Process for preparing fluorobenzene and catalyst therefore

Abstract

The invention relates to process for the manufacture or preparation of fluorinated benzene, in particular monofluorobenzene, in a vapor-phase fluorination process. The process of the invention, for example, can comprise a batch or continuous manufacture or preparation of fluorinated benzene, in particular monofluorobenzene, using hydrogen fluoride (HF) in gas phase as fluorination gas. Also, in this process of the invention, for example, fluorination catalysts are involved.

Claims

1. A process for the manufacture of a fluorinated benzene, in a vapor-phase fluorination process comprising the steps of: a) provision of a chlorinated benzene as starting compound; b) provision of a fluorination gas consisting of anhydrous hydrogen fluoride (HF); c) provision of a fluorination catalyst; d) provision of a reactor system, resistant to hydrogen fluoride (HF), and comprising a vaporizer for the starting compound of a), and a condenser for the vapor-phase fluorination reaction product, and a reservoir for collecting the fluorination reaction product; e) at least one vapor-phase reaction stage comprising reacting of a) a vaporized chlorinated benzene with b) anhydrous hydrogen fluoride (HF) in gas phase in the presence of c) the fluorination catalyst, so as to produce a vapor-phase fluorination reaction product; f) withdrawing the vapor-phase fluorination reaction product formed in the vapor-phase reaction step e) from the reactor or reactor system of d), and transferring the vapor-phase fluorination reaction product to the condenser and condensing for collecting the condensed fluorination reaction product; and g) hydrolysing the fluorination reaction product obtained and collected according to f), in water, to obtain a fluorinated benzene; and h) phase separation of the organic phase of fluorinated benzene, from water phase to obtain fluorinated benzene wherein the fluorination catalyst is selected from the group consisting of MgF.sub.2 based catalyst, SbCl.sub.5/C based catalyst, Cr.sub.2O.sub.3 based catalyst, and FeCl.sub.3/C based catalyst, and wherein the said catalyst is pre-fluorinated with hydrogen fluoride (HF).

2. The process for the manufacture of a fluorinated benzene according to claim 1, wherein the Cr.sub.2O.sub.3 based catalyst is an activated and/or re-activated Cr.sub.2O.sub.3 based catalyst.

3. The process for the manufacture of a fluorinated benzene according to claim 2, wherein the activated and/or re-activated Cr.sub.2O.sub.3 based catalyst is activated and/or re-activated by treatment with an oxygen containing gas; and/or wherein the Cr.sub.2O.sub.3 based catalyst is pre-fluorinated with hydrogen fluoride (HF).

4. The process for the manufacture of a fluorinated benzene according to claim 2, wherein the activated and/or re-activated Cr.sub.2O.sub.3 based catalyst is activated and/or re-activated by treatment with Zn dopant, by treatment with Ni dopant.

5. The process for the manufacture of a fluorinated benzene according to claim 4, wherein the activated and/or re-activated Cr.sub.2O.sub.3 based catalyst is activated and/or re-activated by treatment with Ni dopant, and wherein the said Ni dopant activated and/or re-activated Cr.sub.2O.sub.3 based catalyst is supported on AlF.sub.3 as a carrier.

6. The process for the manufacture of a fluorinated benzene according to claim 2, wherein the activated and/or re-activated Cr.sub.2O.sub.3 based catalyst is activated and/or re-activated by treatment with Mg dopant, and wherein the said Mg dopant activated and/or re-activated Cr.sub.2O.sub.3 based catalyst is additionally treated with carbon (C) to yield an activated and/or re-activated Cr—Mg—C fluorination catalyst.

7. The process for the manufacture of a fluorinated benzene according to claim 1, wherein e) the at least one vapor-phase reaction stage comprising reacting of a) a vaporized chlorinated benzene with b) anhydrous hydrogen fluoride (HF) in gas phase in the presence of c) the fluorination catalyst, so as to produce a vapor-phase fluorination reaction product, is performed in a reactor or reactor system of d) which is heated to the reaction temperature of at least about 200° C.; and then the feed into the reactor or reactor system of d), of hydrogen fluoride (HF) feed and halogenated benzene feed, is adjusted in relation to the employed kg-scale quantity of the fluorination catalyst of c), based on 1 kg of the fluorination catalyst, such that the said feed is adjusted to about 3.33 mol/h (0.667 kg/h) HF and about 1.11 mol/h halogenated benzene (about 0.125 kg/h based on chlorobenzene), both feeds fed over the vaporizer, which is operated at 180° C., and based on an operation period of the vaporizer of 1 h.

8. The process for the manufacture of a fluorinated benzene according to claim 1, wherein the fluorinated benzene is monofluorobenzene.

9. The process for the manufacture of a fluorinated benzene according to claim 1, further comprise i) purifying the fluorinated benzene, obtained in h) by distillation under atmospheric pressure to obtain purified fluorinated benzene.

10. The process for the manufacture of a fluorinated benzene according to claim 7, wherein the reaction temperature is at least about 250° C.

