Thermal mitigation in CF3CCL3 (CFC-113a) coupling reactions

Abstract

The present invention relates to thermal mitigation of methods of coupling CFC compounds having CCl3 end groups in the presence of hydrogen.

Description

TECHNICAL FIELD

[0001] The present invention relates to mitigating heat during exothermic reactions involving trifluorotrichloroethane. BACKGROUND

[0002] Hydrofluoroolefins (HFOs) having low ozone depletion potential (ODP) and low global warming potential (GWP) have replaced saturated CFCs (chlorofluorocarbons) and HCFCs (hydrochlorofluorocarbons) in a variety of applications for several years, and are replacing hydrofluorocarbons that tend to have high GWP values. Thus, low ODP and GWP materials for use as refrigerants, solvents, foam blowing agents, cleaning agents, aerosol propellants, dielectrics, fire extinguishing agents, and power cycle working fluids continue to receive attention. Although processes for making olefin compounds such as 1,1,1,4,4,4 hexafluoro-2-butene (HFO-1336mzz) have been reported, there remains a need for process improvements to facilitate scaling up these processes for commercial production.

[0003] The preparation of olefinic refrigerants, including but not limited to 1,1,1,4,4,4 hexafluoro-2-butene (HFO-1336mzz) as well as mixtures of Z- and E-isomers, has been described, for example, in U.S. Patent Publication No. 20190248719, the disclosure of which is incorporated herein by reference. In addition, any Z-1,1,1,4,4,4 hexafluoro-2-butene produced can be isomerized to E-1,1,1,4,4,4 hexafluoro-2-butene, as disclosed, for example, in U.S. Patent No. 10,479,745, the disclosure of which is incorporated herein by reference in its entirety.

[0004] As disclosed in U.S. Patent Publication No. 20190248719, HFO-1336mzz can be prepared from trifluorotrichloroethane (CFC-CF3CCl3) by a series of reactions by contacting 1,1,1-trifluorotrichloroethane with hydrogen gas in the presence of a catalyst comprising ruthenium to produce an intermediate E / Z-CFO-1316mxx (E / Z-CF3CCl=CCICF3) comprising 1316mxx. The coupling reaction of CFC-113a is typically conducted at temperatures of 150 °C to 300 °C. Temperature control is typically provided by a recirculating hot oil system.

[0005] The exotherm of trifluorotrichloroethane coupling using conventional hot oil recirculation is difficult and often uncontrollable, resulting in a runaway reaction. Problems associated with a runaway reaction often result in the destruction of the catalyst and reactor components. Applicants have unexpectedly discovered that modulating and providing a uniform temperature in the commercial process reaction zone, and keeping the reaction gain at a level below 2, successfully mitigates heat, avoids / reduces hot spot formation, and prevents a runaway reaction that can have a high exothermic reaction. SUMMARY

[0006] The present invention relates to a method of mitigating heat during the coupling of 1,1,1-trichloro-2,2,2-trifluoroethane (HCFC-113a).

[0007] The present invention relates to a method of mitigating heat during the coupling of 1,1,1-trichloro-2,2,2-trifluoroethane (HCFC-113a) by conducting the reaction in the presence of a diluent.

[0008] The present invention relates to a method comprising passing a reactor feed of 1,1,1-trichloro-2,2,2-trifluoroethane (HCFC-113a) through one or more catalyst-filled tubes, contacting the one or more tubes with a heat exchange liquid, monitoring for hot spot formation within the one or more tubes, monitoring for temperature changes in the heat exchange liquid, calculating a steady state measurement of reactor gain in the tubes defined by the equation , and adding a diluent to the reactor feed.

[0009] The present invention relates to a method comprising passing a reactor feed of 1,1,1-trichloro-2,2,2-trifluoroethane (HCFC-113a) and a diluent through one or more catalyst-filled tubes, contacting the one or more tubes with a heat exchange liquid, monitoring for hot spot formation within the one or more tubes, monitoring for temperature changes in the heat exchange liquid, maintaining a steady state measurement of reactor gain in the tubes defined by the equation by the amount of diluent in the reactor feed.

