CA1072939A - Waterproof catalyst and process for hydrogen-deuterium exchange - Google Patents
Waterproof catalyst and process for hydrogen-deuterium exchangeInfo
- Publication number
- CA1072939A CA1072939A CA227,189A CA227189A CA1072939A CA 1072939 A CA1072939 A CA 1072939A CA 227189 A CA227189 A CA 227189A CA 1072939 A CA1072939 A CA 1072939A
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- CA
- Canada
- Prior art keywords
- carbon
- support
- catalyst
- platinum
- hydrophobic polymer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
- B01J23/42—Platinum
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
- B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
- B01J31/06—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides containing polymers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J33/00—Protection of catalysts, e.g. by coating
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
- B01J37/0018—Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/02—Impregnation, coating or precipitation
- B01J37/0215—Coating
- B01J37/0219—Coating the coating containing organic compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/02—Impregnation, coating or precipitation
- B01J37/024—Multiple impregnation or coating
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B5/00—Water
- C01B5/02—Heavy water; Preparation by chemical reaction of hydrogen isotopes or their compounds, e.g. 4ND3 + 7O2 ---> 4NO2 + 6D2O, 2D2 + O2 ---> 2D2O
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/02—Impregnation, coating or precipitation
- B01J37/0215—Coating
- B01J37/0221—Coating of particles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/02—Impregnation, coating or precipitation
- B01J37/024—Multiple impregnation or coating
- B01J37/0248—Coatings comprising impregnated particles
Abstract
ABSTRACT
This disclosure is directed to a catalyst which is use-ful for promoting the exchange of hydrogen in water for deuterium in hydrogen gas to enrich the concentration of deuterium in water.
The catalyst comprises an inert support, a hydrophobic resin coat-ing, such as polytetrafluoroethylene, and an active catalytic agent, such as platinum on carbon or other high surface area carrier. The catalyst is made by first coating the support with a polytetrafluoroethylene emulsion which is then dried. Platinum on carbon or the like is admixed with another polytetrafluoroethy-lene emulsion and this admixture is then applied to the support and dried.
This disclosure is directed to a catalyst which is use-ful for promoting the exchange of hydrogen in water for deuterium in hydrogen gas to enrich the concentration of deuterium in water.
The catalyst comprises an inert support, a hydrophobic resin coat-ing, such as polytetrafluoroethylene, and an active catalytic agent, such as platinum on carbon or other high surface area carrier. The catalyst is made by first coating the support with a polytetrafluoroethylene emulsion which is then dried. Platinum on carbon or the like is admixed with another polytetrafluoroethy-lene emulsion and this admixture is then applied to the support and dried.
Description
BACK GROUN D
Deuterium, the stable hydrogen isotope of mass 2, occurs in natural hydrogen, ~ater and other hydrogen-bearing com-pounds in an average abundance of 0.015 mole percent. Deuterium is of interest to research workers as a tracer in biological processes and chemical reactions, but by far finds its greatest demand in the form of heavy water, D20, as a moderator for nuclear reactors.
Early processes for the preparation of heavy water included either chemical exchange between hydrogen and steam or vacuum distillation of water for initial separation, followed by electrolysis for final concentration. Subsequently a more efficient process of dual-temperature exchange of deuterium between hydrogen sulfide and water became widely used.
In the selection of a particular isotope-separation process a distinction must be made between the enrichment of a few grams of an unusual isotope and the production of many tons of an isotope for industrial use. In the former case, principal emphasis must be given to the selection of a process that gives as large a separation in a single piece of equipment as possible, ~ith only secondary consideration being given to the economics or the energy consumption of the process. In the large scale production of deuterium, however, a large enrichment per unit of processing equipment is only of secondary importance. Of paramount importance is the efficiency and reversibility of the process, that is, the cost of the operation both in power and capital investment. A
process typical of the first alternative is the electrolysis of water; a process that may be expensi~e if used for the production o~ large quantities of heavy water if inexpensive hydro-electric power is not available. The second alternative is represented by the reversible process of H2S/H2n chemical exchange which not only ~m/~
., . . . . - , : ' ' ' ' . : ,, , '' ': ' .
' ' ' . ': '' ' lO'~Z~3~
has a relatively small separation factor but which, through the use of a dual-temperature arrangement, is deliberately designed - for an even smaller enrichment factor to provide a less costly method of refluxing material within the process.