11. The process for the manufacture of a fluorinated benzene according to claim 10, wherein the reaction temperature is at least about 280° C.

12. The process for the manufacture of a fluorinated benzene according to claim 7, wherein the halogenated benzene feed is monochlorobenzene (chlorobenzene) feed.

Description

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(1) As briefly described in the Summary of the Invention, and defined in the claims and further detailed by the following description and examples herein.

(2) In particular, the present invention relates to a process for the manufacture of a fluorinated benzene, preferably monofluorobenzene, in a vapor-phase fluorination process comprising the steps of: a) provision of a chlorinated benzene as starting compound; b) provision of a fluorination gas consisting of anhydrous hydrogen fluoride (HF); c) provision of a fluorination catalyst, optionally of an activated and/or reactivated, and/or of a pre-fluorinated fluorination catalyst; d) provision of a reactor or reactor system, resistant to hydrogen fluoride (HF), and comprising a vaporizer for the starting compound of a), and a condenser for the vapor-phase fluorination reaction product, and a reservoir for collecting the fluorination reaction product; e) at least one vapor-phase reaction stage comprising reacting of a) a vaporized chlorinated benzene with b) anhydrous hydrogen fluoride (HF) in gas phase in the presence of c) the fluorination catalyst, so as to produce a vapor-phase fluorination reaction product; f) withdrawing the vapor-phase fluorination reaction product formed in the vapor-phase reaction step e) from the reactor or reactor system of d), and transferring the vapor-phase fluorination reaction product to the condenser and condensing for collecting the condensed fluorination reaction product; and g) hydrolysing the fluorination reaction product obtained and collected according to f), in water, to obtain a fluorinated benzene, preferably monofluorobenzene; and h) phase separation of the organic phase of fluorinated benzene, preferably monofluorobenzene, from water phase to obtain fluorinated benzene, preferably monofluorobenzene; and g) optionally purifying the fluorinated benzene, preferably monofluorobenzene, obtained in h) by distillation under atmospheric pressure to obtain purified fluorinated benzene, preferably purified monofluorobenzene.

(3) The inventive process disclosed hereunder delivers fluorobenzene in high yield in environmental friendly and economic feasible manner involving a step of a gas-phase fluorination of a halogenated, preferably chlorinated, benzenze with HF-gas to obtain the corresponding a fluorinated benzene, preferably monofluorobenzene. The general gas-phase (vapor-phase) fluorination reaction step is given above in Scheme 1.

(4) If the halogenated benzene employed in the present invention as a starting material contains more than one halogen, e.g., chlorine, the then multi-fluorinated benzenes, are obtained by the vapor-phase chlorine-fluorine exchange or fluorination reaction.

(5) In particular, according to the present invention the halogenated benzene preferably is chlorobenzene (monochlorobenzene), and the fluorinated benzene then is preferably fluorobenzene (monofluorobenzene).

(6) As a reference for scale orientation, and for reason of calculating quantities, reference is made to the molecular weight of benzene of 78.114 g/mol, and of monofluorobenzene of 96.10 g/mol.

(7) For reason of adapting and/or controlling process parameters, here the boiling point of benzene of about 80° C., and that of monofluorobenzene of about 85° C. are also given, each for ambient pressure.

(8) In an embodiment, the invention relates to a process for the manufacture of a fluorinated a fluorinated benzene, wherein the fluorination catalyst is selected from the group consisting of Cr.sub.2O.sub.3 based catalyst, MGF.sub.2 based catalyst, SbCl.sub.5/C based catalyst, and FeCl.sub.3/C based catalyst.

(9) In an embodiment, the invention relates to a process for the manufacture of a fluorinated benzene as described herein and in the claims, wherein the fluorination catalyst is selected from the group consisting of MgF.sub.2 based catalyst, SbCl.sub.5/C based catalyst, and FeCl.sub.3/C based catalyst, and wherein the said catalyst is pre-fluorinated with hydrogen fluoride (HF).

(10) In an embodiment, the invention relates to a process for the manufacture of a fluorinated benzene as described herein and in the claims, wherein the fluorination catalyst is selected from the group Cr.sub.2O.sub.3 based catalyst.

(11) In an embodiment, the invention relates to a process for the manufacture of a fluorinated benzene as described herein and in the claims, wherein the Cr.sub.2O.sub.3 based catalyst is an activated and/or re-activated Cr.sub.2O.sub.3 based catalyst.

(12) In an embodiment, the invention relates to a process for the manufacture of a fluorinated benzene as described herein and in the claims, wherein the activated and/or re-activated Cr.sub.2O.sub.3 based catalyst is activated and/or re-activated by treatment with an oxygen containing gas; and/or wherein the Cr.sub.2O.sub.3 based catalyst, preferably the activated and/or re-activated Cr.sub.2O.sub.3 based catalyst, is pre-fluorinated with hydrogen fluoride (HF).

