Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C17/00—Preparation of halogenated hydrocarbons
  • C07C17/25—Preparation of halogenated hydrocarbons by splitting-off hydrogen halides from halogenated hydrocarbons
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C17/00—Preparation of halogenated hydrocarbons
  • C07C17/35—Preparation of halogenated hydrocarbons by reactions not affecting the number of carbon or of halogen atoms in the reaction
  • C07C17/354—Preparation of halogenated hydrocarbons by reactions not affecting the number of carbon or of halogen atoms in the reaction by hydrogenation
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C17/00—Preparation of halogenated hydrocarbons
  • C07C17/38—Separation; Purification; Stabilisation; Use of additives
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C21/00—Acyclic unsaturated compounds containing halogen atoms
  • C07C21/02—Acyclic unsaturated compounds containing halogen atoms containing carbon-to-carbon double bonds
  • C07C21/18—Acyclic unsaturated compounds containing halogen atoms containing carbon-to-carbon double bonds containing fluorine
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2527/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
  • C07C2527/02—Sulfur, selenium or tellurium; Compounds thereof
  • C07C2527/053—Sulfates or other compounds comprising the anion (SnO3n+1)2-
  • C07C2527/054—Sulfuric acid or other acids with the formula H2Sn03n+1

Definitions

• Fluorinated olefins as a class, have many and varied uses, including as chemical intermediates and monomers.
• U.S. Patent No. 5,679,875 discloses methods for manufacturing 1 ,1 ,1 ,2,3- pentafluoropropene and 1 ,1 ,1 ,2,3-pentafluoropropane
• U.S. Patent No. 6,031 ,141 discloses a catalytic process using chromium-containing catalysts for the dehydrofluorination of hydrofluorocarbons to fluoroolefins
• 2006/0106263 discloses the production and purification of hydrofluoroolefin compounds; and WO98/33755 discloses catalytic process for the dehydrofluorination of hexafluoropropanes to pentafluoropropenes.
• the desired fluorinated olefins of the present invention comprise one or more C2 to C6 fluoroalkenes, preferably compounds having a formula as follows:
• X 1 is a C1 , C2, C3, C4, or C5 unsaturated, substituted or unsubstituted, alkyl radical, each R is independently Cl, F, Br, I or H, and z is 1 to 3.
• R is independently Cl, F, Br, I or H
• z is 1 to 3.
• Preferred processes of the present invention comprise reacting a fluorinated olefin starting material with a degree of halogen substitution of N+1 having substantially the same number of carbon atoms as the fluorinated olef ⁇ n(s) to be synthesized with a degree of halogen substitution of N.
• the fluorinated olefin starting material having a degree of fluorine substitution of N + 1 is exposed to reaction conditions effective to produce a reaction product containing one or more fluorinated alkanes having the same number of carbons atoms as the olefin.
• this olefin conversion step comprises a reaction that is sometimes referred to herein for convenience, but not necessarily by way of limitation, as a reduction or hydrogenation step.
• the fluorinated alkane is then preferably converted to a fluorinated olefin having a degree of fluorine substitution of N.
• this alkane conversion step comprises a reaction that is sometimes referred to herein for convenience, but not necessarily by way of limitation, as a dehydrohalogenation reaction or more particularly in certain embodiments as a dehydrofluorination or dehydrochlorination reaction.
• the present processes preferably comprise the steps of
• the reactant of formula (I) comprises a three carbon olefin of formula (IA) wherein z is 0, namely
• a saturated terminal carbon of the compounds of formulas (I) or (IA) is fully substituted with fluorine (for example, n on the saturated terminal carbon is 3 and each X on that carbon is F), and even more preferably n is 3 and each X in the compound is F.
• the fluorinated alkane produced by the conversion step has a degree of fluorine substitution of N+1.
• the converting step (a) wherein the olefin is converted to an alkane is carried out under conditions effective to provide a formula (I) conversion of at least about 40%, more preferably at least about 55%, and even more preferably at least about 70%. In certain preferred embodiments the conversion is at least about 90%, and more preferably about 99%. Further in certain preferred embodiments, the conversion of the compound of formula (I) to produce a compound of formula (II) is conducted under conditions effective to provide a formula (II) selectivity of at least about 60%, more preferably at least about 80%, and more preferably at least about 90%, and even more preferably about 100%.