In the electrolysis process referred to above, the pre-enrichment process involved a steam-hydrogen exchange. Because the only successful catalysts were those that operated in the vapor phase this process has not been economically attractive for large-scale production. However, the separation factor increases as the temperature decreases and therefore it is preferred to run at as low a temperature as possible thus favoring the liquid phase.
When these catalysts are used with liquid water they are to a large extent poisoned or inactivated in the process. Considerable effort has therefore been directed toward the development of a liquid phase catalyst for the exchange of deuterium with water.
Onè example of an approach to the problem of the enrichment of water with deuterium is to, in effect, water-proof the catalyst with a sealant which is permeable to water vapor and hydrogen gas, as shown in Canadian Patent 907,292. As disclosed in this patent the catalyst is sealed with a hydrophobic polymer, such as a polyalkylsilicone, polytetrafl~oroethylene, polyethylene, polypropylene or like polymers; in which a siloxane polymer is ; preferred. This development is characterized by two major points:
(1) the hydrophobic polymer sealant is applied directed ~o a catalyst support that already has a catalytic material deposited therein, and (2) the hydrophobic polymer sealant particles enter the pores of a catalyst and deposit on the pore surface. It has been found that the efficiency or relative specific activity of these catalysts has not been sufficiently high for large-scale economic operations.
It is therefore an object of this invention to provide an improved catalyst for effecting the enrichment of water with deuterium.
cm/~
.
10~2~3 Another object to provide an improved method for the preparation of a catalyst for the production of deuterium.
These and other objects are set forth in greater detail in the following description of this invention.
~m/p ~ . -.
10~ 3~
_E INVENT ION
This invention is directed to a catalyst for promoting the deuterium enrichment of water. The catalyst comprises as its active element a noble metal of Group VIII of the Periodic Table, such as platinum. The platinum is placed on carbon as a suitable form for use in this process. The platinum-carbon is supported on an inert support material such as alumina. It has been found that an efficient catalyst can be made by the use of a hydrophobic polymer, such as polytetrafluoroethylene, applied ]o directly on the inert support followed by the addition of the platinum-carbon admixed in a hydrophobic polymer emulsion, such as a polytetrafluoroethylene emulsion. By this procedure, the inert support and the platinum-carbon are coated to prevent water from getting into the pores of the support or the carbon.
It has also been found that a particularl~ efficient catalyst can be made by closely controlling the amount and manner of distribution of the platinum in the catalyst.
In the process of this invention an inert catalyst support is first coated with a hydrophobic polymer, such as poly-tetrafluoroethylene, which is then dried and calcined. A noblemetal, such as platinum, is dispersed on carbon which is then slurried with a polytetrafluoroethylene suspension. The inert support is then coated with the suspension and then dried and calcined. In this procedure the polytetrafluoroethylene serves as a binder for the platinum-carbon particles as well as a sealant which prevents liquid water from contacting the platinum-carbon catalytic surface. The relative sizes of the carbon pores and the second polytetrafluoroethylene emulsion are selected so that the polytetrafluoroethylene emulsion coats the carbon rather than entering the pores of the carbon particles.
An advantage o~ this invention is that the size of the inert support can be varied by using pellets, spheres, or any other shape and by maximizing the size and shape of the support to _ 5 _ cm/ ~
107Z93~
minimize flooding in the deuterium exchange column.
A further advantage of the invention is that it facilitates optimizing both the platinum to carbon ratio and the amount of carbon-platinum to that of the inert support to control catalyst activity. For example, if a catalyst with 1% platinum loading is desired, one could disperse 1 gram of platinum on 1 gram of carbon and then place this mixture on 98 grams of inert support. However, since the platinum to carbon ratio is so high, the platinum dispersion will be very poor and the catalyst activity low. On the other hand, one gram of platinum can be dispersed on 10 grams of carbon and then this mixture placed on 89 grams of inert support. In this case because the platinum loading on the carbon is much reduced the dispersion will be improved and the final catalytic activity much superior to that of the previous example.
In using the platinum-carbon catalyst of this invention it may be disposed in a layer on a suitable support, e.g., of porous sintered glass or metal, in a column. Liquid water and hydrogen gas are then passed counter-current flow with each other through the column so that the liquid~ water and hydrogen gas are brought into contact with one another and in contact with the catalyst.
