A kind of selective hydrogenation method of C4 fraction

Abstract

A method for selective hydrogenation of carbon four fractions. The material to be hydrogenated and H2 enter the first-stage isothermal reactor, and the material after the first-stage reaction enters the second-stage adiabatic reactor. The reactor is loaded with a selective hydrogenation catalyst, and the reaction product enters the gas-liquid after cooling Separation tank for separation; the selective hydrogenation catalyst loaded in the first-stage isothermal reactor is the same or different from the selective hydrogenation catalyst loaded in the second-stage adiabatic reactor, and at least one reactor is loaded with alumina and Selective hydrogenation catalysts on niobium oxide composite supports. Adopting the method of the invention has very obvious good effects on the effective utilization of the C4 fraction rich in alkynes after the extraction of butadiene, the reduction of waste of resources and the improvement of economic benefits.

Description

technical field

[0001] The invention relates to a method for producing butadiene by selective hydrogenation of carbon four fractions rich in alkynes discharged after butadiene extraction. Background technique

[0002] The cracked C4 fraction usually contains 40% to 60% butadiene by mass in the pyrolysis of hydrocarbons to produce ethylene. Butadiene is an important monomer in the synthetic rubber industry. The extraction of butadiene from the cracked C4 fraction usually adopts solvent extraction methods, such as acetonitrile method, N-methylpyrrolidone method and dimethylformamide method. Due to the high concentration of alkynes in the extracted C4 fraction, and there is no industrial use value at present, it can only be used for combustion treatment. However, because of the danger of explosion of high-concentration alkynes, it is recommended for safety reasons in industrial production. Considering that when separating alkynes, an equal amount of butadiene should be dischar...

Examples

Embodiment 1

[0065] The C4 fraction rich in alkynes is diluted with the C4 raffinate, and the weight ratio of the C4 fraction rich in alkynes to the C4 raffinate is 1:1. The first stage uses an isothermal bubbling bed reactor and catalyst 1, the reaction temperature is 50°C, and the molar ratio of hydrogen to alkyne is 1.5; the second stage uses an adiabatic bubbling bed reactor and catalyst 2, and the reaction inlet temperature is 40°C , the molar ratio of hydrogen to alkyne is 1.0; the reaction pressure of the first stage and the second stage are both 1.5MPa, and the liquid space velocity is 8h -1 ; Catalysts 1 and 2 were reduced at 120°C for 6h under a hydrogen atmosphere. Table 2 is the composition of materials before and after the reaction.

[0066] Material composition before and after table 2 reaction

[0067]

Embodiment 2

[0069] The C4 fraction rich in alkynes is diluted with the C4 raffinate, and the weight ratio of the C4 fraction rich in alkynes to the C4 raffinate is 1:3. The first stage uses an isothermal bubbling bed reactor with a reaction temperature of 40°C and a molar ratio of hydrogen to alkyne of 1.0; the second stage uses an adiabatic bubbling bed reactor with a reaction inlet temperature of 30°C and The molar ratio is 1.0; the reaction pressure of the first stage and the second stage are both 1.5MPa, and the liquid space velocity is 10h -1 ; Catalyst 3 was used in both reactors, and catalyst 3 was reduced at 120°C for 6h under a hydrogen atmosphere. Table 3 is the composition of materials before and after the reaction.

[0070] Table 3 Composition of materials before and after reaction

[0071]

Embodiment 3

[0073] Dilute the alkyne-rich C4 fraction with raffinate C4, and the weight ratio of the alkyne-rich C4 fraction to the raffinate C4 is 1:2. The first stage uses an isothermal bubbling bed reactor and catalyst 4, the reaction temperature is 50°C, and the molar ratio of hydrogen to alkyne is 2.0; the second stage uses an adiabatic bubbling bed reactor and catalyst 5, and the reaction inlet temperature is 40°C , the molar ratio of hydrogen to alkyne is 1.5; the reaction pressure of the first stage and the second stage are both 2.0MPa, and the liquid space velocity is 12h -1 ; Catalyst 4 and Catalyst 5 were reduced at 120°C for 6h under a hydrogen atmosphere. Table 4 is the composition of materials before and after the reaction.

[0074] Material composition before and after table 4 reaction

[0075]

technical field

[0001] The invention relates to a method for producing butadiene by selective hydrogenation of carbon four fractions rich in alkynes discharged after butadiene extraction. Background technique

[0002] The cracked C4 fraction usually contains 40% to 60% butadiene by mass in the pyrolysis of hydrocarbons to produce ethylene. Butadiene is an important monomer in the synthetic rubber industry. The extraction of butadiene from the cracked C4 fraction usually adopts solvent extraction methods, such as acetonitrile method, N-methylpyrrolidone method and dimethylformamide method. Due to the high concentration of alkynes in the extracted C4 fraction, and there is no industrial use value at present, it can only be used for combustion treatment. However, because of the danger of explosion of high-concentration alkynes, it is recommended for safety reasons in industrial production. Considering that when separating alkynes, an equal amount of butadiene should be dischar...

Examples

Embodiment 1

[0065] The C4 fraction rich in alkynes is diluted with the C4 raffinate, and the weight ratio of the C4 fraction rich in alkynes to the C4 raffinate is 1:1. The first stage uses an isothermal bubbling bed reactor and catalyst 1, the reaction temperature is 50°C, and the molar ratio of hydrogen to alkyne is 1.5; the second stage uses an adiabatic bubbling bed reactor and catalyst 2, and the reaction inlet temperature is 40°C , the molar ratio of hydrogen to alkyne is 1.0; the reaction pressure of the first stage and the second stage are both 1.5MPa, and the liquid space velocity is 8h -1 ; Catalysts 1 and 2 were reduced at 120°C for 6h under a hydrogen atmosphere. Table 2 is the composition of materials before and after the reaction.

[0066] Material composition before and after table 2 reaction

[0067]

Embodiment 2

[0069] The C4 fraction rich in alkynes is diluted with the C4 raffinate, and the weight ratio of the C4 fraction rich in alkynes to the C4 raffinate is 1:3. The first stage uses an isothermal bubbling bed reactor with a reaction temperature of 40°C and a molar ratio of hydrogen to alkyne of 1.0; the second stage uses an adiabatic bubbling bed reactor with a reaction inlet temperature of 30°C and The molar ratio is 1.0; the reaction pressure of the first stage and the second stage are both 1.5MPa, and the liquid space velocity is 10h -1 ; Catalyst 3 was used in both reactors, and catalyst 3 was reduced at 120°C for 6h under a hydrogen atmosphere. Table 3 is the composition of materials before and after the reaction.

[0070] Table 3 Composition of materials before and after reaction

[0071]

Embodiment 3

[0073] Dilute the alkyne-rich C4 fraction with raffinate C4, and the weight ratio of the alkyne-rich C4 fraction to the raffinate C4 is 1:2. The first stage uses an isothermal bubbling bed reactor and catalyst 4, the reaction temperature is 50°C, and the molar ratio of hydrogen to alkyne is 2.0; the second stage uses an adiabatic bubbling bed reactor and catalyst 5, and the reaction inlet temperature is 40°C , the molar ratio of hydrogen to alkyne is 1.5; the reaction pressure of the first stage and the second stage are both 2.0MPa, and the liquid space velocity is 12h -1 ; Catalyst 4 and Catalyst 5 were reduced at 120°C for 6h under a hydrogen atmosphere. Table 4 is the composition of materials before and after the reaction.

[0074] Material composition before and after table 4 reaction

[0075]

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