Formation of haloolefins within the adiabatic reaction zone

Abstract

This invention provides a system for efficiently performing dehalogenation and hydrogenation of hydrohaloalkanes. [Solution] The present invention is a process for efficiently dehalogenating hydrohaloalkanes CF3CFClCH3 and recovering haloolefins CF3CF=CH2 by using a plurality of series-connected adiabatic reactors 260, 261, and 262 that generate reaction products and perform thermal decomposition, and heat exchangers 250, 280, and 281 that have fluid communication between each pair of reactors in series and generate intermediate products.

Description

Technical Field

[0001] The present disclosure relates to a process for producing haloolefins such as fluoropropene within an adiabatic reaction zone.

Background Art

[0002] Hydrochlorocarbons (HCCs), hydrochlorofluorocarbons (HCFCs), and chlorofluorocarbons (CFCs) are versatile compounds that have been used in a wide variety of applications, including as aerosol propellants, refrigerants, cleaning agents, blowing agents for thermoplastic and thermosetting foams, heat transfer media, gas dielectrics, fire extinguishing and fire suppression agents, working fluids for power cycles, polymerization media, particulate removal fluids, carrier fluids, buffing abrasives, and replacement desiccants. The industry has been working for the past several decades to find alternatives to HCCs, HCFCs, and CFCs that have lower potential for ozone layer depletion and other environmental benefits. In the search for replacements for HCCs, CFCs, and HCFCs, the use of hydrofluorocarbons (HFCs) has been noted in many industries.

[0003] HFCs are not a cause of stratospheric ozone layer depletion but are a concern because they contribute to the "greenhouse effect," i.e., they contribute to global warming. As a result of contributing to global warming, HFCs have also come under intense scrutiny, and their widespread use may be limited in the future as was the case with CFCs and HCFCs. Therefore, there is a need for chemical compounds that have both a low ozone depleting potential (ODP) and a low global warming potential (GWP).

[0004] Certain hydrofluoroolefins (HFOs) have been identified as having both a low ozone depletion potential (ODP) and a low global warming potential (GWP). CF3CF=CH2 (HFO-1234yf) and CF3CH=CHF (HFO-1234ze), both of which have zero ozone depletion potential and a low global warming potential, have been identified as potential refrigerants. Other hydrofluoroolefins, such as CF3CH=CHCF3 (HFO-1336mzz) and the hydro(fluoro)chloroolefin CF3-CH=CHCl (HCFO-1233zd), have been identified as blowing agents. Other HFOs also have value as alternatives in other applications.

[0005] Hydrofluoroolefins and intermediates for producing hydrofluoroolefins can be produced by the dehydrohalogenation of hydrochloroalkanes, hydrochlorofluorocarbons, or hydrofluorocarbons, collectively "hydrohaloalkanes".

[0006] Chloroolefins, chlorofluoroolefins, and fluoroolefins, collectively "haloolefins", can all be desired products for use as intermediates for producing desired chemical compounds, for example, having both a low ozone depletion potential (ODP) and a low global warming potential (GWP). For example, chloroolefins, chlorofluoroolefins, and fluoroolefins can all be intermediates used to produce HFO-1234yf, or HFO-1234ze, or HFO-1336mzz, or HCFO-1233zd.

[0007] The dehydrohalogenation reaction produces corrosive HCl or HF. The dehydrohalogenation reaction can be catalytic or pyrolytic. Such reactions can be carried out at relatively high temperatures (e.g., above 180 °C for catalytic reactions or above 350 °C for pyrolytic reactions). The dehydrohalogenation reaction is also endothermic, and thus the reaction rate is very sensitive to temperature / heat supply.

[0008] The characteristics of the above-described dehalogenation reaction must be addressed in the process design and reaction zone. In a typical dehalogenation process, a single multi-tube reactor is used to facilitate heat transfer and maintain the temperature of the endothermic reaction. [Overview of the project] [Means for solving the problem]

[0009] This disclosure relates to a process for producing a product comprising at least one haloolefin (haloalkene) by dehalogenation of a hydrohaloalkane. Thus, the process is a dehalogenation process. The process is carried out in the liquid or gas phase, in the presence or absence of a catalyst, at a temperature sufficient to carry out the conversion of the hydrohaloalkane to a haloolefin in an adiabatic reaction zone. Specifically, the adiabatic reaction zone comprises at least two series-connected adiabatic reactors and has heat exchangers arranged sequentially, with fluid communication between each pair of reactors in series. In other words, the reaction zone comprises at least two reactors, each reactor operating adiabatically and arranged in series, with a heat exchanger arranged in series between the two reactors. The process further comprises the step of recovering the product comprising the haloolefin from the reaction zone.

[0010] Therefore, according to one aspect of the present disclosure, a process is provided for the dehalogenation of hydrohaloalkanes in an adiabatic reaction zone, the process being (a) A step of providing an adiabatic reaction zone comprising at least two series-connected adiabatic reactors and having heat exchangers arranged sequentially and providing fluid communication between each pair of reactors in series, (b) A step of introducing a starting material containing a hydrohaloalkane into a first adiabatic reactor among the reactors connected in series to produce a reaction product, (c) A step of passing the reaction product from the preceding reactor to a heat exchanger to generate an intermediate product, (d) A step of introducing the intermediate product from the heat exchanger to the subsequent adiabatic reactor to generate the reaction product, (e) A step in which steps (c) and (d) are optionally repeated one or more times in order, (f) A step of recovering the final product, wherein the final product is a reaction product generated in the final adiabatic reactor, and the final adiabatic reactor is a subsequent adiabatic reactor that does not have a subsequent adiabatic reactor in the adiabatic reaction zone downstream of the final adiabatic reactor. The final product contains a haloolefin.

[0011] The process disclosed herein provides an adiabatic reaction zone comprising at least two series-connected adiabatic reactors (step (a)). Starting materials comprising a hydrohaloalkane are introduced into a first adiabatic reactor within the adiabatic reaction zone (step (b)).

[0012] Optionally, the process further includes step (a') prior to step (b), in which a starting material containing a hydrohaloalkane is introduced into a heat exchanger in the adiabatic reaction zone upstream of the first adiabatic reactor to produce a heated starting material. The heated starting material from step (a') is the starting material introduced into the first adiabatic reactor in step (b).

[0013] Optionally, the starting material may contain other components. Alternatively, the other components may be introduced into the first adiabatic reactor separately from the starting material.

[0014] Subsequently, the reaction product from the first adiabatic reactor passes through a heat exchanger to provide an intermediate product (step (c)). The intermediate product is then introduced into a subsequent adiabatic reactor (step (d)) to produce a reaction product, and the process continues to achieve the desired conversion of the hydrohaloalkane or other desired result.

[0015] Optionally, the processes disclosed herein include repeating steps (c) and (d) one or more times. In one embodiment, steps (c) and (d) are performed 1 to 9 times, i.e., steps (c) and (d) are repeated 0 to 8 times, resulting in the adiabatic reaction zone having a total of 2 to 10 adiabatic reactors connected in series. When steps (c) and (d) are repeated once, the reaction zone has a total of three reactors: a first adiabatic reactor, a second adiabatic reactor, and a final adiabatic reactor. Thus, the second and final adiabatic reactors are subsequent reactors in step (d), respectively.

[0016] In one option of the process disclosed herein, steps (c) and (d) are not repeated, and the adiabatic reaction zone consists of two adiabatic reactors (a first adiabatic reactor and a final (subsequent) adiabatic reactor).

[0017] The process further includes a step of recovering the final product, which is the reaction product generated in the final adiabatic reactor.

[0018] As described herein, the adiabatic reactor is arranged in series with a heat exchanger located between two series-connected reactors within an adiabatic reaction zone. Thus, in the adiabatic reaction zone, the first adiabatic reactor has no preceding reactor, and the final adiabatic reactor has no succeeding reactor. Similarly, the adiabatic reaction zone includes at least a first adiabatic reactor and a final adiabatic reactor, or in other words, at least one preceding reactor (the first adiabatic reactor) and at least one succeeding reactor (the final adiabatic reactor). The heat exchanger is located upstream of each succeeding reactor and is in fluid communication with each succeeding reactor.

[0019] Hydrohaloalkanes are given by formula Y 1 Y 2 CH-CXY 3 Y 4 The formula has such that X is halo and each Y is 1, 2, 3, and 4. iis independently H, halo, alkyl, or haloalkyl, where halo is F, Cl, Br, or I, provided that at least one Y i is halo or haloalkyl. A haloolefin has the formula Y 1 Y 2 C=CY 3 Y 4 and may have the formula: BRIEF DESCRIPTION OF THE DRAWINGS

[0020] [Figure 1] FIG. 1 is a flow diagram showing a prior art dehydrohalogenation process having a single multi-tube reactor operating isothermally. [Figure 2] FIG. 2 is a flow diagram showing one embodiment of the dehydrohalogenation process of the present disclosure having three adiabatic reactors with an adiabatic reaction zone disposed upstream of each subsequent adiabatic reactor and in fluid communication with a heat exchanger for each subsequent adiabatic reactor. DETAILED DESCRIPTION OF THE INVENTION

[0021] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," or any other variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0022] Where a quantity, concentration, or other value or parameter is given as a range, a preferred range, or a list of preferred upper and / or preferred lower values, these shall be understood to specifically disclose all ranges formed by any pair of any upper or preferred upper range values ​​and any lower or preferred lower range values, regardless of whether the ranges are disclosed separately. Where a numerical range is described herein, unless otherwise indicated, this range is intended to encompass its endpoints and all integers and fractions within that range.

