DESC:FIELD OF THE INVENTION
The present invention provides a selective, simple, cost effective and industrially viable process for preparing trans-isomer of hydrofluoroolefins such as HFO-1234ze(E) and HCFO-1233zd(E) by limiting the formation of corresponding Z-isomer.
BACKGROUND OF THE INVENTION
Hydrofluoroolefins, such as (E)-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) and (E)-1-chloro-3,3,3-trifluoropropene (HCFO-1233zd(E) being environmentally benign are being developed to replace saturated chlorofluorocarbons for use in the industry as refrigerants, solvents, cleaning agents, foam expansion agents, aerosol propellants, heat transfer media, dielectrics, fire extinguishing agents, sterilants and power cycle working fluids.
Various processes are known for preparation of HFO-1234ze(E) or HCFO-1233zd(E) such as:
JP Patent No. 6197637 discloses a process for preparing (E)-1,3,3,3-tetrafluoropropene by reacting (E) and/or (Z)-1-chloro-3,3,3-trifluoropropene with a metal catalyst such as chromium oxide and aluminium oxide to produce (E)-1,3,3,3-tetrafluoropropene.
U.S. Patent No. 10450248 discloses a method for producing 1,3,3,3-tetrafluoropropene (HFO-1234ze) by reacting HCFO-1233zd in the presence of a catalyst such as chromium oxyfluoride, chromium oxide, metal fluoride etc. in a vapour phase at an elevated temperature to produce a product composition comprising HFO-1234ze.
PCT Pub. No. 2012030781 provides an integrated manufacturing process to co-produce (E)-1-chloro-3,3,3-trifluoropropene, (E)-1,3,3,3-tetrafluoropropene and 1,1,1,3,3-pentafluoropropane, comprising fluorination of 1,1,1,3,3-pentachlorpropane (HCC-240fa) followed by dehydrofluorination of 1,1,1,3,3-pentafluoropropane (HFC-245fa). The process involves the formation of undesired cis-isomers i.e., HCFO-1233zd(Z) and HFO-1234ze(Z) that are later isomerized to desired (E)-isomer.
U.S. Patent No. 10118879 provides a method for preparation of HCFO-1233zd(E) by reacting a composition containing HCFO-1233zd(Z) and HCFC-244fa in vapour phase in presence of a chromium trifluoride (CrF3) catalyst at a temperature between 80°C and 250°C at a pressure to simultaneously isomerize HCFO-1233zd(Z) to form HCFO-1233zd(E) and dehydrohalogenating HCFC-244fa to HCFO-1233zd(E).
U.S. Pat. No. 8642819 discloses a process for manufacturing (E)-1-chloro-3,3,3-trifluoropropene by fluorinating 1,1,1,3,3-pentachloropropane (HCC-240fa) followed by separation of E-isomer from Z-isomer. It also discloses a process for isomerization of the Z-isomer to the desired E-isomer.
It is very well known that preparation of E-isomers of HFO-1234ze and HCFO-1233zd inadvertently involves formation of Z-isomer that needs to be either separated or isomerized into desired E-isomer. So, it remains a challenge in the art to limit the formation of Z-isomer that makes the process expensive requiring its separation or conversion to desired E-isomer.
The inventors of the present invention found that the formation of Z-isomer can be supressed during the preparation of E-isomers of HFO-1234ze and HCFO-1233zd thereby making the process more cost effective and industrially viable.

OBJECT OF THE INVENTION
The object of the present invention is to provide a selective, simple, cost effective and industrially viable process for preparing E-isomers of HFO-1234ze and HCFO-1233zd by controlling the formation of corresponding Z-isomer.

SUMMARY OF THE INVENTION
The present invention provides a process for selective preparation of trans-isomer of hydrofluoroolefin, comprising a step of supplying corresponding cis-isomer to raw material feed.

