FILM OZONOLYSIS IN A TUBULAR OR MULTITUBULAR REACTOR

Abstract

The disclosure relates to a method of performing ozonolysis or ozone-based oxidation on a liquid or emulsified reagent using a tubular falling firm reactor with one or multiple tubes wherein the combined ozone and carrier gas flow is co-current.

Claims

1.-62. (canceled)

63. A method of performing ozonolysis or ozone-based oxidation on a liquid or emulsified reagent using an industrial scale tubular falling film reactor with multiple tubes wherein the combined ozone and carrier gas flow is co-current, and wherein the ozonolysis occurs continuously without accumulation of large amounts of hazardous intermediates, and wherein the tubes are cooled by flow of a coolant.

64. The method of claim 63, wherein method comprises two or more industrial scale tubular falling film reactors with multiple tubes connected in series to process a continuous stream of the liquid or emulsified reagent.

65. The method of claim 63, wherein the carrier gas is selected from air, oxygen (O.sub.2), and an oxygen (O.sub.2)/nitrogen (N.sub.2) mixture.

66. The method of claim 65, wherein the carrier gas is an oxygen/nitrogen mixture comprising about 10% to about 30% oxygen and about 70% to about 90% nitrogen, or 7.5-12.5% oxygen and 87.5-92.5% nitrogen.

67. The method of claim 63, wherein the liquid or emulsified reagent is an emulsion in water.

68. The method of claim 63, wherein the reactor comprises the multiple tubes in parallel enclosed in a cylindrical reactor.

69. The method of claim 63, wherein the diameter of the tube(s) is between 5 mm and 30 mm.

70. The method of claim 69, wherein the diameter of the tube(s) is between 10 mm and 25 mm.

71. The method of claim 63, wherein the gas flow rate is from 10 to 1500 L/min in each of said tube or tubes.

72. The method of claim 63, wherein the gas flow rate is about 150 L/min in each of said tube or tubes.

73. The method of claim 63, wherein the tubes are between 1 and 7 meters in length.

74. The method of claim 73, wherein the tubes are about 6 meters in length.

75. The method of claim 63, wherein the liquid or emulsified reagent comprises a compound selected from hydroxycitronellene, methoxycitronellene, a rose ketone, fatty acid methyl esters, triglycerides, fatty acids, fatty alcohols, fatty esters, diterpenes, sesquiterpenes, monoterpenes, allyl ethers, alpha olefins, rosin acids, tertiary amines, alkenes, alkynes, amides, carboxylic acids, and aromatic compounds, provided that said compound is susceptible to ozone oxidation.

76. The method of claim 75, wherein the liquid or emulsified reagent comprises hydroxycitronellene.

77. The method of claim 75, wherein the liquid or emulsified reagent comprises methoxycitronellene.

78. The method of claim 75, wherein the liquid or emulsified reagent comprises a fatty acid methyl ester.

79. The method of claim 76, wherein the liquid or emulsified reagent comprises methyl oleate.

80. The method of claim 75, wherein the liquid or emulsified reagent comprises abietic acid or an ester thereof, pinene, limonene, ionone, or dihydromyrcenol,

81. The method of claim 63, wherein the product is selected from hydroxymelonal, methoxymelonal, methyl azealdehyde, nonanal, cyclocitral, or mixtures thereof.

82. The method of claim 63, wherein the product is hydroxymelonal.

83. The method of claim 63, wherein the product is methoxymelonal.

84. The method of claim 63, wherein the product is a mixture of methyl azealdehyde and nonanal.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0090] FIG. 1 is a diagram of the vertical cross-section of a multitubular reactor.

[0091] FIG. 2 is a diagram of the detail denoted by II in FIG. 1, on a larger scale.

[0092] FIG. 3 is a diagram of the cross-section along line III-III in FIG. 1.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0093] The disclosure relates to the ozonolysis or ozone-related reactions which occur on the free surface of a film of a liquid or emulsified reagent or reagent mixture that is subject to the controlled amount of a gaseous reagent comprising ozone (O.sub.3). The liquid or emulsified reagent or reagent mixture is the starting material which is reacted with ozone to yield oxidized product(s). The starting material is generally an alkene, alkyne, or any other compound that may be oxidized with ozone. The reaction products may be further reduced or oxidized to generate corresponding carbonyls, alcohols, and/or acids.

