JPH0346446B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a process for making secondary and primary amines using improved oxidation catalysts. US Pat. No. 4,264,776 discloses and claims a process for preparing secondary amines by catalytic oxidation of tertiary amines with oxygen over a carbon catalyst. The catalyst is an activated carbon of the type known in the art and is characterized by a high absorption capacity for gases, vapors, and colloidal solids, and a relatively large specific surface area. Activation of commercially available carbon catalysts is usually carried out by heating the carbon to high temperatures (800°C to 900°C) with water vapor or carbon dioxide, which results in a porous granular structure and a large specific surface area. US Pat. No. 4,072,706 discloses a method for oxidative removal of phosphonomethyl groups from tertiary amines using a molecular oxygen-containing gas with an activated carbon catalyst. It is understood that any source or form of carbon can be used as a catalyst or substrate in the method of this disclosed invention. U.S. Pat. No. 3,969,398 teaches the use of activated carbon in the catalytic oxidation of N-(phosphonomethylimino)diacetic acid. It is stated that carbon catalysts useful in this claimed process are available under a number of trade names. US Pat. No. 3,497,564 discloses the use of amorphous or graphitic carbon as a catalyst in the oxidative dehydrogenation of alkylbenzenes. It is taught that any source of activated carbon can be used in this method. Japanese Patent Application No. 56-17634 describes the activation of an SO ₃ /SO ₂ conversion carbon material useful as a reduction catalyst for selectively converting SO ₃ in various gases such as air and exhaust gas to SO ₂ . A method is disclosed. Carbon materials such as cylindrical activated carbon are treated with an oxidizing acid, e.g. nitric acid, and then heated at 300°C under an inert gas.
Heat treated at ~700°C. US Pat. No. 4,158,643 teaches a method for oxidative modification of activated carbon supports by adding oxygen to the surface of the activated carbon and then impregnating the carbon support with an inert hydrophobic compound. The carbon support, which can be any commercially available activated carbon for gas phase activation, is useful for long-term oxidation of carbon monoxide in the presence of sulfur dioxide. U.S. Pat. No. 3,243,383 teaches a method for regenerating catalysts used to polymerize olefins to liquid products. According to this disclosure, a spent cobalt oxide on carbon catalyst is heated in an inert atmosphere, cooled, and then treated with nitric acid, nitrogen oxide, or nitrogen dioxide. None of the above references suggest that the surface of the carbon catalyst, in particular where acidic and basic surface oxides may be present, may play a significant role in the amine oxidation rate. The present invention uses an activated carbon catalyst from which oxides have been removed from the surface in order to catalytically oxidize a tertiary amine or a secondary amine in the presence of oxygen or an oxygen-containing gas to selectively produce a secondary amine or a primary amine. Provided is a method characterized by using. To effect the removal of such surface oxides, the carbon material may be treated with oxidizing agents such as nitric acid, CrO ₃ , H ₂ O ₂ , hypochlorite, etc. or H ₂ O, H ₂ O/NH ₃ , CO ₂ , exposed to an oxidizing gas such as NO _x , air, and then heated to a temperature of approximately 500 °C.