DETAILED DESCRIPTION OF THE INVENTION
As used herein, hydrofluoroolefin refers to 1-chloro-3,3,3-trifluoropropene; 1,3,3,3-tetrafluoropropene and corresponding (E)/trans and (Z)/cis isomers thereof.
As used herein, the raw material feed is the initial feed comprising of a fluorinating agent and any one or more of chloroalkane, fluoroalkane, and chlorofluoroalkene selected from a group consisting of 1,1,3,3,3-pentachloropropane, 1,1,3,3,3-pentafluoropropane, 1-chloro-3,3,3-trifluoropropene or a mixture thereof.
The present invention provides a process for selective preparation of trans-isomer of hydrofluoroolefin, comprising a step of supplying corresponding cis-isomer to raw material feed.
In another embodiment, the present invention provides a process for selective preparation of (E)-1-chloro-3,3,3-trifluoropropene, comprising a step of supplying (Z)-1-chloro-3,3,3-trifluoropropene to the raw material feed.
In another embodiment, the present invention provides a process for selective preparation of (E)-1,3,3,3-tetrafluoropropene, comprising a step of supplying (Z)-1,3,3,3-tetrafluoropropene to the raw material feed.
In another embodiment of the present invention, when hydrofluoroolefin is 1-chloro-3,3,3-trifluoropropene, the raw material feed comprises of HCC-240fa.
In another embodiment, the present invention provides a process for selective preparation of (E)-1-chloro-3,3,3-trifluoropropene, comprising a step of supplying (Z)-1-chloro-3,3,3-trifluoropropene to the raw material feed comprising HCC-240fa.
In another embodiment of the present invention, when hydrofluoroolefin is (E)-1,3,3,3-tetrafluoropropene, the raw material feed comprises any one or more of 1-chloro-3,3,3-trifluoropropene and 1,1,3,3,3-pentafluoropropane.
In another embodiment, the present invention provides a process for selective preparation of (E)-1,3,3,3-tetrafluoropropene, comprising a step of supplying (Z)-1,3,3,3-tetrafluoropropene to the raw material feed comprising any one or more of 1-chloro-3,3,3-trifluoropropene and 1,1,3,3,3-pentafluoropropane.
In another embodiment of the present invention, cis-isomer is supplied to raw material feed either by recycling of cis-isomer formed in the process or by supplying fresh feed of cis-isomer.
The presence of cis-isomer in the raw material feed either by supplying fresh feed of cis-isomer or by recycling helps in supressing its further formation.
In another embodiment, the present invention provides a process for preparation (E)-1-chloro-3,3,3-trifluoropropene, comprising a step of supplying (Z)-1-chloro-3,3,3-trifluoropropene either by recycling (Z)-1-chloro-3,3,3-trifluoropropene formed in the process or by supplying fresh feed of (Z)-1-chloro-3,3,3-trifluoropropene to raw material feed.
In another embodiment, the present invention provides a process for preparation (E)-1,3,3,3-tetrafluoropropene, comprising a step of supplying (Z)-1,3,3,3-tetrafluoropropene either by recycling (Z)-1,3,3,3-tetrafluoropropene formed in the process or by supplying fresh feed of (Z)-1,3,3,3-tetrafluoropropene to raw material feed.
In another embodiment, the present invention provides a process for preparation (E)-1-chloro-3,3,3-trifluoropropene, comprising a step of supplying (Z)-1-chloro-3,3,3-trifluoropropene either by recycling (Z)-1-chloro-3,3,3-trifluoropropene formed in the process or by supplying fresh feed of (Z)-1-chloro-3,3,3-trifluoropropene to raw material feed comprising HCC-240fa.
In another embodiment, the present invention provides a process for preparation (E)-1,3,3,3-tetrafluoropropene, comprising a step of supplying (Z)-1,3,3,3-tetrafluoropropene either by recycling (Z)-1,3,3,3-tetrafluoropropene formed in the process or by supplying fresh feed of (Z)-1,3,3,3-tetrafluoropropene to raw material feed comprising any one or more of 1-chloro-3,3,3-trifluoropropene and 1,1,3,3,3-pentafluoropropane.
In an embodiment, the amount of cis-isomer supplied to the raw material feed is in the range of 1 to 30%.
In another embodiment, the present invention provides a process for preparation of (E)-1-chloro-3,3,3-trifluoropropene, wherein the amount of (Z)-1-chloro-3,3,3-trifluoropropene supplied to the raw material feed is in the range of 1 to 30%, preferably in the range of 10 to 25% and most preferably, in the range of 12 to 18%.
In another embodiment, the present invention provides a process for preparation of (E)-1,3,3,3-tetrafluoropropene, the amount of (Z)-1,3,3,3-tetrafluoropropene supplied to the raw material feed is in the range of 1 to 30%, preferably in the range of 10 to 25% and most preferably, in the range of 12 to 18%.
In another embodiment, the present invention provides a process for selective preparation of trans-isomer of hydrofluoroolefin, wherein the raw material feed comprising chloroalkane, fluoroalkane or chlorofluoroalkene or mixture thereof and a fluorinating agent is passed through a catalyst. The fluorinating agent is anhydrous hydrogen fluoride.
