Patent Description:
Chlorofluorocarbon (CFC) based chemicals have been widely used in industry in a variety of different applications including as refrigerants, aerosol propellants, blowing agents and solvents, among others. However, certain CFCs are suspected of depleting the Earth's ozone layer. Accordingly, more environmentally friendly substitutes have been introduced as replacements for CFCs. For example, <NUM>,<NUM>,<NUM>,<NUM>,<NUM>-pentafluoropropane (HFC-245fa) is recognized as having favorable physical properties for certain industrial applications, such as foam blowing agents and solvents, and therefore is consider to be a good substitute for the CFCs previously used for these applications. Unfortunately, the use of certain hydrofluorocarbons, including HFC-245fa, in industrial applications is now believed to contribute to the global warming. Accordingly, more environmentally friendly substitutes for hydrofluorocarbons are now being sought.

The compound <NUM>-chloro-<NUM>,<NUM>,<NUM>-trifluoropropene, also known as HCFO-1233zd or simply 1233zd, is a candidate for replacing HFC-245fa in some applications, including uses as blowing agents and solvents. 1233zd has two isomers with different physical properties. As one example of the different properties between the two isomers, 1233zd(Z) has a boiling point of approximately <NUM>, whereas 1233zd(E) has a boiling point of approximately <NUM>. In some applications, it is desirable to use either pure 1233zd(E), pure 1233zd(Z), a particular blend of the (Z) and (E) isomers, or a particular blend of one or both of the 1233zd isomers and another compound in order to control the properties of the solution. For example, in some solvent applications, it is desirable to have a relatively high boiling point. In some such applications, pure 1233zd(Z) may have more desirable physical properties (e.g., a higher boiling point) than either pure 1233zd(E) or mixtures of the two 1233zd isomers.

Processes for synthesizing 1233zd are known. For example, <CIT> discloses a process for preparing 1233zd via the gas-phase reaction of <NUM>,<NUM>,<NUM>,<NUM>,<NUM>-penta-chloropropane (HCC-240fa) with hydrogen fluoride (HF). However, this process produces relatively low yields of 1233zd.

<CIT> describes a catalytic liquid phase reaction of HCC-240fa with HF to produce 1233zd in higher yields. However the presence of the fluorination catalyst promotes the formation of heavy by-products, oligomers, and tars which can build up in the reactor over time and lead to catalyst dilution and catalyst deactivation, resulting in loss of productivity due to excessive downtime to remove these by-products from the reactor on a periodic basis.

<CIT> discloses a non-catalytic liquid phase reaction of HCC-240fa with HF to reduce the formation of heavy by-products. However, one drawback of not using a catalyst is the problem of slower reaction rates, resulting in the formation of significant amounts of stable underfluorinated intermediates comprising tetrachloro-fluoropropanes including <NUM>,<NUM>,<NUM>,<NUM>-tetrachloro-<NUM>-fluoropropane (HCFC-241fa), trichloro-difluoropropanes including <NUM>,<NUM>,<NUM>-trichloro-<NUM>,<NUM>-difluoropropane (HCFC-242fa) and <NUM>,<NUM>,<NUM>-trichloro-<NUM>,<NUM>-difluoropropane (HCFC-242fb) and dichlorotrifluoropropanes including <NUM>,<NUM>-dichloro-<NUM>,<NUM>,<NUM>-trifluoropropane (HCFC-243fa) and <NUM>,<NUM>-dichloro-<NUM>,<NUM>,<NUM>-trifluoro-propane (HCFC-243fb) can be formed, which significantly decreases the single pass productivity of HCFC-1233zd.

<CIT> describes a process to produce trans-<NUM>-chloro-<NUM>,<NUM>,<NUM>-trifluoropropene (HCFO-1233zd(E)) at high purity on a commercial scale.

<CIT> describes a process for the production of <NUM>-chloro-<NUM>,<NUM>,<NUM>-trifluoropropene (HCFC-1233zd) comprising the steps of: (a) reacting HCC-<NUM> and HF in a high pressure liquid phase reactor to generate an effluent reaction stream comprising HCFC-1233zd, intermediates and byproducts of HCFC-1233zd, HCl and unreacted HCC-<NUM> and HF; and (b) at least partially condensing the effluent stream from reaction step (a) to form a condensate comprising HCFC-1233zd.

