PROCESS FOR THE PRODUCTION OF ALKOXYLATES

Abstract

A process for producing alkoxylates features a high growth ratio without the need of interim storage of a pre-polymer produced in a first reactor. The process may involve reacting a monomeric educt in the presence of a catalyst and a starting material in a first reactor equipped with a first circulation loop and thereafter passing a pre-polymer that is produced of the first circulation loop to a second reactor equipped with a second circulation loop, where a desired polymer is produced. The first reactor may comprise a smaller volume than the second reactor. The growth ratio, defined as a final batch volume of the second reactor divided by a minimum initial volume of the starting material in the first reactor, is at least 80:1.

Claims

1.-19. (canceled)

20. A process for producing alkoxylates comprising: reacting a monomeric educt in the presence of a catalyst and a starting material in a first reactor with a first circulation loop to produce at least a pre-polymer; and passing the pre-polymer from the first reactor to a second reactor with a second circulation loop to produce a polymer, wherein the first reactor comprises a volume that is smaller than a volume of the second reactor, wherein at least one of the first reactor or the second reactor is a jet loop reactor, wherein a growth ratio defined as a final batch volume of the second reactor divided by a minimum initial volume of the starting material in the first reactor is at least 80:1.

21. The process of claim 20 wherein the volume of the second reactor is more than twice the volume of the first reactor.

22. The process of claim 20 wherein the volume of the second reactor is more than six times the volume of the first reactor.

23. The process of claim 20 wherein the volume of the second reactor is more than nine times the volume of the first reactor.

24. The process of claim 20 wherein the volume of the first reactor has a total reactor volume of less than 10 m.sup.3.

25. The process of claim 20 wherein the reaction in the first reactor is started with the minimum initial volume of the starting material corresponding to between a fifth volume part and a twentieth volume part of a total volume of pre-polymer produced in the first reactor.

26. The process of claim 20 wherein a majority of a volume of the pre-polymer produced in the first reactor is transferred to the second reactor.

27. The process of claim 20 wherein a volume of the pre-polymer produced in the first reactor is between an eighth volume part and a twelfth volume part of a total volume of the polymer produced in the second reactor.

28. The process of claim 20 comprising reacting a monomeric educt in the second reactor, wherein a total mass of educts reacted in the first reactor is between an eighth mass part and a twelfth mass part of a total mass of educts reacted in the second reactor.

29. The process of claim 20 comprising in the first reactor: preheating and mixing the starting material; adding the catalyst; drying; heating to a reaction temperature; adding the monomeric educt; and obtaining the pre-polymer.

30. The process of claim 20 wherein the growth ratio defined as the final batch volume of the second reactor divided by the minimum initial volume of the starting material in the first reactor is at least 100:1.

31. The process of claim 20 wherein the starting material is selected from a group of alcohols, acids, esters, diols, triols, polyols, amines, amides, monosaccharides, disaccharides, and polysaccharides.

32. The process of claim 20 wherein the monomeric educts are selected from a class of cyclic ethers that includes but is not limited to alkylene oxides.

33. The process of claim 20 comprising dosing the monomeric educt to a reaction mass in the first reactor continuously, intermittently, individually, simultaneously in any ratio, consecutively, or in combination thereof.

34. The process of claim 20 wherein the polymer is a polyether polyol or a polyethylene glycol or a polypropylene glycol or a methoxypolyethylene glycol.

35. The process of claim 20 wherein both the first reactor and the second reactor are jet loop reactors.

36. A plant for performing the process of claim 20, the plant comprising: the first reactor with the first circulation loop; the second reactor with the second circulation loop, the second reactor being larger by volume than the first reactor, the second circulation loop being larger than the first circulation loop; and at least one of: a connection line between the first circulation loop and the second reactor, or a connection line between the first circulation loop and the second circulation loop, wherein the second circulation loop comprises a jet loop reactor, a pump, and a heater/cooler.

37. The plant of claim 36 wherein the first circulation loop comprises a jet loop reactor, a pump, and a heater/cooler.

38. The plant of claim 37 comprising a line starting at a branch connection of the first circulation loop downstream of the pump and upstream of the heater/cooler of the first circulation loop and connecting the first circulation loop with the second reactor in the second circulation loop.

Description

[0049] In the following preferred embodiments of the present invention will be further illustrated referring to the attached drawings, wherein

[0050] FIG. 1 is a simplified schematic view of an exemplary plant comprising a smaller and a larger jet loop reactor according to a possible embodiment of the present invention;

[0051] FIG. 2 is a block diagram showing a mass balance according to an exemplary embodiment of the present invention.

[0052] In the following referring to FIG. 1 a preferred embodiment of the present invention is illustrated. The drawing is simplified showing only those main components of the plant which are of interest for the comprehension of the present invention. The plant comprises a first smaller reactor 11 which serves to prepare a pre-polymer and which is equipped with a first circulation loop 10. Said first circulation loop 10 comprises a first smaller reactor 11, an output line 12 starting from the bottom of the first smaller reactor 11 for conveying a reaction mixture within the circulation loop 10 by means of a pump 13. The pump 13 conveys the reaction mixture within the first circulation loop 10 which comprises a branch connection 14 from which a first line 15 leads to a heat exchanger/cooler 16 designated to cool the reaction mixture which is recycled within the first circulation loop via output line 12, pump 13, line 15, heat exchanger 16 and line 17 back to the top of the reactor 11.