• the converting step (b) wherein the alkane is converted to a fluorinated olefin having a degree of fluorination of N is carried out under conditions effective to provide a formula (II) conversion of at least about 40%, more preferably at least about 55%, and even more preferably at least about 70%. In certain preferred embodiments the conversion is at least about 90%, and more preferably about 95%. Further in certain preferred embodiments, the conversion of the compound of formula (II) to produce a compound of formula (III) is conducted under conditions effective to provide a formula (III) selectivity of at least about 60%, more preferably at least about 80%, and more preferably at least about 90%, and even more preferably about 98%.
• FIG. 1 is a schematic process flow diagram according to one embodiment of the present invention.
• FIG. 2 is a semi-schematic process flow diagram according to one embodiment of the hydrogenation step of the present invention.
• a feed stream 1 comprising at least one fluorinated olefin having a degree of halogen substitution, and preferably a degree of fluorine substitution, of N+1 is subjected to a first converting step 50.
• the converting step 50 preferably involves also a feed stream 2 comprising a reducing agent.
• the converting step 50 preferably includes providing one or more reaction vessels, at least one of which preferably contains a reduction or hydrogenation catalyst, and introducing streamsi and 2 into the vessel(s) under conditions effective to achieve the desired conversion.
• the streams 1 and 2 in the figure are shown for convenience as being separate streams, this is done for convenience and the present invention is not so limited.
• stream 1 and stream 2 might each comprise several separate streams, each of which is introduced into the vessel(s) at different times and/or at different locations.
• stream 1 and stream 2 might each comprise several separate streams, each of which is introduced into the vessel(s) at different times and/or at different locations.
• the preferred converting step 50 produces at least one reaction product stream 3 which contains a fluorinated alkane in accordance with the present invention.
• Stream 3 is used as a reactant in conversion step 51 , optionally stream 3 is further purified before fed to step 51 , wherein the fluorinated alkane in stream 3 is converted to a fluorinated olefin have a degree of halogen substitution, and in certain preferred embodiments fluorine substitution, of N in accordance with the present invention.
• the converting step 51 preferably includes providing one or more reaction vessels, at least one of which preferably contains a dehydrohalogenation catalyst and introducing at least stream 3 into the vessel(s) under conditions effective to produce the desired fluoroolefin.
• the conversion step 51 produces a reaction product which includes not only the desired fluoroolefin, but also HF.
• a separation step 52 in which at least a portion of the HF is separated from the stream to produce at least a first stream 6 relatively rich (in comparison to the feed stream 4) in the fluorinated olefin and at least a second stream relatively rich (in comparison to the feed stream 4) in HF.
• the reduction step may be conducted in batch operation, it is preferred that the reduction reaction is carried out as a substantially continuous operation.
• the reduction reaction may involve in certain embodiments a liquid phase reaction, it is contemplated that in preferred embodiments the reduction reaction comprises, and even more preferably consists of, at least two vapor phase reaction stages.
• reaction conversion and selectivity can be achieved at relatively high levels by the use of at least two reaction stages wherein the first stage of reaction is conducted under conditions effective to achieve a first, relatively low rate of conversion to produce a first stage reaction effluent, and at least a second stage of reaction which is fed by at least a portion of said first stage effluent and which is conducted under conditions effective to achieve a second rate of conversion higher than said first rate.
• reaction conditions are controlled in each of the first and second stages in order to achieve the desired conversion in accordance with the present invention.
• reaction conditions is intended to include the singular and means control of any one or more processing parameters which can be modified by the operator of the reaction to produce the conversion of the feed material in accordance with the teachings contained herein.
• conversion of the feed material may be controlled or regulated by controlling or regulating any one or more of the following: the temperature of the reaction, the flow rate of the reactants, the presence of diluent, the amount of catalyst present in the reaction vessel, the shape and size of the reaction vessel, the pressure of the reaction, and any one combinations of these and other process parameters which will be available and known to those skilled in the art in view of the disclosure contained herein.
• the step of controlling the conversion in the first stage of the hydrogenation reaction is achieved by judicious selection and control of the amount of catalyst present in the first stage of reaction relative to the feed rate of one or more of the reactants and/or by judicious selection and control of the reaction temperature, and preferably by judicious selection and control of both of these process parameters.
