CN103566975B - A kind of N-alkene isomerization catalyst and preparation method thereof - Google Patents

Abstract

A normal olefin isomerization catalyst, comprising a carrier and a modified compound, the modified compound is a polyol, the mass ratio of the modified compound to the carrier is 0.01 to 0.4:1, and the carrier includes molecular sieves and binder. The catalyst uses a modifying compound to modify the catalytic active component, which can significantly improve the isomerization selectivity of the catalyst.

Description

A kind of normal olefin isomerization catalyst and preparation method thereof

technical field

The invention is an olefin isomerization catalyst and a preparation method thereof, specifically, a normal olefin skeleton isomerization catalyst and a preparation method thereof.

Background technique

With the increasingly stringent environmental protection requirements, the demand for clean gasoline continues to increase. Isobutene, methylpentene and dimethylbutene obtained by skeletal isomerization of normal C ₄ -C ₆ olefins can be etherified to prepare high-octane gasoline additives to improve gasoline quality.

USP5,382,743 discloses a method of using ZSM-35 molecular sieve to carry out skeletal isomerization reaction of n-pentene under the condition of hydrogen, and finds that the reaction under the condition of hydrogen is conducive to improving the reactivity of the catalyst and reducing the loss of activity rate and prolong catalyst life.

USP5,817,907 discloses a method for skeletal isomerization of linear olefins. The catalyst used contains at least one pretreated molecular sieve. , Theta-1, EU-1, OMEGA, Mordenite, Nu-10, Nu-86, Nu-87, Ferrierite ZSM-35, ZSM-12 and ZSM-23. The pretreatment method is to contact the molecular sieve with hydrocarbon molecules containing C ₄ -C ₂₀ in the presence of an inert gas. The preferred hydrocarbons are C ₄ -C ₁₂ monoolefins, polyolefins or alkanes, etc., more preferably C ₄ -C 20 C ₁₂ alkanes. The space velocity of the pretreatment is 0.1h ^-1 ~ 45h ^-1 , the temperature is 300°C ~ 550°C, the pressure is 0.1MPa ~ 1.0MPa, and the treatment time is 0.5 ~ 48 hours. Pretreatment causes coke to deposit in the pores of the molecular sieve, and the pore volume of the molecular sieve is significantly reduced, thereby improving the selectivity of isomerized olefins and having good stability. However, before the olefin isomerization reaction, a step of high-temperature pre-coking treatment using hydrocarbons as raw materials under an inert atmosphere is added, which complicates the reaction process.

Contents of the invention

The purpose of the present invention is to provide a normal olefin isomerization catalyst and its preparation method. The catalyst uses a modifying compound to modify the catalytic active components, which can significantly improve the isomerization selectivity of the catalyst.

The normal olefin isomerization catalyst provided by the present invention includes a carrier and a modified compound, the modified compound is a polyol, and the mass ratio of the modified compound to the carrier is 0.01 to 0.4:1, and the carrier includes Molecular sieves and binders.

The present invention uses polyhydric alcohol to modify the catalytic active component of normal olefin skeletal isomerization, the catalyst preparation method is simple, does not need to increase the processing flow of side additions, and is easy to control, and the obtained catalyst is used for normal olefin skeletal isomerization reaction, The selectivity of isomerization is obviously improved, and the yield of isomerization product is increased.

Detailed ways

In the present invention, the polyhydric alcohol is used as the active component of isomerization—the modified compound of the molecular sieve, and the molecular sieve is impregnated with its aqueous solution. After drying, the polyhydric alcohol is deposited on the surface of the molecular sieve, which can effectively improve its physical and chemical properties and improve its isomerization performance. . The invention adopts a simple in-situ treatment method to prepare the catalyst, is easy to operate, and the content of the modified compound in the catalyst is easy to control.