[0053] Thus as long as the branch connection 14 is open to line 15 the reaction mixture is recycled within a closed circulation loop 10, which is the case in a first reaction phase, wherein the pre-polymer is prepared. A small volume of a starting material 20 of for example about 0.5 m.sup.3 is provided at the beginning of the reaction in the first smaller reactor 11, which may be for instance about a tenth part of the total volume of the first smaller reactor 11. Thereafter one or more than one monomeric educts are added via line 18 and the pre-polymer is prepared within the first reactor 11. Said reactor 11 preferably is a jet loop reactor comprising an injection device 19 with a jet nozzle and designed to inject the monomeric educt and the circulation reaction mixture flowing in line 17 into the first reactor. A first reaction phase comprises preheating the starting material 20 (initiator), adding the catalyst, drying, heating to reaction temperature, adding successively the designated calculated amount of one or more than one monomeric educts via line 18, and circulating the reaction mixture within the loop 10 until all monomeric educts have reacted with the pre-polymer. Thereafter the branch connection 14 to line 15 is closed and an alternative line 21 is opened by which preferably the whole amount of the obtained pre-polymer is transferred to a second larger reactor 22 which is equipped with a second larger circulation loop 25 and which can be considered as the main reactor in the process according to the present invention. Within said second larger circulation loop 25, the pre-polymer obtained in the first smaller circulation loop 10 as described above is reacted to the final designated polymer. The volume of the second larger reactor 22 may be for instance about ten times as large as the volume of the first smaller reactor 11. Thus for example a volume of about 5 m.sup.3 of pre-polymer prepared in the smaller first circulation loop 10 may be transferred via line 21 to the second larger reactor 22, which may have a total reactor volume of for example about 50 m.sup.3.

[0054] The second larger main reactor 22 wherein the pre-polymer 23 is provided which has been prepared before in the first smaller reactor 11 is equipped with the second larger circulation loop 25. The second larger circulation loop 25 further comprises a line 24 starting from the bottom of the second larger reactor 22, a pump 26 in said line for conveying the reaction mixture within the second larger circulation loop 25 via line 27 through a heat exchanger/cooler 28 for cooling the reaction mixture which is then recycled via line 29 to the top of the main reactor 22.

[0055] A further amount of one or more monomeric educts is added successively via line 30 to a second injection device 31 comprising a jet nozzle and a mixing device for mixing the reaction mixture flowing within line 29 and the monomeric compound added via line 30 and injecting said mixture in the top region into the main reactor 22. Thus, the second larger circulation loop 25 as well is a jet circulation loop with thorough mixing of reaction components and injecting them via a jet nozzle preferably at high speed and in a finely dispersed manner into the second larger reactor 22. Within the second circulation loop 25 the reaction mixture is recycled until the whole provided volume of pre-polymer 23 has been reacted with the added monomeric compound or compounds to the designated polymeric compound with a specific molecular weight. The reaction is completed after the whole amount of one or more than one monomeric educts have been added via line 30. Here it is to mention that these one or more than one educts may be the same as have been used before for the production of the pre-polymer in the first circulation loop. This, however, is not mandatory as alternatively different monomeric educts may be added in the reaction phase executed in the second larger circulation loop.

[0056] In the following referring to the block diagram of FIG. 2, an exemplary embodiment of the present invention is illustrated in further detail. The block diagram is simplified and only shows the main mass streams being of interest for the understanding of the process according to the present invention. For instance, about 700 kg/batch of glycerol is used as the starting material 20 in the first step of the process wherein a pre-polymer is prepared within the first smaller reactor 11. To the glycerol, for example about 90 kg/batch KOH dissolved in 90 kg/batch of water is added as the catalyst 32. The starting material is now dried and water as waste from vacuum drying is discharged via line 33 to a water-collecting device 34. For example about 4300 kg/batch of propylene oxide is added as monomeric raw material 18 to the first reactor 11 in the smaller first circulation loop.

[0057] About 5000 kg/batch of pre-polymer produced in the smaller first reactor 11 is passed to the second larger jet reactor 22. An amount of 6700 kg/batch of ethylene oxide and 33000 kg/batch of propylene oxide is added to the second larger reactor 22 as further monomeric educt compounds (see 30). By reacting these further amounts of monomeric educts 30 with the pre-polymer in the second larger reactor 22 for example about 45000 kg/batch of a polyol product is produced in the second larger reactor. This polyol product may be subjected to a post-treatment 39 with a neutralization agent 35 added via line 36 to the post-treatment reactor 39. Thereafter about 45000 kg/batch of a final polyol product may be conveyed via line 37 to a filtration device 38, wherein the polyol product is purified.

LIST OF REFERENCE NUMBERS

[0058] 10 first circulation loop [0059] 11 first smaller reactor [0060] 12 output line [0061] 13 pump [0062] 14 branch connection [0063] 15 line [0064] 16 heat exchanger [0065] 17 line [0066] 18 line [0067] 19 injection device [0068] 20 starting material [0069] 21 alternative line [0070] 22 second larger reactor [0071] 23 pre-polymer [0072] 24 line [0073] 25 second circulation loop [0074] 26 pump [0075] 27 line [0076] 28 heat exchanger/cooler [0077] 29 line [0078] 30 line [0079] 31 injection device [0080] 32 catalyst [0081] 33 line [0082] 34 collecting device [0083] 35 neutralization agent [0084] 36 line [0085] 37 line [0086] 38 filtration device [0087] 39 post-treatment reactor