[0023] Before referring to the details of the embodiments described below, some terms will be defined or clarified.

[0024] As used herein, the term "haloolefin" means a molecule containing carbon, fluorine, and / or chlorine, and / or bromine, and / or iodine, as well as a carbon-carbon double bond. Examples are described throughout this specification.

[0025] The term "hydrohaloolefin," as used herein, means a molecule containing hydrogen, carbon, fluorine, and / or chlorine, and / or bromine, and / or iodine, as well as a carbon-carbon double bond (halo = fluoro, chloro, bromo, iod). Examples are described throughout this specification. Hydrofluoroolefins may be designated as "HFO". Hydrochlorofluoroolefins may be designated as "HCFO".

[0026] Those skilled in the art should recognize that certain haloolefins and certain hydrohaloolefins have (E- and Z-) isomers. Therefore, the products produced herein may contain one or both of these isomers. The relative amounts of the isomers may vary depending on the reaction conditions.

[0027] The term "hydrohaloalkane," as used herein, means a molecule containing hydrogen, carbon, fluorine, and / or chlorine, and / or bromine, and / or iodine, and which does not have a carbon-carbon double bond (halo = fluoro, chloro, bromo, iod). Examples are described throughout this specification.

[0028] The term "dehalogenation," as used herein, means the loss of HX from a hydrohaloalkane, where X = F, Cl, Br, I, and H and X are located on adjacent carbon atoms in the hydrohaloalkane. For example, the terms "defluorinated," "defluorinated," or "defluorinated," as used herein, mean the process in which hydrogen and fluorine are removed from adjacent carbon atoms in the molecule. The terms "dechlorinated," "dechlorinated," or "dechlorinated," as used herein, mean the process in which hydrogen and chlorine are removed from adjacent carbon atoms in the molecule.

[0029] The term "thermal," as used herein, means relating to or indicating a reactor, process, or conditions within a reaction zone where heat is not intentionally added to or removed from the reaction zone. It will be understood by those skilled in the art that even with the best thermal insulation, some heat may be lost from a reaction zone operating above ambient temperature (or conversely, gained in a reaction zone operating below ambient temperature).

[0030] The term “preceding adiabatic reactor” or “preceding reactor” as used herein means an adiabatic reactor that does not have an adiabatic reactor upstream of it in an adiabatic reaction zone. The term “successive adiabatic reactor” or “successive reactor” as used herein means an adiabatic reactor that has at least one adiabatic reactor upstream of it in an adiabatic reaction zone. The term “final adiabatic reactor” or “final adiabatic reactor” as used herein means an adiabatic reactor that does not have an adiabatic reactor downstream of it in an adiabatic reaction zone. Notwithstanding the foregoing, there may be one or more reactors upstream or downstream of an adiabatic reactor in an adiabatic reaction zone, and there may be multiple adiabatic reaction zones, for which the definitions of preceding adiabatic reactor, succeeding adiabatic reactor, and final adiabatic reactor apply only to the adiabatic reactors in each adiabatic reaction zone.

[0031] The compounds referred to herein may be referred to by code based on fluorochemical nomenclature, chemical structure, and / or chemical name. For convenience and reference, selected compounds with codes, structures, and chemical names are provided in Table 1.

[0032] [Table 1-1]

[0033] [Table 1-2]

[0034] This disclosure provides a process for the dehalogenation of hydrohaloalkanes, the process comprising: (a) providing an adiabatic reaction zone comprising at least two series-connected adiabatic reactors and having heat exchangers arranged sequentially and with fluid communication between each pair of series reactors; (b) introducing a starting material containing a hydrohaloalkane into a first adiabatic reactor of the series-connected reactors to produce a reaction product; (c) passing the reaction product from the preceding adiabatic reactor through a heat exchanger to produce an intermediate product; (d) introducing the intermediate product from the heat exchanger into a subsequent adiabatic reactor to produce a reaction product; optionally repeating steps (c) and (d) one or more times; and (e) recovering a final product, wherein the final product is a reaction product produced in a final adiabatic reactor, and the final adiabatic reactor is a subsequent adiabatic reactor that does not have any subsequent adiabatic reactors in the adiabatic reaction zone downstream of the final adiabatic reactor. In process (c), the heat exchanger is located downstream of the preceding adiabatic reactor and is in fluid communication with the preceding adiabatic reactor.

[0035] This disclosure provides a process for dehalogenating a starting material containing a hydrohaloalkane to produce a final product containing a haloolefin.

[0036] Hydrohaloalkanes are given by formula Y 1 Y 2 CH-CXY 3 Y 4 Y has the following characteristics, where X is F, Cl, Br, or I, and i is 1, 2, 3, and 4. i Each of them is independently selected from H, F, Cl, Br, I, alkyl groups, or haloalkyl groups, provided that at least one Y is included. i is not H, or at least one Y iis a haloalkyl group, and the haloalkyl group is a fluoroalkyl group, a chloroalkyl group, a bromoalkyl group, or an iodoalkyl group, i.e., halo = fluoro, chloro, bromo, or iodo. In some embodiments, the alkyl group is a C1-C3 alkyl group. In some embodiments, the haloalkyl group is a C1-C3 haloalkyl group. The corresponding haloolefin is of formula Y 1 Y 2 C=CY 3 Y 4 It has.

[0037] Hydrohaloalkanes may be hydrochloroalkanes (containing H, Cl, and C) or may comprise hydrochloroalkanes (containing H, Cl, and C). Hydrohaloalkanes may be hydrofluorochloroalkanes (containing H, F, Cl, and C) or may comprise hydrofluorochloroalkanes (containing H, Cl, F, and C). Hydrohaloalkanes may be hydrofluoroalkanes (containing H, F, and C) or may comprise hydrofluoroalkanes (containing H, F, and C). Bromo and iodine-containing hydrohaloalkanes are also intended herein.

[0038] In some embodiments, the disclosure provides a process for producing at least one haloethene (haloethylene) product from a starting material containing a hydrohaloethane. Hydrohaloethane is a compound of formula Y 1 Y 2 CH-CXY 3 Y 4 It may have, where X is halo, and each Y i (i are 1, 2, 3, and 4) independently are H or halo, and halo is F, Cl, Br, I, but with at least one Y i is a halo. An example of a hydrohaloethane is 1-chloro-1,1-difluoroethane (CF2ClCH3), and an example of a haloethylene is vinylidene fluoride (CF2=CH2). A second example of a hydrohaloethane is 1,1-difluoroethane (CHF2CH3), and an example of a haloethylene is vinyl fluoride (CHF=CH2).

[0039] This disclosure provides a process for producing at least one halopropene product from a starting material containing hydrohalopropane. Hydrohalopropane is a compound of formula Y 1 Y 2 CH-CXY 3 Y 4 The formula has, where X is halo and three Y i (i are 1, 2, 3, and 4) independently are H or halo, and other Y i is a C1 alkyl or C1 haloalkyl, where halo is F, Cl, Br, or I, but furthermore, at least one Y i It is a halo or haloalkyl.

[0040] Typical hydrohalopropanes include CF3CFClCH3, CF3CHFCH2Cl, CF3CHClCH2F, CF3CH2CHFCl, CF3CHFCH2F, CF3CH2CHF2, CF3CF2CH3, CF3CFClCH2F, CF3CHFCHFCl, CF3CHClCHF2, CF3CH2CF2Cl, CF3CHClCH3, CF3CHClCH2Cl, CF3CH2CH2Cl, CCl3CH2CHCl2, CCl3CHClCH2Cl, CCl3CH2CH2Cl, CH2ClCCl2CHCl2, and mixtures of two or more of these.

[0041] Hydrohalopropane may be hydrochloropropane or may contain hydrochloropropane. Hydrochloropropane may be CCl3CHClCH2Cl, CCl3CH2CHCl2, CCl3CH2CH2Cl, and mixtures of two or more of these, or may contain these.

[0042] Hydrohalopropane may be or may contain hydrochlorofluoropropane. Hydrochlorofluoropropane may be CF3CHClCCl3, CF3CFClCHCl2, CF3CF2CHCl2, CF3CHFCHCl2, CF3CFClCH2Cl, CF3CF2CH2Cl, CF3CHFCHFCl, CF3CHClCHF2, CF3CH2CF2Cl, CF3CCl2CH3, CF3CHClCH2Cl, CF3CH2CHCl2, CF2ClCH2CHFCl, CF3CFClCH3, CF3CHClCH2F, CF3CHFCH2Cl, CF3CH2CHFCl, CF3CHClCH3, CF3CH2CH2Cl, or a mixture of two or more of these, or may contain these. In one embodiment, hydrochlorofluoropropane is CF3CFClCH3.

[0043] Hydrohalopropane may be hydrofluoropropane or may contain hydrofluoropropane. Hydrofluoropropane may be CF3CF2CH2F, CF3CHFCHF2, CF3CF2CH3, CF3CHFCH2F, CF3CH2CHF2, CF3CH2CH2F, or a mixture of two or more of these, or may contain these. Hydrohalopropane may be hydrofluoropropane. Hydrofluoropropane may be CF3CHFCH2F, or CF3CH2CHF2, or CF3CF2CH3, or a mixture of two or more of these.