<CIT> describes methods and systems for producing hydrochloro-fluoroolefins, particularly trans-<NUM>-chloro-<NUM>,<NUM>,<NUM>-trifluoropropene (HCFO-1233zd(E)) without the use of a catalyst.

Based on the above, there remains a need for means by which partially fluorinated intermediates can be converted into the target product, namely, HCFO-1233zd. This invention satisfies that need.

The present invention provides methods for the production of <NUM>-chloro-<NUM>,<NUM>,<NUM>-trifluoropropene (HCFO-1233zd). The process generally comprises the steps of:.

Non-limiting examples of tetrachlorofluoropropanes include, but are not limited to, <NUM>,<NUM>,<NUM>,<NUM>-tetrachloro-<NUM>-fluoropropane (HCFC-241fa). Non-limiting examples of trichlorodifluoropropanes include, but are not limited to, <NUM>,<NUM>,<NUM>-trichloro-<NUM>,<NUM>-difluoro-propane (HCFC-242fa) and <NUM>,<NUM>,<NUM>-trichloro-<NUM>,<NUM>-difluoropropane (HCFC-242fb). Non-limiting examples of dichlorotrifluoropropanes include, but are not limited to, <NUM>,<NUM>-dichloro-<NUM>,<NUM>,<NUM>-trifluoropropane (HCFC-243fa) and <NUM>,<NUM>-dichloro-<NUM>,<NUM>,<NUM>-trifluoropropane (HCFC-243fb). A preferred feedstock comprises a mixture of HCFC-<NUM>, HCFC-<NUM> and HCFC-<NUM> (HCFC-<NUM>/HCFC-<NUM>).

In certain embodiments, the feedstock contains the sum of tetrachlorofluoropropanes, trichlorodifluoro-propanes and dichlorotrifluoropropanes of at least <NUM> wt%, preferably at least <NUM> wt%, more preferably at least <NUM> wt%, and most preferably at least <NUM> wt%.

In certain embodiments, the solid catalyst may be one or more of halogenated metal oxides in bulk form or supported, metal halides in bulk form or supported, and carbon supported transition metals. Suitable catalysts non-exclusively include halogenated metal oxides (e.g., fluorinated Cr<NUM>O<NUM>, fluorinated Al<NUM>O<NUM>, fluorinated MgO), metal halides (e.g., CrF<NUM>, AlF<NUM>, AlCl<NUM>, FeCl<NUM>, FeCl<NUM>/C) and carbon supported transition metals (zero oxidation state) such as Fe/C, Co/C, Ni/C, and Pd/C.

It should be appreciated by those persons having ordinary skill in the art(s) to which the present invention relates that any of the features described herein in respect of any particular aspect and/or embodiment of the present invention can be combined with one or more of any of the other features of any other aspects and/or embodiments of the present invention described herein, with modifications as appropriate to ensure compatibility of the combinations. Such combinations are considered to be part of the present invention contemplated by this disclosure.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein.

As set forth above, the present invention is directed to a process for producing 1233zd, which comprises:.

In certain embodiments, the feedstock contains the sum of tetrachlorofluoropropanes, trichlorodifluoro-propanes and dichlorotrifluoropropanes of at least <NUM> wt%, preferably at least <NUM> wt%, more preferably at least <NUM> wt%, and most preferably at least <NUM> wt%. Non-limiting examples of tetrachlorofluoropropanes include, but are not limited to, <NUM>,<NUM>,<NUM>,<NUM>-tetrachloro-<NUM>-fluoropropane (HCFC-241fa). Non-limiting examples of trichlorodifluoropropanes include, but are not limited to, <NUM>,<NUM>,<NUM>-trichloro-<NUM>,<NUM>-difluoropropane (HCFC-242fa) and <NUM>,<NUM>,<NUM>-trichloro-<NUM>,<NUM>-difluoropropane (HCFC-242fb). Non-limiting examples of dichlorotrifluoropropanes include, but are not limited to, <NUM>,<NUM>-dichloro-<NUM>,<NUM>,<NUM>-trifluoropropane (HCFC-243fa) and <NUM>,<NUM>-dichloro-<NUM>,<NUM>,<NUM>-trifluoropropane (HCFC-243fb).