In another embodiment, the present invention provides a process for selective preparation of trans-isomer of hydrofluoroolefin, wherein the raw material feed comprising chloroalkane, fluoroalkane or chlorofluoroalkene or mixture thereof and a fluorinating agent is passed through a catalyst at a temperature between 100-450oC.
In another embodiment, the present invention provides a process for selective preparation of trans-isomer of hydrofluoroolefin, wherein the raw material feed comprising chloroalkane, fluoroalkane or chlorofluoroalkene or mixture thereof and a fluorinating agent is passed through a catalyst at a pressure of 0-20 kg/cm2.
In an embodiment of the present invention, the molar ratio of fluorinating agent is in the range of 1 to 20.
In another embodiment of the present invention, when hydrofluoroolefin is (E)-1-chloro-3,3,3-trifluoropropene, the molar ratio of fluorinating agent with respect to HCC-240fa is in the range of 3 to 20.
In another embodiment of the present invention, when hydrofluoroolefin is (E)-1,3,3,3-tetrafluoropropene, the molar ratio of fluorinating agent with respect to feed of 1-chloro-3,3,3-trifluoropropene and/or 1,1,3,3,3-pentafluoropropane is in the range of 1 to 20.
The catalyst is selected from a group consisting of fluorinated chromia, chromium oxide, metal fluoride such as chromium trifluoride (CrF3) or aluminium trifluoride (AlF3) and combinations thereof. The catalyst used is either unsupported, or supported on activated carbon, alumina, or chromium oxides.
In another embodiment of the present invention, the contact time between the raw material feed and the catalyst is in the range from 0.2 second to 150 seconds, from 10 seconds to 125 seconds, or from 50 seconds to 100 seconds.
In another embodiment, the present invention provides a process for selective preparation of (E)-1,3,3,3-tetrafluoropropene, wherein the contact time between the raw material feed comprising 1-chloro-3,3,3-trifluoropropene and/or 1,1,3,3,3-pentafluoropropane and the fluorinating agent with the catalyst is in the range from 0.2 second to 150 seconds, from 10 seconds to 125 seconds, or from 50 seconds to 100 seconds.
In another embodiment, the present invention provides a process for selective preparation of (E)-1-chloro-3,3,3-trifluoropropene, wherein the contact time between the raw material feed of HCC-240fa and fluorinating agent with the catalyst is in the range from 0.2 second to 150 seconds, from 10 seconds to 125 seconds, or from 50 seconds to 100 seconds.
In a specific embodiment, the present invention provides a process for selective preparation of (E)-1,3,3,3-tetrafluoropropene comprising the step of fluorinating 1-chloro-3,3,3-trifluoropropene to prepare 1,1,3,3,3-pentafluoropropane (HFC-245fa) which is dehydrohalogenated to prepare (E)-1,3,3,3-tetrafluoropropene.
In another specific embodiment of the present invention, a preheated mixture of 1-chloro-3,3,3-trifluoropropene and a fluorinating agent is heated in a reactor in the presence of a catalyst to give a product mixture comprising Z and E isomers of 1,3,3,3-tetrafluoropropene, of which Z-isomer is recycled back to the reactor while continuously isolating (E)-1,3,3,3-tetrafluoropropene.
In another specific embodiment of the present invention, a preheated mixture of 1-chloro-3,3,3-trifluoropropene, (Z)-1,3,3,3-tetrafluoropropene and a fluorinating agent is heated in the reactor in presence of a catalyst to isolate (E)-1,3,3,3-tetrafluoropropene.
In another embodiment of the present invention, a preheated mixture of 1-chloro-3,3,3-trifluoropropene and a fluorinating agent is heated in a reactor in presence of a catalyst to obtain a mixture comprising Z and E isomers of 1,3,3,3-tetrafluoropropene and 1,1,3,3,3-pentafluoropropane, of which 1,1,3,3,3-pentafluoropropane is further heated to isolate E isomer of 1,3,3,3-tetrafluoropropene while (Z)-1,3,3,3-tetrafluoropropene is recycled back to the reactor.
In another embodiment of the present invention, a preheated mixture of 1-chloro-3,3,3-trifluoropropene, (Z)-1,3,3,3-tetrafluoropropene and a fluorinating agent is heated in a reactor in presence of a catalyst to obtain a mixture of (E)-1,3,3,3-tetrafluoropropene and 1,1,3,3,3-pentafluoropropane. It involves further heating of 1,1,3,3,3-pentafluoropropane and isolating (E)-1,3,3,3-tetrafluoropropene.
In another embodiment of the present invention, a preheated 1,1,3,3,3-pentafluoropropane is further heated in a reactor in presence of a catalyst to obtain a mixture comprising Z and E isomers of 1,3,3,3-tetrafluoropropene, of which Z-isomer is recycled while isolating (E)-1,3,3,3-tetrafluoropropene.
In another embodiment of the present invention, a preheated mixture of 1,1,3,3,3-pentafluoropropane and (Z)-1,3,3,3-tetrafluoropropene is further heated in a reactor in the presence of a catalyst to isolate (E)-1,3,3,3-tetrafluoropropene.
In another embodiment of the present invention, the preheating of a stream of 1233zd, HFC-245fa or their mixture with Z-1234ze is either performed separately and supplied to the reactor separately or are mixed prior to preheating and supplying to the reactor.
