉国
柴忠义
熊凯
龚凤霞
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Sinopec Beijing Research Institute of Chemical Industry
China Petroleum and Chemical Corp
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China Petroleum and Chemical Corp
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
    • C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
    • C07C5/327—Formation of non-aromatic carbon-to-carbon double bonds only
    • C07C5/333—Catalytic processes
    • C07C5/3335—Catalytic processes with metals
    • C07C5/3337—Catalytic processes with metals of the platinum group
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
    • C07C2523/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals
    • C07C2523/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals of the platinum group metals
    • C07C2523/42—Platinum
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
    • C07C2523/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals
    • C07C2523/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals combined with metals, oxides or hydroxides provided for in groups C07C2523/02 - C07C2523/36
    • C07C2523/56—Platinum group metals
    • C07C2523/58—Platinum group metals with alkali- or alkaline earth metals or beryllium

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  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

The application relates to a method for preparing isobutene by dehydrogenating isobutane, which comprises the following steps: the method comprises the steps of firstly reducing a catalyst, then contacting a feed containing isobutane, steam and hydrogen with the reduced catalyst, and carrying out dehydrogenation reaction to obtain the isobutene, wherein the catalyst comprises an attapulgite modified carrier and a Pt metal component loaded on the modified carrier. According to the method provided by the invention, a novel platinum-based metal catalyst is adopted, and the isobutane conversion rate and the isobutene yield can be greatly increased under certain process conditions, so that the method has the advantages of simple and feasible process steps, low cost and the like.

Description

Method for preparing isobutene by catalytic dehydrogenation of isobutane
Technical Field
The invention relates to a method for preparing isobutene by dehydrogenating isobutane, in particular to a catalytic dehydrogenation method by using a platinum-based bimetallic catalyst.
Background
Isobutene is an important organic chemical raw material, is mainly used for synthesizing methyl tert-butyl ether, butyl rubber and polyisobutylene, and can also be used for synthesizing various organic raw materials and fine chemicals such as methacrylate, isoprene, tert-butyl phenol, tert-butylamine, 1, 4-butanediol, ABS resin and the like. With the development and utilization of isobutene downstream products, the demand for isobutene is larger and larger, and therefore isobutane dehydrogenation technology is receiving more and more attention.
In the sixties of the twentieth century, foreign companies have been continuously researching and developing isobutane dehydrogenation technology, and representative and industrialized processes include FBD-4 process by Snamprogetti, Catofin process by Lummus, Olefiex process by UOP, and the like, and catalysts used by them are classified into two types: chromium-based catalysts and platinum-based catalysts. For example, USP4506032, USP4595673 and the like disclose a catalyst with noble metal platinum supported on an alumina carrier and a preparation method thereof. In the processes, the isobutane conversion rate is 40-60% under the conditions that the reaction temperature is 500-650 ℃ and the reaction pressure is 0.1-6.0 MPa. Therefore, the conversion rate of the product is low and the catalyst is easy to inactivate due to the problems of high reaction temperature, low reaction space velocity, easy carbon deposition on the surface of the catalyst and the like.
Patents CN101138738B and CN101439292A disclose a catalyst and a process for preparing isobutene by oxidative dehydrogenation of isobutane, however, in the presence of oxygen, the target product of oxidative dehydrogenation of isobutane and the raw material isobutane are prone to deep oxidation reaction, resulting in low conversion rate of raw material isobutane and low yield of target product isobutene.
Disclosure of Invention
The inventors have conducted extensive and intensive studies in the field of isobutane dehydrogenation in order to find a method for preparing isobutene by isobutane dehydrogenation. As a result, it was found that a novel platinum-based metal catalyst can be used to greatly increase the isobutane conversion rate and the isobutene yield under certain process conditions.
According to the invention, the method for preparing isobutene by dehydrogenating isobutane comprises the following steps: the method comprises the steps of firstly reducing a catalyst, then contacting a feed containing isobutane, steam and hydrogen with the catalyst, and carrying out dehydrogenation reaction to obtain the isobutene, wherein the catalyst comprises an attapulgite modified carrier and a Pt metal component loaded on the modified carrier.