The present invention uses polyalcohol as a modifying compound to modify the carrier including the isomerization catalytic active component, and the polyalcohol is preferably a C ₂ -C ₇ polyol. _The polyhydric alcohol of described _C2 ～C7 is preferably ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, glycerol, trimethylolethane, pentaerythritol, xylitol and sorbitol one or several.

The carrier described in the catalyst of the present invention includes molecular sieves and binders. The molecular sieve is preferably a mesoporous molecular sieve. It can be silica-alumina molecular sieve, such as ZSM-5, ZSM-11, ZSM-22, ZSM-23, ZSM-35, ZSM-48, ZSM-57, Theta-1, NU-10, TNU-1, TNU-9 , TNU-10, NU-87, one or more of MCM-22 zeolites; it can also be non-silicon-aluminum molecular sieves, selected from phosphorus-aluminum molecular sieves, such as APO-11, titanium-silicon molecular sieves, such as TS-1, phosphoric acid One or more of silica-alumina, such as SAPO-11 molecular sieves. One or any two of ZSM-35, ZSM-22 and SAPO-11 are preferred.

The binder is selected from alumina, silica, titania, magnesia, alumina-magnesia, silica-alumina, silica-magnesia, silica-zirconia, silica-thoria, oxide Silica-beryllia, silica-titania, silica-zirconia, titania-zirconia, silica-alumina-thoria, silica-alumina-titania, silica-alumina-magnesia, One or more of silica-alumina-zirconia clays, preferably alumina.

The carrier of the present invention includes 50-99% by mass of molecular sieve and 1-50% by mass of binder, preferably 60-95% by mass of molecular sieve and 5-40% by mass of binder. The mass ratio of the modified compound to the carrier in the catalyst of the present invention is preferably 0.01-0.3:1.

The olefins suitable for isomerization by the catalyst of the present invention are preferably C ₄ -C ₆ normal olefins.

The preparation method of the catalyst provided by the present invention includes mixing molecular sieves and binders, drying and roasting to obtain a carrier, and then impregnating with an aqueous solution of a modified compound. dry.

The molecular sieve is preferably one or any two of ZSM-35, ZSM-22 and SAPO-11, and the binder is preferably alumina.

The method of mixing molecular sieve and binder in the method of the present invention is extruding, dropping ball, rolling ball or tableting method, preferably extruding. The extruding method is as follows: uniformly mix the molecular sieve with the binder or its precursor, add an appropriate amount of extrusion aid and/or peptizer and knead, and then extrude. The extrusion aid is preferably squash powder, and the peptizing agent is preferably an inorganic acid, such as hydrochloric acid or nitric acid. After the wet strip is cut into pellets, the carrier is obtained by drying and roasting. The temperature of the calcination is preferably 400-650° C., and the calcination time is preferably 1-10 hours.

In the method of the present invention, the molecular sieve can also be pretreated with a modified compound first, then mixed with a binder to form a carrier, and then dried and roasted to obtain a carrier, and then the carrier is impregnated with an aqueous solution of a modified compound. After impregnation, the solid The catalyst is obtained by drying under the conditions of 30-200° C. and 0.01-0.1 MPa, and the modified compound in the catalyst does not include the modified compound used for pretreatment.

The pretreatment method of the above-mentioned molecular sieve is: impregnating the molecular sieve with the aqueous solution of the modified compound, then drying the impregnated solid, then mixing it with the binder to form, drying and roasting to obtain the carrier.

When preparing the catalyst of the present invention, the carrier prepared after calcination can also be impregnated with the aqueous solution of the modified compound for two or more times, and it needs to be dried after each impregnation. The modifying compound used for each impregnation can be the same or different.

The above-mentioned impregnation is to impregnate the carrier with an aqueous solution of the modified compound, which can be saturated impregnation, unsaturated impregnation or supersaturated impregnation, preferably saturated impregnation, also known as incipient wetness impregnation, that is, the volume of the impregnation solution is equal to the amount of liquid absorbed by the carrier; the impregnation time Preferably 0.1 to 24 hours, more preferably 0.5 to 8 hours.