[0044] In one embodiment, the starting material comprises a hydrohalopropane having the formula CF3CFQCH3, where Q is Cl or F. The starting material may also comprise CF3CF2CH3. The starting material may also comprise CF3CFClCH3. Dehalogenation of CF3CFClCH3 yields a product containing CF3CF=CH2. Dehalogenation of CF3CFClCH3 may yield a product containing CF3CF=CH2 and a mixture of E-CF3CH=CHF and Z-CF3CH=CHF.

[0045] In one embodiment, dehalogenation of hydrohalopropane produces a product containing halopropene. In a particular embodiment, the product contains chloropropene. In another embodiment, the product contains fluorochloropropene. In yet another embodiment, the product contains fluoropropene.

[0046] In one embodiment, the hydrohalopropane is CH2ClCHClCCl3 or contains CH2ClCHClCCl3, and the chloropropene is CH2ClCCl=Cl2 (240 dB → 1230 x a) or contains CH2ClCCl=Cl2 (240 dB → 1230 x a).

[0047] In one embodiment, the hydrohalopropane is CF3CFClCH3 or contains CF3CFClCH3, and the hydrofluoropropene is CF3CF=CH2(244bb→1234yf) or contains CF3CF=CH2(244bb→1234yf).

[0048] In another embodiment, the hydrohalopropane is CF3CHFCH2Cl or comprises CF3CHFCH2Cl, and the halopropene is CF3CF=CH2(244eb→1234yf) or comprises CF3CF=CH2(244eb→1234yf).

[0049] In another embodiment, the hydrohalopropane is CF3CHClCH2F or comprises CF3CHClCH2F, and the halopropene is E- and / or Z-CF3CH=CHF(244db→1234ze) or comprises E- and / or Z-CF3CH=CHF(244db→1234ze).

[0050] In another embodiment, the hydrohalopropane is CF3CH2CHFCl or comprises CF3CH2CHFCl, and the halopropene is E- and / or Z-CF3CH=CHF(244fa→1234ze) or comprises E- and / or Z-CF3CH=CHF(244fa→1234ze).

[0051] In another embodiment, the hydrohalopropane is CF3CFClCH2F or comprises CF3CFClCH2F, and the halopropene is E- and / or Z-CF3CF=CHF(235bb→1225ye) or comprises E- and / or Z-CF3CF=CHF(235bb→1225ye).

[0052] In another embodiment, the hydrohalopropane is CF3CF2CH2Cl or comprises CF3CF2CH2Cl, and the halopropene is E- and / or Z-CF3CF=CHCl(235cb→1224yd) or comprises E- and / or Z-CF3CF=CHCl(235cb→1224yd).

[0053] In another embodiment, the hydrohalopropane is CF3CHClCHF2 or comprises CF3CHClCHF2, and the halopropene is CF3CH=CF2(235da→1225zc) or comprises CF3CH=CF2(235da→1225zc).

[0054] In another embodiment, the hydrohalopropane is CF3CH2CF2Cl or comprises CF3CH2CF2Cl, and the halopropene is CF3CH=CF2(235fa→1225zc) or comprises CF3CH=CF2(235fa→1225zc).

[0055] In another embodiment, the hydrohalopropane is CF3CHClCCl3 or comprises CF3CHClCCl3, and the halopropene is CF3CCl=CCl2(223dB → 1213xa) or comprises CF3CCl=CCl2(223dB → 1213xa).

[0056] In another embodiment, the hydrohalopropane is CF3CHClCH2Cl or comprises CF3CHClCH2Cl, and the halopropene is CCl=CH2(243dB → 1233xf) or comprises CCl=CH2(243dB → 1233xf).

[0057] In another embodiment, the hydrohalopropane is CF3CH2CHCl2 or comprises CF3CH2CHCl2, and the halopropene is E- and / or Z-CF3CH=CHCl(243fa→1233zd) or comprises E- and / or Z-CF3CH=CHCl(243fa→1233zd).

[0058] In another embodiment, the hydrohalopropane is CF3CH2CH2Cl or contains CF3CH2CH2Cl, and the halopropene is CF3CH=CH2(253fb→1243zf) or contains CF3CH=CH2(253fb→1243zf).

[0059] In certain embodiments, the hydrohalopropane is CF3CF2CH2F or comprises CF3CF2CH2F, and the halopropene is E- and / or Z-CF3CF=CHF(236cb→1225ye) or comprises E- and / or Z-CF3CF=CHF(236cb→1225ye).

[0060] In another embodiment, the hydrohalopropane is CF3CHFCHF2 or comprises CF3CHFCHF2, and the halopropene is E- and / or Z-CF3CF=CHF(236ea→1225ye) or comprises E- and / or Z-CF3CF=CHF(236ea→1225ye).

[0061] In another embodiment, the hydrohalopropane is CF3CF2CH3 or contains CF3CF2CH3, and the halopropene is CF3CH=CH2(245cb→1234yf) or contains CF3CH=CH2(245cb→1234yf).

[0062] In another embodiment, the hydrohalopropane is CF3CHFCH2F or comprises CF3CHFCH2F, and the halopropene is CF3CH=CH2(245eb→1234yf) or comprises CF3CH=CH2(245eb→1234yf).

[0063] In another embodiment, the hydrohalopropane is CF3CH2CHF2 or comprises CF3CH2CHF2, and the halopropene is E- and / or Z-CF3CH=CHF(245fa→1234ze) or comprises E- and / or Z-CF3CH=CHF(245fa→1234ze).

[0064] In one embodiment, the hydrohaloalkane is or comprises hydrochloropropane, which undergoes hydrofluoric acid treatment and dehalogenation in the presence of HF and a catalyst to form fluoro(chloro)propene. In a particular embodiment, the hydrochloropropane is or comprises 1,1,1,3-tetrachloropropane (250fb), and the product from dehalogenation comprises 3,3,3-trifluoropropene (1243zf).

[0065] If the haloolefin is 1243zf, the process optionally further includes the steps of: chlorinating 1243zf to produce a product containing 243db; dehydrochlorinating 243db to produce a product containing 1233xf; treating 1233xf with hydrogen fluoride to produce a product containing 244bb; and dehydrochlorinating 244bb to produce a product containing 1234yf. Optionally, the process further includes the step of purifying each product. Therefore, in this example, the process may further include the step of purifying the product containing 1243zf, the product containing 243db, the product containing 1233xf, the product containing 244bb, the product containing 1234yf, or two or more of the products.

[0066] If the haloolefin is 1225ye, the process optionally further comprises the steps of hydrogenating 1225ye to produce a product containing 245eb, and dehydrofluorinating 245eb to produce a product containing 1234yf. Optionally, the process optionally further comprises the steps of purifying the product containing 1225ye and / or the product containing 245eb.

[0067] If the haloolefin is 1225zc, the process optionally further comprises the steps of hydrogenating 1225zc to produce a product containing 245fa, and dehydrofluorinating 245fa to produce a product containing E- and / or Z-1234ze. Optionally, the process optionally further comprises the steps of purifying the product containing 245fa and / or the product containing E- and / or Z-1234ze.

[0068] If the haloolefin is 1233xf, the process optionally further comprises the steps of: treating 1233xf with hydrogen fluoride to produce a product containing 244bb; and dehydrochlorinating 244bb to produce a product containing 1234yf. Optionally, the process optionally further comprises the steps of purifying the product containing 1233xf and / or purifying the product containing 244bb and / or purifying the product containing 1234yf.

[0069] If a product containing 1234yf is generated, the process optionally further includes a step of purifying the product containing 1234yf.

[0070] This disclosure provides a process for producing at least one hydrohalobutene product from a starting material containing hydrohalobutene. Hydrohalobutene is a compound of the formula Y 1 Y 2 CH-CXY 3 Y 4 It may have, where X is a halo and two Y i (i are 1, 2, 3, and 4) are C1 alkyl or C1 haloalkyl, and the remaining two Y i It is independently either H or a halo, or one Y i The first is C2 alkyl or C2 haloalkyl, and the remaining three Y i Each is independently either H or halo, and halo is F, Cl, Br, or I, provided that at least one Y i It is a halo or haloalkyl.

[0071] Representative hydrohalobutanes include CF3CHClCHClCF3, CF3CCl2CH2CF3, CF3CH2CHClCF3, and mixtures thereof. Examples of halobutenes include CF3CCl=CHCF3 and E- and / or Z-CF3CH=CHCF3.

[0072] Dehalogenation of hydrohalobutane produces a product containing halobutene. In one embodiment, the hydrohalobutane is hydrochlorofluorobutane or comprises hydrochlorofluorobutane, and the halobutene is fluorobutene or comprises fluorobutene.

[0073] In certain embodiments, the halobutane is CF3CHClCHClCF3 or comprises CF3CHClCHClCF3, and the halobutene is E- and / or Z-CF3CCl=CHCF3(336mdd→1326mxz) or comprises E- and / or Z-CF3CCl=CHCF3(336mdd→1326mxz).

[0074] In another embodiment, the halobutane is CF3CCl2CH2CF3 or comprises CF3CCl2CH2CF3, and the halobutene is E- and / or Z-CF3CCl=CHCF3(336mfa→1326mxz) or comprises E- and / or Z-CF3CCl=CHCF3(336mfa→1326mxz).

[0075] In one embodiment, the halobutane is CF3CHClCH2CF3 or contains CF3CHClCH2CF3, and the halobutene is E- and / or Z-CF3CH=CHCF3(346mdf→1336mzz) or contains E- and / or Z-CF3CH=CHCF3(346mdf→1336mzz).

