HIGH TEMPERATURE METATHESIS PROCESS

Abstract: The invention provides a high temperature metathesis process for the metathesis of Fischer-Tropsch olefins in the C5 to C15 range, said metathesis process including the step of subjecting a Fischer-Tropsch olefin feedstock in the C5 to C15 range to metathesis reaction conditions, said olefin feedstock including mono-methyl branched olefins. The invention also provides alkyl benzenes (AB's), drilling fluids and oxo-alcohols produced from the products of the metathesis process.

Description: HIGH TEMPERATURE METATHESIS PROCESS Field of the Invention This invention relates to a high temperature metathesis process. In particular, the invention relates to the optimisation of the high temperature metathesis process to improve selectivity for a desired product range. Background to the Invention The applicant is aware that olefins in the Cg to C 14 range may be used as detergent and plasticizer precursors as well as for alkylation of benzene, and that C15 to C18 olefin ranges may be used as drilling fluids and drilling fluid precursors, amongst other uses. Conventional thinking was that linear olefins may be used to produce linear alkyl benzene and linear oxo-alcohols which could be used to produce detergents and plasticizers which were believed to be both bio-degradable and suitable for their intended purpose. Thus, previously efforts were concentrated on producing linear oxo-alcohols and lineal alkyl benzene, and thus efforts were focused on linear olefins from which these could be made. Recently, however, a new wave of thinking has lead to the belief that non-linear oxo-alcohols as well as non-linear alkyl chain alkyl benzene could be used alone or together with their linear counterparts for the production of said detergents and plasticizers. in particular short chain branched olefins are believed best suited to produce such non-linear products. Thus, recent efforts have concentrated on the delinearization of the linear olefins in order to use such olefins in the production of the non-linear products. Summary of the Invention Surprisingly, after extensive research, the applicant has found that a peculiar olefin composition in the Cg to C 1 8 range, having both linear and non- linear olefins may be made by metathesis of Fischer-Tropsch olefins in the C5 to C15 range. Thus, according to a first aspect of the invention, there is provided a high temperature metathesis process for the metathesis of Fischer-Tropsch olefins in the C 5 to C 15 range, said metathesis process including the step of subjecting a Fischer-Tropsch olefin feedstock in the C5 to C 1 5 range to metathesis reaction conditions, said olefin feedstock including mono-methyl branched olefins. The high temperature metathesis process may be carried out at a temperature of between 300°C to 600°C. Typically the high temperature metathesis process is carried out at a temperature of between 450°C and 550°C. The operating pressure of the high temperature metathesis process may be between 1 and 30 bar, or even higher. The high temperature metathesis process may use a tungsten or molybdenum based catalyst, for example, WO3 or M0O3, supported or unsupported, with or without co-catalysts. The support can typically be SiO 2 , AI2O3, ZrO 2 , TiO 2 , or mixtures thereof. The high temperature metathesis process Fischer-Tropsch olefinic feedstock in the C 5 to C 15 range may include linear alpha olefins, mono-methyl branched olefins, paraffins, dienes, aromatics, and the like. Typically, the Fischer-Tropsch olefinic feedstock includes one or more olefins selected from the C5 to Cg range. The product of the high temperature metathesis process may include one or more mono-methyl branched olefins in the Cg to C 1 8 range. The product of the high temperature metathesis process may include one or more linear olefins in the Cg to Cιs range. The product of the high temperature metathesis process may include one or more mono-methyl branched olefins and one or more linear olefins in the Cg to C 18 range. The olefins of the product may be internal olefins. The product of the high temperature metathesis process may be used in the production of alkyl benzene, plasticizers, detergents, drilling fluids, and the like, having both a linear fraction and a branched fraction (for alkyl benzene the alkyl chain is branched or linear). Typically, the branched fraction will be mono-methyl branched. However, the branching may be di-methyl and/or ethyl. According to a second aspect of the invention, there is provided a high temperature metathesis process for the metathesis of olefins in the C5 to C15 range, said metathesis process including the step of subjecting an olefinic feedstock in the C5 to C 15 range to metathesis reaction conditions, the process including the recycling of a part of the product of the metathesis reaction to the reaction to increase the selectivity for a desired product range. The olefinic