The catalyst is preferably composed of a relatively inert support of at least one material selected from the group alumina, magnesia, silica, silica gel, chromia, molybdenum oxide, tungstic oxide, nickel oxide and kieselguhr. The preferred support is alpha-alumina which is available in a wide variety of shapes, sizes and structures.
The inert supports are suitably in pellet, granular, or extruded or otherwise shaped forms such as Berl saddles. The inert catalyst support has a sur~ace area of less than 5 square meters per gram préferably less than 2 square meters per gram, so as to avoid undue absorption of water on the catalyst surfaceD
cm/~l~
.
~ 39 The inert support, i.e. in the form of spheres, is mixed with and soaked in a polytetrafluoroethylene emulsion, drained, dried in an air stream under conditions which maintain the spheres constantly in motion, then calcined aL a temperature of about 350C. The amount of polytetrafluoroethylene used is about 2 to 20 weight percent, preferably 5 to 15 percent based on the weight of the spheres, which is enough to cover the surface with a continuous film.
The catalytic material is at least one metal selected from Group VIII of the Periodic Table, in particular platinum, palladium, nickel, iridium and rhodium. Platinum is the preferred catalyst because of high activity. The platinum is deposited on finely divided carbon in accordance with conventional techniques as, for example, formate reduction of chloroplatinic acid. The amount of platinum based on the weight of the carbon is about 1 to 25 percent preferably 3 to 12 percent.
The platinum on carbon is then mixed with a poly-tetrafluoroethylene emulsion, preferably in the presence of a plasticizer, such as methylcellulose. The polytetrafluoroethylene emulsion has a particle size larger than the pore size of the carbon particles. The carbon particles have a pore size from about 15 to 300 A in diameter. The polytetrafluoroethylene is used in an amount which is sufficient to provide a coherent film over the surface of the inert support. A minor amount of plasticizer has ; been found useful, i.e. from 3 to 10 percent based on the weight of the polytetrafluoroethylene; the plasticizer gives a more coherent polytetrafluoroethylene - catalyst film on the coated support.
The calcined spheres are then mixed with the metal-on-carbon catalyst-polytetrafluoroethylene blend and are dried in air at about 90C and then further dried in a vacuum oven at a temperature of about 250C. The calcined spheres are washed and then dried at 90C in air. The amount of catalyst-polytetra-. -cm/p~
.
107X9:~
fluoroethylene blend used on the spheres is an amount sufficient to give a final platinum content of from .02 to 5 percent, pre-ferably from .02 to 2 percent.
The preferred hydrophobic polymer for the present invention is polytetrafluoroethylene. Other hydrophobic polymers or resins which are permeable to water vapor may be used, such as a polyalkylsilicone, polyethylene, polypropylene or similar hydrophobic hydrocarbon polymers of medium to high molecular weight.
cm/p~
93~
EXAMPLES
A catalyst in accordance with present invention was prepared as follows.
1) 200 g of Norton spheres, SA 5218, were soaked in a T~30 Teflon emulsion (E.I. DuPont & Co.), drained and dried in air at 90-110C. The dried spheres were calcined in air at
Deuterium, the stable hydrogen isotope of mass 2, occurs in natural hydrogen, ~ater and other hydrogen-bearing com-pounds in an average abundance of 0.015 mole percent. Deuterium is of interest to research workers as a tracer in biological processes and chemical reactions, but by far finds its greatest demand in the form of heavy water, D20, as a moderator for nuclear reactors.
Early processes for the preparation of heavy water included either chemical exchange between hydrogen and steam or vacuum distillation of water for initial separation, followed by electrolysis for final concentration. Subsequently a more efficient process of dual-temperature exchange of deuterium between hydrogen sulfide and water became widely used.
In the selection of a particular isotope-separation process a distinction must be made between the enrichment of a few grams of an unusual isotope and the production of many tons of an isotope for industrial use. In the former case, principal emphasis must be given to the selection of a process that gives as large a separation in a single piece of equipment as possible, ~ith only secondary consideration being given to the economics or the energy consumption of the process. In the large scale production of deuterium, however, a large enrichment per unit of processing equipment is only of secondary importance. Of paramount importance is the efficiency and reversibility of the process, that is, the cost of the operation both in power and capital investment. A
process typical of the first alternative is the electrolysis of water; a process that may be expensi~e if used for the production o~ large quantities of heavy water if inexpensive hydro-electric power is not available. The second alternative is represented by the reversible process of H2S/H2n chemical exchange which not only ~m/~
., . . . . - , : ' ' ' ' . : ,, , '' ': ' .