When preparing the immersion solution, the concentration of the modified compound aqueous solution is 0.01-5.0 mol/liter, preferably 0.01-3.0 mol/liter. After impregnation, the solvent is removed by drying. Drying conditions are controlled so that the modifying compound does not decompose and does not volatilize. The suitable drying temperature is 40~150°C, preferably 60~120°C, the drying time is 1~24 hours, preferably 2~8 hours, and the drying pressure is 0.01~0.1MPa.

The catalyst provided by the invention is suitable for the skeletal isomerization reaction of normal olefins, especially suitable for the skeletal isomerization reaction of C ₄ -C ₆ normal olefins to prepare isomeric olefins.

The isomerization reaction of normal olefins using the catalyst of the present invention is carried out in the presence of hydrogen. The reaction temperature is 200-550°C, preferably 250-350°C, the pressure is 0.05-1MPa, preferably 0.1-0.5MPa, the feed volume space velocity is 0.5-6.0 hours ^-1 , preferably 1-4 hours ^-1 , hydrogen/ The hydrocarbon volume ratio is 100-5000, preferably 200-2000.

The present invention is further illustrated by examples below, but the present invention is not limited thereto.

In the examples, the preparation of the catalyst of the present invention and the introduction of the modified compound into the carrier all adopt the saturated impregnation method, that is, the incipient wetness impregnation method. The molecular sieves used in the examples were all produced by Hunan Jianchang Catalyst Factory, and the pseudo-boehmite was provided by German Condea Company, and its alumina content on a dry basis was 74% by mass.

Example 1

Take 10788 grams of HZSM-35 molecular sieve with a silica/alumina molar ratio of 25 and mix it with 1637.8 grams of pseudoboehmite, add 65.5 grams of nitric acid with a concentration of 65% by mass and 10770 grams of water, and extrude it with a twin-screw extruder Trilobate strips with a diameter of 1.1 mm were cut into pellets, dried at 120° C. for 4 hours, and calcined at 550° C. for 2 hours to obtain a carrier S ₁ , wherein the content of HZSM-35 molecular sieve was 90% by mass and the content of alumina was 10% by mass.

Take 2000 grams of carrier S ₁ and impregnate 1,939 ml of aqueous solution containing 147.6 grams (1.603 mol) of glycerol at 25°C for 0.5 hour, then dry at 90°C and 0.01MPa for 2 hours to obtain catalyst C ₁ , whose weight is 2146.8 grams, illustrate that catalyst C ₁ contains 146.8 gram glycerin, and the mass ratio of contained alcohol and carrier S ₁ is 0.073.

Example 2

Take 2000 grams _of carrier S1, impregnate 1939 ml of aqueous solution containing 245.7 grams (2.668mol) of glycerol at 25°C for 0.5 hour, then dry at 90°C and 0.01MPa for ₂ hours to obtain catalyst C2, the weight of which is _2245.1 grams, indicating that catalyst C contains 245.1 grams of glycerol, and the mass ratio _of alcohol to carrier S1 is 0.122.

Example 3

Take 2000 grams _of carrier S1, impregnate 1939 ml of aqueous solution containing 361.7 grams (3.928mol) of glycerol at 25°C for 2 hours, then dry at 90°C and 0.01MPa for ₂ hours to obtain catalyst C3 with a weight of 2361.2 grams, illustrate that catalyst C ₃ contains 361.2 grams of glycerin, and the mass ratio of contained alcohol to carrier S ₁ is 0.18.

Example 4

Take 2000 grams of carrier S ₁ , impregnate 1939 ml of an aqueous solution containing 68.5 grams (0.580 mol) of hexanediol at 25°C for 2 hours, then dry at 90°C and 0.01MPa for 3 hours; ) aqueous solution of glycerol in 1933 ml at 25°C for 2 hours, and then dried at 100°C and 0.01MPa for 2 hours to obtain catalyst C ₄ with a weight of 2156.9 grams, indicating that catalyst C ₄ contained 156.9 grams of glycerol and Hexylene glycol, the mass ratio _of contained alcohol and carrier S1 is 0.078.