• the step of judiciously selecting the amount of catalyst to be used in the first stage of reaction includes the step of estimating the amount of catalyst theoretically needed to convert 100% of the feed material. Such an estimate can be obtained by any and all known methods for making such an estimate, which should be apparent to those skilled in the art in view of the teachings contained herein.
• the step of judiciously selecting the amount of catalyst may also involve conducting bench, pilot or similar studies to determine the amount of the particular catalyst being used which is needed to convert 100% of the feed material under the feed rate in other process parameters which have otherwise been chosen. Based upon this estimate, the preferred embodiments of the present invention then include the step of providing in the first stage of reaction an amount of catalyst that is substantially below the amount required for 100% conversion, and even more preferably is sufficiently low so as to result in a conversion of the feed olefin of from about 10% to about 60%, more preferably from about 10% to about 40%, and even more preferably from about 10% to 25%.
• step of judiciously choosing the amount of catalyst may further include running additional bench, pilot or other studies with the reduced amount of catalyst and adjusting the amount of catalyst accordingly. It is contemplated that all such studies and estimates can be achieved without undue experimentation in view of the teachings contained herein.
• the step of controlling conversion in the first reactor stage comprises feeding the olefin reactant into the first stage of reaction at a rate that is substantially above, and at least 60% about 90% above the productivity of the catalyst present in the first stage of reaction.
• Applicants have found, without being bound by or to any particular theory, that the use of such an excess of reactant in the first stage of reaction allows the feed materials to serve as a heat removal medium. Since the reduction or hydrogenation reaction of the present invention is generally exothermic, and usually substantially exothermic, the use of such excess feed material has the effect in preferred embodiments of maintaining the reactor temperature below that which would exist if an excess of feed material were not used, assuming all other process conditions were maintained the same.
• the step of maintaining a very low conversion of reactant in accordance with the present invention in a first stage of reaction has an advantageous affect on the selectivity of the reaction to the desired alkane.
• the amount of conversion which occurs in the first stage of reaction is controlled to be well below that which is desired for the overall reduction step
• applicants have found that an improved, higher percentage of the feed material is converted to the desired alkane in the first reaction stage (that is, improved selectivity is achieved) by controlling the conversion as described herein. More specifically, is preferred in many embodiments that the selectivity to the desired alkane in the first reaction stage is at least about 80%, more preferably at least about 90%, and even more preferably at least about 95%, and in many preferred embodiments about 97% or greater.
• the step of controlling the conversion in the first reaction stage further includes removing heat from the reaction by cooling at least a portion of the reaction mixture. It is contemplated that those skilled in the art will be able to devise without undue experimentation and many means and mechanisms for attaining such cooling in view of the teachings contained herein and all such means and mechanisms are with the scope of the present invention.
• At least a portion of the effluent from the first reaction stage is fed directly, or optionally after some further processing, to a second reaction stage in which the unreacted fluorinated olefin remaining in the effluent after the first reaction stage is converted to the fluorinated alkane in accordance with the present invention. More specifically is preferred that the second reaction stage or subsequent reaction stages if present, is operated under conditions effective to convert the fluorinated olefin contained in the feed stream to the second reactor stage at a conversion rate that is greater than, and preferably substantially greater than, the conversion percentage in the first reaction stage.
• the conversion percentage in the second reaction stage is from about 20% to about 99%, depending in large part upon the total number of reactant stages used to affect the overall conversion step.
• the conversion in the second reaction stage is preferably greater than 95%, and even more preferably about 100%.
• such a two-stage reaction may not be sufficient to produce the desired selectivity to the fluorinated alkane.
• the conversion step may comprise greater than two reaction stages, including in some embodiments as many 10 or more reaction stages.
• the fluorinated olefin conversion step of the present invention comprises about four reaction stages. Although it is understood that the particular parameters used in each reaction stage may vary widely within the scope of the present invention, depending upon many factors, including the desired fluorinated olefin to be produced, the available feedstock, and other specific processing constraints, the following Table provides preferred and more preferred ranges of certain process parameters applicable to certain preferred embodiments of the present invention (all numerical values in the table are understood to be preceded by the word "about.")
• Figure 2 For the purposes of illustration but not necessarily by way of limitation, one arrangement of multiple reaction stages in accordance with a preferred reduction step in accordance with the present invention is illustrated in Figure 2.