According to the method provided by the invention, a novel platinum-based catalyst is adopted, and steam and hydrogen are introduced into the feed stream, so that the conversion rate of isobutane and the selectivity and yield of isobutene are improved.
According to a preferred embodiment of the method of the present invention, the temperature of the reaction is 500-550 ℃, preferably 520-540 ℃. The reaction pressure is normal pressure.
According to a preferred embodiment of the process of the present invention, the isobutane feed volume space velocity in the reaction is 1000--1Preferably 1200-1300h-1(ii) a The volume ratio of the water vapor to the hydrogen is 1: (1-3), preferably1: (1.5-2.5). The volume ratio of hydrogen to isobutane (i.e., hydrogen to oil ratio) is a ratio conventional in the art, such as (0.5-1.2):1, preferably (0.8-1):1,
according to a preferred embodiment of the method of the present invention, the catalyst comprises an attapulgite-modified support and a Pt metal component supported on the modified support. The activity and the anti-carbon deposition capability of the catalyst can be improved by modifying the carrier, so that the isobutane conversion rate and the isobutene yield are improved, and the catalyst has a wide application prospect.
According to a preferred embodiment of the method according to the invention, the amount of attapulgite is 0.5-5 wt. -%, preferably 1-3 wt. -%, like 1.5-2.5 wt. -%, based on the weight of the support (support before modification). Within the range, the catalyst has a good modification effect on the carrier, and can improve the conversion rate of isobutane and the yield of isobutene.
According to a preferred embodiment of the method of the present invention, the support is selected from at least one of alumina, silica and molecular sieves.
According to a preferred embodiment of the process of the present invention, the content of the Pt metal component (content of platinum element) is 0.2 to 0.5 wt%, preferably 0.3 to 0.4 wt%, based on the total weight of the catalyst.
According to a preferred embodiment of the process according to the invention, the catalyst further comprises a Mg metal component supported on the modified support, i.e. in this case on the modified support, as a Pt-Mg bimetallic component. The activity and the stability of the catalyst can be further improved and the service life can be prolonged under the combined action of the bimetallic components loaded on the modified carrier; the method can improve the conversion rate of the isobutane and the yield of the isobutene, and can reduce the process cost.
According to a preferred embodiment of the process according to the invention, the content of the Pt metal component (content of platinum element) is 0.2-0.5 wt%, preferably 0.3-0.4 wt%, based on the total mass of the catalyst; the content of the Mg metal component (content of magnesium element) is 12 to 18% by weight, preferably 14 to 16% by weight. Within the range, on the basis of ensuring the improvement of the conversion rate of the isobutane and the yield of the isobutene, the consumption of the noble metal Pt is less, and the process cost is favorably reduced.
According to a preferred embodiment of the method of the present invention, the catalyst is composed of an attapulgite-modified carrier and a Pt-Mg bimetallic component supported on the modified carrier. The content of the Pt metal component is 0.2 to 0.5 wt%, preferably 0.3 to 0.4 wt%, based on the total mass of the catalyst; the content of the Mg metal component is 12 to 18 wt%, preferably 14 to 16 wt%. The attapulgite may be present in an amount of 0.5 to 5 wt%, such as 1 to 3 wt%, preferably 1.5 to 2.5 wt%, based on the weight of the support.
According to a preferred embodiment of the process according to the invention, the catalyst is prepared by a process comprising the steps of:
s1, preparing a modified carrier, which comprises the steps of adding attapulgite into a carrier or a precursor thereof, adding acid liquor for kneading, and then forming, drying and roasting to obtain the attapulgite modified carrier;
s2, loading a metal component, namely soaking the modified carrier in a solution containing a platinum compound, and then drying and roasting to obtain the catalyst.
According to a preferred embodiment of the method of the present invention, in step S1, the acid solution is dilute nitric acid, such as 2 wt% dilute nitric acid. The roasting temperature is 500-700 ℃, and the roasting time is 4-6 hours.
