Method for producing internal olefin through gas phase catalysis under vacuum condition

Abstract

The invention provides a method for producing internal olefin by gas-phase catalysis under vacuum condition, which comprises the following steps: introducing alpha-olefin into gasification equipment to form gas-phase alpha-olefin, introducing the gasified alpha-olefin into a vacuumized fixed bed reactor, filling a high-silicon molecular sieve catalyst in the reactor, reacting at 150-300 DEG C for 1-3 hours, and separating the gas-phase alpha-olefin from the fixed bed reactor to obtain the internal olefin. The reaction space velocity is 0.1-0.2 h <-1 >, and cooling to obtain an isomerization product internal olefin. According to the invention, isomerization of long-chain end olefin double bonds can be realized through catalysis of the catalyst in the fixed bed reactor to obtain internal olefin, and isomerization processing of high-carbon-number straight-chain olefin is satisfied. The internal olefin prepared by the method has the advantages of high conversion rate, simple process and strong continuity, and greatly saves the catalyst input cost and the catalyst replacement cost.

Description

Technical Field

[0001] The invention relates to the technical field of internal olefin preparation, and in particular to a method for preparing internal olefin under gas phase catalysis under vacuum conditions. Background Art

[0002] Olefins are key functional groups in many natural products and industrial products, and are also important precursors of other organic molecules. Internal olefins in the middle position are usually present in natural products. In the field of fuel oil, olefins with internal C=C have higher octane numbers and higher combustion efficiency than those with terminal C=C. In the field of synthesis, internal olefins have great uses. However, among the methods that can form olefins (condensation, elimination, dehydrogenation, olefination, cross-coupling, metathesis and other reactions), there are relatively few methods that can directly obtain internal olefins in the middle position. Invention patent publication number CN101044105A uses a multi-step method for isomerizing alpha olefins to generate internal olefins, and obtains a mixture including olefin isomers and low-content oligomers. The patent mainly uses a combination of alkyl aluminum compounds and salts of Group VIII transition metals for catalytic generation of internal olefins. The method is to catalyze in the liquid phase at a temperature of about 50 to 200° C., wherein the catalyst is a mixture of salts of transition metals of Group VI of cobalt, iron, palladium, platinum, osmium, iridium, rhodium, ruthenium and mixtures thereof and an alkyl aluminum compound. The catalyst uses a noble metal catalyst, resulting in high production costs, and uses a liquid phase method, which has the problem of large catalyst separation and loss. The above patent specifically specifies the method as a liquid phase reaction. It has been verified that the efficiency of the liquid phase reaction is not high, and some materials are coked, resulting in low product purity. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for producing internal olefins under gas phase catalysis under vacuum conditions, thereby avoiding chain scission or polymerization reactions between olefins or internal olefin molecules under long-term high temperature, avoiding coking to block equipment or affect product quality, and solving the above-mentioned technical problems existing in the prior art.

[0004] The present invention is achieved by adopting the following technical solutions:

[0005] A method for producing internal olefins under vacuum conditions by gas phase catalysis comprises the following steps: introducing α-olefins into a gasification device to form gas phase α-olefins, the gasified α-olefins entering a vacuum fixed bed reactor, the reactor being filled with a high silicon molecular sieve catalyst, the reaction temperature being 150-300°C, the reaction space velocity being 0.1-0.2h -1 , and after cooling, the isomerization product internal olefin is obtained.

[0006] The vacuum is at an absolute pressure of 1000-100Pa, and the vacuum is formed by a method not limited to one or a combination of dry vacuum, water ring vacuum, Roots vacuum, steam injection, and water injection.

[0007] The gasification equipment is not limited to horizontal heaters, heating kettles, vertical heaters, vertical rising film heaters, vertical falling film heaters and other related gasification equipment.

[0008] The structural formula of the α-olefin is R n –CH=CH 2 , wherein R is a straight chain alkyl group, and n=10-18. A single α-olefin can be used, or multiple α-olefins can be mixed for reaction. The specific adjustment is made according to the needs of the actual application.

[0009] The high-silicon molecular sieve catalyst is selected from amorphous, spherical, and hollow-shell high-silicon molecular sieve catalysts.

[0010] Through the above technical scheme, the method provided by the present invention can realize the isomerization of the double bonds of long-chain terminal olefins to obtain internal olefins through a fixed bed reactor through catalyst catalysis, which satisfies the isomerization processing of high-carbon straight-chain olefins. The internal olefins prepared in this way have high conversion rate, simple process, strong continuity, and isomerization selectivity of more than 93%. Expensive metals or metal salts are not used as co-catalyst components, which reduces the operating cost, and the aging cycle is more than 2 years, while greatly saving the catalyst investment cost and the cost of replacing the catalyst. DETAILED DESCRIPTION

[0011] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only used as examples, but are not used to limit the scope of the present invention. Those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, variations, improvements, equivalent solutions, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0012] The instruments or raw materials in the present invention without indicating the manufacturer are all conventional commercial instruments or raw materials.

[0013] Unless otherwise mentioned, the detection indicators involved in the embodiments of the present invention are detected by conventional detection methods in the art.