• the reduction step 50 may be conducted in a batch-wise or semi- continuous operation, it is preferred that the reduction step 50 is a continuous operation of the general type shown in Figure 2.
• a first stage reactor 5OA is provided with catalyst in an amount effective to provide a conversion of the fluorinated olefin contained in stream 1 of from about 10% to about 60% in accordance with the present invention.
• the first reaction stage of the present invention for example vessel 50A 1 is provided with a means for cooling the reaction mixture (not shown).
• the reaction vessel 5OA may be a jacketed reaction vessel in which the space between the vessel and the jacket contains a cooling medium to remove heat from the reactor.
• a cooling medium to remove heat from the reactor.
• other means for cooling the reaction mixture may be employed, such as the use of an internal cooling coil, the introduction of additional cooling diluent to the reaction mixture, and the like.
• the effluent 3A from the first reaction stage is preferably, but not necessarily, further cooled prior to its introduction into the second reaction stage, such as reaction vessel 5OB, for example by use of a heat exchanger 6OA.
• the heat exchanger 6OA, and/or one or more of the downstream heat exchangers 6OB and 6OC may be desirable for the heat exchanger 6OA, and/or one or more of the downstream heat exchangers 6OB and 6OC, to provide the capability of adding heat to the effluent prior to its introduction into the next reaction stage. This capability is desirable in certain embodiments because it is generally, although not exclusively, preferred that the level of conversion in each subsequent reaction stage is higher than in the immediately preceding prior stage.
• reaction stages can occur inside a single vessel, provided that means and mechanisms necessary to control conversion are provided.
• the type of catalyst(s) used for the hydrogenation step of the present invention in view of the teachings contained herein.
• one or more of the hydrogenation catalyst disclosed in US Patent 5, 679,875, which is incorporated herein by reference, maybe used for one or more of the reaction stages in accordance with the present invention.
• the catalyst preferably comprises palladium supported on carbon, such as a carbon mesh.
• certain embodiments of the present methods comprise bringing a fluorinated olefin in accordance with formula I and a hydrogenation agent, such as H 2 , into contact with a first amount of catalyst in a first reaction stage to produce a reaction stream comprising hydrofluorocarbon(s), unreacted fluorinated olefin and hydrogen; contacting at least a portion of this first effluent stream with a second amount of catalyst in a second stage of reaction to produce a hydrofluorocarbon, wherein the second amount of catalyst is greater than the first amount of catalyst and wherein conversion to the fluorinated olefin is higher in the second stage of reaction
• at least a portion of the effluent from the second and/or any subsequent stages of reaction is then contacted with a catalyst for dehydrofluorination to produce a product stream comprising the desired fluorinated propene and HF.
• the dehydrofluorination step is followed by a preferred separation step comprising feeding at least a portion of the product stream through an extraction operation using an extraction agent, such as a stream of sulfuric acid, to extract HF from the product stream.
• an extraction agent such as a stream of sulfuric acid
• the dehydrohalogenation reaction step may be preformed using a wide variety of process parameters and process conditions in view of the overall teachings contained herein, such as for example it is contemplated that the dehydrohalogenation step may comprise, in certain nonpreferred embodiments, a liquid phase reaction.
• this reaction step comprise a gas phase reaction, preferably in the presence of catalyst, preferably a metal catalyst, and even more preferably one or more transition metal-based catalysts (including in certain preferred embodiments transition metal halide catalysts), such as FeCI 3 , chromiumoxyfluoride, Ni (including Ni mesh), NiCI 2 , CrF 3 , and mixtures thereof, supported or in bulk.
• transition metal-based catalysts including in certain preferred embodiments transition metal halide catalysts
• Other catalysts include carbon-supported catalysts, antimony-based catalysts (such as SbCI 5 ), aluminum-based catalyst (such as AIF 3 , AI 2 O 3 , and fluorinated AI 2 O 3 ).
• catalysts may be used depending on the requirements of particular embodiments, including for example palladium-based catalyst, platinum-based catalysts, rhodium-based catalysts and ruthenium-based catalysts. Of course, two or more any of these catalysts, or other catalysts not named here, may be used in combination.
• the catalysts are fluorinated.
• fluoridation of the catalysts comprises exposing the catalyst to a stream of HF at about reaction temperature and pressure.
• the gas phase dehydrohalogenation reaction may be conducted, for example, by introducing a gaseous form of a compound of formula (II) into a suitable reaction vessel or reactor.