' ' ' . ': '' ' lO'~Z~3~
has a relatively small separation factor but which, through the use of a dual-temperature arrangement, is deliberately designed - for an even smaller enrichment factor to provide a less costly method of refluxing material within the process.
In the electrolysis process referred to above, the pre-enrichment process involved a steam-hydrogen exchange. Because the only successful catalysts were those that operated in the vapor phase this process has not been economically attractive for large-scale production. However, the separation factor increases as the temperature decreases and therefore it is preferred to run at as low a temperature as possible thus favoring the liquid phase.
When these catalysts are used with liquid water they are to a large extent poisoned or inactivated in the process. Considerable effort has therefore been directed toward the development of a liquid phase catalyst for the exchange of deuterium with water.
Onè example of an approach to the problem of the enrichment of water with deuterium is to, in effect, water-proof the catalyst with a sealant which is permeable to water vapor and hydrogen gas, as shown in Canadian Patent 907,292. As disclosed in this patent the catalyst is sealed with a hydrophobic polymer, such as a polyalkylsilicone, polytetrafl~oroethylene, polyethylene, polypropylene or like polymers; in which a siloxane polymer is ; preferred. This development is characterized by two major points:
(1) the hydrophobic polymer sealant is applied directed ~o a catalyst support that already has a catalytic material deposited therein, and (2) the hydrophobic polymer sealant particles enter the pores of a catalyst and deposit on the pore surface. It has been found that the efficiency or relative specific activity of these catalysts has not been sufficiently high for large-scale economic operations.
It is therefore an object of this invention to provide an improved catalyst for effecting the enrichment of water with deuterium.
cm/~
.
10~2~3 Another object to provide an improved method for the preparation of a catalyst for the production of deuterium.
These and other objects are set forth in greater detail in the following description of this invention.
~m/p ~ . -.
10~ 3~
_E INVENT ION
This invention is directed to a catalyst for promoting the deuterium enrichment of water. The catalyst comprises as its active element a noble metal of Group VIII of the Periodic Table, such as platinum. The platinum is placed on carbon as a suitable form for use in this process. The platinum-carbon is supported on an inert support material such as alumina. It has been found that an efficient catalyst can be made by the use of a hydrophobic polymer, such as polytetrafluoroethylene, applied ]o directly on the inert support followed by the addition of the platinum-carbon admixed in a hydrophobic polymer emulsion, such as a polytetrafluoroethylene emulsion. By this procedure, the inert support and the platinum-carbon are coated to prevent water from getting into the pores of the support or the carbon.
It has also been found that a particularl~ efficient catalyst can be made by closely controlling the amount and manner of distribution of the platinum in the catalyst.
In the process of this invention an inert catalyst support is first coated with a hydrophobic polymer, such as poly-tetrafluoroethylene, which is then dried and calcined. A noblemetal, such as platinum, is dispersed on carbon which is then slurried with a polytetrafluoroethylene suspension. The inert support is then coated with the suspension and then dried and calcined. In this procedure the polytetrafluoroethylene serves as a binder for the platinum-carbon particles as well as a sealant which prevents liquid water from contacting the platinum-carbon catalytic surface. The relative sizes of the carbon pores and the second polytetrafluoroethylene emulsion are selected so that the polytetrafluoroethylene emulsion coats the carbon rather than entering the pores of the carbon particles.
An advantage o~ this invention is that the size of the inert support can be varied by using pellets, spheres, or any other shape and by maximizing the size and shape of the support to _ 5 _ cm/ ~
107Z93~
minimize flooding in the deuterium exchange column.
A further advantage of the invention is that it facilitates optimizing both the platinum to carbon ratio and the amount of carbon-platinum to that of the inert support to control catalyst activity. For example, if a catalyst with 1% platinum loading is desired, one could disperse 1 gram of platinum on 1 gram of carbon and then place this mixture on 98 grams of inert support. However, since the platinum to carbon ratio is so high, the platinum dispersion will be very poor and the catalyst activity low. On the other hand, one gram of platinum can be dispersed on 10 grams of carbon and then this mixture placed on 89 grams of inert support. In this case because the platinum loading on the carbon is much reduced the dispersion will be improved and the final catalytic activity much superior to that of the previous example.