In preferred embodiments, distillation is used to isolate tetrachlorofluoropropanes, trichlorodifluoropropanes and dichlorotrifluoropropanes from a product stream comprising HCFO-1233zd(E), HCFO-1233zd(Z), HCFC-241fa, HCFC-242fa, HCFC-242fb, HCFC-243fa, and HCFC-243fb. These intermediates can be isolated as individual compounds or as a mixture. As disclosed in <CIT>, such a product stream can be obtained by reacting HCC-240fa with anhydrous HF in a liquid phase reactor in the absence of any catalyst.

The reaction of tetrachlorofluoropropanes (HCFC-<NUM>), trichlorodifluoropropanes (HCFC-<NUM>) and dichlorotrifluoropropanes (HCFC-<NUM>) may be conducted in any suitable reaction vessel or reactor, but it should preferably be constructed from materials which are resistant to the corrosive effects of hydrogen fluoride such as nickel and its alloys, including Hastelloy, Inconel, Incoloy, and Monel or vessels lined with fluoropolymers. These may be single pipe or multiple tubes packed with a solid catalyst. Three kinds of catalysts can be used, which include <NUM>) bulk or supported metal halides, <NUM>) bulk or supported halogenated metal oxides, and <NUM>) bulk or supported zero-valent metals. Useful catalysts non-exclusively include fluorinated Cr<NUM>O<NUM>, fluorinated Al<NUM>O<NUM>, fluorinated MgO, CrF<NUM>, AlF<NUM>, AlCl<NUM>, FeCl<NUM>, MgF<NUM>, FeCl<NUM>/C and carbon supported transition metals (zero oxidation state) such as Fe/C, Co/C, Ni/C, and Pd/C. The HCFC-<NUM>/HCFC-<NUM> feed is introduced into the reactor either in pure form, impure form, or together with an optional inert gas diluent such as nitrogen, argon, or the like.

In some embodiments of the invention, the HCFC-<NUM>/HCFC-<NUM>/HCFC-<NUM> feedstock is pre-vaporized or preheated prior to entering the reactor. Alternatively, the HCFC-<NUM>/HCFC-<NUM>/HCFC-<NUM> feed is vaporized inside the reactor. Useful reaction temperatures may range from about <NUM> to about <NUM>. Preferred temperatures may range from about <NUM> to about <NUM>, and more preferred temperatures may range from about <NUM> to about <NUM>. The reaction may be conducted at atmospheric pressure, super-atmospheric pressure or under vacuum. The vacuum pressure can be from about <NUM> kPa (<NUM> Torr) to about <NUM> kPa (<NUM> Torr). Contact time of the HCFC-<NUM>/HCFC-<NUM>/HCFC-<NUM> feed with the catalyst may range from about <NUM> seconds to about <NUM> seconds, however, longer or shorter times can be used.

In preferred embodiments, HF is co-fed to the reactor together with the HCFC-<NUM>/HCFC-<NUM>/HCFC-<NUM> feed. HF is pre-vaporized or preheated prior to entering the reactor. Alternatively, HF is vaporized inside the reactor. The applicants unexpectedly found that the presence of HF co-feed can significantly suppress the formation of some undesirable by-products non-exclusively including dichlorodifluoropropenes (HCFO-<NUM> isomers), trichlorofluoropropenes (HCFO-<NUM> isomers), tetrachloropropenes (HCO-<NUM> isomers), etc. The molar ratio of HF/organic can be ranged from <NUM>:<NUM> to <NUM>:<NUM>, preferably from <NUM>:<NUM> to <NUM>:<NUM>, and more preferably from <NUM>:<NUM> to <NUM>:<NUM>.

In preferred embodiments, the process flow is in either the down or up direction through a bed of the catalyst. It may also be advantageous to periodically regenerate the catalyst after prolonged use while in place in the reactor. Regeneration of the catalyst may be accomplished by any means known in the art, for example, by passing air or air diluted with nitrogen over the catalyst at temperatures of from about <NUM> to about <NUM>, preferably from about <NUM> to about <NUM>, for from about <NUM> hour to about <NUM> days. This is followed by H2 treatment at temperatures of from about <NUM> to about <NUM>, preferably from about <NUM> to about <NUM> for supported transition metal catalysts or followed by HF treatment at temperatures of from about <NUM> to about <NUM> and preferably from about <NUM> to about <NUM> for halogenated metal oxide catalysts and metal halide catalysts.