[0076] This disclosure provides a process for producing at least one hydrohalopenten product from a starting material containing hydrohalopentan. Hydrohalopentan is a compound of formula Y 1 Y 2CH-CXY 3 Y 4 It may have, where X is halo and three Y i is a C1 alkyl or C1 haloalkyl group, and the remaining Y i is either H or a halo, or one Y i is a C2 alkyl or C2 haloalkyl group, and one Y i is a C1 alkyl or C1 haloalkyl group, and the remaining Y i is either H or a halo, or one Y i (i is 1, 2, 3, and 4) is a C3 alkyl or C3 haloalkyl, and the remaining Y i is H or halo, and halo is F, Cl, Br, or I, but with at least one Y i It is a halo or haloalkyl.

[0077] Hydrohalopentanes can be selected from CF3CCl2CH2C2F5, CF3CHClCHClC2F5, CF3CHClCH2C2F5, CF3CF(CF3)CFClCH3, and mixtures thereof. Examples of halopentenes include CF3CCl=CHC2F5, CF3CH=CHC2F5, and CF3CF(CF3)CF=CH2.

[0078] Higher-grade haloalkenes can also be produced using the processes disclosed herein.

[0079] The dehalogenation process is carried out within an adiabatic reaction zone. The adiabatic reaction zone comprises at least two series-connected adiabatic reactors and has a fluid-connected heat exchanger positioned between each pair of series reactors.

[0080] The adiabatic reaction zone comprises a first adiabatic reactor and a final adiabatic reactor. The first adiabatic reactor is an adiabatic reactor that precedes any adiabatic reactor or heat exchanger downstream of the first adiabatic reactor within the adiabatic reaction zone. The final adiabatic reactor is an adiabatic reactor that follows any adiabatic reactor or heat exchanger upstream of the final adiabatic reactor within the adiabatic reaction zone.

[0081] The first adiabatic reactor is located upstream of the heat exchanger and is in fluid communication with the heat exchanger. The heat exchanger is in fluid communication with the subsequent adiabatic reactor and is located upstream of the subsequent adiabatic reactor.

[0082] In one embodiment, the adiabatic reaction zone consists of two reactors (a first adiabatic reactor and a final adiabatic reactor). In this embodiment, the heat exchanger is located downstream of the first adiabatic reactor and upstream of the final adiabatic reactor.

[0083] Those skilled in the art will understand the relationship between a first adiabatic reactor having no preceding (upstream) reactors, a subsequent reactor having at least one preceding reactor, and a final reactor having no subsequent (downstream) reactors and being the subsequent reactor in step (c). The adiabatic reactors within the adiabatic reaction zone are in fluid communication with a heat exchanger, which is located between the two reactors.

[0084] In one embodiment, the adiabatic reaction zone consists of a first adiabatic reactor, a second adiabatic reactor (which may also be referred to as a subsequent adiabatic reactor), and a final adiabatic reactor, which is also a subsequent adiabatic reactor according to step (d) of the process disclosed herein, thus comprising a total of three reactors, each reactor operating adiabatically, with a heat exchanger positioned between the first and second adiabatic reactors, and another heat exchanger positioned between the second and final adiabatic reactors. Thus, steps (c) and (d) are repeated once. Those skilled in the art may intend to use more than three reactors, such as repeating steps (c) and (d) two or three or more times.

[0085] The number of adiabatic reactors and heat exchangers, where a heat exchanger is placed between two reactors in the adiabatic reaction zone, may be limited based on practical reasons such as controlling cost and complexity, or on achieving specific goals such as the transformation of starting materials or the formation of specific products. Two or more adiabatic reactors are used in the adiabatic reaction zone, for example, with 2 to 10 reactors (0 to 8 repetitions of steps (c) and (d)), or with 2 to 4 reactors (0 to 2 repetitions of steps (c) and (d)).

[0086] The adiabatic reactor may be of any shape that facilitates the implementation of a dehalogenation process as disclosed herein. In certain embodiments, each reactor is a cylindrical tube or pipe, which may be linear or coiled. A plug-flow design is preferred because it minimizes backmixing, resulting in a lower overall conversion rate.

[0087] Due to the corrosive nature of the dehalogenation processes described herein, the adiabatic reactors used within the adiabatic reaction zones disclosed herein are constructed from corrosion-resistant materials. Such materials include stainless steel, specifically austenitic or copper-clad steel, or nickel alloys, or gold, or gold-plated or quartz. Nickel alloys are commercially available and include, for example, high-nickel alloys such as Monel® nickel-copper alloy, Hastelloy® nickel alloy, and Inconel® nickel-chromium alloy. In one embodiment, the reactor is constructed from a nickel alloy. The adiabatic reactor may be lined with a fluoropolymer, provided that the fluoropolymer is suitable for the temperature. Other materials may include SiC or graphite for corrosion resistance.

[0088] In addition to the adiabatic reactors of the adiabatic reaction zone disclosed herein, heat exchangers, effluent lines, units related to mass transfer, contact vessels (premixers), distillation columns, and feed and material transfer lines associated with the reactors, heat exchangers, vessels, columns, and units used in the processes of the embodiments disclosed herein should be made of corrosion-resistant materials such as those described above.

[0089] This disclosure provides an adiabatic reaction zone. The adiabatic reaction zone comprises at least two adiabatic reactors. A heat exchanger is positioned between each pair of reactors (see also the discussion in Figure 2 below). In one embodiment of the process disclosed herein, the process includes the steps of: providing an adiabatic reaction zone comprising at least two series-connected adiabatic reactors and having a heat exchanger arranged in sequence and providing fluid communication between each pair of reactors in series; introducing a starting material comprising a hydrohaloalkane into the adiabatic reaction zone, wherein a first reaction product is produced in the first adiabatic reactor; passing the first reaction product from the first adiabatic reactor through the heat exchanger to produce an intermediate product; then introducing the intermediate product from the heat exchanger into a subsequent adiabatic reactor, wherein a second reaction product is produced; and optionally, passing the second reaction product from the subsequent adiabatic reactor through the heat exchanger before introducing the second reaction product into a third adiabatic reactor (if any), etc.

[0090] Notwithstanding the foregoing, other process steps may be carried out upstream of the adiabatic reaction zone. Upstream process steps may include, for example, a process for preparing hydrohaloalkanes to be used in the dehalogenation process described herein, or the vaporization of starting materials supplied to the first adiabatic reactor. Upstream process steps may be carried out in one or more reactors. For clarity, even if one or more reactors are located upstream of the dehalogenation process, the “first adiabatic reactor” as referred to herein refers to the first adiabatic reactor in a series of adiabatic reactors in which the dehalogenation process is carried out, and the heat exchanger is located between the first adiabatic reactor in series and the second (subsequent) adiabatic reactor in series. Therefore, any reactor in which a process step is carried out upstream of the adiabatic reaction zone, and thus upstream of the first adiabatic reactor as thus defined, may not be considered the “first adiabatic reactor”.

[0091] Within the adiabatic reaction zone described herein, other reactions (processes and reaction zones) may occur downstream of the dehalogenation process.

[0092] A heat exchanger is used within the process and adiabatic reaction zone of this disclosure. The heat exchanger is positioned between two adiabatic reactors in series. Since dehalogenation is an endothermic process, the heat exchanger exchanges the heat used by the reaction. The heat exchangers used herein may be shell and tube heat exchangers. Among other things, the heat exchanger may be a fin and tube heat exchanger, a microchannel heat exchanger, and a vertical or horizontal single-pass tube or plate type heat exchanger, or an electric heater. The heat exchanger may provide heat by electric heating. The heat exchanger may use the process flow as the heat exchange fluid. Other designs may be used to suit the physical and chemical requirements of the process, including the temperature and corrosive properties of the reaction components.

[0093] Each heat exchanger can refer to multiple heat exchangers in sequence, meaning two or more heat exchangers. If multiple heat sources are available, multiple heat exchangers may be used, although a particular heat source (such as steam) may not be able to heat to the desired temperature due to thermal decomposition or adiabatic reactions.

[0094] In one embodiment, each heat exchanger may operate independently of other heat exchangers in the adiabatic reaction zone. Each heat exchanger may operate to provide intermediate products that have the same temperature as the intermediate products exiting another heat exchanger in the adiabatic reaction zone.

[0095] In another embodiment, each heat exchanger may operate to provide intermediate products having a different temperature from the intermediate products exiting the other heat exchangers in the adiabatic reaction zone.

[0096] In one embodiment, each adiabatic reactor in the reaction zone operates at the same temperature. In another embodiment, at least one adiabatic reactor in the adiabatic reaction zone operates at a different temperature from the other(s) adiabatic reactors in the adiabatic reaction zone. It should be understood that if the adiabatic reaction zone consists of two adiabatic reactors, each reactor may operate at the same or different temperatures, and if the adiabatic reaction zone consists of three or more adiabatic reactors, each reactor may operate independently at the same or different temperatures as the other reactors in the adiabatic reaction zone.

[0097] In one embodiment, adiabatic reactors within an adiabatic reaction zone operate at different temperatures. For example, a first adiabatic reactor may operate at a higher temperature than subsequent adiabatic reactors. Surprisingly, it has been found that operating the first adiabatic reactor at a different temperature than subsequent adiabatic reactors alters the product profile. Therefore, if a particular secondary product is more desirable for some reason than other secondary products (e.g., ease of separation from the main product, commercial value of the secondary product, etc.), the adiabatic reactors may operate at different temperatures. In one embodiment, a first or preceding adiabatic reactor operates at a higher temperature than subsequent adiabatic reactors, and two or more adiabatic reactors within an adiabatic reaction zone are intended.