[0094] Performing ozone-based oxidation reactions in industrial-scale tubular falling film reactors (e.g., those originally designed for other processes, such as sulfonation) is advantageous for a variety of reasons. For example, tubular falling film sulfonation reactors operate by exposing relatively small volumes of liquid reagent(s) to relatively high volumes of reactive gaseous reagent(s) that have been diluted with an inert carrier gas or mixture thereof. Due to their continuous mode of operation, the reactors are efficient and exhibit reasonably high throughput rates per reactor tube, but do not allow for the accumulation of intermediates. Moreover, these reactors handle exothermic processes well because they include excellent heat dissipation features. The method described herein provides a safe and efficient means of performing ozonolysis reactions on an industrial scale by taking advantage of the aforementioned benefits of tubular falling film sulfonation reactors.

[0095] Examples of tubular falling film sulfonation reactors are described in GB 2,043,067 B, which is incorporated herein by reference. Tubular or multitubular co-current reactors are particularly useful due to their relatively low cost and mechanical simplicity. Such reactors can be adapted to use for ozonation reactions.

[0096] An additional safety advantage can be realized over traditional ozonolysis approaches if the reaction is carried out in water or as an emulsion with water. The flashpoint of the liquid reagent(s) can be eliminated or dramatically reduced in the presence of water, thereby minimizing the risk of fire in the event of an uncontrolled exotherm or explosion. Furthermore, the use of an emulsion allows for easier control of the liquid reagent in terms of concentration, distribution within the ozonolysis device tubes, and temperature.

[0097] As shown in FIGS. 1-3, the reactor 1 contains a set of parallel tubes 10 enclosed in a cylindrical housing, which is connected at one end to a gaseous reagent feeding chamber 70 and at the other end to a product collection chamber 40.

[0098] Gaseous ozone from an external source, such as a corona discharge or electrolysis driven ozone generating device, flows through conduit 12 into the feeding chamber 70 where it enters the tubes 10 and reacts with the liquid or emulsified reagent.

[0099] Reaction product(s) emerge from the tubes 10 into the product collection chamber 40, from which the reaction product(s) are removed via conduit 13 and collected in an external vessel.

[0100] A liquid coolant, such as water and/or glycol, flows into the reactor housing through conduit 20, around the tubes 10 and out of the reactor housing via conduit 21. Alternatively, the liquid coolant flows into the reactor housing through conduit 21 and out via conduit 20. The in conduit 20 and out conduit 21 direction of flow for the liquid coolant is preferred, however, because the exothermic reaction between ozone and the liquid or emulsified reagent(s) takes place preferentially at the portion of the tubes 10 that is closest to the feeding chamber 70. Numerous diaphrams 22, located inside the reactor housing and oriented perpendicular to the tubes 10, increase alter the path and increase the turbulence of the coolant flowing through the reactor housing. The coolant is separated from the gas feeding chamber and the product collection chamber by plates 23 and 24, respectively, which are oriented normal to, and positioned at the ends of the tubes 10.

[0101] Additional configurations for cooling the reactor that are not depicted in FIGS. 1-3 are also effective and may be employed. For example, the reactor housing interior may contain two separate cooling sections, one to cool the end of the tubes 10 that is connected to the feeding chamber 70 and one too cool the end of the tubes 10 that is connected to the product collection chamber 40, to enhance the overall cooling capacity.

[0102] A third tube plate 25 is positioned between the gas feeding chamber 70 and plate 23 such to define a feeding chamber 15 for the liquid or emulsified reagent(s). One or more conduits 16 are used to feed the liquid or emulsified reagent(s) into the feeding chamber 15, which also contains a device as shown in FIG. 2 for introducing the liquid or emulsified reagent(s) into one end of the tubes 10.

[0103] As shown in FIG. 2, each tube 10 has a cylindrical portion 30 with a slightly larger diameter than the remainder of the tube, which is connected to the tube by a frusto-conical section 31. The cylindrical portion 30 contains passages 38 for introducing the liquid or emulsified reagent(s) into the tube 10. The cylindrical portion 30 fits, with suitable clearance, in a cylindrical sleeve 33, the latter of which facilitates for the formation of liquid-tight seals between the cylindrical portion 30 and plates 23 and 25. The cylindrical sleeve 33 contains passages 36 for the liquid or emulsified reagent(s), of suitable size and circumferential distribution as not to generate head losses when allowing passage of the liquid or emulsified reagent(s) into the cylindrical portion 30.