The treatment sequence is to thermally decompose the carbon material in an oxygen-free atmosphere within the range of 1500°C to 1500°C. However, the treatment can also be carried out by simultaneously pyrolyzing the carbon material in the presence of NH ₃ and oxygen-containing gases which react at the pyrolysis temperature with oxides on the surface of the carbon. Suitable oxygen-containing gases include water vapor, NO _x , O ₂ , CO ₂ , SO ₂
and mixtures of such gases. That is, in another specific embodiment of the present invention,
In an improved selective process for the production of secondary and primary amines by combining a tertiary amine or a secondary amine with oxygen or an oxygen-containing gas under reaction conditions in the presence of an activated carbon catalyst, the oxide is It can be seen that an improved method is provided which involves using activated carbon catalyst removed from the surface of the catalyst. As used herein, the term "oxide" is intended to mean a carbon functionality containing oxygen and an oxygen-containing heteroatom functionality. Also, other heteroatomic functional groups that do not contain oxygen can be removed from the surface of the carbon material during processing. The activated carbon used in the process of the invention, prepared as described above, exhibits unexpectedly good activity, ie, reaction rate, in the selective production of secondary amines for catalytic oxidation of tertiary amines. Additionally, the oxidative removal of carboxymethyl and phosphonomethyl groups from tertiary and secondary amines and the catalytic oxidation of N-(phosphonomethylimino)-diacetic acid are significantly enhanced with the carbon catalyst used in the present invention. can. When the carbon material is first subjected to the step of removing surface oxides as described above, the activity of carbon as a catalyst in the oxidation of tertiary amines to secondary amines and the oxidation of secondary amines to primary amines is It can be greatly improved. In carbon catalytic oxidation reactions, the analysis of the catalytic mechanism is based on the catalytic activity, surface area and/or
There is a tendency to suggest a possible correlation between pore size distribution. It has now been found that the presence of basic and acidic oxides on the surface of carbon materials can play a significant role in the oxidation process. Although applicants do not wish to be bound by any particular theory, it is believed that the catalytic activity of the catalyst can be substantially increased if acidic oxides are removed from the surface of the carbon. U.S. Pat. No. 4,264,776, the teachings of which are incorporated herein by reference, describes various carbon materials that can be used as feedstock to make activated carbon catalysts used in the practice of this invention. The carbon catalyst is typically commercially available activated carbon with carbon content ranging from about 10% for bone char to about 98% for some charcoals and nearly 100% for activated carbons derived from organic polymers. The non-carbonaceous nature of commercially available carbon materials typically varies depending on factors such as precursor sources, processing and activation methods. For example, inorganic "ash" components containing aluminum and silicon may be present in large amounts with some alkali metals and alkaline earths. The latter group influences the acidic-basic properties of activated carbon. Among other inorganic elements commonly found in activated carbon are iron and titanium. Depending on the feedstock source and activation procedure, large amounts of oxygen may be present along with smaller amounts of hydrogen, nitrogen, sulfur, and other organic functional groups. Despite the variety of elements and impurities that individual commercially available carbon materials may contain, the process of the present invention is applicable to all commercially available activated carbon catalyst materials. Below is a list of some activated carbons that exhibit increased activity after treatment. This list is provided for illustrative purposes and is not to be construed as limiting the applicability of activated carbon for use in the present invention. Preferably,
Although the carbon is in powder form, granules or any other suitable particulate form or shape can be used in the practice of this invention. Product Name Sales Darco G-60Spec I.C.I.
America (ICI-America)
Norit SG Extra, Wilmington, Delaware American Norit Co., Inc. Amer.Norit Co., Inc.
Noritz EN4 American Noritz Company, Inc., Jacksonville, Florida Noritz EXW American Noritz Company, Inc., Jacksonville, Florida Noritz A American Noritz Company, Inc., Jacksonville, Florida Noritz Ultra-C, Jacksonville, Florida American Noritz Company, Inc. Noritz ACX, Jacksonville, Florida American Noritz Company, Inc. XZ Barnebey-Cheney, Jacksonville, Florida
NW Barneby Each, located in Columbus, Ohio JV Barneby Each, located in Columbus, Ohio BL Pulv. Calgon Corporation (Calgon) located in Columbus, Ohio
Corporation) Pittsburgh Activated Corporation
Carbon Division (Pittsburgh, Activated)
Carbon Division) PWA Pulv. Calgon Corporation Pittsburgh Activated Carbon Division located in Pittsburgh, Pennsylvania PCB Fines Calgon Corporation Pittsburgh Activated Carbon Division located in Pittsburgh, Pennsylvania P-100 No. located in Pittsburgh, Pennsylvania・American Carbon Incorporated (No.