[0010] The embodiments disclosed herein relate to a method of passing a CFC having a CCI3 end group (including but not limited to HCFC-113a) through one or more catalyst-filled tubes suitable for an exothermic coupling reaction in indirect exchange relationship with a heat exchange medium (including but not limited to an oil such as Dowtherm). The present method also relates to assessing hot spot formation that can not be detectable by placing thermocouples along the length of each tube to monitor for hot spots, exchanging the heat generated by the coupling reaction within each of the tubes, and using the thermocouples to determine the presence of a hot spot. In contrast, Applicants have developed a method of determining how hot spots vary with changes in inlet temperature. This can be assessed by modeling, where a continuous case is run with an increase in inlet temperature, and then the change in predicted hot spot temperature is observed. There is a risk of "missing" a hot spot relying solely on fixed sensor locations in the catalyst bed. The system is operated in response to changes in hot spot temperature, and the reactor gain is maintained at a value of , where reactor gain (G) is defined as , where T = temperature, change in hot spot temperature, and Changes in oil temperature at the inlet should avoid the consequences of not doing so.

[0011] In one embodiment disclosed herein, a diluent is added to the reaction zone to mitigate heat.

[0012] In another embodiment disclosed herein, an inert diluent is added to the reaction medium in the reaction zone to mitigate heat.

[0013] In certain embodiments, coupling CFC-113a in the presence of hydrogen is carried out in the presence of R-143a, R-123, R-134a and CFC 113a, wherein the reactant ratio of H2:113a (H2:organics ratio) is between 1-5:1, preferably 2-4:1, most preferably 3:1.

[0014] In certain embodiments, coupling CFC-113a in the presence of hydrogen is carried out in the presence of CFC 113a diluent, with a H2:113a ratio of 3:3.5-6.

[0015] In certain embodiments, coupling CFC-113a in the presence of hydrogen is carried out in the presence of R-143a, R-123, R-134a diluent, wherein the reactant ratio of H2:hot diluent is between 1-5:1, preferably 1-2:1, most preferably 1:1.5 or 1:1.

[0016] In another embodiment disclosed herein, an inert diluent is added to the reaction medium in the reaction zone in large scale (e.g. commercial scale) to mitigate heat.

[0017] In certain embodiments disclosed herein, an inert diluent that is inert under reaction conditions is added to mitigate heat in an exothermic reaction at a temperature between 50°C-300°C.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description is for describing particular embodiments only and is not intended to be limiting thereof. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the application, suitable methods and materials are described below. In addition, the materials, methods, and examples are illustrative only and are not intended to be limiting. DETAILED DESCRIPTION

[0019] The foregoing summary and the following detailed description are exemplary and explanatory only and are not intended to be limiting of the application as claimed. Other features and advantages of any one or more embodiments will become apparent from the following detailed description, from the drawings and from the claims.

[0020] The present invention relates to thermal mitigation of exothermic reactions involving perhalogenated compounds by using HFC and HCFC diluents that are generally inert under the reaction conditions, including temperatures between at least 50°C - 300°C.

[0021] Before addressing the details of the embodiments described herein, certain terms are defined or clarified as follows.

[0022] As used herein, the term "hydro(halo)alkane" means a molecule containing hydrogen, carbon, and optionally fluorine and / or chlorine and / or bromine and / or iodine and no carbon-carbon double bonds (halogen - fluorine, chlorine, bromine, iodine). Examples are described throughout this specification. The term hydro(halo)alkane includes both alkanes and halo-substituted alkanes.

[0023] The term "coupling" means an addition reaction in which two molecules of the same compound react with each other, also known as a conjugation reaction.