(13) In an embodiment, the invention relates to a process for the manufacture of a fluorinated benzene as described herein and in the claims, wherein the activated and/or re-activated Cr.sub.2O.sub.3 based catalyst is activated and/or re-activated by treatment with Zn dopant, preferably by treatment with ZnCl.sub.2 as dopant, by treatment with Ni dopant, preferably by treatment with NiCl.sub.2 as dopant.

(14) In an embodiment, the invention relates to a process for the manufacture of a fluorinated benzene as described herein and in the claims, wherein the activated and/or re-activated Cr.sub.2O.sub.3 based catalyst is activated and/or re-activated by treatment with Ni dopant, preferably by treatment with NiCl.sub.2 as dopant, and wherein the said Ni dopant activated and/or re-activated Cr.sub.2O.sub.3 based catalyst is supported on AlF.sub.3 as a carrier.

(15) In an embodiment, the invention relates to a process for the manufacture of a fluorinated benzene as described herein and in the claims, wherein the activated and/or re-activated Cr.sub.2O.sub.3 based catalyst is activated and/or re-activated by treatment with Mg dopant, preferably by treatment with Mg as dopant, and wherein the said Mg dopant activated and/or re-activated Cr.sub.2O.sub.3 based catalyst is additionally treated with carbon (C) to yield an activated and/or re-activated Cr—Mg—C fluorination catalyst.

(16) In an embodiment, the invention relates to a process for the manufacture of a fluorinated benzene as described herein and in the claims, wherein in the said process for the manufacture of a fluorinated benzene in e) the at least one vapor-phase reaction stage is comprising reacting of a) a vaporized chlorinated benzene with b) anhydrous hydrogen fluoride (HF) in gas phase in the presence of c) the fluorination catalyst, so as to produce a vapor-phase fluorination reaction product,

(17) is performed in a reactor or reactor system of d) which is heated to the reaction temperature of at least about 200° C., preferably of at least about 250° C., more preferably to a reaction temperature of about 280° C.; and

(18) then the feed into the reactor or reactor system of d), of hydrogen fluoride (HF) feed and halogenated benzene feed, preferably monochlorobenzene (chlorobenzene) feed, is adjusted in relation to the employed kg-scale quantity of the fluorination catalyst of c), based on 1 kg of the fluorination catalyst, such that the said feed is adjusted to about 3.33 mol/h (0.667 kg/h) HF and about 1.11 mol/h halogenated benzene (about 0.125 kg/h based on chlorobenzene), both feeds fed over the vaporizer, which is operated at 180° C., and based on an operation period of the vaporizer of 1 h.

(19) An advantageous a reactor or reactor system d), resistant to hydrogen fluoride (HF), is a Monel tube, preferably a Monel tube that is electrically heated. For example, the Monel tube can have the following exemplary dimension, of a diameter (d) of about 10 cm, and a volume of about 6.5 l.

(20) Preferably the Monel tube is equipped with an electrical heater capable to achieve and sustain a vapor-phase reaction temperature in a range of from about 200° C. to about 300° C., preferably in a range of from about 250° C. to about 300° C., more preferably in a range of from about 270° C. to about 290° C.; and for example of about 280° C.

FURTHER DETAILS OF THE INVENTION

(21) As briefly described in the Summary of the Invention, and defined in the claims and further detailed by the following description and examples herein,

(22) The process of the present invention, in case of using chromium (Cr) based fluorination catalysts, is further related to a vapor-phase fluorination process, comprising a fluorination catalyst activation stage comprising contacting the fluorination catalyst with an oxidizing agent-containing gas flow for at least one hour; before and/or during the at least one reaction stage comprising reacting a halogenated benzene, e.g., chlorinated benzene, as starting material with hydrogen fluoride (HF) in gas phase in the presence of the chromium (Cr) based fluorination catalyst, so as to produce a fluorinated benzene.

(23) For example, the process of the present invention can comprise a plurality of reaction stages alternating with a plurality of regeneration stages, wherein the reaction stages comprises reacting the chlorinated compound with hydrogen fluoride in gas phase in the presence of the fluorination catalyst, and the regeneration stages comprise contacting the fluorination catalyst with an oxidizing agent-containing gas flow.

(24) For example, the process of the present invention can be performed such that the oxidizing agent-containing gas flow of the activation stage and/or the regeneration stages is an oxygen-containing gas flow.

(25) For example, the process of the present invention can be performed such that the activation stage and/or the regeneration stages comprise contacting the fluorination catalyst with the oxidizing agent-containing gas flow for at least 2 hours, preferably for at least 4 hours, more preferably for at least 10 hours, and even more preferably for at least 15 hours.

(26) For example, the process of the present invention can be performed such that the oxidizing agent-containing gas flow of the activation stage and/or the regeneration stages contains hydrogen fluoride in addition to the oxidizing agent, and wherein the proportion of oxidizing agent in the oxidizing agent-containing gas flow of the activation stage and/or the regeneration stages is preferably from 2 to 98 mol-%, and more preferably from 5 to 50 mol-%, relative to the total amount oxidizing agent and hydrogen fluoride.