Example 5

Take 2000 grams of carrier S1, impregnate 1939 ml of _an aqueous solution containing 53.3 grams (0.293 mol) of sorbitol at 25 ° C for 2 hours, and then dry at 90 ° C and 0.01 MPa for 2 hours; then use 260.2 grams (2.887 mol) of ) 1928 ml aqueous solution of butanediol was soaked at 25°C for 2 hours, and then dried at 90°C and 0.02MPa for 4 hours to obtain catalyst C ₅ with a weight of 2312.8 grams, indicating that catalyst C ₅ contained 312.8 grams of glycerol and Butanediol, the mass ratio _of contained alcohol to carrier S1 is 0.156.

Example 6

Mix 9600 grams of HZSM-35 molecular sieve with a molar ratio of silica to alumina of 25 and 3243.2 grams of pseudoboehmite, add 129.7 grams of nitric acid with a concentration of 65% by mass and 9587 grams of water, and extrude with a twin-screw extruder Trilobate strips with a diameter of 1.1 mm were cut into pellets, dried at 120°C for 4 hours, and calcined at 550°C for 2 hours to obtain a carrier S ₂ , in which the content of HZSM-35 molecular sieve was 80% by mass and the content of alumina was 20% by mass.

Take 2000 grams of carrier S ₂ , impregnate 1880 ml of an aqueous solution containing 286.1 grams (4.609mol) of ethylene glycol at 25°C for 2 hours, then dry at 90°C and 0.01MPa for 2 hours; then use 78.2 grams (0.751 1,601 ml of aqueous solution of pentanediol was soaked at 25°C for 2 hours, and then dried at 90°C and 0.01MPa for 4 hours to obtain catalyst C ₆ with a weight of 2,363.6 grams, indicating that catalyst C ₆ contained 363.6 grams of pentadiene Alcohol and ethylene glycol, the mass ratio of contained alcohol and carrier S2 is _0.182 .

Example 7

Mix 7764 grams of HZSM-35 molecular sieve with a molar ratio of silica to alumina of 25 and 5724.3 grams of pseudoboehmite, add 229 grams of nitric acid with a concentration of 65% by mass and 7756 grams of water, and extrude with a twin-screw extruder Trilobate strips with a diameter of 1.1 mm were cut into pellets, dried at 120°C for 4 hours, and calcined at 600°C for 4 hours to obtain a carrier S ₃ , in which the content of HZSM-35 molecular sieve was 65% by mass and the content of alumina was 35% by mass.

Take 2000 grams of carrier S ₃ , impregnate 1,788 ml of aqueous solution containing 438.9 grams (4.766 mol) of glycerol at 25°C for 2 hours, then dry at 90°C and 0.01MPa for 3 hours to obtain catalyst C ₇ with a weight of 2438.2 grams, illustrate that catalyst C7 contains _438.2 grams of glycerol, and the mass ratio _of contained alcohol to carrier S3 is 0.219.

Example 8

Take 10164 grams of HZSM-35 molecular sieves with a molar ratio of silicon oxide to aluminum oxide of 25, impregnate 10670 ml of an aqueous solution containing 428.6 grams (4.654 mol) of glycerol at 25 ° C for 0.5 hours, and then dry at 120 ° C and 0.01 MPa After 4 hours, the pretreated molecular sieve was obtained.

The above-mentioned pretreated molecular sieve was mixed with 2481.1 grams of pseudoboehmite, 99.2 grams of nitric acid and 10152 grams of water with a concentration of 65% by mass were added, and a trefoil strip with a diameter of 1.1 mm was extruded with a twin-screw extruder. Cut into pellets, dry at 180°C for 24 hours, and bake at 420°C for 4 hours to obtain a carrier S ₄ , in which the molecular sieve content is 85% by mass and the alumina content is 15% by mass.