[0014] Example 1

[0015] A method for producing internal olefins under gas phase catalysis under vacuum conditions, specifically comprising the following steps:

[0016] The fixed bed reactor system was evacuated to an absolute pressure of 1000Pa using a Roots vacuum pump, and a certain amount of α-olefin was pumped into the vertical heater for gasification through a metering pump. The α-olefin was a mixture of four linear α-olefins with carbon atoms of C12, C14, C16, and C18 in a mass ratio of 1:1:1:1. The gasified α-olefin entered the reactor, which was filled with an amorphous high-silicon molecular sieve catalyst. The reaction temperature was 150°C and the reaction space velocity was 0.1h -1 , and after cooling, the isomerization product internal olefin is obtained.

[0017] Example 2

[0018] A method for producing internal olefins under gas phase catalysis under vacuum conditions, specifically comprising the following steps:

[0019] The fixed bed reactor system was evacuated to an absolute pressure of 500Pa using a dry vacuum pump, and a certain amount of α-olefin was pumped into the horizontal heater for gasification through a metering pump. The carbon number of the α-olefin was C16 straight chain α-olefin. The gasified α-olefin entered the reactor, which was filled with a spherical high-silicon molecular sieve catalyst. The reaction temperature was 300°C and the reaction space velocity was 0.2h -1 , and after cooling, the isomerization product internal olefin is obtained.

[0020] Example 3

[0021] A method for producing internal olefins under gas phase catalysis under vacuum conditions, specifically comprising the following steps:

[0022] The fixed bed reactor system was evacuated to an absolute pressure of 500Pa using a water ring vacuum pump, and a certain amount of α-olefin was pumped into the vertical rising film heater through a metering pump for vaporization. The carbon number of the α-olefin was C18 straight chain α-olefin. The vaporized α-olefin entered the reactor, which was filled with a spherical high-silicon molecular sieve catalyst. The reaction temperature was 200°C and the reaction space velocity was 0.2h -1 , and after cooling, the isomerization product internal olefin is obtained.

[0023] Example 4

[0024] A method for producing internal olefins under gas phase catalysis under vacuum conditions, specifically comprising the following steps:

[0025] The fixed bed reactor system was evacuated to an absolute pressure of 100Pa using a steam ejector, and a certain amount of α-olefin was pumped into the vertical falling film heater through a metering pump for vaporization. The carbon number of the α-olefin was a mixture of C16 and C18 straight-chain α-olefins in a mass ratio of 1:1. The vaporized α-olefin entered the reactor, which was filled with an empty shell high-silicon molecular sieve catalyst. The reaction temperature was 250°C and the reaction space velocity was 0.17h -1, and after cooling, the isomerization product internal olefin is obtained.

[0026] Comparative Example

[0027] The reactor was not vacuumed, and the other steps were the same as in Example 2. The specific steps were as follows:

[0028] A certain amount of α-olefin is pumped into the horizontal heater for gasification through a metering pump. The carbon number of α-olefin is C16 straight chain α-olefin. The gasified α-olefin enters the fixed bed reactor, which is filled with spherical high-silicon molecular sieve catalysts. The reaction temperature is 300°C and the reaction space velocity is 0.2h -1 , and after cooling, the isomerization product internal olefin is obtained.

[0029] The α-olefin conversion rates of Examples 1-4 and the comparative example were obtained by gas chromatography-mass spectrometry. The test results are shown in Table 1.

[0030] Table 1 Test indicators of each sample

[0031] name Conversion rate / % Yield / % Example 1 90.4 97.5 Example 2 96.7 95.6 Example 3 93.5 96.1 Example 4 97 96.4 Comparative Example 85.3 80.6

[0032] It can be seen from the test results that the isomerization conversion rate of the method of the present invention is high, and the yield can reach more than 95%, which is much higher than the conventional isomerization reaction, and no expensive metals or metal salts are used as co-catalyst components, which reduces the operating cost and greatly saves the catalyst investment cost and the cost of replacing the catalyst.

[0033] It should be understood by those skilled in the art that the above embodiments are only examples and do not limit the present invention. The purpose of the present invention has been fully and effectively achieved. The functional and structural principles of the present invention have been demonstrated and explained in the embodiments, and the embodiments of the present invention may be deformed or modified in any way without departing from the principles.

Claims

1. A method for producing internal olefins under gas phase catalysis under vacuum conditions, characterized in that: The process comprises the following steps: introducing α-olefin into a gasification device to form gaseous α-olefin, the gasified α-olefin enters a vacuum fixed bed reactor, a high-silicon molecular sieve catalyst is filled in the reactor, the reaction temperature is 150-300°C, and the reaction space velocity is 0.1-0.2h -1 , and after cooling, the isomerization product internal olefin is obtained.

2. The method according to claim 1, characterized in that The vacuum refers to an absolute pressure of 1000-100Pa.

3. The method according to claim 1, characterized in that The vacuum is formed by any one of dry vacuum, water ring vacuum, Roots vacuum, steam injection, water injection or a combination of these.

4. The method according to claim 1, characterized in that The gasification equipment is selected from any one of a horizontal heater, a heating kettle, a vertical heater, a vertical rising film heater or a vertical falling film heater.

5. The method according to claim 1, characterized in that The structural formula of the α-olefin is R n -CH=CH2, wherein R is a straight chain alkyl group, and n=10-18.

6. The method according to claim 1, characterized in that The high-silicon molecular sieve catalyst is selected from amorphous, spherical, and hollow-shell high-silicon molecular sieve catalysts.