(27) For example, the process of the present invention can be performed such that the oxidizing agent-containing gas flow of the activation stage and/or the regeneration stages does not contain hydrogen fluoride, and preferably is air.

(28) For example, the process of the present invention can be performed such that the activation stage and/or the regeneration stages comprise contacting the fluorination catalyst with a hydrogen fluoride gas flow, either before contacting the fluorination catalyst with the oxidizing agent-containing gas flow; or after contacting the fluorination catalyst with the oxidizing agent-containing gas flow.

(29) For example, the process of the present invention can be performed such that the activation stage comprises a preliminary step of reacting the halogenated, e.g., the chlorinated, benzene as the starting material with hydrogen fluoride (HF) in gas phase in the presence of the fluorination catalyst, prior to contacting the halogenated, e.g., the chlorinated, benzene as the starting material with the oxidizing agent-containing gas flow.

(30) For example, the process of the present invention can be performed such that the oxidizing agent-containing gas flow is contacted with the fluorination catalyst during the activation stage and/or the regeneration stages at a temperature of from 250 to 500° C., preferably from 300 to 450° C., more preferably from 350 to 450° C.

(31) For example, the process of the present invention can be performed such that the fluorination catalyst is a supported catalyst, and is preferably supported on a support selected from fluorinated alumina, fluorinated chromia, fluorinated activated carbon or graphite carbon.

(32) For example, the process of the present invention can just be performed such that the fluorination catalyst is an unsupported catalyst.

(33) For example, the process of the present invention can be performed such that the fluorination catalyst further comprises a co-catalyst selected from Co, Zn, Mn, Mg, V, Mo, Te, Nb, Sb, Ta, P, Ni or mixtures thereof, preferably Ni, and wherein said co-catalyst is preferably present in an amount from about 1 wt.-% to about 10 wt.-% of said fluorination catalyst.

(34) For example, the process of the present invention can be performed such that the fluorination catalyst is a mixed chromium/nickel catalyst, the atomic ratio of nickel to chromium being preferably from about 0.5 to about 2 and more preferably approximately 1.

(35) For example, the process of the present invention can be further performed such that the molar ratio of hydrogen fluoride (HF) to halogenated, e.g., the chlorinated, benzene as the starting material is from about 2:1 to about 15:1, preferably about 3:1 to about 10:1, more preferably about 3:1 to about 5:1.

(36) For example, the process of the present invention can be further performed such that the reaction stages are carried out at a pressure of from about 1 to about 20 bar, preferably from about 5 to about 15 bar, more preferably from about 7 to about 10 bar.

(37) The Cr-Based Catalysts:

(38) The general gas-phase (vapor-phase) fluorination reaction step with hydrogen fluoride (HF) as fluorination gas and fluorination catalyst based on chromium, for example, Cr.sub.2O.sub.3, is shown in representative Scheme 2.

(39) ##STR00002##

(40) The patent publication U.S. Pat. No. 2,745,886 (1955), as already described above, relates to a fluorination catalyst, and to a process for fluorinating halohydrocarbons to highly fluorinated products with the aid of this catalyst.

(41) In the present invention the fluorination catalyst of the U.S. Pat. No. 2,745,886 (1955) is analogously used for the gas-phase (vapor-phase) fluorination reaction step with hydrogen fluoride (HF) as fluorination gas. Herein the hydrated chromium fluoride may be activated with oxygen as particularly described in the U.S. Pat. No. 2,745,886 (1955), and that the catalyst material so activated is very effective in catalyzing the vapor-phase fluorination reaction of halogenated, e.g., the chlorinated, benzene as the starting material and hydrogen fluoride (HF) as the fluorination gas. In fact, the catalysts are believed to be basic chromium fluorides, and more active than CrF.sub.3. The said catalysts are also more effective in directing the course of the vapor-phase fluorination to greater conversions and yields of more highly fluorinated products, and at much lower temperatures, than has been achieved before.

(42) In a particular embodiment of the present invention, the fluorination catalyst was prepared according to example 3 part B as described U.S. Pat. No. 2,745,886 starting with Cr.sub.2O.sub.3 (99% purity) and HF (anhydrous, 100%) giving CrF.sub.3×3H.sub.2O, and, after adding 2 wt.-% graphite and formation of pellets, the catalyst was activated with oxygen.

(43) In analogy to example 3 part B as described U.S. Pat. No. 2,745,886, the catalyst in accordance with the present invention was prepared by passing a stream of oxygen through a bed of 3/16 inch by 3/16 inch disc-shaped pellets containing 2 weight percent graphite prepared according to the following procedure: A catalyst in accordance with the invention was prepared by reacting high purity chromium trioxide (CrO.sub.3) with an excess of 70 weight percent hydrofluoric acid. The semi-crystalline bright green reaction product was heated in a drying oven at 80° C. to sensible dryness. This sensibly dry product, consisting preponderantly of α-CrF.sub.3×3H.sub.2O was ground to pass through a 10 mesh screen, admixed with 2 weight percent graphite, and was pressed into 3/16 inch by 3/16 inch disc-shaped pellets.