American Carbon, Inc.) Nuchar CN Westvaco Corporation Carbon Department, Columbus, Ohio
Carbon Corporation
Nutiya C-1000N West Vaco Corporation Carbon Department, Covington, Virginia Nutiya C-190A West Vaco Corporation Carbon Department, Covington, Virginia Nutiya C-115A West Vaco Corporation Carbon Department, Covington, Virginia John Carbon Department Covington, Virginia Code 1551 Allied Amer.Norit Co., Ltd.
Inc.) Baker &
Baker and Adamson
Division) Noritz 4x14 mesh located in Jacksonville, Florida American Norrit Company, Inc. Gl-9615 Barnebee Each, Jacksonville, Florida VG-8408 Barnebee Each, Columbus, Ohio VG-8590 Bar, Jacksonville, Florida Witco Chemical Co., Ltd., Columbus, Ohio NB-9377 Grade 235 Witco Chemical Co., Columbus, Ohio
Corp.) Activated Carbon Division Grade 337 Witco Chemical Corporation New York, New York Activated Carbon Division
carbon division
Grade 517 Witco Chemical Corporation Activated, New York, New York
carbon division
Grade 256 Witco Chemical Corporation Activated, New York, New York
carbon division
Columbia SXAC Union Carbide, New York, New York
Carbide, New York, New York In the practice of producing activated carbon catalysts, a method of treatment, in each case by a single or multi-stage process resulting in the total chemical reduction of oxides on the carbon surface, i.e. the reduction or removal of acidic oxides from the carbon surface. It can be performed. In the two-stage method, the carbon material is first mixed with, for example, liquid nitric acid, nitrogen dioxide, CrO ₃ , air, oxygen,
It can be treated with oxides such as H ₂ O ₂ , hypochlorite or mixtures of gases obtained by evaporating nitric acid. This treatment can be performed using either gas or liquid oxidizers. When using liquid, approximately 10g of _HNO3 per 100g of aqueous solution
Concentrated nitric acid containing ~80g is preferred. Preferred gaseous oxidizing agents include oxygen, nitrogen dioxide and nitric acid vapor. A particularly effective oxidizing agent is nitric acid in the gas phase, including nitric acid carried into the vapor phase by the entrained gas and the vapor obtained by distilling liquid nitric acid. For liquid oxidizers, the temperature approx.
Temperatures from 60°C to about 90°C are suitable, although for gaseous oxidizing agents it is often advantageous to use temperatures from about 50°C to about 500°C or even higher temperatures for the process. Treatment can be carried out by placing the carbon from the manufacturer into a round bottom flask containing a magnetic stirring bar. Liquid nitric acid is chosen as the oxidizing agent for purposes of illustration. The amount of carbon used is determined by the desired % carbon addition (% carbon addition = grams of carbon used per 100 ml of nitric acid solution) and the volume of nitric acid solution used. Usually 100ml of nitric acid or other liquid oxidizing agent
1g to 200g of carbon is sufficient. Temperature control is
It can be provided by any suitable means.
A condenser and scrubber can be connected to the round bottom of the flask if desired. Add the calculated volume of water, preferably deionized water, to the carbon, then add enough 69% to 71%
% nitric acid to obtain the desired nitric acid solution. The carbon and nitric acid solution is then stirred at the desired temperature for the desired time. From the experimental results, the amount of carbon added, temperature, nitric acid concentration, etc. in the first treatment step are not particularly important for achieving the desired oxidation of the carbon material;
Therefore, it can be appropriately determined over a wide range. The highest carbon loading is preferred for economic reasons. After stirring, the carbon is filtered and the resulting wet cake may or may not be washed and/or dried before pyrolysis. The time for treating the carbon with the oxidizing agent can vary widely from about 5 minutes to about 10 hours. Preferably, a reaction time of about 30 minutes to about 6 hours is sufficient. When concentrated nitric acid is the oxidizing agent, a contact time of about 30 minutes to about 3 hours is sufficient. In the second step, the oxidized carbon material is heated to a temperature of about 500°C to about 1500°C, preferably about 800°C to 1200°C.