[0024] As disclosed herein, coupling reactions of CFCs and HCFCs can be conducted at temperatures between 50°C and 300°C in reactors provided with thermal control, including the use of suitable diluents. Many reactor configurations are possible and can be operated in batch, semi-batch, or continuous mode. Reactors can be provided with equipment to increase contact between fluids and can similarly be operated in batch, semi-batch, and continuous mode. In addition to the reactors disclosed herein, preheaters and vaporizers, heat exchangers, feed and effluent lines, units related to mass transfer, contact vessels (pre-mixers), distillation columns, and valves related to the reactors, heat exchangers, vessels, columns, and units used in the processes of the various embodiments disclosed herein should be constructed of corrosion-resistant materials.

[0025] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but can include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

[0026] The transitional phrase "consisting of" excludes any element, step, or ingredient not specified. If there is any conflict between a definition in the specification and a definition in the claims, the claim definition prevails. The transitional phrase "consisting essentially of" is used to define compositions, methods, features, components, or elements that include additional materials, steps, features, components, or elements that do not materially affect the basic and novel characteristics of the claimed invention, especially the mode of action in any of the methods of the invention. The term "consisting essentially of" is intermediate in meaning between "comprising" and "consisting of."

[0027] The transitional phrase "consisting essentially of" is used to define compositions, methods, features, components, or elements that include additional materials, steps, features, components, or elements that do not materially affect the basic and novel characteristics of the claimed invention, especially the mode of action in any of the methods of the invention. The term "consisting essentially of" is intermediate in meaning between "comprising" and "consisting of."

[0028] In cases where Applicants have defined the application or portions thereof with the open term "comprising", it should be readily understood that unless otherwise specified the description should be interpreted to allow that the steps, features or components described with the term can also be present in the application, and that not every outlet of the application requires the exclusion of a component, step, feature, integers, or group thereof.

[0029] Also, the use of "a" or "an" is employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the application. This description should be read to include one, or at least one and the singular also includes the plural, unless it is obvious that it is meant otherwise.

[0030] As used herein, the term "about" is intended to account for variations in the experimental error (e.g., plus or minus approximately 10% of the indicated value, ±1%, ±2%, ±3,... ±10%). Unless otherwise clear from context, all measurements reported herein are understood to be modified by the term "about," whether or not the term is expressly used.

[0031] When a range, preferably a range or a list of preferred upper and / or lower values is given for a molecular weight, equivalent, concentration, or other value or parameter, it is understood that all ranges formed from any pair of an upper or preferred value and a lower or preferred value are expressly disclosed, whether the range is explicitly disclosed. Whenever a numerical range is given, it is intended to include all values from the lower to the upper bound, including the bounds themselves, and all integers and fractions within the range, unless otherwise indicated.

[0032] As used herein, the term "compound" refers to all stereoisomers, geometric isomers, tautomers, and isotopes of the described structure or chemical. Unless otherwise specified, a compound identified herein by name or structure is intended to include other tautomeric forms, as appropriate.

[0033] As used herein, the term "catalyst" refers to a substance that speeds up a chemical reaction but is not consumed by the reaction; thus it can be recovered at the end of the reaction without undergoing a chemical change.

[0034] As used herein, a run-away reaction means a thermally unstable reaction system that exhibits an uncontrolled reaction acceleration rate resulting in rapid increases in temperature and pressure.

[0035] To mitigate the heat involved in the commercial production of HCFO-1316 involving perhalogenated compounds, Applicants have unexpectedly discovered that the addition of HFC and HCFC diluents that are generally inert at temperatures between 50°C - 300°C and pressures up to 400 psig, achieves uniform temperature and control, reduces hot spot formation, and as measured by the reactor gain defined by the equation Steady state measurements of the reactor gain remain below a value of 2.

[0036] Applicants have unexpectedly discovered that HFCs such as HFC-143a, HCFC-123, HFC-134a, and CFC 113a have the benefit of being inert under the reaction conditions CFC-113a conjugation conditions (e.g., temperatures between 50°C - 300°C and pressures up to 400 psig from atmospheric pressure). HCFC-123, HFC-134a, and CFC 113a also have the advantage of being non-flammable. Furthermore, although HFC-143a and HCFC-123 are byproducts of the conjugation reaction between CFC-113a, it is beneficial to use them as thermal diluents rather than disposing of them as waste.