feedstock may be a Fischer-Tropsch olefinic feedstock including mono-methyl branched olefins. Typically, the olefinic feedstock includes one or more olefins in the C5 to Cg range. Where the desired product range includes olefins in the Cg to C18 range, the process includes a separation stage wherein a recycle fraction in the C5 to C 8 range is separated from the product and recycled to the reaction. The quantity of recycle in the feedstock may be selected to provide a C9 and higher selectivity of above 50%. Generally, the quantity of recycle in the feedstock is selected to provide a Cg and higher selectivity of above 50%. Typically, the recycle makes up between 20% and 80% of the reaction feedstock. Usually, the recycle makes up between about a third and three quarters of the reaction feedstock. The total yield of high temperature metathesis process product in the Cg to Ci8 range is above 40%. Typically, the total yield of high temperature metathesis process product in the Cg to Cιs range is about 50%. The total feedstock conversion of the high temperature metathesis process of the invention is typically in the range of 60% to 90%, usually about 80%. The ratio of linear to branched high temperature metathesis process products is typically greater than 1 :1. Usually, the ratio of linear to branched high temperature metathesis process products is greater than 2:1. Generally, the ratio of linear to branched high temperature metathesis process products is about 3: 1. The branching of the high temperature metathesis process products is predominantly mono-methyl branching, although some di-methyl, and/or ethyl branching may also be present. The product of the high temperature metathesis process may be used in the production of alkyl benzene, plasticizers, detergents, drilling fluids, and the like, having both a linear fraction and a branched fraction (for alkyl benzene the alkyl chain is branched or linear), the ratio of linear to branched fractions being related to the ratio of linear to branched high temperature metathesis process products used in their production. Description of the Drawing and Examples The invention will now be described, by way of non-limiting illustration only, with reference to the accompanying line diagram. In the diagram, reference numeral 10 generally indicates a high temperature metathesis process broadly in accordance with the invention. The process 10 includes a reactor 12 operated at between 450°C and 550°C and at an operating pressure of between 1 and 30 bar. A Fischer- Tropsch olefinic feedstock 14 including mono-methyl branched olefins, is fed into the reactor 12. The feedstock 14 includes olefins in the C5 to Cg range. Usually the feedstock 14 will be purified of oxygenates which may poison the catalyst by extractive distillation (not shown), prior to being fed to the reactor 12. The reaction product 16 includes both linear and branched internal olefins in the C 2 to Cιβ range. The reaction product 16 is fed to a separator 18 where it is cut into a light product stream 20 including C 2 to C 4 , a recycle stream 22 including C5 to C 8 , and a heavy product 24 including product in the desired Cg to C 1 8 range. The recycle stream 22 is combined with the feedstock 14 to form the total feedstock of the reactor 12. The recycle stream 22 is between a third and three quarters of the feedstock 14. The total yield of heavy product stream 24 is about 50%, while the feedstream 14 conversion is about 80%, with a selectivity for Cg to C 1 8 of about 60%. The ratio of linear to branched product in heavy product stream 24 is about 3:1 Examples Several runs were made by passing olefin containing feed downwards through a vertical pipe reactor, unless otherwise stated. This reactor (25.4 mm in diameter and 400 mm in length) was positioned in a temperature- controlled electric furnace with a thermocouple positioned in the catalyst bed to monitor reaction temperatures. About 100 mm depth of glass beads (2 mm diameter) were placed at the bottom of the pipe reactor supported by a layer of quartz wool. Another layer of quartz wool was placed on top of the glass beads as support for the catalyst bed comprising of about 12 g of catalyst. This was topped with another layer of quartz wool and the remainder of the reactor filled with glass beads. The catalyst was activated by heating at 550°C in flowing air for 12 hours, followed by heating at 600°C for 2 hours under a flow of nitrogen and finally the catalyst was cooled under a flow of nitrogen to reaction temperature (typically 500°C). Example 1 In this Example a catalyst in the form of a WO 3 supported on SiO 2 was used, in which the WO 3 and SiO 2 were in a mass ratio of 8:92. The process was operated in the temperature range of 400 to 550°C and at a LHSV of 1 h " 1 . As a feed was used a C 7 SLO narrow cut after NMP extraction, containing 3-methyl-1 -hexene (0.7870%), 5-methyl-1 -hexene (1.9068%), 4-methyl-1- hexene (3.1737%), 2-methyl-1 -hexene (4.1847%), 2-methylhexane (1.6501 %), 3-methylhexane (2.8000%), 1 -heptene (74.5710%), n-heptane (6.3012%), 2-methyl-2-hexene (0.6832%), 3-heptene (0.3163%), 2-heptene (0.7038%) and dienes, cyclic olefins and aromatics (2.4386%) amongst others, based on mass% calculations. Results are set forth in the following table, Table 1 : Table 1 Example 2 In this Example a catalyst in form of a WO 3 supported on SiO 2 was used, in which the WO 3 and SiO 2 were in a mass ratio of 8:92. The process was operated at 500°C and by recycling some of the olefins formed back to the reactor. As a feed was used a C SLO narrow cut after NMP extraction, containing 3-methyl-1 -hexene (0.7870%), 5-methyl-1 -hexene (1.9068%), 4- methyl-1 -hexene (3.1737%), 2-methyl-1 -hexene (4.1847%), 2-methylhexane (1 .6501 %), 3-methylhexane (2.8000%), 1 -heptene (74.5710%), n-heptane (6.3012%), 2-methyl-2-hexene (0.3163%), 2-heptene (0.7038%) and dienes, cyclic olefins and aromatics (2.4386%) amongst others, based on mass% calculations. Results are set forth in the following table, Table 2: Table 2 (a) 1.0 LHSV based on fresh feed; 6.0 LHSV with recycle (1:5 recycle ration); (Recycle C 5 - C 10 ) (b) 1.4 LHSV based on fresh feed; 5.6 LHSV with recycle (1:3 recycle ratio); (Recycle C 5 - C 9 ) (c) 1.4 LHSV based on fresh feed; 5.6 LHSV with recycle 1:3 recycle ratio; (Recycle C&e - C 8 ) (d) 2.0 LHSV based on fresh feed; 5.0 LHSV with recycle 1:1.5 recycle ratio); Recycle C45 - C 7 ) Example 3 In this Example a catalyst in the form of a WO 3 supported on SiO 2 were in a mass ratio of 8:92. The process was operated at 500°C and at a LHSV of 3 h "1 . As a feed was used a C 5 SLO co-monomer grade cut containing 99% 1 -pentene. The C 5 - C 7 fraction was recycled (1 : 1 recycle ratio) back to the reactor in order to increase the yield towards the Cs - C 14 fraction. Results are set forth in the following table, Table 3: Table 3 The applicant believes that it is an advantage of the invention as illustrated, that the high operating temperatures result in a high degree of resistance to poisoning of the metathesis catalyst by feedstock components, such as branched olefins, dienes, aromatics, and the like. The applicant believes that it is a further advantage of the invention as illustrated that by recycling a cut of the product which is below the desirable carbon length range, high selectivity to desired products is achieved..

Claims: Claims: 1. A high temperature metathesis process for the metathesis of Fischer-Tropsch olefins in the C 5 to C 15 range, said metathesis process including the step of subjecting a Fischer-Tropsch olefin feedstock in the C5 to C 1 5 range to metathesis reaction conditions, said olefin feedstock including mono-methyl branched olefins. 2. The high temperature metathesis process as claimed in claim 1 , wherein said process is carried out at a temperature of between 300°C to 600°C. 3. The high temperature metathesis process as claimed in claim 1 , wherein said process is carried out at a temperature of between 450°C and 550°C. 4. The high temperature metathesis process as claimed in any one of claims 1 to 3, wherein said process is carried out at a pressure of between 1 and 30 bar. 5. The high temperature metathesis process as claimed in any one of claims 1 to 4, wherein said process is carried out in the presence of a tungsten or molybdenum based catalyst. 6. The high temperature metathesis process as claimed in any one of claims 1 to 4, wherein said process is carried out in the presence of a WO 3 or M0O3 catalyst. 7. The high temperature metathesis process as claimed in any one of the preceding claims, wherein said Fischer-Tropsch olefinic feedstock in the C5 to C15 range includes at least linear alpha olefins and mono-methyl branched olefins. 8. The high temperature metathesis process as claimed in any one of the preceding claims, wherein said Fischer-Tropsch olefinic feedstock includes one or more olefins selected from the C 5 to Cg range. 9. The high temperature metathesis process as claimed in any one of the preceding claims, wherein the product of the high temperature metathesis process includes one or more mono-methyl branched olefins in the Cg to C18 range. 10. The high temperature metathesis process as claimed in any one of the preceding claims, wherein the product of the high temperature metathesis process includes one or more linear olefins in the Cg to C18 range. 11. The high temperature metathesis process as claimed in any one of the preceding claims, wherein the olefins of the product are internal olefins. 12. The high temperature metathesis process as claimed in any one of the preceding claims, wherein the product of the high temperature metathesis process is used in the production of alkyl benzene, plasticizers, detergents, and/or drilling fluids, having both a linear fraction and a branched fraction. 