[0098] In one embodiment, each heat exchanger may be independently located within a vessel having a preceding or succeeding adiabatic reactor. In another embodiment, each heat exchanger may be independently located within a vessel separate from the preceding or succeeding adiabatic reactor. Fluid communication is maintained between the succeeding adiabatic reactors via the heat exchangers, as previously described.

[0099] Optionally, a heat exchanger may be used to heat the starting material to a desired reaction temperature upstream of the first adiabatic reactor, either within or outside the adiabatic reaction zone. In one embodiment, the heat exchanger is located upstream of the first adiabatic reactor within the adiabatic reaction zone. In such an embodiment, the process includes step (a') of introducing a starting material containing a hydrohaloalkane into a heat exchanger in the adiabatic reaction zone upstream of the first adiabatic reactor to produce heated starting material. The heated starting material from step (a') is the starting material introduced into the first adiabatic reactor in step (b).

[0100] The processes and adiabatic reaction zones disclosed herein provide a larger reactor volume to accommodate relatively slow dehalogenation reactions. The total reactor volume is increased over multi-tube reactors without complexity while controlling the temperature of the endothermic process.

[0101] The processes disclosed herein are carried out in the gas phase, either in the presence of an added catalyst (catalytic process) or in the absence of an added catalyst (thermal decomposition process), at a temperature sufficient to convert the hydrohaloalkane in the reaction zone to a haloolefin (haloalkene).

[0102] Each of the adiabatic reactors in the adiabatic reaction zone disclosed herein can independently operate as a catalytic or pyrolytic adiabatic reactor. That is, each reactor may be catalytic, each reactor may be pyrolytic, or a combination of catalytic and pyrolytic reactors may be used. More specifics regarding options for pyrolytic processes and suitable catalysts for catalytic processes are provided below.

[0103] In some embodiments, regardless of whether it is a catalytic or pyrolysis process, an inert diluent gas (an optional component) is used as a carrier gas for hydro(chloro)fluoropropane. In one embodiment, the carrier gas is selected from nitrogen, argon, helium, or carbon dioxide. In addition, the carrier gas may contain unconverted starting materials in reactors other than the first adiabatic reactor, among other recycled products, HF, and HCl. The carrier gas may contain organic materials that do not adversely affect the process chemistry.

[0104] In one embodiment, at least one adiabatic reactor operates as a pyrolysis reactor. That is, the adiabatic reaction zone comprises one or more adiabatic reactors operating as pyrolysis reactors. In such embodiments, the process is carried out by pyrolysis (thermal dehalogenation) of the starting material to produce hydrofluoroolefin products, i.e., by pyrolysis. The terms “thermal decomposition” or “pyrolysis,” as used herein, mean a chemical change caused by heating in the absence of an added catalyst. “Absence of an added catalyst” means that no material is added to the adiabatic reactor in order to intentionally increase the reaction rate by reducing the activation energy of the dehalogenation process. Despite the foregoing, the surface of the adiabatic reactor may have some catalytic properties.

[0105] If the dehalogenation process is a pyrolysis process, the gas flow through the pyrolysis reactor can enter the reactor through perforated baffles to produce a uniform flow distribution, for example, approaching plug flow. Plug flow is desired because backmixing reduces conversion.

[0106] In other embodiments, the adiabatic pyrolysis reactor is substantially empty, meaning that the free volume of the adiabatic reaction zone is at least about 80%, in another embodiment at least about 90%, and in yet another embodiment at least about 95%. The free volume is the volume of the reaction zone minus the volume of the material constituting the reactor packing, and the free volume may be expressed as a percentage (%) as the ratio of the free volume to the total volume of the reactor at time 100.

[0107] The dehalogenation processes of this disclosure may include defluoride processes, dechlorination processes, or both, depending on the starting materials and the corresponding fluoroolefin products. For example, if the hydrohaloalkane is 244bb, dechlorination produces 1234yf. However, reaction conditions may also result in defluoride to some 1233xf.

[0108] Typically, the pyrolysis temperature for dehydrofluoride is higher than that for dehydrochloride. In certain embodiments, the process is a dehydrofluoride process, and the pyrolysis reactor operates at a temperature of about 500°C to about 900°C. In certain embodiments, the process is a dehydrochloride process, and the adiabatic pyrolysis reactor operates at a temperature of about 300°C to about 700°C. Pyrolysis processes are also disclosed, for example, in U.S. Patents 7,833,434, 8,203,022, and 8,445,735.

[0109] The dehalogenation process of this disclosure may have a reaction pressure of near-atmospheric pressure, atmospheric pressure, or superatmospheric pressure. In one embodiment, the process is carried out at a pressure of about 0 psig to about 200 psig. In one embodiment, the reaction is carried out at a pressure of 10 psig to about 150 psig. In another embodiment, the reaction is carried out at a pressure of 20 psig to about 100 psig.

[0110] In one embodiment, each adiabatic reactor operates as an adiabatic pyrolysis reactor.

[0111] In one embodiment, at least one adiabatic reactor within the adiabatic reaction zone operates as an adiabatic catalytic reactor. That is, the adiabatic reaction zone comprises one or more adiabatic reactors that operate as adiabatic catalytic reactors. In such embodiments, this catalytic adiabatic reactor is filled with a catalyst to produce a hydrofluoroolefin product. Any dehalogenating catalyst may be used.

[0112] For example, the dehalogenation catalyst can be selected from metal halides, metal oxides, metal halide oxides, neutral (or zero-oxidation) metals or metal alloys, or carbon in bulk or supported form.

[0113] The dehalogenation catalyst may be selected from metal halides, metal oxides, or metal oxyhalide catalysts. Examples of dehalogenation catalysts include, but are not limited to, monovalent, divalent, and trivalent metal halides, metal oxides, metal oxyhalides, and combinations of two or more thereof, more preferably monovalent, divalent, and trivalent metal halides, and combinations of two or more thereof.

[0114] Examples of metals include transition metals, alkali metals, and alkaline earth metals. Metal halides, metal oxides, or metal oxyhalides may or may not be supported. Metal halides, metal oxides, or metal oxyhalides can be supported on carbon, alkaline earth metal halides, or alkaline earth metal oxides.

[0115] Examples of metals suitable for use in the hydrogen-dehalogenating catalysts described herein include Cr 3+ Fe 3+ Ca 2+ Mg 2+ Ca 2+ Ni 2+ Zn 2+ , Pd 2+ Li + na + , K + , and Cs +Examples include, but are not limited to, F - Cl - , Br - , and I - Examples of useful monovalent, divalent, or trivalent metal halides include, but are not limited to, LiF, NaF, KF, CsF, MgF2, CaF2, LiCl, NaCl, KCl, CsCl, CrCl3, and FeCl3. Supported metal halide catalysts include CsCl / MgO fluoride and CsCl / MgF2.

[0116] The dehalogenation catalyst can be selected from metal alloys of neutral (i.e., zero-valent) metals or mixtures thereof. Useful metals include, but are not limited to, Pd, Pt, Rh, Fe, Co, Ni, Cu, Mo, Cr, Mn, and combinations of the above as alloys or mixtures. The neutral metal catalyst may or may not be supported. Useful examples of metal alloys include, but are not limited to, stainless steel (e.g., SS316) and austenitic nickel alloys (e.g., Inconel 625, Inconel 660, Inconel 825, Monel 400).

[0117] Other suitable dehalogenation catalysts for the dehalogenation processes disclosed herein include carbon catalysts that can be selected from acid-washed carbon, activated carbon, and three-dimensional matrix carbonaceous materials.

[0118] Dehalogenation catalysts may be alternatively selected from alumina, alumina fluoride, aluminum fluoride, aluminum chlorofluoride; metal compounds supported on alumina, alumina fluoride, aluminum fluoride, or aluminum chlorofluoride; chromium oxide (Cr2O3), chromium fluoride oxide, and cubic chromium trifluoride; magnesium, zinc, and oxides, fluorides, and oxyfluorides of magnesium and mixtures of zinc and / or aluminum; lanthanum oxide, lanthanum fluoride oxide, or mixtures thereof.

[0119] A fluorinating catalyst or a fluorine-containing catalyst can be packed into a catalytic reactor, or a precursor of a fluorinating catalyst or a fluorine-containing catalyst can be formed in situ within the catalytic reactor by introducing HF into the reactor.

[0120] The above detailed description of suitable dehalogenation catalysts is for illustrative purposes only and is not intended to be exhaustive. Those skilled in the art will understand that other dehalogenation catalysts not specifically described herein may be used.

[0121] In catalytic dehalogenation processes, adiabatic catalytic reactors can suitably operate at temperatures of about 150 to about 550°C and pressures of about 0 to about 200 psig, or 10 to 150 psig, or 20 to 100 psig.

[0122] In one embodiment, each adiabatic reactor operates as an adiabatic catalytic reactor.

[0123] The dehalogenation processes disclosed herein produce products containing haloolefins. By-products HF or HCl can be removed by a number of methods, such as distillation or washing with water to produce aqueous solutions of HF or HCl, or by concentrating, decanting, or scrubbing with a base the acid-rich phase to produce an acid-free organic product, which may optionally be further purified using one or any combination of purification techniques known in the art.

[0124] According to this disclosure, the process may include a step of purifying the starting material, a hydrohaloalkane. If the haloolefin produced according to the process of this disclosure is an intermediate for a subsequent reaction(s), the process may further include a step of purifying the intermediate haloolefin product before the subsequent reaction(s).