[0037] Quantification of the heat mitigation using thermal diluents has been demonstrated by modeling. Using Aspen Plus ® Process simulator to develop reactor models. The process assumptions for these examples involve using a typical process recycle composition, reaction conditions run with a series of thermal diluents at a 3: 1 H2: 113a reactant ratio and a 2.5: 1 ratio. Reactor temperature control was achieved using co-current heat transfer oil, and the oil inlet temperature was adjusted to achieve about 60% conversion of 113a to product 1316mxx (Z / E). All runs were at equal total molar flow rates, so all cases represent similar reactor space times.

[0038] The use of these thermal diluents was evaluated using two performance metrics. First, reactor hotspots were assessed by modeling to avoid missing hotspots detected by thermocouples, and a second reactor "gain" was calculated. "Gain" is a steady-state measurement of how well the reactor responds to small oil temperature disturbances. It is defined as the change in hotspot temperature relative to the change in oil temperature:

[0039]

[0040] Therefore, the gain is determined to be a function of the change in reactor oil temperature in order to calculate... .

[0041] If the gain exceeds a value of 2, the reactor may become overly sensitive to temperature disturbances and could lead to a runaway reaction. Hot spot temperatures are measured using thermocouples placed along the length of the catalyst-filled reactor tube. These metrics are evaluated for two catalyst activity levels: medium-range and low-range, where the catalyst comprises Ru, Pt, Pd, or Rh on a support, which can be carbon, washed carbon, SiC, CaF2, or alumina. The catalyst concentration ranges from 0.1% to 5%. The catalyst is activated by flowing H2 at temperatures ranging from 100°C to 30°C for 2 to 10 hours.

[0042] Some embodiments disclosed herein relate to a method of coupling CFCs or HCFCs by passing CFCs or HFCs (including, but not limited to, CFC-113a (RCCl3, where R can be a straight-chain or branched C2-C4 fluoroalkyl, fluorochloroalkyl, hydrofluoroalkyl, or hydrochlorofluoroalkyl, e.g., R = C2F5, C3F7, C4F9, HCF2CF2, CF3CHF, HCF2C2F4, HCF2C3F6)) through one or more tubes packed with catalyst, the catalyst being suitable for exothermic coupling reactions with an indirect heat exchange medium (including, but not limited to, oils, such as Dowtherm). The coupling reaction is carried out in a catalyst-filled tube, wherein the number of tubes is... indivual, The method involves one, up to 10, 20, 30, or 40 or more, and is configured as a shell-and-tube reactor, wherein a heat exchange fluid enters the shell side of the reactor to cool the outer surface of the catalyst-filled tubes. The method also involves arranging thermocouples along the length of each tube to monitor hot spots, exothermic reactions generated within each tube, and using the thermocouples to determine the presence of hot spots, detect changes in the temperature of the hot spots and the heat exchange fluid, and pass a diluent through the tubes to maintain reaction gain within the reaction zone defined by the tubes. The reaction gain (G) is defined as Where T = temperature, Changes in hotspot temperature, and Changes in oil inlet temperature.

[0043] In one embodiment disclosed herein, a diluent is added to the reaction zone to mitigate heat.

[0044] In another embodiment disclosed herein, an inert diluent is added to the reaction medium in the reaction zone to mitigate heat.

[0045] In certain embodiments, coupling CFC-113a in the presence of hydrogen is carried out in the presence of R-143a, R-123, R-134a, and CFC 113a, wherein the reactant ratio of H2:113a (H2:organics ratio) is between 1-5: 1, preferably 2-4: 1, most preferably 3: 1.

[0046] Simulated experiments with and without diluents were carried out, and the results for the medium range catalyst activity cases are shown in Table 1, and the results for the low range catalyst activity cases are shown in Table 2.

[0047]

[0048]

[0049] In both catalyst states, the cases with no hot diluent or N2 had high predicted gains and hot spots, indicating unstable reactor operation. In contrast, when either the HFC or the reactant 113a was used as a hot diluent, the hot spots were moderated and the gains were significantly reduced. This moderating effect increased with increasing fluid heat capacity.