Pyrolysis, ie heat treatment, within the range of °C. In one embodiment of the invention, the pyrolysis comprises:
It is carried out in an atmosphere such as nitrogen containing small amounts of water vapor or carbon dioxide, which are believed to promote thermal decomposition. As one skilled in the art will appreciate in view of this disclosure, oxides are removed from the carbon surface at pyrolysis temperatures, but the presence of oxygen-containing gases such as water vapor or carbon dioxide must be avoided. This is because the carbon is cooled below its pyrolysis temperature to avoid reformation of surface oxides. It is therefore preferred that the pyrolysis is carried out in an inert gas atmosphere such as nitrogen, argon or helium. The wet cake or dry carbon is placed in a ceramic pyrolysis dish which is placed together in a quartz tube. 1 of the present invention
In an embodiment, nitrogen gas is passed through water at about 70° C. and then through a quartz tube during pyrolysis. In another embodiment, prior to pyrolysis, the quartz tube is flushed with several tube volumes of dry nitrogen, and then
Maintain a dry, static nitrogen atmosphere. The quartz tube containing the pyrolysis dish is placed in a suitable pyrolysis apparatus at about 930° C. for the desired time and then cooled while maintaining a nitrogen atmosphere. Pyrolysis can last from about 5 minutes to 60 hours, but from 10 minutes to
6 hours is usually satisfactory. Shorter times are preferred for economic reasons. This is because, as expected, by continuously exposing carbon to high temperatures for long periods of time,
This is because a defective carbon catalyst for oxidation may be produced. Furthermore, although Applicants do not wish to be bound by any particular theory, it is believed that prolonged heating at pyrolysis temperatures favors the formation of graphite, and that graphite is It is believed that activated carbon is not as satisfactory for the oxidative conversion of secondary amines to secondary and primary amines. Preferably, the pyrolysis takes place in a slightly humid atmosphere or an atmosphere containing _NH3 . because,
This is because it is thought that a more active catalyst can be produced in a shorter time. In a preferred embodiment of the activated carbon catalyst production, the carbon material is pyrolyzed in one step by simultaneously passing a gas stream consisting of NH ₃ and an oxygen-containing gas, e.g. H ₂ O/NH ₃ through the carbon. It will be done. Although not a critical feature of the invention,
The flow rate of the air stream must be fast enough to obtain adequate contact between the fresh gas reactant and the carbon surface, but slow enough to prevent excessive carbon weight loss and material loss. If a gas mixture gives the desired result, e.g. NH ₃ /CO ₂ , NH ₃ /O ₂ , NH ₃ /
Many _NH3 /oxygen-containing gas mixtures can be used, such as _H2O and _NH3 / _NOx . Typically, the oxygen-containing gas/ _NH3 ratio may range from 0:100 to 90:10. Additionally, nitrogen can be used as a diluent to prevent significant loss of carbon at high oxygen-containing gas concentrations. Ammonia is a basic gas and is thought to itself promote the decomposition of various oxide groups on the surface of carbon materials. Any other chemical that generates _NH3 during pyrolysis will also prove satisfactory as a source of _NH3 . For economic reasons,
A _NH3 / _H2O stream is most preferred for carrying out the method of activated carbon catalyst production. The carbon material treated by the above method is
When used in the catalytic oxidation of amines and secondary amines, they exhibit substantially increased activity, ie, faster reaction rates than commercially available activated carbons. Reaction rates can be increased, for example, by a factor of 30 and more than those obtained with other untreated commercially available activated carbon catalysts, all other oxidation reaction conditions being unchanged. Surprisingly,
Even initially inert carbons such as carbon black and charcoal can be activated by the method of the invention. In addition to the catalytic oxidation of tertiary and secondary amines, the carbon catalyst prepared by the above method can be used for the oxidative removal of carboxymethyl and phosphonomethyl groups from tertiary amines and for the catalytic removal of N-(phosphonomethyl-imino)diacetic acid. Improves catalytic oxidation of The invention can be explained more clearly by the following examples. Example 1 This example illustrates the improved results obtained with the catalyst of the present invention when used to convert tertiary amines to secondary amines. Twenty-two powdered activated carbon samples were obtained from commercially available raw materials;
A portion of each was subjected to the two-step process described above.