(44) The dimensions of the catalyst bed and the conditions of the activation step were the same as described in example 3 of U.S. Pat. No. 2,745,886, except that oxygen was employed instead of air, e.g., according to the following procedure: The catalyst pellets produced as described here-above were packed to a height of about 12 inches in the 2 inch nickel reaction tube as described in the examples of U.S. Pat. No. 2,745,886, or alternatively or preferably, into a Monel tube as described herein-above and employed in in the context of the present invention. The catalyst pellets were then activated by heating them to, and holding them for two hours at, 500° C. in a stream of oxygen. Of course, alternatively also air as described in example of U.S. Pat. No. 2,745,886 can be used.

(45) The Cr-based catalysts prepared above are amorphous to X-ray diffraction analysis.

(46) For example, the process of preparing a Cr-based fluorination catalysts for use in the vapor-phase process of the present invention can be performed such that the method of preparing a catalyst useful in promoting the fluorination by vapor-phase reaction with hydrogen fluoride, said method comprising heating a mixture of a major proportion of hydrated chromium fluoride and a minor proportion of chromium trioxide at a temperature above about 400° C. for a time sufficiently long to convert at least part of the hydrated chromium fluoride to a basic chromium fluoride.

(47) For example, the process of preparing a Cr-based fluorination catalysts for use in the vapor-phase process of the present invention can be performed such that the method of preparing a catalyst useful in promoting the fluorination by vapor-phase reaction with hydrogen fluoride, said method consisting essentially of heating a hydrated chromium fluoride to a temperature in the range of from about 350° to 750° C. in the presence of oxygen.

(48) For example, the process of preparing a Cr-based fluorination catalysts for use in the vapor-phase process of the present invention can be performed such that the method of preparing a catalyst useful in promoting the fluorination by vapor-phase reaction with hydrogen fluoride, said method consisting essentially of heating a hydrated chromium fluoride to. a temperature in the range of from about 350° C. to about 650° C., while passing a: stream of a gas comprising molecular oxygen therethrough for a time sufficiently long for a small though effective amount of oxygen to react therewith.

(49) For example, the process of preparing a Cr-based fluorination catalysts for use in the vapor-phase process of the present invention can be performed such that in the said process the gas stream is oxygen.

(50) For example, the process of preparing a Cr-based fluorination catalysts for use in the vapor-phase process of the present invention can be performed such that in the said process the gas stream is air.

(51) For example, the process of preparing a Cr-based fluorination catalysts for use in the vapor-phase process of the present invention can be performed such that the said method is comprising heating a bed of CrF.sub.3×3H.sub.2O to an activation temperature in the range of from 350° to 650° C., while passing a stream of a gas comprising molecular oxygen therethrough, the flow of gas being maintained through said bed within said activation temperature range for a time sufficiently long to convert at least part of the hydrated chromium fluoride to a basic chromium fluoride.

(52) For example, the process of preparing a Cr-based fluorination catalysts for use in the vapor-phase process of the present invention can be performed such that the said the CrF.sub.3×3H.sub.2O is the alpha hydrate.

(53) In the context of the present invention the material “Hastelloy®” is mentioned, and therefore shall be explained in more detail hereinafter.

(54) Hastelloy® C is an alloy represented by the formula NiCr21Mo14W, alternatively also known as “alloy 22” or “Hastelloy® C-22. The said alloy is well known as a corrosion resistant nickel-chromium-molybdenum-tungsten alloy and has excellent resistance to oxidizing reducing and mixed acids. The said alloy is used in flue gas desulphurization plants, in the chemical industry, environmental protection systems, waste incineration plants, sewage plants. Apart from the before said example, in other embodiments of the invention, in general nickel-chromium-molybdenum-tungsten alloy from other manufactures, and as known to the skilled person, of course can be employed in the present invention. A typical chemical composition (all in weight-%) of such nickel-chromium-molybdenum-tungsten alloy is, each percentage based on the total alloy composition as 100%: Ni (nickel) as the main component (balance) of at least about 51.0%, e.g. in a range of from about 51.0% to about 63.0%; Cr (chromium) in a range of from about 20.0 to about 22.5%, Mo (molybdenum) in a range of from about 12.5 to about 14.5%, W (tungsten or wolfram, respectively) in a range of from about 2.5 to about 3.5%; and Fe (iron) in an amount of up to about 6.0%, e.g. in a range of from about 1.0% to about 6.0%, preferably in a range of from about 1.5% to about 6.0%, more preferably in a range of from about 2.0% to about 6.0%.