• the vessel is comprised of materials which are resistant to corrosion as Hastelloy, Inconel, Monel and/or fluoropolymers linings.
• the vessel contains catalyst, for example a fixed or fluid catalyst bed, packed with a suitable dehydrohalogenation catalyst, with suitable means to heat the reaction mixture to the desired reaction temperature.
• reaction temperature for the dehydrohalogentation step is from about 150 0 C to about 600 0 C, preferably about from 200°C to about 550 0 C, and even more preferably from about 220 0 C to about 450 0 C.
• reaction pressures may be used, depending again on relevant factors such as the specific catalyst being used and the most desired reaction product.
• the reaction pressure can be, for example, superatmospheric, atmospheric or under vacuum.
• an inert diluent gas and/or an oxidizing agent such as nitrogen, oxygen and mixture of nitrogen and oxygen, may be used in combination with the compound of formula (II) as a feed to the deydrohalogenation step.
• an oxidizing agent such as nitrogen, oxygen and mixture of nitrogen and oxygen
• the feed streamed comprise formula (II) compound in an amount of from about 5% to greater than 95% by weight based on the combined weight of diluent and formula (II) compound.
• the amount of catalyst used will vary depending on the particular parameters present in each embodiment.
• the contact time which is expressed as the ratio of the volume of the catalyst (ml) to the total feed flow (ml/sec) is from about 0.1 seconds to about 1000 seconds, and preferably from about 2 seconds to about 120 seconds.
• One preferred dehydrohalogenation reaction comprises a dehydrofluorination reaction.
• the desired product of formula (III) is HFO-1234yf
• the compound of formula (II) comprises 1 ,1 ,1 ,2,3 pentafluoropropane.
• the catalyst it is preferred to use as the catalyst a fluorinated chromium oxide catalyst, and aluminum fluoride catalyst, a ferric fluoride catalyst, and a mixture of catalysts comprising magnesium fluoride and aluminum fluoride.
• nickel-based catalyst, a carbon based catalyst, or a combination of these may be used.
• reaction temperatures are preferably from about 200° C to about 550° C, more preferably from about 220 0 C to about 450 0 C, and even more preferably from about 250° C to about 375° C.
• the reaction temperature is preferably from about 200° C to about 600° C, and even more preferably from about 300° C to about 500° C.
• the contact time is from about 0.1 sec to about 1000 seconds, and preferably from about 2 sec to about 120 seconds.
• the conversion is at least about 50%, more preferably at least about 65%, and even more preferably at least about 90%.
• the selectivity to HFO-1234yf is at least about 70%, more preferably at least about 80% and more preferably at least about 90%.
• Another preferred dehydrohalogenation reaction comprises a dehydrochlorination reaction.
• the compound of formula (II) comprises 1 ,1 ,1 ,3-tetrafluoro-3-chloropropane.
• a nickel-based catalyst at a reaction temperature of from about 200 0 C to about 550 0 C, more preferably from about 25O 0 C to about 500 0 C, and even more preferably from about 300 to 400°C.
• an activated carbon catalyst at a reaction temperature of from about 250 0 C to about 550 0 C, more preferably from about 300 0 C to about 550°C, and even more preferably about 400°C.
• a catalyst comprising 3% palladium on carbon at a reaction temperature of from about 200 0 C to about 500 0 C, more preferably from about 225°C to about 475°C, and even more preferably about 400 0 C.
• a catalyst comprising 2% nickel on carbon at a reaction temperature of from about 400 0 C to about 500 0 C, more preferably from about 400 0 C to about 500 0 C, and even more preferably about 450 0 C.
• a catalyst comprising chromiumoxyfluoride at a reaction temperature of from about 200°C to about 500°C, more preferably from about 250°C to about 450°C, and even more preferably about 300°C.
• an oxidizing gas such as nitrogen and/or oxygen or mixture of nitrogen and oxygen, in a formula (ll):inert (or oxygen) volume ratio of from about 100:0.5 to about 100:75, with a ratio of about 100:2 being even more preferred.
• the contact time is from about 0.1 to about 1000 sec, and preferably from about 3 to about 120 sec.
• the conversion is at least about 50%, more preferably at least about 65%, and even more preferably at least about 90%.