In a particular embodiment, HCFO-1233zd, HFC-245fa or their mixture with (Z)-1,3,3,3-tetrafluoropropene is mixed in the preheater and then passed to superheater where preheated HF is mixed and then fed to reactor.
In another embodiment of the present invention, a stream of 1233zd, HFC-245fa or their mixture with Z-1234ze is separately preheated and mixed and again super-heated before supplying to the reactor.
As used herein, the preheating is performed at a temperature range between 120 to 180°C while superheating is performed at a temperature between 180 to 250°C
The present invention provides a process for preparation of (E)-1,3,3,3-tetrafluoropropene by converting raw material feed of 1-chloro-3,3,3-trifluoropropene or 1,1,3,3,3-pentafluoropropane or a mixture thereof into (E)-1,3,3,3-tetrafluoropropene, wherein (Z)-1,3,3,3-tetrafluoropropene is also supplied with the raw material feed either by recycling of (Z)-1,3,3,3-tetrafluoropropene formed in the process or by supplying fresh feed of (Z)-1,3,3,3-tetrafluoropropene.
In an embodiment, the undesired (Z)-1,3,3,3-tetrafluoropropene formed in the process is recycled back to raw material feed of reactant.
In another embodiment, fresh feed of (Z)-1,3,3,3-tetrafluoropropene is supplied to the raw material feed.
In another specific embodiment, the present invention provides a process for preparation of (E)-1-chloro-3,3,3-trifluoropropene, comprising a step of heating a composition comprising HCC-240fa and (Z)-1-chloro-3,3,3-trifluoropropene with a fluorinating agent in presence of a catalyst.
In another specific embodiment of the present invention, (Z)-1-chloro-3,3,3-trifluoropropene is supplied either by recycling of (Z)-1-chloro-3,3,3-trifluoropropene formed in the process or by supplying fresh feed of (Z)-1-chloro-3,3,3-trifluoropropene.
In another specific embodiment of the present invention, HCC-240fa and a fluorinating agent is preheated before being supplied to the reactor.
In another specific embodiment of the present invention, HCC-240fa and a fluorinating agent is superheated before being contacted with the catalyst.
In another specific embodiment the present invention, the reaction of HCC-240fa with a fluorinating agent in the presence of a catalyst gives a mixture of (E)-1-chloro-3,3,3-trifluoropropene and (Z)-1-chloro-3,3,3-trifluoropropene, of which (Z)-1-chloro-3,3,3-trifluoropropene is recycled back to the reactor.
In an embodiment, the process of the present invention is carried out in vapour phase.
The process of the present invention is carried out at a temperature of 100-450oC and at a pressure of 0-20 kg/cm2.
In a preferred embodiment, fluorinated chromia is used as catalyst and anhydrous hydrogen fluoride is used as a fluorinating agent.
In an embodiment, the process of the present invention is carried out in a continuous manner, wherein feed of the reactants is continuously supplied and product is continuously isolated.
The reactor used in the present invention is constructed from materials which are resistant to the corrosive effects of the HF and catalyst, such as Hastelloy-C, Inconel, Monel, and Incoloy.
In an embodiment, (E)-1,3,3,3-tetrafluoropropene and (E)-1-chloro-3,3,3-trifluoropropene are obtained with a purity of 97%-99%.
In an embodiment, the (E)-1,3,3,3-tetrafluoropropene is obtained with a selectivity of 40% to 77%, preferably 72% to 77%.
In an embodiment, the (E)-1-chloro-3,3,3-trifluoropropene is obtained with a selectivity of 50%-140%.
The higher amount of R-1233zd (cis) in inlet feed compared to reactor outlet feed, indicates that there is an equilibrium of R-1233zd (trans) and R-1233zd(cis) and also some amount of R-1233zd(cis) got converted to R-245fa.
The (E)-1,3,3,3-tetrafluoropropene and (E)-1-chloro-3,3,3-trifluoropropene are isolated by any method known in the art, for example, extraction and distillation or a mixture thereof.
The 1,1,3,3,3-pentafluoropropane, 1-chloro-3,3,3-trifluoropropene and 1,1,3,3,3-pentachloropropane used as raw materials in present invention can be prepared by various methods known in the art or can be obtained commercially.
The reagent i.e., anhydrous hydrogen fluoride used in the above process are obtained commercially.
Unless stated to the contrary, any of the words “comprising”, “comprises” and includes mean “including without limitation” and shall not be constructed to limit any general statement that it follows to the specific or similar items or matters immediately following it.
Embodiments of the invention are not mutually exclusive but may be implemented in various combinations. The described embodiments of the invention and the disclosed examples are given for the purpose of illustration rather than limitation of the invention as set forth in the appended claims.
The following examples are given by way of illustration and therefore should not be construed to limit the scope of the present invention.

