Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
  • C09K5/08—Materials not undergoing a change of physical state when used
  • C09K5/10—Liquid materials

Definitions

• the present invention relates to heat transfer fluids or heat transfer fluids based on polyphenylmethanes having improved thermal stability and more particularly heat transfer fluids usable at high temperature comprising at least one composition of polyphenylmethanes and at least one mixture of benzyl isomers 1, 2 , 3,4-tetrahydronaphthalenes and / or a composition of partially hydrogenated polyphenyls.
• Heat transfer fluids are widely used to provide rigorous temperature control in chemical industry operations and must have a number of physicochemical characteristics.
• heat transfer fluids which must be used in a very wide range of temperatures, that is to say ranging from -30 ° C to + 400 ° C, must have, in addition to a good heat transfer, a boiling point at high atmospheric pressure, good thermal stability, low viscosity over a wide range of temperatures, even at low temperature during, in particular when used, a slight tendency to corrode the materials of the apparatus, low sensitivity to 'oxidation. They must also cause low risk to the environment in the event of leaks and also low risk of fire.
• thermal stability is a determining criterion and is the concern of manufacturers and producers of heat transfer fluids.
• R, R, R, R and R is chosen from the hydrogen atom and a low alkyl radical such as CH 3 . and n is 1 or 2.
• the subject of the invention is therefore a heat transfer or heat transfer fluid which can be used at temperatures at most equal to 370 ° C and, preferably, between 320 ° C and 360 ° C, characterized in that it comprises at least a mixture of isomers of formula:
• compositions (I) comprising a mixture of products of formula (A):
• n, and n 2 0 or 1 and which contains products (A) such as ⁇ -r- n j ⁇ O and products (A) such as n ⁇ + ⁇ ⁇ l and products of formula (B ):
• compositions (II) comprising a mixture of two products (C) and (D) in which: * the product (C) is a mixture of isomers of formula:
• product (D) is a mixture of isomers of formula
• compositions (III) comprising a mixture of two products (A1) and (A2), such as:
• compositions (IV) comprising the two products (A1) and (A2) and, at least one compound chosen from the following products (E1), (E2) or (E3): * (E1) is an isomer or a mixture of 'isomers of formula:
• Ri and R2 represent a hydrogen atom.
• (E2) is an isomer or a mixture of isomers of the same general formula as (E1), except that R, and R 2 represent a methyl and the coefficients r are replaced by s and have the same meaning.
• (E3) is an isomer or a mixture of isomers of the same general formula as (E1), except that R, and R 2 are different and represent a hydrogen atom or a methyl radical and the coefficients r are replaced by t and have the same meaning.
• the compositions (I) can contain product (A) with 2 rings, (methylbenzyl) xylene, and product (A) with 3 rings which is designated by bis (methylbenzyl) xylene.
• compositions (I) which can be used according to the present invention
• JARYTHERM AX 320 having a weight content of compounds with 2 and 3 aromatic rings greater than 99%.
• compositions (H) which can be used according to the present invention
• compositions can be obtained by methods described in patents EP 136 230-B1, EP 299 867-B1, EP 384 818-B1, EP 500 435-B1 which consist in carrying out the chlorination of toluene or xylene and then carrying out a condensation of the Friedel and Crafts type either on toluene or on xylene (mixture of isomers), or on a toluene and xylene mixture, or on benzene, or on a benzene and toluene mixture.
• the unprocessed reagent (s) are removed directly by distillation and then the crude product can be subjected to a dechlorination treatment as described in patent EP 306 398-B1.
• the compositions (II) can be obtained by a process described in patent EP 136 230-B1 which consists, in a first step, in reacting chlorine on toluene by radical reaction in the presence of free radical generator at a temperature between 50 ° C and 110 ° C and then in a second step, the reaction product from the first step is subjected to a condensation reaction with toluene in the presence of FeCl 3 at a temperature between 50 ° C and 100 ° C.
• compositions (I) can be obtained according to a process described in patent EP 0 50 435-B1 which consists in carrying out the condensation of (methyl) benzyl chloride with xylene in the presence of FeCl 3 .