• the selectivity to HFO-1234ze, and even more preferably to trans-HFO-1234ze is at least about 70%, more preferably at least about 80% and more preferably at least about 90%.
• the direction of flow of the gaseous components in the dehydrohalogenation step is not critical, but in certain preferred embodiments the process flow is in the down direction through a bed of the catalyst.
• the dehydrohalogenation catalyst is dried, pre-treated and activated. It may also be advantageous in certain embodiments to periodically regenerate the catalyst after prolonged use while in place in the reactor. Pre-treatment may include heating the catalyst to about 250°C to about 430 0 C with a stream of nitrogen or other inert gas. The catalyst may then be activated by treating it with a stream of HF diluted with a large excess of nitrogen gas in order to obtain high catalyst activity. Regeneration of the catalyst may be accomplished by any means known in the art such as, for example, by passing air or oxygen over the catalyst at temperatures of from about 100 0 C to about 400 0 C for from about 1 hour to about 3 days depending on the size of the reactor.
• the dehydrofluorination reaction in addition to producing a fluorinated olefine, preferably fluorinated propene, also produces HF.
• HF is removed from the dehydrofluorination product stream by countercurrent extraction with sulfuric acid.
• the product stream containing the HF is fed in one direction to a column, preferably a packed column.
• a stream of sulfuric acid is fed, preferably countercurrently, to the same packed column.
• Appropriate column packing is readily determinable by one skilled in the art.
• Suitable column packing materials include those made of non- metallic polymeric materials, metals and alloys that are not reactive in the presence of HF or sulfuric acid, such as PTFE, PFA, hastelloy, monel, and noble metals.
• the stream of sulfuric acid contains from about 50% to about 100% sulfuric acid, and more preferably about 80% sulfuric acid.
• the stream of sulfuric acid is continuously fed to the top of the packed column at a feed rate of about twice the feed rate of the product stream, which in preferred embodiments is fed from the bottom of the packed column and moves in an generally upward direction substantially counter currently to the substantially down flowing stream containing the sulfuric acid.
• a stream comprising sulfuric acid and HF is removed from the bottom of the column and preferably at least a portion of the stream, and most preferably substantially all of the stream, is recycled back to the extraction tower.
• the recycling step is repeated preferably until the HF concentration in the column bottom is greater than about 10 % by weight HF.
• the sulfuric acid and HF mixture containing greater than about 10% by weight HF is charged into a separate vessel. The mixture is then heated to a temperature sufficient to vaporize and flash off HF, which is collected.
• Another embodiment includes purifying the HF collected from the flash distillation.
• the HF or HCI generated from the dehydrohalogenation reaction is scrubbed from the product stream using water or caustic solutions.
• Comparative Example C-1 Reaction of hexafluoropropene and hydrogen A small jacketed, single stage reactor with an outer jacket connected to a circulating cooling bath of 31 °C is charged with 0.2g of 1% Pd/C (4-6 mesh) mixed with nichrome mesh of a similar size to give a total catalyst bed volume of 1 cc. Prior to the introduction of hydrogen and hexafluoropropene gases, the bed temperature is initially about 21 0 C. However, when hydrogen (0.37 mol/h) and hexafluoropropene (0.26 mol/h) are introduced, the bed temperature rises to nearly 70 0 C in about 1 minute.
• Comparative Example C-2 Reaction of hexafluoropropene and hydrogen The same small, jacketed single stage reactor as in Example C-1 is charged with a small amount of 1% Pd on carbon. Hydrogen and hexafluoropropene are premixed and then introduced into the reactor. The temperature of the catalyst bed is allowed to stabilize at 69 0 C. Exit gases are analyzed to determine conversion and selectivity for CF 3 CHFCF 2 H. The average conversion is 93.2% while the average selectivity is 95.7%.
• Comparative Example C-3 Reaction of hexafluoropropene and hydrogen Comparative Example C-2 is repeated using the same single stage reactor, except the temperature of the circulating fluid is reduced to 21 0 C. The temperature of the bed stabilizes at 61.5 0 C. Under these conditions, the conversion is reduced to 88.6% while the selectivity increases to 97.0%.
• Examples 1 and 2 Multi-Stage Reduction Reactions
• the reactors used in the following examples are multi-stage reactors constructed from sections of 1.5" schedule 40, 316 SS pipe.