(55) Optionally, the percentage based on the total alloy composition as 100%, Co (cobalt) can be present in the alloy in an amount of up to about 2.5%, e.g. in a range of from about 0.1% to about 2.5%. Optionally, the percentage based on the total alloy composition as 100%, V (vanadium) can be present in the alloy in an amount of up to about 0.35%, e.g. in a range of from about 0.1% to about 0.35%. Also, the percentage based on the total alloy composition as 100%, optionally low amounts (i.e. ≤0.1%) of other element traces, e.g. independently of C (carbon), Si (silicon), Mn (manganese), P (phosphor), and/or S (sulfur). In such case of low amounts (i.e. ≤0.1%) of other elements, the said elements e.g. of C (carbon), Si (silicon), Mn (manganese), P (phosphor), and/or S (sulfur), the percentage based on the total alloy composition as 100%, each independently can be present in an amount of up to about 0.1%, e.g. each independently in a range of from about 0.01 to about 0.1%, preferably each independently in an amount of up to about 0.08%, e.g. each independently in a range of from about 0.01 to about 0.08%. For example, said elements e.g. of C (carbon), Si (silicon), Mn (manganese), P (phosphor), and/or S (sulfur), the percentage based on the total alloy composition as 100%, each independently can be present in an amount of, each value as an about value: C≤0.01%, Si≤0.08%, Mn≤0.05%, P≤0.015%, S≤0.02%. Normally, no traceable amounts of any of the following elements are found in the alloy compositions indicated above: Nb (niobium), Ti (titanium), Al (aluminum), Cu (copper), N (nitrogen), and Ce (cerium).

(56) Hastelloy® C-276 alloy was the first wrought, nickel-chromium-molybdenum material to alleviate concerns over welding (by virtue of extremely low carbon and silicon contents). As such, it was widely accepted in the chemical process and associated industries, and now has a 50-year-old track record of proven performance in a vast number of corrosive chemicals. Like other nickel alloys, it is ductile, easy to form and weld, and possesses exceptional resistance to stress corrosion cracking in chloride-bearing solutions (a form of degradation to which the austenitic stainless steels are prone). With its high chromium and molybdenum contents, it is able to withstand both oxidizing and non-oxidizing acids, and exhibits outstanding resistance to pitting and crevice attack in the presence of chlorides and other halides. The nominal composition in weight-% is, based on the total composition as 100%: Ni (nickel) 57% (balance); Co (cobalt) 2.5% (max.); Cr (chromium) 16%; Mo (molybdenum) 16%; Fe (iron) 5%; W (tungsten or wolfram, respectively) 4%; further components in lower amounts can be Mn (manganese) up to 1% (max.); V (vanadium) up to 0.35% (max.); Si (silicon) up to 0.08% (max.); C (carbon) 0.01 (max.); Cu (copper) up to 0.5% (max.).

(57) The following examples are intended to further illustrate the invention without limiting its scope.

EXAMPLES

(58) Representative, example procedures are described hereinafter in the embodiment following examples. In the process of the present invention particular focus was put on a continuous gas phase (vapor-phase) fluorination step. Accordingly, the skilled person will readily understand that additional equipment has to be used, as applicable, e.g., inlets, outlets, pipes, measurement equipment for pressure, temperature, flow-measurement and the like, are employed as commonly known in the field of art, even if not specifically indicated herein below for reason of conciseness only.

Example 1

(59) Synthesis of Fluorobenzene in Gas Phase Over Cr.sub.2O.sub.3 Based Catalyst.

(60) The fluorination catalyst was prepared according to example 3 part B in U.S. Pat. No. 2,745,886 starting with Cr.sub.2O.sub.3 (99% purity) and HF (anhydrous, 100%) giving CrF.sub.3×3 H.sub.2O and—after adding 2 wt % graphite and formation of pellets, the catalyst was activated with oxygen. See description below.

(61) ##STR00003##

(62) Preparation of Vapor-Phase Fluorination Catalyst:

(63) In analogy to example 3 part B as described U.S. Pat. No. 2,745,886, the catalyst in accordance with the present invention was prepared by passing a stream of oxygen through a bed of 3/16 inch by 3/16 inch disc-shaped pellets containing 2 weight percent graphite prepared according to the following procedure: A catalyst in accordance with the invention was prepared by reacting high purity chromium trioxide (CrO.sub.3) with an excess of 70 weight percent hydrofluoric acid. The semi-crystalline bright green reaction product was heated in a drying oven at 80° C. to sensible dryness. This sensibly dry product, consisting preponderantly of α-CrF.sub.3×3H.sub.2O was ground to pass through a 10 mesh screen, admixed with 2 weight percent graphite, and was pressed into 3/16 inch by 3/16 inch disc-shaped pellets.

(64) The dimensions of the catalyst bed and the conditions of the activation step were the same as described in example 3 of U.S. Pat. No. 2,745,886, except that oxygen was employed instead of air, e.g., according to the following procedure: The catalyst pellets produced as described here-above were packed to a height of about 12 inches in the 2 inch nickel reaction tube as described in the examples of U.S. Pat. No. 2,745,886, or alternatively or preferably, into a Monel tube as described herein-above and employed in in the context of the present invention. The catalyst pellets were then activated by heating them to, and holding them for two hours at, 500° C. in a stream of oxygen. Of course, alternatively also air as described in example of U.S. Pat. No. 2,745,886 can be used.