[0125] The processes disclosed herein optionally further include a step of recovering a haloolefin from the final product. The haloolefin may be recovered using the examples described herein using processes known to those skilled in the art. The processes disclosed herein optionally further include a step of purifying the haloolefin. Processes for recovering and / or purifying the haloolefin may include distillation, concentration, decantation, absorption in water, scrubbing with a base, and combinations of two or more thereof.

[0126] In certain embodiments, various azeotropic compositions or azeotropic mixture-like (i.e., near-azeotropic mixture) compositions containing hydrofluoropropene products may be used in processes for recovering and / or purifying haloolefins or intermediate products.

[0127] In one embodiment, HF may be added to a product containing 1234yf. In one embodiment, HF may be present in a product containing 1234yf. In either embodiment, 1234yf and HF are combined to form an azeotropic or near-azeotropic mixture of 1234yf and HF. The azeotropic or near-azeotropic mixture of HF and 1234yf may also be formed as a distillate from a distillation column in which a non-azeotropic mixture of HF and 1234yf is present in the feed. Separation of 1234yf includes isolating the azeotropic or near-azeotropic mixture of 1234yf and HF, and subjecting the azeotropic or near-azeotropic mixture of 1234yf and HF to further processing to produce HF-free 1234yf using a procedure similar to that disclosed in U.S. Patent No. 7,897,823. Azeotropic or near-azeotropic composition of HFO-1234yf and HF is disclosed in U.S. Patent No. 7,476,771, and the process described therein may also be used to recover hydrofluoroolefin products.

[0128] In another embodiment, HF may be added to a product containing E- and / or Z-1234ze to produce an azeotropic or near-azeotropic composition containing E- and / or Z-1234ze and HF. The azeotropic or near-azeotropic composition containing E- and / or Z-1234ze and HF may be isolated, for example, by distillation for separation from other products.

[0129] The azeotropic or near-azeotropic compositions of E- and / or Z-1234ze and HF are subjected to further processing to produce HF-free E- and / or Z-1234ze using a procedure similar to that disclosed in U.S. Patent No. 7,897,823.

[0130] In addition, the techniques applied in U.S. Patents 7,423,188 and 8,377,327 may be used to recover HF-free E- and / or Z-1234ze produced according to the processes disclosed herein. U.S. Patent 7,423,188 discloses azeotropic or near-azeotropic compositions of the E-isomers of 1234ze and HF. U.S. Patent 8,377,327 discloses azeotropic or near-azeotropic compositions of the Z-isomers of 1234ze and HF.

[0131] The Disclosure also provides a process for preparing 1234yf, comprising the steps of: (v) providing an adiabatic reaction zone comprising at least two series-connected adiabatic reactors and having heat exchangers arranged sequentially and providing fluid communication between each pair of reactors in series; (w) providing a composition comprising 1230xa; (x) contacting the composition comprising 1230xa with a fluorinating agent such as HF to produce a product comprising 1233xf; (y) contacting the product comprising 1233xf with a fluorinating agent such as HF to produce a product comprising 244bb in a liquid-phase or gas-phase reactor; and (z) dehydrochlorinating the product comprising 244bb in the adiabatic reaction zone to produce a product comprising 1234yf.

[0132] A process for preparing 1234yf is also provided, comprising the following steps: (v') providing an adiabatic reaction zone comprising at least two series-connected adiabatic reactors and heat exchangers arranged sequentially with fluid communication between each pair of reactors in series; (w') providing a composition comprising 243db; (x') contacting the composition comprising 243db with a dehalogenating agent or dehalogenating catalyst to produce a product comprising 1233xf; (y') contacting the product comprising 1233xf with a fluorinating agent such as HF to produce a product comprising 244bb in a liquid-phase or gas-phase reactor; and (z') dehydrochlorinating the product comprising 244bb in the adiabatic reaction zone to produce a product comprising 1234yf.

[0133] The disclosure also provides a process for preparing 1234yf, which may include the following steps: (v'') providing an adiabatic reaction zone comprising at least two series-connected adiabatic reactors and having heat exchangers arranged sequentially and providing fluid communication between each pair of reactors in series; (w'') providing a composition comprising 243db; (x'') contacting the composition comprising 243db with a dehalogenating agent or dehalogenating catalyst to produce a product comprising 1233xf in the adiabatic reaction zone; (y'') contacting the product comprising 1233xf with a fluorinating agent such as HF to produce a product comprising 244bb in a liquid-phase or gas-phase reactor; and (z'') dehydrochlorinating the product comprising 244bb to produce a product comprising 1234yf.

[0134] The dehydrochlorination steps (z) and (z') are carried out as disclosed herein, and include the steps of: (aa) introducing starting materials containing a product including 244bb into a first adiabatic reactor of series-connected reactors to produce a reaction product; (bb) passing the reaction product from the preceding adiabatic reactor to a heat exchanger to produce an intermediate product; (cc) introducing the intermediate product from the heat exchanger to a subsequent adiabatic reactor to produce a reaction product; (dd) optionally repeating steps (bb) and (cc) in sequence one or more times; and (ee) recovering a final product containing a haloolefin, the final product being the reaction product produced in the final adiabatic reactor. Optionally, step (z'') is also carried out with respect to steps (z) and (z') as described above.

[0135] Similarly, the dehydrochlorination step (x'') is carried out in an adiabatic reaction zone as disclosed herein, and includes the steps of: (aa') introducing starting materials containing 243db into a first adiabatic reactor of series-connected reactors to produce a reaction product; (bb') passing the reaction product from the preceding adiabatic reactor to a heat exchanger to produce an intermediate product; (cc') introducing the intermediate product from the heat exchanger to a subsequent adiabatic reactor to produce a reaction product; (dd') optionally repeating steps (bb') and (cc') in sequence one or more times; and (ee') recovering a final product containing a haloolefin, the final product being the reaction product produced in the final adiabatic reactor. The haloolefin in step (ee') contains 1233xf. Step (x'') is followed by steps (y'') and (z'').

[0136] Steps (w)~(y), (w')~(y'), (w''), (y''), and (z'') can be carried out using known methods with all their associated variations, such methods are not reproduced herein for the sake of brevity. For example, in step (z''), 244bb is dehydrochlorinated by pyrolysis or catalytically to produce a product containing the desired product 1234yf as a component of the reactor effluent.

[0137] The reactions described in steps (z), (z'), and (z'') above may be carried out in temperature ranges of approximately 200°C to 800°C, approximately 300°C to 600°C, or approximately 400°C to 500°C. Suitable reactor pressures are in the range of approximately 0 psig to 200 psig, approximately 10 psig to 150 psig, or approximately 20 to 100 psig, or approximately 40 psig to 80 psig.

[0138] The processes described in steps (v)-(z), (v')-(z'), and (v'')-(z'') optionally further include processing the 1233xf-containing products generated in steps (x), (x'), and (x'') respectively before using the processed products containing 1233xf in steps (y), (y'), and (y''). In this specification, “processing” means separating 1233xf from the products generated in steps (x), (x'), and (x'') and / or purifying 1233xf from the 1233xf-containing products to provide processed products containing 1233xf. For clarity, the “product containing 1233xf” in step (y), (y'), or (y'') may be the product from step (x), (x'), or (x''), respectively, as described herein, or the product after processing the product from step (x), (x'), or (x''), respectively.

[0139] The processes described in steps (v)-(z), (w')-(z'), and (v'')-(z'') optionally further include processing the 244bb-containing products generated in steps (y), (y'), and (y'') respectively before using the processed products containing 244bb in steps (z), (z'), and (z''). In this specification, “processing” means separating 244bb from the products generated in steps (y), (y'), and (y'') and / or purifying 244bb from the 244bb-containing products to provide processed products containing 244bb. For clarity, the “244bb-containing products” in steps (z), (z'), or (z'') may be the products from steps (y), (y'), or (y''), respectively, as described herein, or the products after processing the products from steps (y), (y'), or (y''), respectively.

[0140] In process step (x), the composition containing 1230xa is contacted with a fluorinating agent in the presence of a fluorinating catalyst to produce a product mixture containing 1233xf. In one embodiment, step (x) is carried out in the gas phase using a fluorinating catalyst. The gas-phase fluorinating catalyst may be selected from metal oxides, hydroxides, halides, oxyhalides, inorganic salts thereof, and mixtures thereof, any of which may be optionally halogenated. Examples of metals include, but are not limited to, chromium, aluminum, cobalt, manganese, nickel, iron, and two or more combinations thereof. In another embodiment, step (x) is carried out in the liquid phase using a fluorinating catalyst. The liquid-phase fluorinating catalyst may be selected from metal chlorides and metal fluorides, including, but are not limited to, SbCl5, SbCl3, SbF5, SnCl4, TiCl4, FeCl3, and two or more combinations thereof.

[0141] In process step (x') or process step (x''), 243db is dehydrochlorinated to produce a product mixture containing 1233xf. In this step, dehydrochlorination can be carried out in the gas phase using a dehydrochlorination catalyst, or in the liquid phase using a dehydrochlorination agent, such as a base. For example, International Publication 2012 / 115934 discloses a gas-phase reaction of 243db with a carbon catalyst. International Publication 2012 / 115938 discloses a gas-phase reaction of 243db using a chromium oxyfluoride catalyst. International Publication 2017 / 044719 discloses a reaction of 243db with an alkane fluoride to produce 1233xf in the presence of a fluorination catalyst, as well as other compounds useful for producing 1234yf. International Publication 2017 / 044724 discloses a liquid-phase reaction of 243db using caustic. As will be known to those skilled in the art, other methods may be used when starting with a compound having formula (III).

