Preparation method and production device for propylene

Patent metadata

Field	Value
Publication number	US-12269786-B2
Application number	US-202118245982-A
Country	US
Kind code	B2
Filing date	Oct 29, 2021
Priority date	Oct 31, 2020
Publication date	Apr 8, 2025
Grant date	Apr 8, 2025

Abstract

A process for producing propylene involves dehydration of isopropanol. The dehydration process includes a step of subjecting a starting material containing isopropanol to a dehydration reaction in the presence of a dehydration catalyst comprising alumina to produce a product containing propylene. The starting material has a water content of 0.1 to 10.0 wt % (relative to 100 wt % of the total mass of the starting material), and the product has a total content of C2 unsaturated impurities and C3-C4 unsaturated impurities of 80 ppm or less (relative to 100 wt % of the total mass of the product).

First claim

The invention claimed is:

1. A dehydration process, comprising a dehydration step of subjecting a starting material containing isopropanol to a dehydration reaction in the presence of a dehydration catalyst comprising alumina to produce a product containing propylene, wherein the starting material has a water content of 3.0 to 5.0 wt %, relative to 100 wt % of the total mass of the starting material, and the product has a total content of C 2 unsaturated impurities and C 3 -C 4 unsaturated impurities of 80 ppm or less, relative to 100 wt % of the total mass of the product, wherein said product has a C 2 unsaturated impurities content of 50 ppm or less, and the conversion rate of isopropanol is 96.0-99.9%.

2. The dehydration process according claim 1 , wherein said product has a C 2 unsaturated impurities content of 30 ppm or less, relative to 100 wt % of the total mass of the product, and/or has a C 3 -C 4 unsaturated impurities content of 30 ppm or less, relative to 100 wt % of the total mass of the product, and/or has a propylene content of 65.0 to 69.8 wt %, relative to 100 wt % of the total mass of the product.

3. The dehydration process according to claim 1 , wherein said starting material has an isopropanol content of 90.0-99.9 wt %, relative to 100 wt % of the total mass of said starting material, and/or the conversion rate of isopropanol is 97.0-99.8%.

4. The dehydration process according to claim 1 , wherein said dehydration catalyst comprising alumina is selected from solid acid catalysts comprising alumina.

5. The dehydration process according to claim 1 , wherein the operating conditions of the dehydration step include: a reaction temperature of 150-450° C. , a reaction pressure of 0.05-1.0 MPaG, and a volume space velocity of 0.05-5.0 h -1 .

6. The dehydration process according to claim 1 , further comprising the step of separating an isopropanol/water mixture from said product,
or, further comprising the steps of:
1) washing the product with an absorbent to obtain a crude propylene product and a rich absorption liquid,
2) subjecting the crude propylene product to separation to remove heavy components, to obtain refined propylene, and
3) subjecting the rich absorption liquid to separation, to obtain an isopropanol/water mixture.

7. The dehydration process according to claim 6 , wherein the mixture has a water content of 10-20 wt %, relative to 100 wt % of the total mass of the mixture.

8. The dehydration process according to claim 6 , further comprising a recycling step of recycling 90 wt % or more, or substantially 100 wt % of the mixture to the dehydration step.

9. The dehydration process according to claim 8 , wherein in the recycling step, the at least a portion of the mixture is mixed with the starting material of the dehydration step, optionally supplemented with an additional amount of water, to increase or decrease) the water content of the staring material to a predetermined level.

