Process for the production in continuous of hydrocarbons from synthesis gas, in slurry reactors and for the separation from the solid phase of the liquid phase produced

• US 20050000861A1
• Filed: 05/05/2004
• Published: 01/06/2005
• Est. Priority Date: 05/15/2003
• Status: Active Grant

• Current Assignee: Eni SPA (Eni Petroleum Company Incorporated), EniTecnologie S.p.A. (Eni Petroleum Company Incorporated), Institut Francais Du Petrole
• Original Assignee: Eni SPA (Eni Petroleum Company Incorporated), EniTecnologie S.p.A. (Eni Petroleum Company Incorporated), Institut Francais Du Petrole
• Inventors: Belmonte, Giuseppe, Clerici, Gabriele Carlo Ettore
• Granted Patent: US 7,098,251 B2
• Time in Patent Office: Days
• US Class Current: 208/251.R
• CPC Class Codes: B01D 2311/04 Specific process operations in the feed stream; Feed pretreatment
• CPC Class Codes: B01D 2311/103 Heating
• CPC Class Codes: B01D 2311/12 Addition of chemical agents
• CPC Class Codes: B01D 2311/14 Pressure control
• CPC Class Codes: B01D 2311/16 Flow or flux control
• CPC Class Codes: B01D 61/145 Ultrafiltration
• CPC Class Codes: B01D 61/147 Microfiltration
• CPC Class Codes: B01D 61/16 Feed pretreatment
• CPC Class Codes: B01D 61/18 Apparatus therefor
• CPC Class Codes: B01J 2208/00256 in a heat exchanger for the heat exchange medium separate from the reactor
• CPC Class Codes: B01J 2208/003 involving reactant slurries
• CPC Class Codes: B01J 8/006 by filtration
• CPC Class Codes: B01J 8/228 externally, i.e. the particles leaving the vessel and subsequently re-entering it
• CPC Class Codes: C10G 2/342 with moving solid catalysts
• CPC Class Codes: C10G 2300/301 Boiling range
• CPC Class Codes: C10G 2300/4081 Recycling aspects

Abstract

Hydrocarbons are prepared, liquid at the reaction temperature, by feeding synthesis gas into three-phase turbulent reactors wherein the solid phase, consisting of the catalyst in particle form, is kept in suspension in the liquid phase by the rising synthesis gas. The reaction product is separated/filtrated in continuous from the catalyst dispersed therein, by means of a separation/filtration unit consisting of several filtration cartridges, each consisting of at least two porous filtering elements, the first having an average pore diameter ranging from 0.5 to 15 μm, whereas the second has an average pore diameter ranging from 0.002 to 0.1 μm.

Claims

1. A process for the production in continuous of hydrocarbons from synthesis gas in slurry reactors which comprises:

a. continuously feeding to the bottom of-a reactor for Fischer-Tropsch reactions, containing in suspension in the reaction product, a catalyst based on supported cobalt, a synthesis gas consisting essentially of hydrogen and carbon monoxide;

b. continuously discharging from the head of the reactor, a stream consisting essentially of light synthesis products in vapour phase and non-reacted reaction gas;

c. continuously discharging from the reactor, the heavy reaction product consisting essentially of a liquid hydrocarbon phase;

d. subjecting the heavy reaction product, before or after being discharged, to a separation/filtration treatment using a device which comprises a series of filtration cartridges, each consisting of a first filtering element made of a porous or meshed material with an average size of the pores or meshes ranging from 0.5 to 15 μ

m, which is positioned above a second filtering element, suitable for micro/ultra-filtration, made of a porous material with an average pore size ranging from 0.002 to 0.1 μ

m, said second filtering element being inserted in a metallic structure coaxially connected to the first filtering element;

e. sending the heavy reaction product coming from step (d), in liquid phase, having a content of fine or sub-micronic particles lower than 5 ppm to a subsequent treatment unit, or discharging it and cooling it to room temperature;

f. recycling the solids coming from the separation/filtration step to the reaction reactor.

2. The process according to claim 1, wherein the reactor for reactions of the Fischer-Tropsch type is a bubble reactor consisting of a vessel inside which chemical reactions are triggered, which take place in three-phase systems where a gaseous/vapour phase is bubbled into a suspension of a solid in a liquid.

3. The process according to claim 1 or 2, wherein the gaseous/vapour phase consists essentially of the synthesis gas and light reaction products in vapour phase, the dispersing liquid phase is the heavy reaction product or linear hydrocarbons, essentially with a high number of carbon atoms, and the solid phase is represented by the catalyst.

4. The process according to any of the previous claims, wherein the light reaction products consist essentially of hydrocarbon mixtures with a number of carbon atoms ranging from 1 to 25 and a boiling point, for the C₅-C₂₅ fraction, equal to or lower than about 150°

C.

5. The process according to any of the claims from 1 to 3, wherein the heavy reaction product consists essentially of paraffinic waxes, liquid at the reaction temperature, comprising mixtures of saturated, linear hydrocarbons, with a high number of carbon atoms having a boiling point, at atmospheric pressure, higher than 150°

C.

6. The process according to any of the previous claims, wherein the Fischer-Tropsch reaction is carried out at temperatures equal to or higher than 150°

C, a pressure ranging from 0.5 to 20 MPa being maintained inside the reactor.

7. The process according to any of the previous claims, wherein the catalyst is based on cobalt dispersed on a solid carrier selected from at least one oxide of one or more of the following elements:

Si, Ti, Al, Zr, Mg.

8. The process according to claim 7, wherein the cobalt is present in quantities ranging from 1 to 50% by weight with respect to the total weight.

9. The process according to claim 7 or 8, wherein the catalyst comprises, with respect to the total, from 0.05 to 5% by weight of ruthenium and from 0.05 to 5% by weight of at least a third element selected from those belonging to group 3.

10. The process according to claim 7 or 8, wherein the catalyst comprises, as promoting element, tantalum in quantities ranging from 0.05-5% by weight, with respect to the total.

11. The process according to any of the previous claims, wherein the catalyst is used in the form of a finely subdivided powder with an average diameter of the granules ranging from 10 to 700 μ

m.

12. The process according to any of the previous claims, wherein the separation/filtration treatment takes place by means of filtration cartridges situated inside or outside the synthesis reactor.

13. The process according to claim 12, wherein the filtration cartridges are situated outside the synthesis reactor.

14. The process according to the previous claims, wherein the separation/filtration unit comprises at least one degasification apparatus.

15. The process according to claim 14, wherein the degasification apparatus essentially consists of a vertical vessel in which the suspension remains for a time ranging from 1 to 5 minutes.

16. The process according to claim 12, wherein the filtration device is situated inside the synthesis reactor.

17. The process according to any of the previous claims, wherein, at the end of their filtering cycle, the separation/filtration units are periodically washed in countercurrent with a stream of light synthesis hydrocarbons.

18. Filtration cartridges for suspensions also at high temperatures, optionally coming from Fischer-Tropsch syntheses, comprising a first cylindrical filtering element made of a porous or meshed material with an average size of the pores or meshes ranging from 0.5 to 15 μ

m, which is positioned above a second filtering element, suitable for micro/ultra-filtration, made of a porous material with an average pore size ranging from 0.002 to 0.1 μ

m, said second filtering element being inserted in a metallic structure coaxially connected to the first filtering element.