[0142] Step (x'') is a dehydrochlorination step that may be carried out in an adiabatic reaction zone in accordance with the disclosure provided herein.

[0143] The process may further include one or more steps prior to step (v') or step (v''). In one embodiment, a process comprising steps (t') and (u'), and steps (t'') and (u''), respectively, is carried out prior to step (v') or step (v''), the process comprising: contacting 250fb with HF and a catalyst under conditions that produce a product containing (t') or (t'')1243zf; and contacting the product containing (u') or (u'')1243zf with chlorine in the presence or absence of a catalyst that produces a product containing 243db.

[0144] The product of step (t') or (t'') may be separated and / or purified before being used in step (u') or (u''). The product of step (u') or (u'') may be separated and / or purified before being used in step (v') or (v''). For clarity, the “product containing 1243zf” in step (u') or (u'') may be the product from step (t') or (t''), respectively, as described herein, or the product after processing the product from step (t') or (t''), respectively.

[0145] Following step (z), step (z'), or step (z''), the process for the preparation of 1234yf may further include separation steps to achieve a desired degree of separation of 1234yf from other components present in the product, and / or other treatments to achieve a desired purity. For example, the product from step (z), step (z'), or step (z'') containing 1234yf may further include one or more of HCl, HF, unconverted 244bb, 3,3,3-trifluoropropyne, 245cb, and 1233xf (the latter being primarily inherited from the preceding step (y), step (y'), or step (y''), respectively).

[0146] HCl can be optionally recovered from the dehydrochlorination reaction. Recovery of HCl can be carried out by conventional distillation, where it is removed from the distillate. Alternatively, HCl can be removed or recovered using water or a caustic scrubber. When a water scrubber is used, HCl is removed as an aqueous solution. When a caustic scrubber is used, HCl is removed from the reaction zone as a chloride salt in an aqueous solution.

[0147] After the recovery or removal of HCl, the remainder of the product from the dehydrochlorination process may be transferred to a distillation column for separation. For example, 1234yf may be collected from the column overhead, and optionally, the collected 1234yf may be transferred to another column for further purification. Of the remaining material not collected from the overhead, a fraction may be accumulated in the reboiler. For example, this fraction may contain 1233xf and 244bb. After separation from the fraction, 244bb may be returned as recycled to the dehydrochlorination process (z), or process (z'), or process (z'').

[0148] This disclosure also provides an adiabatic reaction zone for the dehalogenation process disclosed herein. The reaction zone is provided comprising at least two reactors, each reactor operating adiabatically, and a heat exchanger is positioned between the at least two reactors.

[0149] The adiabatic reaction zone of this disclosure comprises (a) a first adiabatic reactor in fluid communication with a starting material source, through which a starting material containing a hydrohaloalkane is passed to the first adiabatic reactor, and the starting material is converted into a reaction product; (b) a heat exchanger in fluid communication with the first adiabatic reactor, located downstream of the first adiabatic reactor, and through which the reaction product is passed, the reaction product is heated to produce an intermediate product; and (c) a heat exchanger in fluid communication with the heat exchanger, located downstream of the heat exchanger, The adiabatic reaction zone further comprises: a subsequent adiabatic reactor through which intermediate products are flowed from a heat exchanger, the subsequent adiabatic reactor through which intermediate products react to form reaction products; and optionally, (d) one or more combinations of a heat exchanger and a subsequent reactor, which are in series and in fluid communication with the subsequent adiabatic reactor (c), wherein, with respect to each heat exchanger, the reaction products are heated to form intermediate products, and with respect to each adiabatic reactor, the intermediate products react to form reaction products. Optionally, the adiabatic reaction zone further comprises a heat exchanger upstream of the first adiabatic reactor and in fluid communication with the first adiabatic reactor.

[0150] An adiabatic reaction zone may comprise two or more subsequent adiabatic reactors. As described above, an adiabatic reaction zone comprises a first adiabatic reactor and subsequent adiabatic reactors. In one embodiment, the adiabatic reaction zone comprises at least three adiabatic reactors. Thus, such a reaction zone comprises a first adiabatic reactor, a second adiabatic reactor, and a third adiabatic reactor, where each of the second and third adiabatic reactors is a subsequent adiabatic reactor, and the third adiabatic reactor is also the final adiabatic reactor.

[0151] The reaction system may include an adiabatic reaction zone as disclosed herein, as well as a separation and / or purification system downstream of the adiabatic reaction zone, which is in fluid communication with the adiabatic reaction zone.

[0152] The reaction system may include operations upstream of the adiabatic reaction zone and in fluid communication with the adiabatic reaction zone, including means for preheating the starting material. In one embodiment, the reaction system includes a heat exchanger upstream of the reaction zone and in fluid communication with the reaction zone for preheating the starting material. In one embodiment, the reaction system includes an evaporator for vaporizing the starting material, the evaporator is in fluid communication with the adiabatic reaction zone.

[0153] Detailed description of the drawing Figure 1 is a flow chart showing a prior art reaction system for a dehalogenation hydrogen process, where the reaction system 100 has a single multi-tube reactor 105, and multiple tubes are shown by multiple lines within the reactor. The reaction zone 101 consists of the reactor 105 and is identified by a shaded area enclosed by a dotted line. The starting material 110 containing hydrohaloalkanes enters the evaporator 115, where the starting material becomes vaporized starting material 120, which passes through the heat exchanger 125 to produce heated starting material 130. From the heat exchanger 125, the heated starting material 130 passes through the superheater 135, from which it becomes superheated starting material 140. The superheated starting material 140 is introduced into the multi-tube reactor 105. From the reactor 105, the reaction product 145 passes through the heat exchanger 125 to yield cooled reaction product 150. Next, the cooled reaction product 150 is further cooled by passing through the heat exchanger 155 to yield product 160.

[0154] Figure 2 is a flow chart showing the dehalogenation process of the present disclosure, in which the reaction system 200 includes an adiabatic reaction zone 205 consisting of three adiabatic reactors in series. The adiabatic reaction zone 205 consists of adiabatic reactors 260, 261, and 262, and heat exchangers 250, 280, and 281, and is identified by a shaded area enclosed by a dotted line (step (a)). Starting material 210 containing a hydrohaloalkane enters the evaporator 215, where the starting material becomes vaporized starting material 220, which passes through the heat exchanger 225 to produce heated starting material 230. From the heat exchanger 225, the heated starting material 230 passes through the superheater 235 to produce superheated starting material 240. The superheated starting material 240 enters the adiabatic reaction zone 205, passes through the heat exchanger 250 to produce starting material 251 for the first adiabatic reactor 260 (step (a')). The starting material 251 is introduced into the first adiabatic reactor 260 (step (b)). From the first adiabatic reactor 260, the reaction product 270 passes through the heat exchanger 280, where it is heated and exits as intermediate product 271 (step (c)). The intermediate product 271 is introduced into the subsequent (second) adiabatic reactor 261, where reaction product 272 is produced (step (d)). From the second adiabatic reactor 261, the reaction product 272 passes through the heat exchanger 281, where it is heated and exits as intermediate product 273 (step (e), repeated step (c)). The intermediate product 273 is introduced into the subsequent (third and final) adiabatic reactor 262, where reaction product 274 is produced (step (e), repeated step (d)). From the third reactor 262, the reaction product 274 passes through the heat exchanger 225 to yield cooled reaction product 275. The cooled reaction product 275 is then further cooled by passing through the heat exchanger 255 to yield recoverable product 276 (step (e)).

[0155] Figure 2 shows the use of the process flow (reaction product 274) as a heat exchange fluid when heat is exchanged between the vaporized starting material 220 and the reaction product 274.

[0156] Selected Embodiments Embodiment (1) provides a process for the dehalogenation of hydrohaloalkanes in an adiabatic reaction zone, the process comprising: (a) providing an adiabatic reaction zone comprising at least two series-connected adiabatic reactors and having heat exchangers arranged sequentially and providing fluid communication between each pair of reactors in series; (b) introducing a starting material containing a hydrohaloalkane into a first adiabatic reactor of the series-connected reactors to produce a reaction product; and (c) heating the reaction product away from the preceding reactor. The process includes (d) passing the mixture through an exchanger to generate an intermediate product, (e) introducing the intermediate product from the heat exchanger into a subsequent adiabatic reactor to generate a reaction product, (f) optionally repeating steps (c) and (d) in order one or more times, and (g) recovering a final product containing a haloolefin, wherein the final product is a reaction product generated in the final adiabatic reactor, and the final adiabatic reactor is a subsequent adiabatic reactor that does not have a subsequent adiabatic reactor in the adiabatic reaction zone downstream of the final adiabatic reactor.

[0157] Embodiment (2) is a hydrohaloalkane of formula Y 1 Y 2 CH-CXY 3 Y 4 The formula has, where X is F, Cl, Br, or I, and Y i Each of the elements is independently H, F, Cl, Br, or I, an alkyl group, or a haloalkyl group, where i is 1, 2, 3, and 4, and halo is F, Cl, Br, or I, but with at least one Y i is not H, or at least one Y i This is the process described in Example (1), where haloalkyl is used.

[0158] Embodiment (3) is the process described in Embodiment (2), wherein the hydrohaloalkane is a hydrohaloethane.

[0159] Embodiment (4) is the process described in Embodiment (2), wherein the hydrohaloalkane is 1-chloro-1,1-difluoroethane (CF2ClCH3).