[0104] The outer surface of a second sleeve 50 is in contact with the inner surface of the cylindrical portion 30, except for a central section, owing to the presence of a wide annular groove 51. The inner surface of the cylindrical portion 30 and groove 51 define an annular space for receiving the liquid or emulsified reagent(s) that enter the tube 10 from the passages 36 and 38, which open into groove 51. A seal groove 34 is positioned between the cylindrical sleeve 33 and the frusto-conical section 31. Suitable axial passages 52, shown only diagrammatically in FIG. 2, allow the liquid reagent to discharge into the tube interior from the annular space defined by groove 51. The sleeve 50 comprises a beveled or frusto-conical end with the same opening angle as the frusto-conical section 31.

[0105] Between one end of the second sleeve 50 and the frusto-conical section 31 there is an annular slot oriented according to the generatrices of a truncated cone, the width of this slot being defined by the gap space between sleeve 50 and the frusto-conical section 31. The gap space between sleeve 50 and the frusto-conical section 31 may be adjusted by a threaded crown 54 screwed into the end of the cylindrical portion 30 that is closest to the gas feeding chamber 70. It is thus possible, by screwing up or down the sleeve 50 in the cylindrical portion 30, to adjust the cross-section of the annular slot between the edge of the sleeve 50 and the frusto-conical section 31. The annular slot, being orientated according to the generatrices of a cone, favors the distribution of the liquid reagent in the form of a film entirely around the inner surface of the tube 10.

[0106] The inner diameter of sleeve 50 is suitably the same as the inner diameter of the tube 10 so that the gaseous reagent coming from the distribution chamber 70 may be brought to brush the free surface of the film 60 without resulting in a significant head loss.

[0107] Starting materials for the method described herein include any compound that may be oxidized by ozonolysis. Specific examples of starting materials for this process include hydroxycitronellene, methoxycitronellene, fatty acid methyl esters (FAME), triglycerides, fatty acids, fatty alcohols, fatty esters, diterpenes, sesquiterpenes, monoterpenes, allyl ethers, alpha olefins, and rosin acids.

[0108] In one embodiment, a tube reactor for ozonolysis includes a tube (see, e.g., 10 in FIG. 1) with a 5 to 30 mm internal diameter (e.g., 10 mm) and a length of 1 to 7 m (e.g., 1.7 m). The tube is constructed of a suitable material (e.g., stainless steel) and is connected to a gaseous reagent feeding chamber (see, e.g., 70 in FIG. 1) that allows gas to flow through the center of the tube and liquid to be flowed in a film on the wall of the tube through annular slots (e.g., as shown in FIG. 2; component II in FIG. 1). The tube is enclosed in a jacket (see, e.g., 1 in FIG. 1) for circulating liquid coolant around it (see, e.g., 10 in FIG. 1), with the end of the tube protruding through a liquid-sealed orifice (see, e.g., 24 in FIG. 1). A liquid/gas separation vessel is connected to the bottom of the reaction tube (see, e.g., 10 in FIG. 1). The excess gas flows into an ice condenser and then into an ozone destruction unit. The collected liquid product is pumped into sampling containers for analysis by a peristaltic pump.

[0109] In one embodiment, the gas inlet (see, e.g., 12 in FIG. 1) is connected to an ozone generator, and the liquid inlet is connected to a stirred feed tank equipped with a peristaltic pump. The liquid inlet pipe is also jacketed and cooled to control the temperature of the feed liquid or emulsified reagent.

[0110] In one embodiment, for emulsion preparation, water is combined with the organic reagent in a ratio (e.g., 5:1) ranging from stoichiometric (i.e., 1:1) to very dilute (e.g., 100:1) in the feed tank and stirred vigorously such that a homogenous emulsion is maintained. Deionized water is used for the emulsions.

[0111] In one embodiment, a mixture of O.sub.2 and N.sub.2 gas is used to feed the ozone generator and to comprise the ozone carrier gas for the ozonolysis reaction.

[0112] In one embodiment, conversions of starting materials are determined by gas chromatography (GC) and are calculated on the basis of the disappearance of starting material. Samples are prepared by extracting the organic components of the emulsion into a homogenous organic solvent phase. Analysis of the composition of the aforementioned organic phase is accomplished by gas chromatography.