According to a preferred embodiment of the method according to the invention, in step S1, the attapulgite is present in an amount of 1-3 wt.%, preferably 1.5-2.5 wt.%, based on the weight of the support. The carrier is at least one selected from alumina, silica and molecular sieves.
According to a preferred embodiment of the method of the invention, the carrier is an alumina carrier, a certain amount of alumina powder and a certain amount of attapulgite are mixed, a 2 wt% nitric acid aqueous solution is added for kneading, strip extrusion molding, drying at 120 ℃, and roasting at 500-700 ℃ for 4-6 hours to obtain the modified carrier.
According to a preferred embodiment of the method according to the invention, the modified support is impregnated with a solution of a magnesium-containing compound before, after or simultaneously with the impregnation of the modified support with a solution of a platinum-containing compound. The content of the Pt metal component in the catalyst is 0.2 to 0.5 wt%, preferably 0.3 to 0.4 wt%, based on the catalyst; the content of the Mg metal component is 12 to 18 wt%, preferably 14 to 16 wt%.
According to a preferred embodiment of the method of the present invention, in step S2, the platinum-containing compound is selected from at least one of chloroplatinic acid and potassium chloroplatinate. The magnesium compound is selected from at least one of magnesium nitrate, magnesium chloride and magnesium sulfate.
According to a preferred embodiment of the method of the present invention, in step S2, the impregnation time is 6-10 hours, the calcination temperature is 500-800 ℃, and the calcination time is 5-8 hours.
In step S2, the modified carrier is sequentially immersed in a chloroplatinic acid solution and a magnesium nitrate solution, and then dried and calcined to obtain a bimetallic catalyst; for example, the modified carrier is first soaked in chloroplatinic acid solution for 6-10 hr, dried at 120 deg.c and roasted at 800 deg.c for 5-8 hr, then soaked in magnesium nitrate solution for 6-10 hr, dried at 120 deg.c and roasted at 800 deg.c for 5-8 hr to obtain the bimetallic catalyst.
According to a preferred embodiment of the method of the present invention, the reduction may be performed by a reduction method known in the art. For example, reduction with hydrogen is carried out for 10 hours under a constant temperature condition of 480 ℃.
According to the method provided by the invention, a novel platinum-based metal catalyst is adopted, and the isobutane conversion rate and the isobutene yield can be greatly increased under certain process conditions, so that the method has the advantages of simple and feasible process steps, low cost and the like. For example, in one specific example, using the process of the present invention, the isobutane conversion is 50-70% and the isobutene yield is 45-60%.
Detailed Description
The present invention will be more fully understood by those skilled in the art by describing in detail the present invention with reference to the following examples, which are not intended to limit the scope of the present invention in any way.
The method for calculating the isobutane conversion rate comprises the following steps: isobutane conversion rate is the amount of isobutane converted/amount of isobutane in the feed;
method for calculating isobutene selectivity: isobutylene selectivity is the amount of isobutylene in the product/amount of isobutane converted;
the method for calculating the yield of isobutene comprises the following steps: the yield of isobutene is isobutane conversion × isobutene selectivity.
The preparation of the catalyst adopts an impregnation method, wherein the preparation of the platinum metal catalyst comprises the following steps: the platinum catalyst is prepared by impregnating metal platinum on a modified carrier, and then drying and roasting the carrier. The catalyst in the examples was prepared specifically as follows:
s1, mixing a certain amount of alumina powder with a certain amount of attapulgite, adding 2 wt% nitric acid aqueous solution for kneading, extruding and molding, drying at 120 ℃, and roasting at the temperature of 500-700 ℃ for 4-6 hours to obtain a modified carrier;
s2, soaking the modified carrier in a chloroplatinic acid solution for 6-10 hours, drying at 120 ℃, and roasting at 800 ℃ for 5-8 hours.
Of course, the support may be replaced by other supports, such as at least one of a precursor of alumina, silica, a precursor of silica, a molecular sieve, and a precursor thereof.