[0050] CLAIM implementation embodiments (1)-(17)

[0051] (1) A method comprising:

[0052] a. coupling a CFC or HCFC terminated with a CCI3 group in the presence of hydrogen and a catalyst in a reaction zone,

[0053] b. monitoring the temperature at a plurality of spaced locations in the reaction zone to detect hot spots, and

[0054] c. adding a diluent to the reaction zone to reduce hot spot formation.

[0055] (2) The method of claim embodiment 1, wherein the CFC or HCFC comprises coupling 1,1,1-trichloro-2,2,2-trifluoroethane (HCFC-113a) to form a product mixture comprising E / Z-CFO-1316mxx (E / Z-CF3CCI=CCICF3).

[0056] (3) The method of any of claim embodiments 1 or 2, wherein the diluent comprises one of 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123), 1,1,1,2-tetrafluoroethane (HFC- 134a), 1 1,1,1-trifluoroethane (HFC-143a), or an excess of CFC-113a.

[0057] (4) The method of any of claim embodiments 1 to 3, wherein the coupling is conducted at a H2: 113a ratio between 1-5: 1.

[0058] (5) The method of any of claim embodiments 1 to 4, wherein the H2: 113a ratio comprises about 3: 1.

[0059] (6) The method of any of claim embodiments 1 to 5, wherein the coupling is conducted at a H2: 113a ratio comprising about 3:3.5.

[0060] (7) The method of any of claim embodiments 1 to 6, wherein the coupling is conducted at a H2:diluent ratio between 1-5: 1 to 1 : 1-5.

[0061] (8) A method comprising:

[0062] a. passing a CFC or HCFC through a plurality of parallel catalyst tubes to couple the CFC or HCFC,

[0063] b. exchanging exothermic heat from the tubes with a heat exchange fluid,

[0064] c. determining the presence of hot spots with the thermocouples, and detecting changes in the heat exchange fluid, and

[0065] d. passing a diluent through the tubes to maintain reactor gain wherein reactor gain (G) is defined as where T = temperature, change in hot spot temperature, and change in oil at the inlet.

[0066] (9) A method comprising: controlling a reactor gain of a chemical reaction, circulating a heat transfer oil through a reaction zone in which catalytic coupling is conducted, determining the reactor gain of the reaction zone, wherein reactor gain where T = temperature, change in hot spot temperature, and change in oil temperature of the reaction zone, and adding a diluent to the reaction zone to reduce or minimize hot spot formation, and the reactor gain .

[0067] (10) The method according to any one of embodiments 8 or 9, wherein the diluent comprises one of 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,1,1-trifluoroethane (HFC-143a) or an excess of CFC-113a.

[0068] (11) The method according to any one of claims 8 to 10, wherein the coupling comprises coupling of CFC-113a at an H2:113a ratio between 1-5:1 and 1:1-5.

[0069] (12) The method according to any one of claims 8 to 11, wherein the H2:113a ratio comprises about 3:1.

[0070] (13) The method according to any one of claims 8 to 12, wherein the coupling is performed at an H2:113a ratio of about 3:3.5.

[0071] (14) The method according to any one of claims 8 to 13, wherein the diluent comprises 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123).

[0072] (15) The method according to any one of claims 8 to 13, wherein the diluent comprises 1,1,1,2-tetrafluoroethane (HFC-134a).

[0073] (16) The method according to any one of claims 8 to 13, wherein the diluent comprises 1,1,1,2-tetrafluoroethane (HFC-143a).

[0074] (17) A composition formed by the method according to any one of embodiments 1 to 16.

[0075] (18) The method according to any one of embodiments 1 or 8, wherein the CFC and / or HCFC with the CCl3 group is defined by the formula RCl3, wherein R can be a straight-chain or branched C2-C4 fluoroalkyl, fluorochloroalkyl, hydrofluoroalkyl, or hydrochlorofluoroalkyl, preferably R is selected from one of C2F5, C3F7, C4F9, HCF2CF2, CF3CHF, HCF2C2F4, or HCF2C3F6.