• the amount of catalyst used to charge each reaction stage is calculated by first estimating the productivity of the catalyst (grams of feed converted per gram of catalyst per hour). The productivity is estimated from scoping studies using a small reactor. Next, the desired production rate is set at about 10 Ib per hour, allowing the total amount of catalyst needed for 100% conversion to be estimated. Using this information, an estimated amount of catalyst needed to convert 10-15% of the olefin in the first reactor is calculated.
• Catalyst loading in the following examples is as follows: Section 1 (1.5" x 1 foot): 10g of catalyst (1 wt % Pd on 4-8 mesh carbon) with the remainder filled with VA SS protruded packing, catalyst equally distributed throughout.
• Section 2 (1.5" x 2 foot): 25 g catalyst distributed as in Section 1.
• Section 3 (1.5" x 3 foot): 73.4 g catalyst with 1200cc of packing distributed as in Section 1.
• Example 1 Multi-stage reduction of hexafluoropropene
• Hexafluoropropene is introduced to the multi-stage reactor and reduced continuously over a period of 58 hours during which the average feed rate is 14.5 Ib/h (or about 16.4 L per minute). The average hydrogen feed rate is 25 L per minute. Samples are taken at various points along the series of reactors to follow the percent conversion and selectivity. After the second reaction stage, the conversion is about 40%; after the fourth reaction stage, the conversion is 99.5% with selectivity for CF 3 CHFCF 2 H of 99%. The temperature of the gases immediately exiting the reaction stages is 66 0 C for the first stage, 104 0 C for the second stage, 173 0 C for the third stage, and 100C for the fourth stage. The maximum temperature in any reaction stage is about 23O 0 C. The first bath is maintained at 55 0 C while the second bath is maintained at 111 0 C.
• Example 2 Multi-stage reduction of 1 ,2,3,3,3-Pentafluoropropene-1
• 1 ,2,3,3,3-Pentafiuoropropene-1 is hydrogenated using the same reactor as in Example 1 using a feed rate of 14.6 Ib/h for a total of 64 hours.
• the average hydrogen feed rate is 25 liters per minute.
• Samples are taken at various points along the series of reactors to follow the percent conversion and selectivity. After the second reactor, the conversion is about 54%. While after the fourth reactor, the conversion is 100% with the selectivity for CF 3 CHFCH 2 F of 98%.
• the temperature of the gases immediately exiting the reactors is 99 0 C for the first reactor, 95 0 C for the second reactor, 173 0 C for the third reactor, and 104 0 C for the fourth reactor.
• the maximum temperature in any reactor is about 24O 0 C.
• the first bath is maintained at 59 0 C
• the second bath is maintained at 116 0 C.
• the following dehydrofluorination reactions are performed in a cylindrical Monel reactor. Heating is provided by inserting the reactor into an electric furnace. Process temperatures are recorded using a multi-point thermocouple placed inside the reactor and within the catalyst bed. The hydrofluorocarbon is fed into the bottom of the vertically mounted reactor and vaporized before reaching the catalyst bed. Effluent gases are passed through a gas sampling valve to monitor the progress of the reaction using GC analysis.
• Example 3 Dehydrofluorination of 1,1, 1,2,3, 3-hexafluoropropane (HFC- 236ea) over fluorinated Cr 2 O 3 catalyst
• HFC-236ea is passed over 20cc of fluorinated Cr 2 O 3 at a rate of 12 g/h at a temperature range of from 250 to 35O 0 C at 1atm.
• Table Ex3 below, as the reaction temperature increases from 250 to 35O 0 C, the conversion of HFC-236ea is increased from 65.2% to 96.0%, while the selectivity to 1225yeZ is slightly decreased from 97.0% to 94.6%.
• 1225 isomers appear to be the only products.
• the catalysts for use in this example include AIF 3 , FeF 3 , and 10%MgF 2 - 90%AIF 3 .
• HFC-236ea is passed over 20cc of each catalyst at a rate of 12 g/h at 35O 0 C at 1 atm.
• both AIF 3 and 10%MgF 2 -90%AIF 3 provide high activity (> 95% HFC-236ea conversion) for dehydrofluorination of HFC- 236ea, while FeF 3 exhibits much lower activity ( ⁇ 60% HFC-236ea conversion).
• the selectivity to 1225yeZ over the AIF 3 and 10%MgF 2 -90%AIF 3 catalysts is about 92% at 35O 0 C.