The preparation of the platinum-magnesium bimetallic catalyst comprises the following steps: the modified carrier is impregnated with metal platinum and metal magnesium, and then the modified carrier is dried and roasted to obtain the catalyst. The catalyst in the examples was prepared specifically as follows:
s1, mixing a certain amount of alumina powder with a certain amount of attapulgite, adding 2 wt% nitric acid aqueous solution for kneading, extruding and molding, drying at 120 ℃, and roasting at the temperature of 500-700 ℃ for 4-6 hours to obtain a modified carrier;
s2, soaking the modified carrier in a chloroplatinic acid solution for 6-10 hours, drying at 120 ℃, roasting at 800 ℃ for 5-8 hours, then soaking in a magnesium nitrate solution for 6-10 hours, drying at 120 ℃ and roasting at 800 ℃ for 5-8 hours.
Of course, the support may be replaced by other supports, such as at least one of a precursor of alumina, silica, a precursor of silica, a molecular sieve, and a precursor thereof.
According to the process of the invention, the catalyst loaded in the reactor is first reduced with hydrogen, for example for 10 hours at a constant temperature of 480 ℃, and then the feed containing isobutane, steam and hydrogen is brought into contact with said reduced catalyst in the reactor. The reaction apparatus used in the present invention is any suitable reaction apparatus known to those skilled in the art. The process conditions are as follows: the reaction temperature is 500-550 ℃, preferably 520-540 ℃, the reaction pressure is normal pressure, preferably normal pressure, and the isobutane feeding volume space velocity is 1000-1500h-1Preferably 1200--1(ii) a The volume ratio of the water vapor to the hydrogen is 1 (1-3), preferably 1 (1.5-2.5); the hydrogen-oil ratio is (0.5-1.2):1, preferably (0.8-1): 1.
Example 1
Using a 100ml evaluation device, charging 85g of the modified carrier loaded platinum-based bimetallic catalyst, wherein the modified carrier comprises attapulgite accounting for 1.5 wt% of alumina, and active components of platinum: 0.3%, magnesium: 12 percent; the reaction temperature is 530 ℃, the reaction pressure is normal pressure, and the space velocity of the feeding volume is 1000h-1The ratio of water vapor to hydrogen is 1:1, hydrogen to oil ratio of 1:1, and the dehydrogenation results are shown in table 1.
Example 2
Using a 100ml evaluation device, charging 85g of the modified carrier loaded platinum-based bimetallic catalyst, wherein the modified carrier comprises attapulgite accounting for 1.5 wt% of alumina, and active components of platinum: 0.3%, magnesium: 14 percent; the reaction temperature is 520 ℃, the reaction pressure is normal pressure, and the space velocity of the feeding volume is 1000h-1The ratio of water vapor to hydrogen is 1: 1.5, hydrogen to oil ratio of 1:1, and the dehydrogenation results are shown in Table 1.
Example 3
85g of the modified carrier-supported platinum-based bimetallic catalyst of the invention in which the amount of attapulgite was 1.5 wt% based on the amount of alumina and the activity was charged by using a 100ml evaluation apparatusThe components are platinum: 0.5%, magnesium: 12 percent; the reaction temperature is 500 ℃, the reaction pressure is normal pressure, and the feeding volume space velocity is 1200h-1The ratio of water vapor to hydrogen is 1:1, hydrogen to oil ratio of 1:1, and the dehydrogenation results are shown in table 1.
Example 4
Using a 100ml evaluation device, charging 85g of the modified carrier loaded platinum-based bimetallic catalyst, wherein the modified carrier comprises attapulgite accounting for 1.5 wt% of alumina, and active components of platinum: 0.3%, magnesium: 16 percent; the reaction temperature is 520 ℃, the reaction pressure is normal pressure, and the space velocity of the feeding volume is 1400h-1The ratio of water vapor to hydrogen is 1:2, hydrogen to oil ratio of 1:1, and the dehydrogenation results are shown in table 1.