[0113] In one embodiment, the ratio of water to organic reagent ranges from 1:1 to 100:1 (e.g., 5:1), the ozone concentration ranges from 2.5% to 10% (e.g., 5%), the gas flow rate ranges from 10 to 20 L/min (e.g., 15 L/min), the ozone mass flow rate ranges from 32.6 to 135 g/h (e.g., 65.9 g/h), the emulsion flow rate ranges from 1 to 5 kg/h (e.g., 2 kg/h), and the cooling temperature ranges from 0 to 20 C. (e.g., 10 C.), to yield starting material conversion percentages ranging from 13.70% to 52.63% (e.g., 26.76%).

[0114] In another embodiment, 1-6 pilot tube reactors (e.g., 3) can be connected in series, with gas and liquid being separated at the bottom of each tube. Tubes can be from 1-6 m in length (e.g., 1.7 m), and the tubes can range in diameter from 5-50 mm (e.g., the first 2 tubes being 25 mm in diameter and the 3.sup.rd tube being 10 mm in diameter). The organic liquid feed can be flowed in a solution of reagent and nonanoic acid in ranges from 1:1 to 100:1 (e.g., 3:1) through the first tube to the second and third tube in series at rates ranging from 1-99 kg/hr (e.g., 4.2 kg/hr). The gas can be flowed co-currently at ozone concentration in ranges from 0.5% to 10% (e.g., 5.1%) from the 3.sup.rd tube through the 2.sup.nd to the 1.sup.st tube at a flow rate from 10 to 1500 L/min (e.g., 150 L/min), and the cooling jacket temperature can be maintained between 0 and 50 C. (e.g., 15 C.) to yield conversion percentages between 93-100% (e.g., 97.6%).

EXAMPLES

Example 1

Film Ozonolysis in a Monotubular Reactor

Ozonolysis Reactor Details

[0115] A pilot tube reactor was used for ozonolysis, including a tube with a 10 mm internal diameter and a length of 1.7 m (e.g., 10 in FIG. 1). The tube was constructed of 316 stainless steel and was connected to a gaseous reagent feeding chamber (e.g., 70 in FIG. 1) that allowed gas to be flowed through the center of the tube and liquid to be flowed in a film on the wall of the tube through annular slots (e.g., as shown in FIG. 2; component II in FIG. 1). The tube was enclosed in a steel jacket (e.g., 1 in FIG. 1) for circulating cooling fluid around the reaction tube (e.g., 10 in FIG. 1) with the end of the tube protruding through a liquid-sealed orifice (e.g., 24 in FIG. 1). A liquid/gas separation vessel was connected to the bottom of the reaction tube (e.g., 10 in FIG. 1). The excess gas flowed through to an ice condenser followed by an ozone destruction unit. The collected liquid product was pumped through a peristaltic pump to sampling containers for analysis.

[0116] The gas inlet (e.g., 12 in FIG. 1) was connected to an Ozonia Ozat CFS-2G ozone generator and the liquid inlet was connected to a stirred feed tank equipped with a peristaltic pump. The liquid inlet pipe was also jacketed and cooled to control the temperature of the feed liquid reagent.

Ozonolysis Reagent and Product Details

[0117] Methoxycitronellene was >99% pure and was obtained from reaction of methanol with dihydromyrcene. Fatty acid methyl esters (FAME) was obtained from multiple sources including soy, palm, and algal oils and consisted of 72-89% methyl oleate as the primary component.

[0118] When methoxycitronellene is reacted, the major product is methoxymelonal. When FAME is reacted, the major products are methyl azelaldehyde and nonanal.

[0119] For the emulsion preparation, water was combined with the organic reagent in a 5:1 ratio in the feed tank and stirred vigorously such that a homogenous emulsion was maintained. Deionized water was used for all of the emulsions.

[0120] A mixture of 95% O.sub.2 and 5% N.sub.2 gas was used to feed the ozone generator and to comprise the carrier gas for O.sub.3 to the reaction.

[0121] Conversions of starting materials were determined by GC (Agilent 6890N) and were calculated based on the disappearance of the starting material on a gross adjusted basis. Samples were prepared by extracting the organic components of the emulsion into a homogenous ethyl acetate solvent phase and analyzing the composition of said organic phase by gas chromatography.

[0122] Example reaction conditions and product distributions are outlined in Tables 1 and 2. Reactions were performed at various O.sub.3 concentrations and mass flow rates.