[0160] Embodiment (5) is the process described in Embodiment (2), wherein the hydrohaloalkane is hydrohalopropane and the haloolefin is halopropene.

[0161] Embodiment (6) is the process described in Embodiment (2), wherein the hydrohalopropane is selected from CF3CFClCH3, CF3CHFCH2Cl, CF3CHClCH2F, CF3CH2CHFCl, CF3CHFCH2Cl, CF3CHClCH3, CF3CHFCH2F, CF3CH2CF2H, CF3CF2CH3, CF3CFClCH2F, CF3CHFCHFCl, CF3CHClCHF2, CF3CH2CF2Cl, CF3CHClCH2Cl, CCl3CH2CHCl2, CF3CH2CH2Cl, CF3CHClCH3, CCl3CHClCH2Cl, CCl3CH2CH2Cl, CH2ClCCl2CHCl2, and mixtures of two or more of these.

[0162] Embodiment (7) is the process described in Embodiment (5), wherein the hydrohalopropane comprises hydrochlorofluoropropane and the halopropene comprises hydrofluoropropene.

[0163] Embodiment (8) is the process described in Embodiment (5), wherein the hydrohalopropane is CF3CFClCH3 and the halopropene is CF3CF=CH2.

[0164] Embodiment (9) is the process described in Embodiment (8), further comprising the following steps upstream of step (b): (w) providing a composition containing 1,1,2,3-tetrachloropropene (1230xa); (x) contacting the composition containing 1230xa with a fluorinating agent such as HF to produce a product containing 1233xf; (y) contacting the product containing 1233xf with a fluorinating agent such as HF to produce a product containing 244bb in a liquid-phase or gas-phase reactor; and optionally (z) separating 244bb from the product of step (y), wherein the product of step (y), or the product of step (z) if optional step (z) is performed, is the starting material in step (b).

[0165] Embodiment (10) is the process described in Embodiment (8), further comprising the following steps upstream of step (b): (w') providing a composition containing CF3CHClCH2Cl(243db); (x') contacting the composition containing 243db with a dehydrohalogenating agent or dehydrohalogenating catalyst to produce a product containing CF3CCl=CH2(1233xf); (y') contacting the product containing 1233xf with a fluorinating agent such as HF to produce a product containing CF3CFClCH3(244bb) in a liquid-phase or gas-phase reactor; and optionally (z') separating 244bb from the product of step (y'), wherein the product of step (y'), or the product of step (z') if optional step (z') is performed, is the starting material in step (b).

[0166] Embodiment (11) is the process according to Embodiment (10), further comprising the steps of contacting CCl3CH2CH2Cl(250fb) with HF and a catalyst under conditions that produce a product containing (t')CF3CH=CH2(1243zf) prior to step (w'), and chlorinating the product containing (u')1243zf by contacting 1243zf with chlorine in the presence or absence of the catalyst to produce a product containing CF3CHClCH2Cl(243db).

[0167] Embodiment (12) is the process described in Embodiment (8), further comprising the following steps upstream of step (b): (w'') providing a composition containing CF3CHClCH2Cl(243db); (x'') contacting the composition containing 243db with a dehydrohalogenating agent or dehydrohalogenating catalyst to produce a product containing CF3CCl=CH2(1233xf) in an adiabatic reaction zone; (y'') contacting the product containing 1233xf with a fluorinating agent such as HF to produce a product containing CF3CFClCH3(244bb) in a liquid-phase or gas-phase reactor; and optionally (z'') separating 244bb from the product of step (y''), wherein the product of step (y''), or the product of step (z'') if the optionally performed step (z''), is the starting material in step (b).

[0168] Embodiment (13) is the process according to Embodiment (12), further comprising: a step of contacting CCl3CH2CH2Cl(250fb) with HF and a catalyst under conditions that produce a product containing (t'')CF3CH=CH2(1243zf) prior to step (w''); and a step of chlorinating the product containing (u'')1243zf, by contacting 1243zf with chlorine in the presence or absence of the catalyst to produce a product containing CF3CHClCH2Cl(243db).

[0169] Embodiment (14) is the process according to any one of Embodiments (9), (10), (11), (12), or (13), further comprising processing the product containing CF3CCl=CH2(1233xf) to separate 1233xf from the product containing 1233xf.

[0170] Embodiment (15) is the process according to any one of Embodiments (9), (10), (11), (12), or (13), further comprising processing the product containing CF3CFClCH3(244bb) to separate 244bb from the product containing 244bb.

[0171] Embodiment (17) is the process according to any one of Embodiments (9), (10), (11), (12), (13), or (14), further comprising processing the product containing CF3CFClCH3(244bb) to separate 244bb from the product containing 244bb.

[0172] Embodiment (18) is the process according to any one of Embodiments (9), (10), (11), (12), (13), or (15), further comprising processing the product containing CF3CCl=CH2(1233xf) to separate 1233xf from the product containing 1233xf.

[0173] Numerous aspects and embodiments are described above, but these are merely illustrative and not limiting. After reading this specification, those skilled in the art will understand that other aspects and embodiments are possible without departing from the scope of this disclosure. [Examples]

[0174] Comparative Example In this comparative example, a single reactor is operated isothermally at a temperature of 480°C and a pressure of 70 psig. The reactor has several empty tubes with a heat-conducting fluid flowing through a shell surrounding the reactor to transfer the energy consumed by the endothermic reaction. The reactor is made of Inconel 600 to provide corrosion resistance. A continuous flow of 244bb starting material is supplied to the reactor. The reaction product is analyzed after 1 hour and the conversion of 244bb to 1234yf is measured as 16.3%, defined as (moles of 1234yf produced) / (moles of 244bb supplied). The productivity of the single isothermal reactor, defined as (1234yf production rate) / (total reactor volume), is given a value of 100 for comparison with Examples 1 and 2. The weight and manufacturing cost of the Inconel 600, a commercial-scale reactor designed using the Aspen In-Plant Cost Estimator™ version 8.8 (available from Aspen Technology, Inc., Newtown, PA), are also set to 100 for comparison with Examples 1 and 2.

[0175] (Example 1) In this Example 1, the adiabatic reaction zone consists of two reactors of equal volume operating in adiabatically in series. The inlet temperature to the first adiabatic reactor is 480°C and the pressure is 70 psig. The adiabatic reactor includes empty pipes made of Inconel 600. A continuous flow of 244bb starting material is introduced into the first adiabatic reactor at the same feed rate as in the comparative example. The reaction product from the first adiabatic reactor is heated to 480°C in a heat exchanger before entering the second adiabatic reactor. The reaction product from the second adiabatic reactor is analyzed after 1 hour, and the conversion of 244bb to 1234yf is measured as 16.3%. The productivity of the two series adiabatic reactors is 39 compared to a single isothermal reactor. The total weight of Inconel 600 for both reactors is 50% of the weight required in the comparative example. The total manufacturing cost is 41% of the cost of the single isothermal reactor used in the comparative example.

[0176] (Example 2) In this Example 2, the adiabatic reaction zone consists of three reactors of equal volume operating in adiabatically in series. The inlet temperature to the first adiabatic reactor is 480°C and the pressure is 70 psig. The reactors are the same diameter as those used in Example 1 and are made from empty Inconel 600 pipes. A continuous flow of 244bb starting material is introduced into the first adiabatic reactor at the same feed rate as in the Comparative Example and Example 1. The reaction products from the first and second adiabatic reactors are heated to 480°C in a heat exchanger before entering the second and third adiabatic reactors, respectively. The reaction product from the third adiabatic reactor is analyzed after 1 hour and the conversion of 244bb to 1234yf is measured as 16.3%. The productivity of the three series adiabatic reactors is 55 compared to a single isothermal reactor. The total weight of Inconel 600 for both reactors is 35% of the weight required in the Comparative Example. The total manufacturing cost is 28% of the cost of a single isothermal reactor used in the comparative example.

Claims

1. A process for the dehalogenation of hydrohaloalkanes within an adiabatic reaction zone, (a) A step of providing an adiabatic reaction zone comprising at least two series-connected adiabatic reactors and heat exchangers arranged sequentially and having fluid communication between each pair of reactors in series, (b) A step of introducing a starting material containing a hydrohaloalkane into the first adiabatic reactor among the series-connected reactors, so that each reactor operates as a pyrolysis reactor to produce a reaction product, (c) A step of passing the reaction product from the preceding reactor to a heat exchanger to generate an intermediate product for achieving the desired transformation, (d) A step of introducing the intermediate product from the heat exchanger to a subsequent adiabatic reactor to generate a reaction product, (e) A step in which steps (c) and (d) are optionally repeated one or more times in order, (f) A step of recovering a final product containing a haloolefin, wherein the final product is the reaction product produced in the final adiabatic reactor, the final adiabatic reactor is a subsequent adiabatic reactor that does not have a subsequent adiabatic reactor in the adiabatic reaction zone downstream from the final adiabatic reactor, the hydrohaloalkane is hydrohalopropane, the haloolefin is halopropene, and the hydrohalopropane is CF 3 CFClCH 3 And the aforementioned Hello Project Pen is CF 3 CF=CH 2 That is the process.

2. The process according to claim 1, wherein the adiabatic reaction zone comprises at least three adiabatic reactors.

3. The process according to claim 1, wherein an inert diluent gas is used as a carrier gas for the hydrochlorofluoropropane.

4. The process according to claim 1 or 2, wherein at least one adiabatic reactor operates at a temperature of about 300°C to about 700°C.

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