The reaction typically yields a reaction product comprising HCFO-1233zd and one or more compounds other than HCFO-1233zd. The reaction product typically takes the form of a mixture of the following: unreacted starting materials, e.g., HCFC-<NUM> isomers, HCFC-<NUM> isomers, and HCFC-<NUM> isomers, and HF in case HF is co-fed; target products, e.g., HCFO-1233zd; and by-products, e.g., HCl, HF, HFO-1234ze, HFC-245fa, HCFC-244fa, HCFO-<NUM> isomers, HCFO-<NUM> isomers, HCO-<NUM> isomers, etc..

Desirable levels of raw material conversion and HCFO-1233zd selectivity can be impacted by operating parameters, including conditions such as reaction temperature, pressure, and residence time. The reaction will be carried out at conditions sufficient to effect the formation of target product. Selectivity to HCFC-1233zd (the sum of two isomers) with the preferred catalysts is about <NUM>% or more, more preferably about <NUM> or more, and most preferably about <NUM>% or more. Conversion of raw material is preferably about <NUM>% or more, more preferably about <NUM>% or more, and most preferably about <NUM>% or more.

HCFC-1233zd may be recovered from the reaction product as either or both of E and Z-isomers thereof. Recovery of compounds from the reaction product may be affected by any means known in the art, such as by extraction and preferably by distillation. For example, the distillation may be conducted in a standard distillation column at a pressure less than about <NUM> kPa (<NUM> psig), preferably less than about <NUM> kPa (<NUM> psig), and most preferably less than <NUM> kPa (<NUM> psig). The pressure of distillation column inherently determines the distillation operating temperature. HCl may be recovered by operating the distillation column at from about -<NUM> to about <NUM>, preferably from about -<NUM> to about -<NUM>. HCFO-1233zd may be recovered by operating the distillation column at from about -<NUM> to about <NUM>. Single or multiple distillation columns may be used. If, desired, the HCFO-1233zd(E) and HCFO-1233zd(Z) may be separated from each other by means known in the art, such as extraction and distillation.

In a preferred embodiment, HCl is removed from the reaction products. More preferably, the HCl is removed prior to the recovery of HCFC-1233zd from the reaction product mixture. The HCl in the product stream is recovered using an HCl column. High purity HCl is isolated from the top of the column and absorbed in deionized water as concentrated HCl. Alternatively, HCl can be recovered or removed from the product stream by using water or caustic scrubbers. When water extractor is used, HCl aqueous solution of various concentrations is formed. When caustic scrubber is used, HCl is neutralized as a chloride salt in aqueous solution.

In certain embodiments, the essentially HCl-free organic/HF mixture is fed to a sulfuric extractor or a phase separator for removal of HF from this mixture. HF is either dissolved in the sulfuric acid or phase separated from the organic mixture. For embodiments utilizing a sulfuric acid adsorption system, sulfuric acid is preferably added such that the weight ratio of sulfuric acid to hydrogen fluoride ranges from about <NUM>:<NUM> to about <NUM>:<NUM>. More preferably the weight ratio ranges from about <NUM>:<NUM> to about <NUM>:<NUM> and most preferably from about <NUM>:<NUM> to about <NUM>:<NUM>. The HF is then desorbed from the sulfuric acid/HF mixture by stripping distillation and recycled back to the fluorination reactor. For embodiments utilizing a phase separator, preferably the extraction is conducted at a temperature of from about -<NUM> to about <NUM>, more preferably from about -<NUM> to about <NUM>, and most preferably from about <NUM> to about <NUM>. The HF is then phase-separated and recycled back to the reactor. The organic mixture either from the overhead of the sulfuric acid extractor or from the bottom layer of the phase separator may require treatment (scrubbing or adsorption) to remove traces of HF before it is sent to next unit operation for product isolation.

In certain embodiments, the isomers HCFO-1233zd(E) and HCFO-1233zd(Z) are isolated as two products. Acid free crude product is first sent to a distillation column, from which HCFO-1233zd(E) exits the top of the column together with some light components having lower boiling points than HCFO-1233zd(E) while HCFO-1233zd(Z) exits from the bottom of the column together with some heavy components having higher boiling points than HCFO-1233zd(Z). The overhead stream and the bottom stream are then sent to two separate columns for further purification to obtain HCFO-1233zd(E) and HCFO-1233zd(Z) products.