EXAMPLES
Example 1: Preparation of (E)-1-chloro-3,3,3-trifluoropropene
HCC-240fa feed (78gm/hr) and hydrogen fluoride (72gm/hr) were preheated at 200°C and then super heated at 230°C and then passed in tubular Inconel reactor and reacted in presence of fluorinated chromia (430 gm) at a pressure of 5 kg/cm2g and at a temperature of 250°C to obtain a feed ‘2’ containing (Z) and (E)-1-chloro-3,3,3-trifluoropropene isomers. The feed ‘2’ composition was analysed using GC.
Selectivity:
(E)-R1233zd: 58%; (Z)- R1233zd: 16.6%
The undesired (Z)-1-chloro-3,3,3-trifluoropropene isomer from feed ‘2’ was recycled back to raw material feed in tubular reactor which supressed the further formation of (Z)-isomer. The (E)-1-chloro-3,3,3-trifluoropropene was separated and isolated continuously.
Selectivity:
(E)- R1233zd: 74.6 %; (Z)- R1233zd: 100ppm;
Purity (by GC): 99.6%
Example 2: Preparation of (E)-1-chloro-3,3,3-trifluoropropene
HCC-240fa feed (78gm/hr), hydrogen fluoride (72gm/hr) and (Z)-1-chloro-3,3,3-trifluoropropene feed were preheated separately at 200°C and then super heated at 230°C and combined. The combined feed ‘1’ was then passed in tubular Inconel reactor and reacted in presence of fluorinated chromia (430 gm) at a pressure of 5 kg/cm2g and at a temperature of 250°C to obtain (E)-1-chloro-3,3,3-trifluoropropene.
Selectivity:
(E)- R1233zd: 79.5%; (Z)- R1233zd: Nil
Purity (by GC): 99.8
Example 3: Preparation of (E)-1-chloro-3,3,3-trifluoropropene
Fluorinated chromia catalyst (600 g) was charged in a single tube reactor which was heated by electrical heater. The temperature of the reactor was brought to 230oC and after that AHF feed was supplied at the rate of 110 g/hr and after 10 minutes, inlet feed was supplied at the rate of 115 g/hr. The reactor outlet was connected to water scrubber where acids were removed. The reaction was continued for 7 hours and acid free outlet stream (495g) was collected from reactor outlet. The inlet and outlet feed analysis is given below.
Compounds Inlet feed mol % Outlet feed Mol %
R245fa 0.00% 45.9%
R-1233zd Trans 5.13% 42.9%
R-1233zd Cis 17.07% 5.2%
R240fa (PCP) 46.52% 0.0%
Conversion of R-240fa: 100%
R-1233zd (trans) selectivity: 50%
Example 4: Preparation of (E)-1-chloro-3,3,3-trifluoropropene
Fluorinated chromia catalyst (600g) was charged in a single tube reactor which was heated by electrical heater. The temperature of the reactor was brought to 230oC and after that AHF feed was supplied at the rate of 119 g/hr and after 10 minutes, inlet feed was supplied at the rate of 129 g/hr. The reactor outlet was connected to water scrubber where acids were removed. The reaction was continued for 10 hours and acid free outlet feed (900g) was collected from reactor outlet. The inlet and outlet feed analysis is given below.
Compounds Inlet feed mol % Outlet feed Mol %
R245fa 0.00% 27.72%
R-1233zd Trans 5.13% 59.71%
R-1233zd Cis 17.07% 6.71%
R240fa (PCP) 46.52% 0.0%
Conversion of R-240fa: 100%
R-1233zd (trans) selectivity: 75%
Example 5: Preparation of (E)-1-chloro-3,3,3-trifluoropropene
Fluorinated chromia catalyst (600g) was charged in a single tube reactor which was heated by electrical heater. The temperature of the reactor was brought to 230oC and after that AHF feed was supplied at the rate of 131 g/hr and after 10 minutes, inlet feed was supplied at the rate of 135 g/hr. The reactor outlet was connected to water scrubber where acids were removed. The reaction was continued for 5.3 hours and acid free outlet feed (510g) was collected from reactor outlet. The inlet and outlet feed analysis is given below.
Compounds Inlet feed mol % Outlet feed Mol %
R245fa 0.03% 8.74%
R-1233zd Trans 23.32% 73.12%
R-1233zd Cis 30.23% 12.12%
R240fa (PCP) 21.74% 0.0%