[0076] A composition formed by the method according to embodiment 18.

[0077] While certain aspects, embodiments, and principles have been described above, it is understood that the description is illustrative only and is not limiting on the application or the appended claims. The various aspects, embodiments, and principles described above can be used alone or in combination with one another.

Claims

1. A method, the method comprising: a. Coupling one of HCFCs or CFCs in the reaction zone in the presence of hydrogen and a catalyst. b. Monitor the temperature at multiple intervals within the reaction zone to detect hot spots, and c. Add diluent to the reaction zone to reduce hot spot formation.

2. The method of claim 1, wherein the CFC comprises coupling 1,1,1-trichloro-2,2,2-trifluoroethane (HCFC-113a) to form a mixture of products comprising E / Z-CFO-1316mxx (E / Z-CF3CCI=CCICF3).

3. The method according to any one of claims 1 or 2, wherein the diluent comprises one of 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,1,1-trifluoroethane (HFC-143a) or an excess of CFC-113a.

4. The method of claim 2, wherein the coupling is performed at an H2:113a ratio between 1 and 5:

1.

5. The method of claim 4, wherein the H2:113a ratio comprises about 3:

1.

6. The method of claim 4, wherein the coupling is performed at an H2:113a ratio of approximately 3:3.

5.

7. The method of claim 3, wherein the coupling is performed at an H2:diluent ratio between 1-5:1 and 1:1-5.

8. A method, the method comprising: d. Couple the CFC by passing it through multiple parallel catalyst tubes. e. Arrange thermocouples along the length of each tube to monitor hot spots. f. Exchange the exothermic heat from the tube with a heat exchange fluid. g. Use the thermocouple to determine the presence of hot spots and detect changes in the heat exchange fluid, and h. Pass the diluent through the tube to maintain reactor gain. The reactor gain (G) is defined as follows: Where T = temperature, Changes in hotspot temperature, and The change in oil temperature in the reaction zone.

9. A method, the method comprising: Controlling reactor gain for a chemical reaction includes circulating heat transfer oil through a reaction zone, performing catalytic coupling in the reaction zone, and determining the reactor gain of the reaction zone, wherein the reactor gain... Where T = temperature, Changes in hotspot temperature, and Changes in oil temperature at the inlet, and the addition of diluent to the reaction zone to reduce or minimize hot spot formation, and the reactor gain. .

10. The method according to any one of claims 8 or 9, wherein the diluent comprises one of 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,1-trifluoroethane (HFC-143a), or an excess of CFC-113a.

11. The method of claim 10, wherein the coupling comprises coupling of CFC-113a at an H2:113a ratio between 1-5:1 and 1:1-5.

12. The method of claim 11, wherein the H2:113a ratio comprises about 3:

1.

13. The method of claim 11, wherein the coupling is performed at an H2:113a ratio of about 3:3.

5.

14. The method according to any one of claims 10, wherein the diluent comprises 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123).

15. The method according to any one of claims 10, wherein the diluent comprises 1,1,1,2-tetrafluoroethane (HFC-134a).

16. The method according to any one of claims 10, wherein the diluent comprises 1,1,1,2-tetrafluoroethane (HFC-143a).

17. A composition formed by the method according to any one of claims 1 to 16.

18. The method according to any one of claims 1 or 8, wherein the CFC and / or HCFC with a CCl3 group is defined by the formula RCCl3, wherein R can be a straight-chain or branched C2-C4 fluoroalkyl, fluorochloroalkyl, hydrofluoroalkyl, or hydrochlorofluoroalkyl, preferably R is selected from one of C2F5, C3F7, C4F9, HCF2CF2, CF3CHF, HCF2C2F4, and HCF2C3F6.

19. A composition formed by the method according to claim 18.

20. The method of claim 9, wherein the inlet temperature is varied to assess hotspot formation.

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