• the catalysts for use in this example include three activated carbon supported metal catalysts, specifically, 0.5 wt% Fe/AC, 0.5 wt% Ni/AC, and 5.0 wt% Co/AC.
• HFC-236ea is passed over 20cc of each catalyst at a rate of 12 g/h at 350 0 C at 1 atm.
• Table Ex5 among the activated carbon supported non-precious metal catalysts, iron exhibits the highest activity.
• the 0.5 wt% Fe/AC catalyst provides a 1225yeZ selectivity of about 90% and an HFC-236ea conversion of about 80%.
• Example 6 Dehydrofluorination of CF 3 CHFCH 2 F (HFC-245eb) over fluorinated alumina and chromium oxide catalysts
• the catalysts for use in this example include two fluorinated metal oxide catalysts, specifically, fluorinated AI 2 O 3 and Cr 2 ⁇ 3 .
• HFC-245eb is passed over 20cc of each catalyst at a rate of 12 g/h at 300 0 C at 1 atm.
• 2,3,3,3-Tetrafluoropropene (HFC- 1234yf) is generated as a reaction product.
• HFC- 1234yf 2,3,3,3-Tetrafluoropropene
• both fluorinated metal oxide catalysts provide an HFC-245eb conversion above 95% and 1234yf selectivity above 96%.
• the catalysts for use in this example include three metal fluoride catalysts, specifically, MgF 2 , AIF 3 , and CeF 4 .
• HFC-245eb is passed over 20cc of each catalyst at a rate of 12 g/h at 350 0 C at 1 atm.
• AIF 3 exhibits the highest activity with high selectivity.
• This catalyst provides an HFC-245eb conversion of about 97% and a 1234yf selectivity of about 97%.
• Example 8 Dehydrofluorination of HFC-245eb over activated carbon and activated carbon-supported Pd catalysts
• the catalysts for use in this example include activated carbon and activated carbon-supported Pd catalysts.
• HFC-245eb is passed over 20cc of each catalyst at a rate of 12 g/h at 1 atm.
• the activated carbon shows very low activity for converting 245eb into 1234yf even at 525 0 C 1 while the 0.5 wt% activated carbon-supported Pd catalyst provides a 245eb conversion of about 92% and a 1234yf selectivity of about 98% at 450 0 C.
• Example 3 (at 35O 0 C), which contains 4.0 wt% HFC- 236ea, 78.9 wt% 1225yeZ, 3.3 wt% 1225yeE, 12.6 wt% HF, and 1.2% unknown is fed to the bottom of a packed column at a feed rate of about 2.9 lbs per hour for about 4 hours.
• a stream of about 80 wt% sulfuric acid (80/20 H 2 SO 4 /H 2 O) is fed continuously to the top of the same packed column at a feed rate of about 5.6 lbs per hour during the same time frame.
• a gaseous stream exiting the top of the column includes a majority of the organics with less than 0.5 wt% HF.
• the concentration of HF in the sulfuric acid in the column bottoms is about 5.8 wt%.
• the column bottoms containing sulfuric acid and HF are recycled back to the extraction tower until the HF concentration is greater than 10 wt% HF. Subsequently, the sulfuric acid and HF mixture is charged into a 2 gallon Teflon ® vessel. The mixture is heated to about 14O 0 C to vaporize and flash off HF, which is collected. The collected HF product contains 6000 ppm water and 217 ppm sulfur. The sulfuric acid contains about 500 ppm of total organic carbon. The HF collected from flash distillation is distilled in a distillation column, and anhydrous HF is recovered. The recovered anhydrous HF contains about 37 ppm of sulfur impurities.
• Example 10 Conversion of 1-bromo, 2,3,3,3-tetrafluoropropene to 2,3,3,3-tetrafluoropropene
• 1-bromo, 2,3,3,3-tetrafluoropropene is introduced to the multi-stage reactor of Example 1 and reduced continuously. Samples are taken at various points along the series of reactors to follow the percent conversion and selectivity. After the second reaction stage, the conversion is about 40%; after the fourth reaction stage, the conversion is 99.5% with selectivity for CF 3 CHFCH 2 Br of 99%.
• the alkane product produced in the multistage reactor are introduced into a catalytic reactor where it is dehydrochlorinated to 2,3,3,3-tetrafluoropropene at a high level of conversion and selectivity.

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