13. The high temperature metathesis process as claimed in claim 12, wherein the branched fraction is mono-methyl branched. 14. The high temperature metathesis process as claimed in claim 13, wherein the branched fraction includes di-methyl, and/or ethyl branching. 15. A high temperature metathesis process for the metathesis of olefins in the Cs to C 15 range, said metathesis process including the step of subjecting an olefinic feedstock in the Cs to C 15 range to metathesis reaction conditions, the process including the recycling of a part of the product of the metathesis reaction to the reaction to increase the selectivity for a desired product range. 16. A high temperature metathesis process as claimed in claim 15, wherein the olefinic feedstock is a Fischer-Tropsch olefinic feedstock including mono-methyl branched olefins. 17. A high temperature metathesis process as claimed in claim 15 or claim 16, wherein the olefinic feedstock includes one or more olefins in the Cs to Cg range. 18. A high temperature metathesis process as claimed in claim 15, wherein the desired product range includes olefins in the Cg to C 18 range. 19. A high temperature metathesis process as claimed in claim 18 wherein the process includes a separation stage wherein a recycle fraction in the C 5 to Cs range is separated from the product and recycled to the reaction. 20. A high temperature metathesis process as claimed in claim 19, wherein the quantity of recycle in the feedstock is selected to provide a Cg and higher selectivity of above 50%. 21. A high temperature metathesis process as claimed in claim 19 or claim 20, wherein the recycle makes up between 20% and 80% of the reaction feedstock. 22. A high temperature metathesis process as claimed in claim 21 , wherein the recycle makes up between about a third and three quarters of the reaction feedstock. 23. A high temperature metathesis process as claimed in any one of claim 18 to 22, wherein the total yield of high temperature metathesis process product in the Cg to Cι 8 range is above 40%. 24. A high temperature metathesis process as claimed in any one of claim 18 to 22, wherein the total yield of high temperature metathesis process product in the C 9 to Cι 8 range is above 50%. 25. A high temperature metathesis process as claimed in any one of claims 15 to 24, wherein the total feedstock conversion is in the range of 60% to 90%. 26. A high temperature metathesis process as claimed in claim 25, wherein the total feedstock conversion is about 80%. 27. A high temperature metathesis process as claimed in any one of claims 15 to 26, wherein the ratio of linear to branched high temperature metathesis process products is greater than 1 : 1. 28. A high temperature metathesis process as claimed in any one of claims 15 to 27, wherein the ratio of linear to branched high temperature metathesis process products is greater than 2: 1. 29. A high temperature metathesis process as claimed in any one of claims 15 to 28, wherein the ratio of linear to branched high temperature metathesis process products is about 3:1. 30. A high temperature metathesis process as claimed in any one of claims 15 to 29, wherein the branching of the high temperature metathesis process products is predominantly mono-methyl branching. 31. A high temperature metathesis process as claimed in any one of claims 15 to 30, wherein the branching of the high temperature metathesis process products includes some di-methyl and/or ethyl branching. 32. A high temperature metathesis process as claimed in any one of claims 15 to 31 , wherein the products of the high temperature metathesis process are used in the production of alkyl benzene, plasticizers, detergents, and/or drilling fluids, having both a linear fraction and a branched fraction with the ratio of linear to branched fractions being related to the ratio of linear to branched high temperature metathesis process products used in their production. 33. A high temperature metathesis process substantially as herein described and illustrated. 34. A new high temperature metathesis process substantially as herein described.

Inventors: BOTHA JAN MATTHEUS, JACOBUS KELVIN STEPHEN, MBATHA MUZIKAYISE MTHOKOZI JUS, NKOSI BONGANI SIMON, REYNHARDT JAN PETRUS KAREL, SCHWIKKARD GAVIN WYATT, SPAMER ALTA, BOTHA, JAN, MATTHEUS, JACOBUS, KELVIN, STEPHEN, MBATHA, MUZIKAYISE, MTHOKOZI, JUSTICE, NKOSI, BONGANI, SIMON, REYNHARDT, JAN, PETRUS, KAREL, SCHWIKKARD, GAVIN, WYATT, SPAMER, ALTA
Applicants: BOTHA JAN MATTHEUS, JACOBUS KELVIN STEPHEN, MBATHA MUZIKAYISE MTHOKOZI JUS, NKOSI BONGANI SIMON, REYNHARDT JAN PETRUS KAREL, SASOL TECH PTY LTD, SCHWIKKARD GAVIN WYATT, SPAMER ALTA, BOTHA, JAN, MATTHEUS, JACOBUS, KELVIN, STEPHEN, MBATHA, MUZIKAYISE, MTHOKOZI, JUSTICE, NKOSI, BONGANI, SIMON, REYNHARDT, JAN, PETRUS, KAREL, SASOL TECHNOLOGY (PTY) LTD, SCHWIKKARD, GAVIN, WYATT, SPAMER, ALTA
Application year: 2000
Main classification: C07C6
IPC codes: C07B61, C07C1, C07C2, C07C4, C07C6, C07C11, C10G2, C10G50