Example 5
Using a 100ml evaluation device, charging 85g of the modified carrier loaded platinum-based bimetallic catalyst, wherein the modified carrier comprises attapulgite accounting for 1.5 wt% of alumina, and active components of platinum: 0.5%, magnesium: 12 percent; the reaction temperature is 530 ℃, the reaction pressure is normal pressure, and the space velocity of the feeding volume is 1000h-1The ratio of water vapor to hydrogen is 1: 3, hydrogen to oil ratio of 1:1, and the dehydrogenation results are shown in Table 1.
Example 6
Using a 100ml evaluation device, charging 85g of the modified carrier loaded platinum-based bimetallic catalyst, wherein the modified carrier comprises attapulgite accounting for 2 wt% of alumina, and active components of platinum: 0.4%, magnesium: 15 percent; the reaction temperature is 540 ℃, the reaction pressure is normal pressure, and the feeding volume space velocity is 1000h-1The ratio of water vapor to hydrogen is 1: 2.5, hydrogen to oil ratio of 1:1, and the dehydrogenation results are shown in Table 1.
Example 7
Using a 100ml evaluation device, charging 85g of the modified carrier loaded platinum-based bimetallic catalyst, wherein the modified carrier comprises attapulgite accounting for 1.5 wt% of alumina, and active components of platinum: 0.3%, magnesium: 16 percent; the reaction temperature is 520 ℃, the reaction pressure is normal pressure, and the space velocity of the feeding volume is 1500h-1The ratio of water vapor to hydrogen is 1:1, hydrogen to oil ratio of 1:1, and the dehydrogenation results are shown in table 1.
Example 8
Using a 100ml evaluation device, charging 85g of the modified carrier loaded platinum-based bimetallic catalyst, wherein the modified carrier comprises attapulgite accounting for 1.5 wt% of alumina, and active components of platinum: 0.5%, magnesium: 12 percent; the reaction temperature is 530 ℃, the reaction pressure is normal pressure, and the space velocity of the feeding volume is 1200h-1The ratio of water vapor to hydrogen is 1:2, hydrogen to oil ratio of 1:1, and the dehydrogenation results are shown in table 1.
Example 9
Using a 100ml evaluation device, charging 85g of the modified carrier loaded platinum-based bimetallic catalyst, wherein the modified carrier comprises attapulgite accounting for 1.5 wt% of alumina, and active components of platinum: 0.4%, magnesium: 16 percent; the reaction temperature is 550 ℃, the reaction pressure is normal pressure, and the space velocity of the feeding volume is 1300h-1The ratio of water vapor to hydrogen is 1: 2.5, hydrogen to oil ratio of 1:1, and the dehydrogenation results are shown in Table 1.
Example 10
Using a 100ml evaluation device, charging 85g of the modified carrier loaded platinum-based bimetallic catalyst, wherein the modified carrier comprises attapulgite accounting for 1.5 wt% of alumina, and active components of platinum: 0.4%, magnesium: 13 percent; the reaction temperature is 540 ℃, the reaction pressure is normal pressure, and the feeding volume space velocity is 1100h-1The ratio of water vapor to hydrogen is 1:1, hydrogen to oil ratio of 1:1, and the dehydrogenation results are shown in table 1.
Example 11
Using a 100ml evaluation device, charging 85g of the modified carrier loaded platinum-based bimetallic catalyst, wherein the modified carrier comprises attapulgite accounting for 1.5 wt% of alumina, and active components of platinum: 0.3%, magnesium: 14 percent. The same process conditions as in comparative example 1 were used to dehydrogenate isobutane, i.e. the reaction temperature was 520 ℃, the reaction pressure was atmospheric, and the feed volume space velocity of isobutane was 1300h-1The hydrogen-oil ratio was 1:1, steam was introduced in addition, the volume ratio of steam to hydrogen was 1:2, and the results of dehydrogenation reactions are shown in tables 1 and 2.
Comparative example 1
Use ofA100 ml evaluation apparatus was charged with 86g of a comparative catalyst having alumina as a carrier and platinum as an active ingredient, wherein the platinum content was 1.0% of the catalyst. The reaction temperature of the feeding is 520 ℃, the reaction pressure is normal pressure, and the feeding volume space velocity of the isobutane is 1300h-1The hydrogen to oil ratio was 1:1, and the results of the dehydrogenation reaction are shown in tables 1 and 2.