10. The dehydration process according to claim 1 , further comprising the step of measuring the C 3 -C 4 unsaturated impurities content of the product and comparing the measured value of the C 3 -C 4 unsaturated impurities content (in ppm) with a preset value, wherein when the measured value of the C 3 -C 4 unsaturated impurities content is greater than the preset value, the conversion rate of isopropanol is measured to obtain a measured value (set as C, in %) of said conversion rate, in which:
1) when the measured value C is between 96.0% and 99.0%, the water content of the starting material is increased by 0.01 to 30 times, with a proviso that the water content after the increase is in a range of 0.1 to 3.0 wt % relative to 100 wt % of the total mass of the starting material,
2) when the measured value C is between 99.0% and 99.5%, the water content of the starting material is increased by 0.01 to 2 times with a proviso that the water content after the increase is in a range of 3.0 to 5.0 wt % relative to 100 wt % of the total mass of the starting material, and
3) when the measured value C is between 99.5% and 99.9%, the water content of the starting material is increased by 0.01 to 2 times with a proviso that the water content after the increase is in a range of 5.0 to 10.0 wt % relative to 100 wt % of the total mass of the starting material.

11. The dehydration process according to claim 1 , further comprising the step of measuring the C 2 unsaturated impurities content of said product and comparing the measured value of the C 2 unsaturated impurities content (in ppm) with a preset value, wherein when the measured value of the C 2 unsaturated impurities content is greater than the preset value, the conversion rate of isopropanol is measured, to obtain a measured value (set as D, in %) of said conversion rate, in which:
1) when the measured value D is between 96.0% and 99.0%, the water content of the starting material is increased by 0.01-50 times with a proviso that the water content after the increase is in a range of 0.1 to 5.0 wt % relative to 100 wt % of the total mass of the starting material, and
2) when the measured value D is between 99.0% and 99.9%, the water content of the starting material is increased by 0.01-3 times with a proviso that the water content after the increase is in a range of 5.0 to 10.0 wt % relative to 100 wt % of the total mass of the starting material.

12. A method for producing propylene, comprising the steps of:
subjecting acetone as a starting material to a hydrogenation reaction in the presence of a hydrogenation catalyst to produce a product containing isopropanol,
separating the isopropanol-containing product to obtain a hydrogen-containing gas and an isopropanol-containing liquid,
separating the isopropanol-containing liquid to obtain isopropanol,
dehydrating the isopropanol to produce a propylene-containing product according to the dehydration process of claim 1 ,
washing the propylene-containing product with an absorbent to obtain a crude propylene product and a rich absorption liquid,
separating the rich absorption liquid to obtain an isopropanol/water azeotrope,
separating and removing heavy components from the crude propylene product to obtain refined propylene.

13. The method according to claim 12 , further comprising the step of:
recycling at least a portion of the isopropanol/water azeotrope to the dehydration step.

14. A plant for producing propylene by the dehydration process of claim 1 , comprising an acetone hydrogenation reactor, a hydrogenation product gas-liquid separator, a fractionating tower, an isopropanol dehydration reactor, a propylene absorption-separation tower, an azeotropic distillation tower and a crude propylene de-heavy fractionator connected in sequence, wherein the acetone hydrogenation reactor is configured to perform hydrogenation reaction on acetone used as a starting material in the presence of a hydrogenation catalyst to produce an isopropanol-containing product, the hydrogenation product gas-liquid separator is configured to separate the isopropanol-containing product to obtain a hydrogen-containing gas and an isopropanol-containing liquid, the fractionating tower is configured to separate the isopropanol-containing liquid to obtain isopropanol, the isopropanol dehydration reactor is configured to perform dehydration reaction on the isopropanol used as a starting material in the presence of an alumina-containing dehydration catalyst to produce a propylene-containing product, the propylene absorption-separation tower is configured to wash the propylene-containing product with an absorbent to obtain a crude propylene product and a rich absorpti

Assignees

• China Petroleum & Chem Corp
• Sinopec Dalian Res Inst Petroleum & Petrochemicals Co Ltd

Inventors

• Qiao Kai
• Zhou Feng
• Yang Xiuna
• Ma Huixia
• Jiang Rui
• Zhang Shumei
• Jin Ping
• Peng Shaozhong

Classifications

• B01J35/51

  Spheres · CPC title

• C07C2521/06

  Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof · CPC title

• C07C2521/04

  Alumina · CPC title

• C07C7/04

  by distillation · CPC title

• C07C1/2076

  by a transformation in which at least one -C(=O)- moiety is eliminated · CPC title