(65) The catalysts prepared above are amorphous to X-ray diffraction analysis.

(66) Apparatus for Vapor-Phase Fluorination:

(67) The reactor consists out of a Monel-tube filled with catalyst pellets, a HF feeding system out of a stainless steel cylinder pressurized with N.sub.2 (dosage from liquid phase over a Bronkhorst flow meter), a vaporizer operated at 180° C. for the chlorobenzene feed, a condenser with a reservoir after the tube reactor still under slight overpressure, a scrubber just filled with water kept (cooled) at 25° C. and another scrubber filled with NaOH and a bubble counter at the exit allowing exhaust gas and the N.sub.2 to exit.

(68) Vapor-Phase Fluorination Process:

(69) The Monel tube (d=10 cm, volume around 6.5 l, electrically heated) was filled with 9 kg catalyst. Once the reactor temperature reached 280° C., the feed was adjusted to 600 g/h (30.0 mol/h) HF and 1126 g/h (10.0 mol/h) chlorobenzene, both fed over the vaporizer, which is operated at 180° C. for 1 h, into the monel tube. A carefully hydrolyzed sample during the reaction showed almost quantitative conversion of chlorobenzene.

(70) Collection of Vapor-Phase Fluorination Product:

(71) All material collected in the reservoir of the condenser was very carefully fed into ice water and the organic phase carefully distilled at atmospheric pressure in a distillation apparatus out of plastics to get 99.9% pure fluorobenzene at 85° C. transition temperature. The isolated yield was 723 g fluorobenzene (75% of theory).

Example 2

(72) Lifetime Experiment

(73) Trial 1 was repeated in a fully automated apparatus (in a 100 h pilot scale run). Samples taken every 5 h showed a continuous degradation (deactivation) of the catalyst (conversion rate analyze by GC). After 55 h, the conversion of chlorobenzene dropped to 56% only, after 100 h only a 10% conversion was observed and the experiment was stopped (a 1001/h N.sub.2-stream was continued for about 2 h to get out HF and organic volatile material).

Example 3

(74) Reactivation of Cr.sub.2O.sub.3 Catalyst.

(75) The principle of reactivation of lower performance Cr-based fluorination catalysts is known from U.S. Pat. No. 5,227,350 (1992).

(76) The reactor was heated to 350° C. (N.sub.2-stream still open) and a synthetic air flow was started with an oxygen concentration at the beginning of 0.5% 02 and 95% N.sub.2, increased to an 02 concentration of 1% after 1 h. An exothermicity could be observed. Over 5 h, the 02 concentration was increased by 1% every hour to reach 5% after 5 h. It could be observed that a hot spot area moved from the entrance to the exit of the reactor over this time period. The 02 was stopped but the N.sub.2-purge was continued at 400° C. reactor temperature for another 5 h to remove (formed) moisture and oxygen absorbed on the catalyst. Afterwards the Cr.sub.2O.sub.3 was pretreated with HF at 200° C. reactor temperature for 1 h with a HF feed of 100 g/h for 15 min continued with an HF feed of 200 g/h for the remaining 45 minutes.

Example 4

(77) Fluorination of Chlorobenzene with Reactivated Cr.sub.2O.sub.3-Catalyst

(78) This trial was done according to example 1. If any, only a very slight deactivation vs. example 1 was observed by showing 5% chlorobenzene in a hydrolyzed sample of the reservoir of the condenser. The obtained yield in fluorobenzene based on converted chlorobenzene again was 75% of theory.

Example 5

(79) Fluorination of Chlorobenzene with MgF.sub.2 Catalyst.

(80) A MgF.sub.2 based catalyst containing 10% CsCl and 90% MgF.sub.2 was prepared and filled as pellets into the reactor tube, the catalyst was pre-fluorinated 1 h with HF and the trial was performed according to example 1. The conversion into chlorobenzene was 60%, the selectivity to fluorobenzene 87%.

Example 6

(81) Fluorination of Chlorobenzene with SbCl.sub.5/C-Catalyst.

(82) A 50% SbCl.sub.5 based catalyst on active carbon (Norrit RB3) was prepared and filled as pellets into the reactor tube, the catalyst was treated with C12-gas (100 g/h) for 0.5 h at 60° C. to be sure to have 100% active SbCl.sub.5 and not SbC.sub.3) and afterwards also pre-fluorinated 1 h with HF; the procedure was performed according to example 1. The conversion in chlorobenzene was 96%, the selectivity to fluorobenzene 98%.

Example 7

(83) Fluorination of Chlorobenzene with FeCl.sub.3/C-Catalyst.

(84) A 90% FeCl.sub.3 based catalyst on active carbon (Norrit RB3) was prepared and filled as pellets into the reactor tube, the catalyst was pre-fluorinated 1 h with HF, the trial was performed according to example 1. The conversion in chlorobenzene was 73%, the selectivity to fluorobenzene 92%.