Comparative example 2
Using a 100ml evaluation device, adopting the catalyst in the comparative example 1, and using the same process conditions as the comparative example 1 to carry out dehydrogenation reaction on the isobutane, wherein the reaction temperature is 520 ℃, the reaction pressure is normal pressure, and the isobutane feeding volume space velocity is 1300h-1The hydrogen-oil ratio was 1:1, steam was introduced in addition, the volume ratio of steam to hydrogen was 1:2, and the results of dehydrogenation reactions are shown in tables 1 and 2.
TABLE 1 Isobutane dehydrogenation conditions and test results
Figure BDA0001234242950000071
Figure BDA0001234242950000081
The reaction time for the dehydrogenation reaction was 150 h.
As can be seen from table 1, under the same evaluation conditions, by using the method for preparing isobutene by dehydrogenating isobutane according to the present invention, the isobutane conversion rate and the isobutene yield are significantly higher than those of the comparative example method, which shows that the novel catalyst (the modified carrier is loaded with the Pt-Mg bimetallic component) in the present application, and after steam is introduced, the conversion rate of isobutane is increased, the reaction of cracking side reaction is reduced, the isobutene selectivity is increased, and the isobutene yield is correspondingly increased. Meanwhile, after long-time operation, the conversion rate of isobutane and the yield of isobutene in the embodiment of the application are still high.
Example 12
85g of the platinum metal catalyst supported on the attapulgite modified carrier of the present invention was charged using a 100ml evaluation apparatus, wherein the modified carrierIn the formula, attapulgite (attapulgite) accounts for 1% of the mass of alumina, and the active components are platinum: 0.5 percent; the reaction temperature is 540 ℃, the reaction pressure is normal pressure, and the feeding volume space velocity of the isobutane is 1200h-1The hydrogen-oil ratio is 1:1, the ratio of water vapor to hydrogen is 1:2, the dehydrogenation results are shown in table 3.
Example 13
Using a 100ml evaluation device, 85g of the attapulgite modified carrier supported platinum metal catalyst of the invention is loaded, wherein in the modified carrier, the attapulgite (attapulgite) accounts for 1% of the mass of alumina, and the active component is platinum: 0.4 percent; the reaction temperature is 530 ℃, the reaction pressure is normal pressure, and the feeding volume space velocity of the isobutane is 1300h-1The hydrogen-oil ratio is 1:1, the ratio of water vapor to hydrogen is 1: the dehydrogenation results are shown in Table 3.
Example 14
85g of the platinum metal catalyst supported on the attapulgite modified carrier of the present invention was loaded using a 100ml evaluation apparatus, wherein in the modified carrier, the attapulgite (attapulgite) accounted for 1.5% by mass of alumina, and the active component was platinum: 0.3 percent; the reaction temperature is 520 ℃, the reaction pressure is normal pressure, and the feeding volume space velocity of the isobutane is 1300h-1The hydrogen-oil ratio is 1:1, the ratio of water vapor to hydrogen is 1:2, the dehydrogenation results are shown in table 3.
Example 15
85g of the platinum metal catalyst supported on the attapulgite modified carrier of the present invention was loaded using a 100ml evaluation apparatus, wherein in the modified carrier, the attapulgite (attapulgite) accounted for 2% by mass of alumina, and the active component was platinum: 0.2 percent; the reaction temperature is 550 ℃, the reaction pressure is normal pressure, and the feeding volume space velocity of the isobutane is 1000h-1The hydrogen-oil ratio is 1:1, the ratio of water vapor to hydrogen is 1:2, the dehydrogenation results are shown in table 3.
Example 16
85g of the platinum metal catalyst supported on the attapulgite modified carrier of the present invention was loaded using a 100ml evaluation apparatus, wherein in the modified carrier, the attapulgite (attapulgite) accounted for 2% by mass of alumina, and the active component was platinum: 0.4 percent; the reaction temperature is 540 ℃, the reaction pressure is normal pressure, and the feeding volume space velocity of the isobutane is 1400h-1The hydrogen-oil ratio is 1:1, the ratio of water vapor to hydrogen is 1: the dehydrogenation results are shown in Table 3.