Conversion of R-240fa: 100%
R-1233zd (trans) selectivity: 131%
Example 6: Preparation of (E)-1,3,3,3-tetrafluoropropene at 250°C
1-chloro-3,3,3-trifluoropropene feed (68 gm/hr) and anhydrous hydrogen fluoride feed (108 gm/hr) were preheated separately at 200oC and then super heated at 230oC and combined. The combined feed ‘1’ was then passed in tubular Inconel reactor and reacted in presence of fluorinated chromia (500gm) at a pressure of 5 kg/cm2g and at a temperature of 250°C to obtain a feed ‘2’ containing (Z) and (E)-1,3,3,3-tetrafluoropropene. The feed ‘2’ composition was analysed using GC.
Selectivity:
(E)-R1234ze: 33.5 %; (Z)-R1233ze: 6.72 %; HFC-245fa: 39.3 %
The undesired (Z)-1,3,3,3-tetrafluoropropene isomer from feed ‘2’ was recycled back to raw material feed in tubular reactor which supressed the further formation of (Z)-isomer. The (E)-1,3,3,3-tetrafluoropropene was separated and isolated continuously.
Selectivity:
(E)-R1234ze: 46.02%; (Z)- R1234ze: Nil; HFC-245fa: 39.3 %
Example 7: Preparation of (E)-1,3,3,3-tetrafluoropropene at 250°C
1-chloro-3,3,3-trifluoropropene feed (50gm/hr), anhydrous hydrogen fluoride (100gm/hr) and (Z)-1,3,3,3-tetrafluoropropene feed were preheated separately at 200oC and then super heated at 230oC and combined. The combined feed ‘1’ was then passed in tubular Inconel reactor and reacted in presence of fluorinated chromia ( gm) at a pressure of 5 kg/cm2g and at a temperature of 250°C to obtain (E)-1,3,3,3-tetrafluoropropene.
Selectivity:
(E)-R1234ze: 47.02%; (Z)- R1234ze: Nil; HFC-245fa: 36.3 %
Example 8: Preparation of (E)-1,3,3,3-tetrafluoropropene at 250°C
R245fa feed (45 gm/hr) ‘1’ is preheated at 200oC and then super heated at 230oC and then passed in tubular Inconel reactor and reacted in presence of fluorinated chromia (430 gm) at a pressure of 5 kg/cm2g and at a temperature of 250°C to obtain a feed ‘2’ containing (Z) and (E)-1,3,3,3-tetrafluoropropene. The feed ‘2’ composition was analysed using GC.
Selectivity:
(E)-R1234ze: 34.5 %; (Z)- R1234ze: 7.72%; HFC-245fa: 39.8 %
The undesired (Z)-1,3,3,3-tetrafluoropropene isomer from feed ‘2’ was recycled back to raw material feed in tubular reactor which supressed the further formation of (Z)-isomer. The (E)-1,3,3,3-tetrafluoropropene was separated and isolated continuously.
Selectivity:
(E)-R1234ze: 48.02%; (Z)- R1234ze: Nil; HFC-245fa: 36.3 %
Example 9: Preparation of (E)-1,3,3,3-tetrafluoropropene at 250°C
R245fa feed (45 gm/hr) ‘1’ and (Z)- 1,3,3,3-tetrafluoropropene feed were preheated separately at 200oC and then super heated at 230oC and combined. The combined feed ‘1’ was then passed in tubular Inconel reactor and reacted in presence of fluorinated chromia (430 gm) at a pressure of 5 kg/cm2g and at a temperature of 250°C to obtain (E)-1,3,3,3-tetrafluoropropene.
Selectivity:
(E)-R1234ze: 42.02%; (Z)- R1234ze: Nil; HFC-245fa: 40.3 %
Example 10: Preparation of (E)-1,3,3,3-tetrafluoropropene at 250°C
1-chloro-3,3,3-trifluoropropene feed (45 gm/hr) and anhydrous hydrogen fluoride feed (80 gm/hr) were preheated separately at 200oC and then super heated at 230oC and combined. The combined feed ‘1’ was then passed in tubular Inconel reactor and reacted in presence of fluorinated chromia (430 gm) at a pressure of 5 kg/cm2g and at a temperature of 250°C to obtain a feed ‘2’ containing (Z) and (E)-1,3,3,3-tetrafluoropropene and R245fa. The feed ‘2’ composition was analysed using GC.
Selectivity:
(E)-R1234ze: 38.5%; (Z)- R1234ze: 9.72%; HFC-245fa: 37.3%
The feed ‘2’ was further heated to 350°C. The undesired (Z)-1,3,3,3-tetrafluoropropene isomer from feed ‘2’ was recycled back to raw material feed in tubular reactor which supressed the further formation of (Z)-isomer. The (E)-1,3,3,3-tetrafluoropropene was separated and isolated continuously.
Selectivity:
(E)-R1234ze: 49.02%; (Z)- R1234ze: Nil; HFC-245fa: 31.3%
Example 11: Preparation of (E)-1,3,3,3-tetrafluoropropene at 350°C
1-chloro-3,3,3-trifluoropropene feed (45 gm/hr), (Z)-1,3,3,3-tetrafluoropropene and anhydrous hydrogen fluoride feed (80 gm/hr) were preheated separately at 200oC and then super heated at 200oC and combined. The combined feed ‘1’ was then passed in tubular Inconel reactor and reacted in presence of fluorinated chromia (430 gm) at a pressure of 5 kg/cm2g and at a temperature of 250°C to obtain product feed ‘2’ containing (E)-1,3,3,3-tetrafluoropropene and R245fa.
The feed ‘2’ was further heated to 350°C. The (E)-1,3,3,3-tetrafluoropropene was separated and isolated continuously.
Selectivity:
(E)-R1234ze: 50.02%; (Z)- R1234ze: Nil; HFC-245fa: 30.3%
Example 12: Preparation of (E)-1,3,3,3-tetrafluoropropene at 350°C
1-chloro-3,3,3-trifluoropropene feed (45 gm/hr) and anhydrous hydrogen fluoride (100gm/hr) were preheated at 200oC and then super heated at 230oC and then passed in tubular Inconel reactor and reacted in presence of fluorinated chromia (430 gm) at a pressure of 5 kg/cm2g and at a temperature of 350°C to obtain a feed ‘2’ containing (Z) and (E)-1,3,3,3-tetrafluoropropene. The feed ‘2’ composition was analysed using GC.
Selectivity:
(E)-R1234ze: 39.9%; (Z)- R1234ze: 8.72%; HFC-245fa: 35.3%
The undesired (Z)-1,3,3,3-tetrafluoropropene isomer from feed ‘2’ was recycled back to raw material feed in tubular reactor which supressed the further formation of (Z)-isomer. The (E)-1,3,3,3-tetrafluoropropene was separated and isolated continuously.