Take 2000 grams of carrier S4, impregnate 1908 ml of aqueous solution containing 113.1 grams (0.957 mol) of hexanediol at 25°C for ₂ hours, then dry at 92°C and 0.01MPa for ₂ hours to obtain catalyst C8, the weight of which is _2112.5 grams, illustrate that catalyst C8 contains 112.5 grams of hexanediol, and the mass ratio of contained alcohol to carrier S4 is _0.056 .

Example 9

Mix 10566 grams of SAPO-11 molecular sieve with 1937.8 grams of pseudoboehmite, add 77.5 grams of nitric acid and 11570 grams of water with a concentration of 65% by mass, and extrude it into a trefoil strip with a diameter of 1.1 mm with a twin-screw extruder. Cut into pellets, dry at 120°C for 4 hours, and bake at 550°C for 2 hours to obtain a carrier S ₅ , in which the molecular sieve content is 88% by mass and the alumina content is 12% by mass.

Take 2000 g of carrier S5, impregnate 1937 ml of aqueous solution containing 33.9 g (0.368 mol) of glycerol at 25°C for _0.5 hour, then dry at 90°C and 0.01MPa for 2 hours to obtain catalyst _C9 , the weight of which is _2033.3 grams, indicating that catalyst _C9 contains 33.3 grams of glycerol, and the mass ratio of contained alcohol to carrier S5 is 0.017.

Example 10

Mix 10452 grams of HZSM-22 molecular sieve with 2091.9 grams of pseudoboehmite, add 83.7 grams of nitric acid and 11536 grams of water with a concentration of 65% by mass, extrude into a trefoil strip with a diameter of 1.1 mm with a twin-screw extruder, cut Granules were dried at 120°C for 4 hours and calcined at 550°C for 2 hours to obtain a carrier S ₆ , in which the molecular sieve content was 87% by mass and the alumina content was 13% by mass.

Take 2000 grams of carrier _S6 , impregnate 1935 ml of aqueous solution containing 90.6 grams (0.984mol) of glycerol at 25°C for 0.5 hour, then dry at 90°C and 0.01MPa for 2 hours to obtain catalyst _C10 , the weight of which is 2090 grams, illustrate that catalyst C ₁₀ contains 90 grams of glycerol, and the mass ratio of contained alcohol to carrier S ₆ is 0.045.

Example 11

Mix 6998.0 grams of HZSM-35 molecular sieve, 3790.0 grams of SAPO-11 molecular sieve and 1637.8 grams of pseudoboehmite, add 65.5 grams of nitric acid with a concentration of 65% by mass and 10770 grams of water, and extrude it into a diameter of 1.1 mm with a twin-screw extruder The trilobal strips were cut into pellets, dried at 120°C for 4 hours, and calcined at 550°C for 2 hours to obtain a carrier S ₇ , in which the molecular sieve content was 90% by mass and the alumina content was 10% by mass.

Take 2000 grams of carrier S ₇ , soak it with 1950 ml of aqueous solution containing 230.6 grams (2.504 mol) of glycerol at 25°C for 0.5 hour, then dry it at 90°C and 0.01MPa for 2 hours to obtain catalyst C ₁₁ with a weight of 2230.1 grams, indicating that catalyst C ₁₁ contains 230.1 grams of glycerol, and the mass ratio of contained alcohol to carrier S ₇ is 0.115.

Example 12

Mix 7998.0 grams of HZSM-35 molecular sieve, 2790.0 grams of HZSM-22 molecular sieve and 1637.8 grams of pseudoboehmite, add 65.5 grams of nitric acid with a concentration of 65% by mass and 10770 grams of water, and extrude it into a diameter of 1.1 mm with a twin-screw extruder The trefoil-shaped strips were cut into pellets, dried at 120°C for 4 hours, and calcined at 550°C for 2 hours to obtain a carrier S ₈ , in which the content of molecular sieves was 90% by mass and the content of alumina was 10% by mass.