Example 17
85g of the platinum metal catalyst supported on the attapulgite modified carrier of the present invention was loaded using a 100ml evaluation apparatus, wherein in the modified carrier, the attapulgite (attapulgite) accounted for 2% by mass of alumina, and the active component was platinum: 0.5 percent; the reaction temperature is 500 ℃, the reaction pressure is normal pressure, and the feeding volume space velocity of the isobutane is 1400h-1The hydrogen-oil ratio is 1:1, the ratio of water vapor to hydrogen is 1: 1.5, the dehydrogenation results are shown in Table 3.
Example 18
85g of the platinum metal catalyst supported on the attapulgite modified carrier of the present invention was charged using a 100ml evaluation apparatus, wherein in the modified carrier, the attapulgite (attapulgite) accounted for 2.5% by mass of alumina, and the active component was platinum: 0.2 percent; the reaction temperature is 550 ℃, the reaction pressure is normal pressure, and the feeding volume space velocity of the isobutane is 1100h-1The hydrogen-oil ratio is 1:1, the ratio of water vapor to hydrogen is 1: 2.5, the dehydrogenation results are shown in Table 3.
Example 19
85g of the platinum metal catalyst supported on the attapulgite modified carrier of the present invention was charged using a 100ml evaluation apparatus, wherein in the modified carrier, the attapulgite (attapulgite) accounted for 2.5% by mass of alumina, and the active component was platinum: 0.4 percent; the reaction temperature is 540 ℃, the reaction pressure is normal pressure, and the feeding volume space velocity of the isobutane is 1400h-1The hydrogen-oil ratio is 1:1, the ratio of water vapor to hydrogen is 1: 3, the dehydrogenation results are shown in Table 3.
Example 20
85g of the platinum metal catalyst supported on the attapulgite modified carrier of the present invention was loaded using a 100ml evaluation apparatus, wherein in the modified carrier, the attapulgite (attapulgite) accounted for 3% by mass of alumina, and the active component was platinum: 0.4 percent; the reaction temperature is 550 ℃, the reaction pressure is normal pressure, and the feeding volume space velocity of the isobutane is 1500h-1The hydrogen-oil ratio is 1:1, the ratio of water vapor to hydrogen is 1:2, the dehydrogenation results are shown in table 3.
TABLE 3 Isobutane dehydrogenation conditions and test results
Figure BDA0001234242950000101
The reaction time was 150 h.
As can be seen from table 2, under the same evaluation conditions, by using the method for preparing isobutene by dehydrogenating isobutane according to the present invention, the isobutane conversion rate and the isobutene yield are both significantly higher than those of the comparative example method, which shows that the novel catalyst (the modified carrier is loaded with the Pt metal component) in the present application, and after steam is introduced, the conversion rate of isobutane is increased, the reaction of cracking side reaction is reduced, the isobutene selectivity is increased, and the isobutene yield is correspondingly increased. Meanwhile, after long-time operation, the conversion rate of isobutane and the yield of isobutene in the embodiment of the application are still high. Meanwhile, compared with the catalyst loaded with the Pt metal component on the modified carrier, the catalyst obtained by loading the Pt-Mg bimetallic component on the modified carrier can further improve the activity and the isobutane conversion rate and the isobutene yield due to the synergistic effect of the bimetallic component.
Any numerical value mentioned in this specification, if there is only a two unit interval between any lowest value and any highest value, includes all values from the lowest value to the highest value incremented by one unit at a time. For example, if it is stated that the amount of a component, or a value of a process variable such as temperature, pressure, time, etc., is 50 to 90, it is meant in this specification that values of 51 to 89, 52 to 88 … …, and 69 to 71, and 70 to 71, etc., are specifically enumerated. For non-integer values, units of 0.1, 0.01, 0.001, or 0.0001 may be considered as appropriate. These are only some specifically named examples. In a similar manner, all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be disclosed in this application.