Selectivity:
(E)-R1234ze: 43.02%; (Z)- R1234ze: Nil; HFC-245fa: 38.3 %
Example 13: Preparation of (E)-1,3,3,3-tetrafluoropropene at 350°C
1-chloro-3,3,3-trifluoropropene feed (45 gm/hr), anhydrous hydrogen fluoride (100gm/hr) and (Z)-1-chloro-3,3,3-trifluoropropene feed were preheated separately at 200oC and then super heated at 230oC and combined. The combined feed ‘1’ was then passed in tubular Inconel reactor and reacted in presence of fluorinated chromia (430 gm) at a pressure of 5 kg/cm2g and at a temperature of 350°C to obtain (E)-1,3,3,3-tetrafluoropropene.
Selectivity:
(E)-R1234ze: 47.22%; (Z)- R1234ze: Nil; HFC-245fa: 33.3%
Example 14: Preparation of (E)-1,3,3,3-tetrafluoropropene at 350°C
R245fa feed (45 gm/hr) ‘1’ is preheated at 200oC and then super heated at 230oC and then passed in tubular Inconel reactor and reacted in presence of fluorinated chromia (430 gm) at a pressure of 5 kg/cm2g and at a temperature of 350°C to obtain a feed ‘2’ containing (Z) and (E)-1,3,3,3-tetrafluoropropene. The feed ‘2’ composition was analysed using GC.
Selectivity:
(E)-R1234ze: 40.5%; (Z)- R1234ze: 8.72%; HFC-245fa: 32.3%
The undesired (Z)-1,3,3,3-tetrafluoropropene isomer from feed ‘2’ was recycled back to raw material feed in tubular reactor which supressed the further formation of (Z)-isomer. The (E)-1,3,3,3-tetrafluoropropene was separated and isolated continuously.
Selectivity:
(E)-R1234ze: 52.02%; (Z)- R1234ze: Nil; HFC-245fa: 29.3%
Example 15: Preparation of (E)-1,3,3,3-tetrafluoropropene at 350°C
R245fa feed (45 gm/hr) ‘1’ and (Z)-1-chloro-3,3,3-trifluoropropene feed were preheated separately at 200oC and then super heated at 230oC and combined. The combined feed ‘1’ was then passed in tubular Inconel reactor and reacted in presence of fluorinated chromia (430 gm) at a pressure of 5 kg/cm2g and at a temperature of 350°C to obtain (E)-1,3,3,3-tetrafluoropropene.
Selectivity:
(E)-R1234ze: 44.02%; (Z)- R1234ze: Nil; HFC-245fa: 34.3 %
Example 16: Preparation of (E)-1,3,3,3-tetrafluoropropene at 350°C
1-chloro-3,3,3-trifluoropropene feed (45 gm/hr) and anhydrous hydrogen fluoride feed (80 gm/hr) were preheated separately at 200oC and then super heated at 230oC and combined. The combined feed ‘1’ was then passed in tubular Inconel reactor and reacted in presence of fluorinated chromia (430 gm) at a pressure of 5 kg/cm2g and at a temperature of 350°C to obtain a feed ‘2’ containing (Z) and (E)-1,3,3,3-tetrafluoropropene and R245fa. The feed ‘2’ composition was analysed using GC.
Selectivity:
(E)-R1234ze: 43.5%; (Z)- R1234ze: 10.72%; HFC-245fa: 30.3%
The feed ‘2’ was further heated to 350°C. The undesired (Z)-1,3,3,3-tetrafluoropropene isomer from feed ‘2’ was recycled back to raw material feed in tubular reactor which supressed the further formation of (Z)-isomer. The (E)-1,3,3,3-tetrafluoropropene was separated and isolated continuously.
Selectivity:
(E)-R1234ze: 44.52%; (Z)- R1234ze: Nil; HFC-245fa: 31.3%
Example 17: Preparation of (E)-1,3,3,3-tetrafluoropropene at 350°C
1-chloro-3,3,3-trifluoropropene feed (45 gm/hr), (Z)-1,3,3,3-tetrafluoropropene and anhydrous hydrogen fluoride feed (80 gm/hr) were preheated separately at 200oC and then super heated at 230oC and combined. The combined feed ‘1’ was then passed in tubular Inconel reactor and reacted in presence of fluorinated chromia (430 gm) at a pressure of 5 kg/cm2g and at a temperature of 350°C to obtain product feed ‘2’ containing (E)-1,3,3,3-tetrafluoropropene and R245fa.
The feed ‘2’ was further heated to 350°C. The (E)-1,3,3,3-tetrafluoropropene was separated and isolated continuously.
Selectivity:
(E)-R1234ze: 56.02%; (Z)- R1234ze: Nil; HFC-245fa: 28.3%
Comparative example 1: Preparation of (E)-1,3,3,3-tetrafluoropropene at 250°C
1-chloro-3,3,3-trifluoropropene feed (68 gm/hr) and anhydrous hydrogen fluoride feed (108 gm/hr) were preheated separately at 200oC and then super heated at 230oC and combined. The combined feed ‘1’ was then passed in tubular Inconel reactor and reacted in presence of fluorinated chromia (500 gm) at a pressure of 5 kg/cm2g and at a temperature of 250°C to obtain a feed ‘2’ containing (Z) and (E)-1,3,3,3-tetrafluoropropene. The feed ‘2’ composition was analysed using GC.
Selectivity:
(E)-R1234ze: 33.5 %; (Z)-R1234ze: 6.72 %; HFC-245fa: 39.3 %
The feed ‘2’ was further heated to 350°C. The (E)-1,3,3,3-tetrafluoropropene was separated and isolated continuously.
Selectivity:
(E)-R1234ze: 32.5%; (Z)-R1234ze: 5.72%
Comparative example 2: Preparation of (E)-1-chloro-3,3,3-trifluoropropene
HCC-240fa feed (78gm/hr) and anhydrous hydrogen fluoride feed (72gm/hr) were preheated separately at 200°C and then super heated at 230°C and combined. The -combined feed ‘1’ was then passed in tubular Inconel reactor and reacted in presence of fluorinated chromia (430 gm) at a pressure of 5 kg/cm2g and at a temperature of 250°C to obtain a feed ‘2’ containing (Z) and (E)-1-chloro-3,3,3-trifluoropropene. The feed ‘2’ composition was analysed using GC.
Selectivity:
(E)-R1233zd: 58%; (Z)-R1233zd: 16.6%
The feed ‘2’ was further heated to 350°C. The (E)-1, 3,3,3 tetrafluoropropene was separated and isolated continuously.
Selectivity:
(E)-R1233zd: 60.05%; (Z)-R1233zd: 14.2%
Purity by GC: 81.1