Take 2000 grams of carrier _S8 , impregnate 1953 ml of aqueous solution containing 280.4 grams (3.045mol) of glycerol at 25°C for 0.5 hour, then dry at 90°C and 0.01MPa for 2 hours to obtain catalyst C12, the weight _of which is _2279.9 grams, it shows that catalyst C contains 279.9 grams _of glycerol, and the mass ratio of contained alcohol to carrier S is 0.14.

Examples 13-29

The following examples evaluate the isomerization reaction performance of the catalysts of the present invention.

Using 1-pentene as the reaction raw material and the carrier not treated with the modified compound as the comparative catalyst, the catalyst of the present invention and the comparative catalyst were respectively evaluated on a small fixed-bed hydrogenation reactor.

The specific operation method is as follows: the catalyst is loaded in the constant temperature zone of the reactor, and hydrogen gas is introduced to adjust the reaction pressure to 0.3 MPa. Raise the temperature of the reactor to 300°C and stabilize it for 2 hours, inject 1-pentene into the reactor, control the reaction temperature to 300°C, feed volume space velocity to 1.7h ^-1 , reaction pressure to 0.3MPa, hydrogen/hydrocarbon The volume ratio was 600, and samples were taken after 12 hours of reaction, and analyzed online by gas chromatography. The reaction results are shown in Table 1.

Table 1

As can be seen from the data in Table 1, the catalyst obtained after the alcohol compound treatment of the present invention has significantly improved isoamylene yield and isoamylene selectivity compared with the unmodified comparative catalyst.

Claims (13)

1. A normal olefin isomerization catalyst, comprising a carrier and a modified compound, the modified compound is a polyol, and the mass ratio of the modified compound to the carrier is 0.01 to 0.4:1, and the carrier includes Molecular sieve and binder, the polyhydric alcohol is C ₂ -C ₇ polyhydric alcohol. 2. The catalyst according to claim 1, characterized in that the mass ratio of the modified compound to the carrier is 0.01-0.3:1. 3. The catalyst according to claim ₁ , characterized in that said C2 _- C7 polyhydric alcohol is selected from the group consisting of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, glycerol, triglycerides, One or more of hydroxymethylethane, pentaerythritol, xylitol and sorbitol. 4. The catalyst according to claim 1, characterized in that the carrier comprises 50-99% by mass of molecular sieve and 1-50% by mass of binder. 5. The catalyst according to claim 1 or 4, characterized in that the molecular sieve is a mesoporous molecular sieve, and the binder is alumina. 6. The catalyst according to claim 5, characterized in that said mesoporous molecular sieve is one or any two of ZSM-35, ZSM-22 and SAPO-11. 7. The catalyst according to claim 1, characterized in that said olefin is a C ₄ -C ₆ normal olefin. 8. A method for preparing the catalyst according to claim 1, comprising mixing molecular sieves and binders, drying and roasting to obtain a carrier, and then impregnating with an aqueous solution of a modified compound. Dry under the condition of ~0.1MPa. 9. The method according to claim 8, characterized in that the molecular sieve is one or any two of ZSM-35, ZSM-22 and SAPO-11, and the binder is alumina. 10. according to the described method of claim 8, it is characterized in that first molecular sieve is carried out pretreatment with modified compound, pretreatment method is to use the aqueous solution impregnation of modified compound, then with the solid drying after impregnating, then mix with binding agent Shaping, drying and roasting to obtain the carrier. 11. The method according to claim 8, characterized in that the carrier obtained after calcination is impregnated with the aqueous solution of the modifying compound for two or more times, and all need to be dried after each impregnation. 12. The method according to claim 8, characterized in that the concentration of the modified compound aqueous solution is 0.01-3.0 mol/liter. 13. The method according to claim 11, characterized in that the same or different modifying compounds are used for each impregnation.