It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.

Claims (18)

1. A method for preparing isobutene by dehydrogenating isobutane comprises the following steps: reducing a catalyst, then contacting a feed containing isobutane, steam and hydrogen with the reduced catalyst, and carrying out dehydrogenation reaction to obtain isobutene, wherein the catalyst comprises an attapulgite modified carrier and a Pt metal component loaded on the modified carrier;
the carrier is alumina;
the preparation method of the attapulgite modified carrier comprises the steps of adding the attapulgite into the carrier or a precursor thereof, adding acid liquor for kneading, and then molding, drying and roasting to obtain the attapulgite modified carrier.
2. The method as claimed in claim 1, wherein the temperature of the reaction is 500-550 ℃; and/or the pressure of the reaction is atmospheric pressure.
3. The method as claimed in claim 1, wherein the reaction temperature is 520-540 ℃.
4. The method as claimed in any one of claims 1 to 3, wherein the isobutane is fed at a volumetric space velocity of 1000--1(ii) a The volume ratio of the water vapor to the hydrogen is 1 (1-3); the hydrogen-oil ratio is (0.5-1.2) to 1.
5. The method as claimed in any one of claims 1 to 3, wherein the isobutane is fed at a volumetric space velocity of 1200-1300h in the reaction-1(ii) a The volume ratio of the water vapor to the hydrogen is 1 (1.5-2.5); the hydrogen-oil ratio is (0.8-1) to 1.
6. A method according to any one of claims 1-3, wherein the attapulgite is present in an amount of 0.5-5 wt% based on the weight of the support.
7. A method according to any one of claims 1-3, wherein the attapulgite is present in an amount of 1-3 wt% based on the weight of the support.
8. A method according to any one of claims 1-3, wherein the attapulgite is present in an amount of 1.5-2.5 wt% based on the weight of the support.
9. A process according to any one of claims 1 to 3, characterized in that the content of the Pt metal component is 0.2 to 0.5 wt. -%, based on the total weight of the catalyst.
10. A process according to any one of claims 1 to 3, characterized in that the content of the Pt metal component is 0.3 to 0.4 wt. -%, based on the total weight of the catalyst.
11. The method according to any one of claims 1 to 3, wherein the catalyst further comprises a Mg metal component supported on the attapulgite-modified support, and the content of the Pt component is 0.2 to 0.5 wt% based on the total mass of the catalyst; the content of the Mg component is 12 to 18 wt%.
12. The method according to any one of claims 1 to 3, wherein the catalyst further comprises a Mg metal component supported on the attapulgite-modified support, and the content of the Pt component is 0.3 to 0.4 wt% based on the total mass of the catalyst; the content of the Mg component is 14 to 16 wt%.
13. A process according to any one of claims 1 to 3, wherein the catalyst is prepared by a process comprising the steps of:
s1, preparing a modified carrier, which comprises the steps of adding attapulgite into a carrier or a precursor thereof, adding acid liquor for kneading, and then forming, drying and roasting to obtain the attapulgite modified carrier;
s2, loading a metal component, namely soaking the attapulgite modified carrier in a solution containing a platinum compound, and then drying and roasting to obtain the catalyst.
14. The method as claimed in claim 13, wherein in step S1, the acid solution is dilute nitric acid; and/or the roasting temperature is 500-700 ℃, and the roasting time is 4-6 hours.
15. The method of claim 13, wherein in step S2, the platinum-containing compound is selected from at least one of chloroplatinic acid and potassium chloroplatinate.
16. The method of claim 13, wherein in step S2, the attapulgite-modified support is impregnated with a solution of a magnesium-containing compound before, after, or simultaneously with the impregnation of the attapulgite-modified support with the solution of the platinum-containing compound.
17. The method of claim 16, wherein the magnesium compound is selected from at least one of magnesium nitrate, magnesium chloride, and magnesium sulfate.
18. The method as claimed in claim 13, wherein in step S2, the impregnation time is 6-10 hours, the calcination temperature is 500-800 ℃, and the calcination time is 5-8 hours.
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