In using the platinum-carbon catalyst of this invention it may be disposed in a layer on a suitable support, e.g., of porous sintered glass or metal, in a column. Liquid water and hydrogen gas are then passed counter-current flow with each other through the column so that the liquid~ water and hydrogen gas are brought into contact with one another and in contact with the catalyst.
The catalyst is preferably composed of a relatively inert support of at least one material selected from the group alumina, magnesia, silica, silica gel, chromia, molybdenum oxide, tungstic oxide, nickel oxide and kieselguhr. The preferred support is alpha-alumina which is available in a wide variety of shapes, sizes and structures.
The inert supports are suitably in pellet, granular, or extruded or otherwise shaped forms such as Berl saddles. The inert catalyst support has a sur~ace area of less than 5 square meters per gram préferably less than 2 square meters per gram, so as to avoid undue absorption of water on the catalyst surfaceD
cm/~l~
.
~ 39 The inert support, i.e. in the form of spheres, is mixed with and soaked in a polytetrafluoroethylene emulsion, drained, dried in an air stream under conditions which maintain the spheres constantly in motion, then calcined aL a temperature of about 350C. The amount of polytetrafluoroethylene used is about 2 to 20 weight percent, preferably 5 to 15 percent based on the weight of the spheres, which is enough to cover the surface with a continuous film.
The catalytic material is at least one metal selected from Group VIII of the Periodic Table, in particular platinum, palladium, nickel, iridium and rhodium. Platinum is the preferred catalyst because of high activity. The platinum is deposited on finely divided carbon in accordance with conventional techniques as, for example, formate reduction of chloroplatinic acid. The amount of platinum based on the weight of the carbon is about 1 to 25 percent preferably 3 to 12 percent.
The platinum on carbon is then mixed with a poly-tetrafluoroethylene emulsion, preferably in the presence of a plasticizer, such as methylcellulose. The polytetrafluoroethylene emulsion has a particle size larger than the pore size of the carbon particles. The carbon particles have a pore size from about 15 to 300 A in diameter. The polytetrafluoroethylene is used in an amount which is sufficient to provide a coherent film over the surface of the inert support. A minor amount of plasticizer has ; been found useful, i.e. from 3 to 10 percent based on the weight of the polytetrafluoroethylene; the plasticizer gives a more coherent polytetrafluoroethylene - catalyst film on the coated support.
The calcined spheres are then mixed with the metal-on-carbon catalyst-polytetrafluoroethylene blend and are dried in air at about 90C and then further dried in a vacuum oven at a temperature of about 250C. The calcined spheres are washed and then dried at 90C in air. The amount of catalyst-polytetra-. -cm/p~
.
107X9:~
fluoroethylene blend used on the spheres is an amount sufficient to give a final platinum content of from .02 to 5 percent, pre-ferably from .02 to 2 percent.
The preferred hydrophobic polymer for the present invention is polytetrafluoroethylene. Other hydrophobic polymers or resins which are permeable to water vapor may be used, such as a polyalkylsilicone, polyethylene, polypropylene or similar hydrophobic hydrocarbon polymers of medium to high molecular weight.
cm/p~
93~
EXAMPLES
A catalyst in accordance with present invention was prepared as follows.
1) 200 g of Norton spheres, SA 5218, were soaked in a T~30 Teflon emulsion (E.I. DuPont & Co.), drained and dried in air at 90-110C. The dried spheres were calcined in air at
2) 4 g of a 25% Pt on carbon (Regal 330R Cabot Corp.) was stirred with a solution of 6 ml of diluted T-30 emulsion (diluted to 150 mg/ml) plus 20 ml of methylcell~lose solution containing 0.3 wt. % methylcellulose.
3) The blended mix of step 2) was applied to the cal-cined spheres of step 1) with stirring, and then the coated beads were dried at 90C in air. After drying, the beads were heated at 150C in a vacuum oven for 2 hours, then heated for an additional 2 hours at 250C in the vacuum oven.
4) The calcined beads were water washed to remove the methylcellulose, then dried at 90C in air.
In all the drying steps, the beads were held constantly in motion during drying. The drying and calcining temperatures used may be varied within conventional ran~es which are sufficiently high to lead to a stable coherent film but below temperatures which would lead to degradation of polytetrafluoroethylene.