The following examples are provided to further illustrate the invention and should not be taken as limitations of the invention.

In this example, <NUM> wt% FeCl<NUM>/carbon was used as a catalyst. A <NUM> x <NUM> (¾ inch x <NUM> inch) tube Inconel <NUM> reactor was used. The reactor was installed in the middle of an electric <NUM>-zone split furnace. Process temperatures were recorded using a multi-point thermocouple placed inside the reactor and within the catalyst bed. The distance between two adjacent probe points was <NUM> (<NUM> inches). <NUM> of solid catalyst was loaded in such a way that its bed was within three adjacent probe points. The reactor was heated to desired temperatures in nitrogen flow and <NUM> GC area% <NUM> (two isomers with 243fb being dominant component)/<NUM> GC area% 242fa feed was then fed into the bottom of the vertically mounted reactor to start a reaction. The reaction effluent was periodically sampled for its compositions.

As shown in Table <NUM>, the percentages of 1233zd (1233zdE plus 1233zdZ) in vapor phase and in liquid phase were about <NUM>%, and about <NUM>%, respectively.

In this example, fluorinated Cr<NUM>O<NUM> was used as a catalyst. A <NUM> x <NUM> (¾ inch x <NUM> inch) tube Inconel <NUM> reactor was used. The reactor was installed in the middle of an electric <NUM>-zone split furnace. Process temperatures were recorded using a multi-point thermocouple placed inside the reactor and within the catalyst bed. The distance between two adjacent probe points was <NUM> (<NUM> inches). <NUM> of solid catalyst was loaded in such a way that its bed was within two adjacent probe points. The reactor was heated to desired temperatures in nitrogen flow and <NUM> GC area%<NUM> (two isomers with 243fb being dominant component)/<NUM> GC area% 242fa feed was then fed into the bottom of the vertically mounted reactor to start a reaction. The reaction effluent was periodically sampled for its compositions. As shown in Table <NUM>, the percentages of 1233zd (1233zdE plus 1233zdZ) in vapor phase and in liquid phase were about <NUM>%, and about <NUM>%, respectively.

In this example, the same fluorinated Cr<NUM>O<NUM> catalyst was used as in Example <NUM>. A <NUM> x <NUM> (¾ inch x <NUM> inch) tube Inconel <NUM> reactor was used. The reactor was installed in the middle of an electric <NUM>-zone split furnace. Process temperatures were recorded using a multi-point thermocouple placed inside the reactor and within the catalyst bed. The distance between two adjacent probe points was <NUM> (<NUM> inches). <NUM> of solid catalyst was loaded in such a way that its bed was within two adjacent probe points. The reactor was heated to desired temperatures in nitrogen flow and <NUM> GC area% <NUM> (two isomers with 243fb being dominant component)/<NUM> GC area% 242fa feed and anhydrous HF were then fed into the bottom of the vertically mounted reactor to start a reaction. The reaction effluent was periodically sampled for its compositions. Applicants unexpectedly found by co-feeding the amount of <NUM> isomer generated was greatly reduced to below <NUM>% (versus about <NUM>% in the absence of HF) while the amount of 1233zd remained about the same.

As used herein, the singular forms "a", "an" and "the" include plural unless the context clearly dictates otherwise. Moreover, when an amount, concentration, or other value or parameter is given as either a range, preferred range, or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the invention be limited to the specific values recited when defining a range.

Claim 1:
A process for the production of <NUM>-chloro-<NUM>,<NUM>,<NUM>-trifluoropropene (HCFO-1233zd) which comprises the steps of:
i. providing a propane feedstock selected from the group consisting of tetrachlorofluoropropanes, trichlorodifluoropropanes, dichlorotrifluoropropanes, and mixtures thereof;
ii. reacting the propane feedstock in a vapor phase reactor in the presence of HF and in the presence of a solid catalyst under conditions effective to form a product stream comprising HCFO-1233zd isomers, HCl and unconverted starting materials,
iii. recovering or removing HCl and HF, and
iv. isolating the HCFO-1233zd E-isomer, the HCFO-1233zd Z-isomer, or both compounds.