CLAIMS:WE CLAIM:
1. A process for selective preparation of trans-isomer of hydrofluoroolefin, comprising a step of supplying corresponding cis-isomer to raw material feed.

2. The process as claimed in claim 1, wherein the amount of cis-isomer supplied to the raw material feed is in the range of 1 to 30%.

3. The process as claimed in claim 1, wherein cis-isomer is supplied to raw material feed either by recycling of cis-isomer formed in the process or by supplying fresh feed of cis-isomer.

4. The process as claimed in claim 1, wherein hydrofluoroolefin is selected from a group consisting of 1-chloro-3,3,3-trifluoropropene, 1,3,3,3-tetrafluoropropene or mixture thereof.

5. The process as claimed in claim 1, wherein the raw material feed comprises hydrogen fluoride and any one or more of chloroalkane, fluoroalkane, chlorofluoroalkene, selected from a group consisting of 1,1,3,3,3-pentachloropropane, 1,1,3,3,3-pentafluoropropane, 1-chloro-3,3,3-trifluoropropene or a mixture thereof.

6. The process as claimed in claim 1, wherein the raw material feed is passed through a catalyst.

7. The process as claimed in claim 6, wherein the catalyst is selected from a group consisting of fluorinated chromia, chromium oxide, metal fluoride such as chromium trifluoride (CrF3) or aluminium trifluoride (AlF3) and combinations thereof.

8. The process as claimed in claim 6, wherein the raw material feed is passed through a catalyst at a temperature between 100-450oC.

9. The process as claimed in claim 6, wherein the raw material feed is passed through a catalyst at a pressure of 0-20 kg/cm2.

10. The process as claimed in claim 1, wherein the process is carried out in vapour phase.