The activities of the catalysts were measured in a 1"
diameter column at 1 atmosphere pressure and a water flow rate of 10 cc min 1 or 1230 lb ft h . Columns were operated inter-mittently over extended periods of time. They were run in the trickle mode duri~g the day only and gas and water flows were shut down at ~ight. ~efore restarting measurements the beds were ~looded ~riefly by closing the water outlet valve and maintaining the hydrogen flow at 5-10 cm s . The columns were then drained and operated under trickle bed conditions. The flooding procedure was used to try to re-establish a uniform water ~low through the _ g _ cm/~ ~
i0`~Z~39 hydrophobic catalyst bed after being inoperative overnight. On a few occasions the columns were operated continuously for periods of about 35 hours. A deuterium enriched liquid phase was recovered from the columns. Table 1 summarizes the activities of these catalysts at 25C, and some of their physical properties. The catalysts were prepared by the procedure described above, with the variation in proportions used set forth below.
Catalyst Final * % Pt on Pt-Carbon cc Teflon Relative**
Number wt.%Pt Carbon used, wt.(~) used stp 2 Activity 1) 0.37 25 20 6 1.00 2) 0.39 25 20 3 1.36 3) 0.06 25 5 3 1.66 4) 0.07 6.25 20 3 8.1 *Based on weight of final product (incl. inert support).
**Activity per unit weight of Pt based on enrichment of deuterium in the water phase.
In another experiment platinum was applied directly to the inert support (0.35 wt ~), coated with Teflon (6 cc) and dried and calcined by the above procedure. The relative activity of this catalyst was 0.05.
.
cm/pl~ , . .
In all the drying steps, the beads were held constantly in motion during drying. The drying and calcining temperatures used may be varied within conventional ran~es which are sufficiently high to lead to a stable coherent film but below temperatures which would lead to degradation of polytetrafluoroethylene.
The activities of the catalysts were measured in a 1"
diameter column at 1 atmosphere pressure and a water flow rate of 10 cc min 1 or 1230 lb ft h . Columns were operated inter-mittently over extended periods of time. They were run in the trickle mode duri~g the day only and gas and water flows were shut down at ~ight. ~efore restarting measurements the beds were ~looded ~riefly by closing the water outlet valve and maintaining the hydrogen flow at 5-10 cm s . The columns were then drained and operated under trickle bed conditions. The flooding procedure was used to try to re-establish a uniform water ~low through the _ g _ cm/~ ~
i0`~Z~39 hydrophobic catalyst bed after being inoperative overnight. On a few occasions the columns were operated continuously for periods of about 35 hours. A deuterium enriched liquid phase was recovered from the columns. Table 1 summarizes the activities of these catalysts at 25C, and some of their physical properties. The catalysts were prepared by the procedure described above, with the variation in proportions used set forth below.
Catalyst Final * % Pt on Pt-Carbon cc Teflon Relative**
Number wt.%Pt Carbon used, wt.(~) used stp 2 Activity 1) 0.37 25 20 6 1.00 2) 0.39 25 20 3 1.36 3) 0.06 25 5 3 1.66 4) 0.07 6.25 20 3 8.1 *Based on weight of final product (incl. inert support).
**Activity per unit weight of Pt based on enrichment of deuterium in the water phase.
In another experiment platinum was applied directly to the inert support (0.35 wt ~), coated with Teflon (6 cc) and dried and calcined by the above procedure. The relative activity of this catalyst was 0.05.
.
cm/pl~ , . .
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. The method of making a catalytic composition for promoting the deuterium enrichment of water which comprises initially coating an inert support selected from the group con-sisting of alumina, magnesia, silica, silica gel, chromia, molybdenum oxide, tungsten oxide, nickel oxide and kieselguhr with a hydrophobic polymer emulsion, drying the coated support, applying to said support a mixture comprising (a) a finely divided noble metal of Group VIII of the Periodic Table dis-persed on carbon and (b) an emulsion of a medium to high molecular weight hydrophobic polymer having a particle size larger than the pore size of the carbon and drying the resultant composition.
2. The process of claim 1 wherein said hydrophobic polymer is polytetrafluoroethylene.
3. The process of claim 1 or 2 wherein said support is alumina.
4. The process of claim 1 wherein said noble metal is platinum.
5. The process of claim 4 wherein said platinum is supported on finely divided carbon which has a pore size of about 15 to 300 .ANG. in diameter.
6. The process of claim 1, 2 or 4 wherein the step of drying the polytetrafluoroethylene coated support includes the step of calcining in air.