• the mixture of isomers of formula (Y) is preferably a mixture of 5-benzyl-1,2,3,4-tetrahydronaphthalene and 6-benzyl-1,2,3,4-tetrahydronaphthalene.
• This mixture of isomers can be obtained by reacting benzyl chloride on 1,2,3,4-tetrahydronaphthalene in the presence of a catalyst of the Friedel and Crafts type such as FeCl 3 .
• the invention also relates to a heat transfer fluid based on a mixture of isomers of formula (Y) and / or on a mixture of partially hydrogenated polyphenyls and at least one polyphenylmethane composition chosen from compositions (I). , (II), (III) or (IV), characterized in that, in addition, (Y) is found to be in admixture with the following compounds (Y1) and (Y2): * (Y1) is a mixture of compounds of monobenzylation of (Y) of formulas:
• the compounds (Y), (Y1) and (Y2) in the mixture (Y) + (Y1) + (Y2) are found to be in the following weight proportions:
• the mixture of isomers of formula (Y) as well as the mixture of isomers of formula (Y) and of compounds (Y1) and (Y2) can be obtained according to a process which consists in reacting benzyl chloride with an excess 1,2,3,4-tetrahydronaphthalene (tetralin) molar in the presence of a mineral halide or a protonic acid.
• This reaction takes place in practice at a temperature between 30 ° C and 150 ° C and, preferably between 50 ° C and 100 ° C.
• ferric chloride antimony trichloride, titanium tetrachloride or also aluminum chloride at weight contents relative to the reagents used usually between 50 ppm and 1% and of preferably between 100 ppm and 0.5%.
• ferric chloride will be used.
• Protonic acids can also be used: sulfuric acid for example at a weight concentration between 70 and 95%. It is also possible to use zeolites or certain mineral oxides.
• the mineral halide or the protonic acid is eliminated by any known technique such as: washing with water and then drying in the case where a protonic acid is used , treatment with sodium methylate as described in patent EP 306,398 B1 in the case where a mineral halide is used.
• compositions can be prepared with well-defined contents of compounds (Y), (Y1) and (Y2).
• the characterization of the compounds (Y), (Y1) and (Y2) and their contents in the various distillation fractions can be carried out by CPG analysis followed by an NMR analysis of the proton in CCI 4 medium with tetramethylsilane as reference. It would not be departing from the scope of the invention if a mixture of more or less hydrogenated compounds of naphthalene were used in place of tetralin. These mixtures generally comprise from 80% to 90% by weight of tetralin, the complement to 100% consisting of variable amounts of decalin and unconverted naphthalene.
• the partially hydrogenated polyphenyls which can be used according to the present invention are partially hydrogenated biphenyls such as phenylcyclohexane or else 80/20 complex mixtures of terphenyls (ortho-, meta-, and para isomers) and more or less hydrogenated quaterphenyls. They are commercially available.
• the polyphenylmethane compositions the compositions of formulas (I) or (II) will preferably be used.
• the heat transfer fluid according to the present invention can be obtained by simple mixing of the products. One can also consider making this mixture by reacting benzyl chloride on toluene (or benzyltoluene) and tetralin.
• the transfer fluid according to the present invention comprises at least 50% by weight and, preferably, at least 75% by weight of at least one polyphenylmethane composition (I), (II), (III) or (IV).
• the 100% weight supplement can comprise a mixture of isomers of formula (Y) or a mixture of products of formula (Y), (Y1) and (Y2) or else partially hydrogenated polyphenyls or alternatively a mixture of isomers of formula (Y) or the mixture of products of formulas (Y), (Y1) and (Y2) with partially hydrogenated polyphenyls.
• the heat transfer fluids according to the present invention consist of mixtures comprising a mixture of isomers of formula (Y) or a mixture of the compounds of formulas (Y), (Y1) and (Y2), and / or partially hydrogenated polyphenyls with polyphenylmethane compositions (I), (II) (III) or (IV) have the advantage of having greater thermal stability than the polyphenylmethane compositions used alone.