TABLE-US-00001 TABLE 1 Methoxycitronellene in a water-based emulsion was oxidized by ozonolysis at different ozone concentrations and flow rates to yield the starting material conversion percentages shown. Ratio of Water Gas O.sub.3 Mass Emulsion Cooling to Organic O.sub.3 Conc Flowrate Flow Flow Temp Conversion of Sample Reagent (w/w) % L/min g/h kg/h C. Starting Material % 1 5:1 2.5 15 32.6 2 10 13.70 2 5:1 2.5 15 32.6 2 10 15.79 3 5:1 5 15 65.9 2 10 26.76 4 5:1 5 15 65.9 2 10 24.71 5 5:1 10 15 135 2 10 48.89 6 5:1 10 15 135 2 10 52.63

TABLE-US-00002 TABLE 2 FAME (89% methyl oleate) in a water-based emulsion was oxidized by ozonolysis at different ozone concentrations and flow rates to yield the starting material conversion percentages shown. Ratio of Water Gas O.sub.3 Mass Emulsion Cooling to Organic O.sub.3 Conc. Flowrate Flow Flow Temp Conversion of Sample Reagent (w/w) % L/min g/h kg/h C. Starting Material % 1 5:1 4 15 52.5 2 25 42.4 2 5:1 4 15 52.5 2 25 38.8 3 5:1 6.4 15 85 2 25 46.5 4 5:1 6.4 15 85 2 25 50.4 5 5:1 9.5 15 128 2 25 50.9 6 5:1 9.5 15 128 2 25 51.3

Example 2

[0123] Ozonolysis Reactor 2 Details

[0124] A second arrangement of involving 3 pilot tube reactors connected in series was used. All 3 tubes were 1.7 m in length, with the first 2 tubes being 25 mm in diameter and the 3.sup.rd tube being 10 mm in diameter. All tubes were equipped with a film distribution head, a cooling jacket, and a gas liquid separator at the bottom. The organic, liquid feed was flowed from the first tube through the second and third tube in series. The gas was flowed co-currently from the 3.sup.rd tube through the 2.sup.nd to the 1.sup.st tube. The cooling jacket temperature was maintained at 15 C.

[0125] In one instance, this reactor was used to process a 75% mixture of vegetable fatty acid in nonanoic acid. The major components of the vegetable fatty acid were estimated as follows: 77.65% oleic acid, 11.64% linoleic acid, 1.98% stearic acid, 4.4% palmitic acid, 2.9% myristic acid. The O.sub.3 was generated using pure O.sub.2 and a generator composed of 2 Pinnacle Quadblocks in a custom cabinet. The results of this run are presented in Table 3.

TABLE-US-00003 TABLE 3 Ozonolysis of vegetable fatty acid in a film ozonolysis reactor. Sample 1 was taken at 10 minutes, Sample 2 at 15 minutes, and Sample 3 at 20 minutes. Conversion was based on disappearance of starting material on GC FID as compared to an internal standard. Ratio of O.sub.3 Vegetable Fatty O.sub.3 Gas Mass Liquid Cooling Conversion of Acid to Conc. Flowrate Flow Flow Temp Starting Material Sample Nonanoic Acid (w/w) % L/min g/h kg/h C. (oleic/linoleic) % 1 3:1 5.1 150 672 4.2 15 95.5/98.1 2 3:1 5.1 150 672 4.2 15 94.0/97.6 3 3:1 5.1 150 672 4.2 15 93.7/97.3

[0126] In another instance, this reactor was used to convert a 25% solution of dihydromyrcenol in water to hydroxymelonal. The results of this run are shown in Table 4.

TABLE-US-00004 TABLE 4 Ozonolysis of dihydromyrcenol, i.e., hydroxycitronellene, in the film ozonolysis reactor to generate hydroxymelonal. Samples were taken every 5 minutes. Conversion was based on GC FID results. Conversion Liquid of Starting Dihydromyrcenol O.sub.3 % Gas flow O.sub.3 Mass Flow Cooling Material Sample to Water Ratio (w/w) (L/min) Flow (g/hr) (ml/min) Temp ( C.) (%) 1 3:1 7.8 80 555.8 80 5-15 99.8 2 3:1 7.8 80 555.8 80 5-15 99.5 3 3:1 7.8 80 555.8 80 5-15 98.5 4 3:1 7.8 80 555.8 80 5-15 97.2 5 3:1 7.8 80 555.8 80 5-15 98.3

[0127] Similar results were obtained for the conversion of -Ionone to generate cyclocitral.

INCORPORATION BY REFERENCE

[0128] The entire disclosure of each of the patent documents and scientific articles referred to herein is incorporated by reference for all purposes.

EQUIVALENTS

[0129] The disclosure can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting on the disclosure described herein. Scope of the disclosure is thus indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.