7. The process of claim 1, 2 or 4 wherein said drying of the resultant composition includes the step of calcining in air.
8. The process of claim 4 wherein the amount of platinum is from 0.02 to 5 percent, by weight of the catalyst.
9. The process of claim 8 wherein the amount of platinum is from 1 to 25 percent, based on the weight of the carbon.
10. A catalyst for the deuterium enrichment of water comprising an inert support selected from the group consisting of alumina, magnesia, silica, silica gel, chromia, molybdenum oxide, tungsten oxide, nickel oxide and kieselguhr; a first coherent film of a hydrophobic polymer on said support; and a second coherent film comprising carbon, a finely divided noble metal of Group VIII and a medium-to-high molecular weight hydrophobic polymer, having a particle size greater than the pore size of said carbon, onto said treated support.
11. A process for promoting the deuterium enrich-ment of water which comprises contacting liquid water and hydrogen gas with a catalyst comprising:
an inert support selected from the group con-sisting of alumina, magnesia, silica, silica gel, chromia, molybdenum oxide, tungsten oxide, nickel oxide and kieselguhr;
a first coherent film of a hydrophobic polymer on said support; and a second coherent film comprising carbon, a finely divided noble metal of Group VIII, and a medium-to-high molecular weight hydrophobic polymer having a particle size greater than the pore size of said carbon, onto the treated support.
an inert support selected from the group con-sisting of alumina, magnesia, silica, silica gel, chromia, molybdenum oxide, tungsten oxide, nickel oxide and kieselguhr;
a first coherent film of a hydrophobic polymer on said support; and a second coherent film comprising carbon, a finely divided noble metal of Group VIII, and a medium-to-high molecular weight hydrophobic polymer having a particle size greater than the pore size of said carbon, onto the treated support.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US47134074A | 1974-05-20 | 1974-05-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1072939A true CA1072939A (en) | 1980-03-04 |
Family
ID=23871255
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA227,189A Expired CA1072939A (en) | 1974-05-20 | 1975-05-16 | Waterproof catalyst and process for hydrogen-deuterium exchange |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS50155492A (en) |
| CA (1) | CA1072939A (en) |
| DE (1) | DE2521924A1 (en) |
| FR (1) | FR2271870A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5120600A (en) * | 1987-09-11 | 1992-06-09 | Atomic Energy Of Canada Limited | Porous composite materials and methods for preparing them |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4217332A (en) * | 1976-06-17 | 1980-08-12 | Engelhard Minerals & Chemicals Corporation | Process for exchanging hydrogen isotopes between gaseous hydrogen and water |
| CA1063587A (en) | 1976-06-25 | 1979-10-02 | John P. Butler | Process for the exchange of hydrogen isotopes between streams of gaseous hydrogen and liquid water and catalyst |
| US4143123A (en) | 1976-06-25 | 1979-03-06 | Atomic Energy Of Canada Limited | Process for the exchange of hydrogen isotopes between streams of gaseous hydrogen and liquid water |
| JPS538391A (en) * | 1976-07-12 | 1978-01-25 | Sumitomo Electric Ind Ltd | Catalytic compositions for water-hydrogen exchange reaction |
| JPS5919733B2 (en) * | 1976-07-12 | 1984-05-08 | 住友電気工業株式会社 | Catalyst for water-hydrogen exchange reaction |
| JPS5919732B2 (en) * | 1976-07-12 | 1984-05-08 | 住友電気工業株式会社 | Catalyst for water-hydrogen exchange reaction |
| US4073748A (en) * | 1977-01-21 | 1978-02-14 | The Mead Corporation | Method for preparing wetproofed catalyst particles and particles produced thereby |
-
1975
- 1975-05-12 JP JP5592575A patent/JPS50155492A/ja active Pending
- 1975-05-16 DE DE19752521924 patent/DE2521924A1/en not_active Withdrawn
- 1975-05-16 FR FR7515399A patent/FR2271870A1/en not_active Withdrawn
- 1975-05-16 CA CA227,189A patent/CA1072939A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5120600A (en) * | 1987-09-11 | 1992-06-09 | Atomic Energy Of Canada Limited | Porous composite materials and methods for preparing them |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2521924A1 (en) | 1975-12-04 |
| FR2271870A1 (en) | 1975-12-19 |
| JPS50155492A (en) | 1975-12-15 |
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