Example 8

(85) Fluorination of Chlorobenzene with Zn Activated Cr-Catalyst.

(86) The catalyst was prepared according to the principle disclosed first time in ICI's U.S. Pat. No. 5,449,656 from 1955 example 3, the Zn content was adjusted to 3%.

(87) 1 kg (19.2 mol) of chromia in form of granules of size 0.5-1.4 mm and surface of 50 m.sup.2/g (Strem chemicals) was added to a solution of 78.6 g (0.5769 mol) ZnCl.sub.2 in 1 l distilled water and stirred for 1 h at room temperature. Afterwards, the material was dried in vacuum (20 mbar/60° C.) until no weight loss could be observed resulting in particles of size 0.5-1.4 mm with 3 wt % Zn. A Monel tube of 10 cm diameter and 40 cm length was filled with the catalyst and HF (100%) was added over a Bronkhorst flow meter for 1 h in a flow rate of 500 g/h and a temperature of 250° C. After 1 h pre-treatment with HF only, 0.5 wt % oxygen was mixed into the HF feed for another 3 hour. Chlorobenzene feed was started over a vaporizer (operated at 180° C.) with a feed of 100 g/h (0.88 mol) and a HF feed of 352.2 g (17.6 mol) at a temperature of 230° C. Operating time was 2 h. The analytical results are similar to the no Zn containing catalyst (out of example 1).

(88) The conversion of chlorobenzene was quantitative, the selectivity to fluorobenzene 99% giving 160 g fluorobenzene (95% of theory) isolated after careful work up into ice water, phase separation and distillation at atmospheric pressure.

Example 9

(89) Fluorination of Chlorobenzene with Ni-Doped Cr-Catalysts.

(90) Elf Atochem in EP0773061 (1994) describes the usage of Ni doped Cr-catalysts prepared out of Cr(NO.sub.3).sub.3 and NiCl.sub.2. The catalyst was prepared according to example 1 in the Elf Atochem patent. The inventive procedure described in example 1 in this patent but at 260° C. gave 94% conversion and a selectivity to fluorobenzene of 98%. The achieved purity after hydrolysis and distillation was 99.9%, the isolated yield was 87% of theory.

Example 10

(91) Fluorination of Chlorobenzene on Ni—Cr Catalyst Supported on AlF.sub.3.

(92) In Arkema's EP2665692 (2011) the Ni—Cr catalyst supported on AlF.sub.3 is used for the production of 1234yf and applied at 230° C. according to example 1 of this invention. The conversion of chlorobenzene with this catalyst was 56%, the achieved selectivity to fluorobenzene was 94%.

Example 11

(93) Simplified Cr-base fluorination catalyst preparation procedure with Cr(NO.sub.3).sub.3 and ammonia and the application in preparation of fluorobenzene.

(94) An aqueous solution of chromium nitrate and aqueous ammonia were slowly mixed in a Hastelloy C4 vessel and dry ice condenser. The precipitated material was collected and the chromium hydroxide heated to 250° C. The catalyst was pressed into pellets, filed in a Ni-tube and fluorinated with HF 100% (2 h). The application of this catalyst according to example 1 gives 79% conversion of Chlorobenzene, a selectivity to fluorobenzene of 97% and a yield of 94%.

Example 12

(95) Preparation of a Cr—Mg—C-Catalyst and Application Thereof in the Preparation of Fluorobenzene.

(96) Preparation Procedure of a of a Cr—Mg—C Catalyst:

(97) 200 g Cr(NO.sub.3)×9H.sub.2O were dissolved in 1 l deionized water, then 500 g MgO and 240 g graphite were added and mixed properly. Cutting the cake into small (0.5 cm×0.5 cm parts) and drying at 100° C. until no water leaves the material gives around 1 kg catalyst.

(98) Prefluorination and Conditioning with HF:

(99) The catalyst was filled into a Ni-tube (after a vaporizer and connected to a condenser with reservoir afterwards) of 120 cm length and a diameter of 5 cm. 100% HF was fed through the catalyst bed over 5 h first with 200 g/h, after 2 h with 500 g/h at 250° C.

(100) Conversion of Chlorobenzene to Fluorbenzene:

(101) The reactor temperature was lowered to 230° C. and chlorobenzene feed (over a vaporizer with 180° C.) was adjusted to 300 g/h (15.0 mol) HF and 563 g (5.0 mol) chlorobenzene, both fed over the vaporizer (operated at 180° C. for 1 h) into the Ni-tube reactor. A carefully hydrolyzed sample during the reaction showed almost quantitative conversion of chlorobenzene.

(102) All material collected in the reservoir of the condenser was very carefully fed into ice water and the organic phase carefully distilled at atmospheric pressure in a distillation apparatus out of plas-tics to get 99.9% pure fluorobenzene at 85° C. transition temperature. The isolated yield was 858 g fluorobenzene (89% of theory).