• DBT ° JARYTHERM DBT, hereinafter referred to as DBT; sold by the company ELF ATOCHEM S.A.
• JARYTHERM BT06 hereinafter designated by BT06; sold by the company ELF ATOCHEM S.A. Its constitution has been described previously.
• AX320 ° JARYTHERM AX320, hereinafter referred to as AX320; sold by the company ELF ATOCHEM S.A.
• L ⁇ X320 has a weight content of 2 and 3 aromatic nuclei> 99%.
• D DOWTHERM RP hereinafter referred to as RP; sold by the company
• DOWTHERM RP is a mixture of isomers of 1,2,3,4-tetrahydro-5- (1-phenylethyl) naphthalene and 1,2,3,4-tetrahydro-6- (1-phenylethyDnaphthalene) which has a d point boiling at atmospheric pressure of 354 ° C.
• THERMINOL 66 is a mixture of partially hydrogenated terphenyls which has a boiling point at atmospheric pressure of 359 ° C.
• 5,404 g is charged to a 10 I reactor fitted with rotary stirring, an ascending cooler, a nitrogen injector, a thermometric sheath, a dropping funnel and heating means of 1,2,3,4-tetrahydronaphthalene at 98.5% purity, ie 40.94 moles.
• the product is brought to 120 ° C. with nitrogen sweeping and stirring.
• the refrigerant outlet is then connected to a water bubbler.
• 6.7 g of anhydrous FeCl 3 are added to the reactor and then 1295.4 g of benzyl chloride at 99% purity, ie 10.24 moles over 3 h 30 min, are introduced, still with nitrogen flushing.
• the molar ratio of 1,2,3,4-tetrahydronaphthalene / benzyl chloride is 4.
• the content by weight of benzyl chloride present in the reaction medium is 0.74%.
• the reaction is continued with stirring and flushing with nitrogen, for 1 hour at 120 ° C. and then 1 hour at 130 ° C.
• the total quantity of HCl released and trapped in the bubbler is equal to 10.2 moles.
• the final content of benzyl chloride in the reaction medium is approximately 0.02% by weight.
• the reactor content (6,325 g) is then placed in a 10 I distillation flask surmounted by an adiabatic column 50 cm high, filled with glass springs (efficiency of the column equal to approximately 3 theoretical plates), surmounted by a simple distillation head and a condenser.
• the unprocessed 1,2,3,4-tetrahydronaphthalene is recovered by distillation under a pressure of 40 mm of mercury.
• the distillation is carried out in 4 hours at a bottom temperature ranging from 130 ° C to 239 ° C and a head temperature ranging from 1 1 5 ° C to 1 18 ° C during most of the distillation with, at the end of the distillation, a rise to 142 ° C.
• 4200 g of a colorless liquid are recovered having a 1,2,3,4-tetrahydronaphthalene content greater than 98.5% and can be recycled in a subsequent operation.
• distillation bottom (2 105 g), containing less than 0.14% by weight of 1,2,3,4-tetrahydronaphthalene is then subjected to an operation for removing small amounts of residual organic chlorine, an operation which consists in treating said distillation bottom with approximately 21 g of powdered CH 3 ONa (1% by weight relative to the weight of product to be treated) in a stirred reactor and, under nitrogen sweep, at 300 ° C for 3 hours.
• a fraction of 1,400 g of a product is collected having a boiling point equal to 218/220 ° C under a pressure equal to 18 mm of mercury and which consists of more than 98.8% by weight of a mixture of 6-benzyl-1,2,3,4-tetrahydronaphthalene (65% by weight) and 5-benzyl, 1,2,3,4-tetrahydronaphthalene (35% by weight), hereinafter designated BTHN.
• the distillation is continued by removing the packing from the column and lowering the pressure to 12 mm of mercury.
• BTHN denotes monobenzyl-1,2,3,4-tetrahydronaphthalene (formula (Y)) which happens to be a mixture of 6-benzyl-1,2,3,4-tetrahydronaphthalene (65% by weight) and 5- 1,2-benzyl, 2,3,4-tetrahydronaphthalene (35% by weight).
• DBTHN denotes the compounds of formula (Y1).
• This mixture - PBTHN - has a boiling point at atmospheric pressure of 359 ° C and a viscosity at 20 ° C equal to 38 mm 2 / s. 3.
• the mixtures of heat transfer fluids were produced by simple mixing, at room temperature, of the heat transfer fluids previously mentioned, in a stirred glass reactor.
• NC means not in accordance with the invention (comparative), C means in accordance with the invention.
• a 1.6 I stainless steel reactor is used fitted with a stirrer, a temperature sensor, and an outlet in connection with a Dean- Starck fitted with an ascending cooler, which is connected to a graduated water tank.
• the reactor is provided with a regulated heating enclosure.
• the evaluation of the thermal stability of a coolant or of a mixture of coolants is carried out on 1 kg of said coolant or of said mixture of coolants and consists in introducing the product to be evaluated into the reactor, closing the reactor, carrying out sweeping with an inert gas and bringing it to the test temperature for a determined time.
• the condensates are collected (bottom of the Dean-Starck) and their quantities are determined as a function of time.
• the gas volume is determined from the graduated water tank.
• Figure 1 shows the amount of condensate in kg / t of product as a function of time in hours at 360 ° C.
• the condensates consist mainly of toluene, xylenes, ethylbenzene.
• FIG. 2 represents the gas evolution in m3 / t of product as a function of time in hours at 360 ° C.
• the non-condensable gaseous products consist mainly of CH 4 , H 2 and by small quantities of light hydrocarbons.
• FIG. 1 and 2 represents DBT, ___ represents the 1 NC mixture,% represents the 2C mixture.
• FIG. 3 represents the simple distillation curves under a pressure of 20 mm Hg of the products having undergone the thermal stability evaluation test.
• ⁇ . represents the DBT distillation curve after 500 hours at 360 ° C
• 4_. represents the distillation curve of the 1 NC mixture after 500 hours at 360 ° C
• the evaluation is carried out as in tests 5.1.
• Figure 4 shows the amount of condensate in kg / t as a function of time in hours at 360 ° C.
• FIG. 5 represents the gas evolution in m3 / t as a function of time in hours at 360 ° C.
• ⁇ represents the DBT
• B represents the mixture 3C.
• 5a - DBT alone, 5f - mixture 5C (DBT / PBTHN, 75/25). brought to 360 ° C for 493 hours.
• Figure 6 shows the amount of condensate in kg / t as a function of time in hours at 360 ° C.
• Figure 7 represents the gas evolution in m3 / t as a function of time in hours at 360 ° C.
• Figure 7 represents the DBT (5a), jj represents the mixture 5C (5f).
• FIG. 8 represents the simple distillation curves under a pressure of 20 mmHg of the products having undergone the thermal evaluation test. These curves show that the content of light and heavy is lower than DBT alone and DBT-RP (mixture 1 NC).
• DBT distillation curve represents the DBT distillation curve after 500 hours at 360 ° C
• m represents the distillation curve of the 1 NC mixture after 500 hours at 360 ° C
• ⁇ represents the distillation curve of the 5C mixture after 493 hours at 360 ° C.
• Table 5 the viscosities at 20 ° C. (in mm 2 / s) and the percentages by weight (%) in anthracene are reported after 493 hours at 360 ° C.
• the tests were carried out at 370 ° C. for 160 hours in a 200 ml stainless steel autoclave equipped with a thermometric sheath and a pressure gauge. 50 g of heat transfer fluid to be tested are loaded, a nitrogen sweep is carried out and the autoclave is closed, which is then placed in an electrically heated sand bath. A regulation makes it possible to maintain the temperature of the heat transfer fluids constantly at 370 ° C.
• 1-cycle compounds by 1-cycle compounds is meant light aromatic compounds such as toluene, xylenes, ethylbenzene and by compounds> 3 product cycles.

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• 2000
  • 2000-03-29 FR FR0003944A patent/FR2807059B1/fr not_active Expired - Fee Related
• 2001
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