Approximately 12 g of carbon was placed in a 250 ml round bottom flask equipped with a magnetic stirrer. Then, 100 ml of 18.1% nitric acid was added to the flask, and the contents were then heated to about 85 to about 100°C for 6
heated for an hour. The carbon was separated from the acid solution by allowing the flask to cool to room temperature and then filtering over a porous frit. The carbon was dried in an oven at 85° C. overnight and then placed in a ceramic pyrolysis dish. The dish and carbon were placed in a quartz tube. Dry nitrogen was passed through the tube while heating the tube and contents to approximately 930°C. Heating was continued for 1 hour. Heating was discontinued and the tube and contents were then allowed to cool to room temperature while maintaining a flow of nitrogen over the carbon during cooling. A portion of the treated and untreated carbon from each sample was
Then N-(phosphonomethylimino) in 92 ml of water
N- was used as a catalyst in the oxidation of 7.3 g of diacetic acid.
Phosphonomethylglycine was produced. Catalyst charge was 1.2 g for each experiment. Data obtained from observations of each reaction are shown in Table 1 below. Amine oxidation was performed in an Autoclave Engineers autoclave at 85°C and oxygen pressure of 50 psig to 55 psig.
It was carried out using an oxygen flow rate of 200 ml/min through the autoclave.

[Table] Example 2 Except for changing the pyrolysis time from 1 hour to 6 hours,
Six portions of Noritz W20 carbon were subjected to the two-step process of Example 1. The results are shown in Table 2. Table 2 Amine oxidation time (minutes) Pyrolysis time (hours) Treated catalyst Untreated catalyst 1 16 69 2 11 - 3 11 - 4 11 - 5 6 - 6 10 - Example 3 Quartz with inner diameter 1.9 cm x length 40.6 cm Calgon in the tube
Add 2.5g of C450 activated carbon. Connect this tube to _N2 flow 70
Connect to an air flow obtained by sparging 10% NH ₄ OH aqueous solution at 70° C. from ml/min to 100 ml/min. This quartz tube was then preheated
Place in a 30.5 cm tube furnace and then pyrolyze at 930° C. for 60 min, then cool to room temperature under a dry N ₂ atmosphere without any air contact. Using the above carbon, heat at 85℃ in a 300ml autoclave manufactured by Autoclave Engineers.
Various tertiary amines are oxidized to secondary amines at a pressure of 3.44×10 ⁵ N/m ² and an O ₂ flow rate of 200 ml/min. Analyze the sample by HPLC. Concentrations of reactants, catalyst loading and reaction times for treated versus untreated catalysts for various tertiary amines, with a reaction end point that can be determined by any one of several suitable methods known to those skilled in the art. Listed in Table 3.

[Table] Example 4 3.55 g of Noritz W-20 activated carbon was placed in a quartz tube with an inner diameter of 1.9 cm and a length of 35.6 cm. The tube was connected to a flow of NH ₃ gas 50 ml/min and steam 89 ml/min and then placed in a preheated 30.5 cm tube furnace;
Next, it was thermally decomposed at 930°C for 30 minutes. The tube was then cooled to room temperature under a dry _N2 atmosphere without any contact with air. The carbon obtained is reduced by 54%
gave. Then, N-(phosphonomethylimino)diacetic acid
7.3 g, 1.2 g of the above catalyst and 92 ml of H ₂ O were mixed in a 300 ml autoclave manufactured by "Autoclave Engineers" and then heated at 70 °C and O ₂ pressure 3.44 ×
Oxidation was carried out at 10 ⁵ N/m ² and an O ₂ flow rate of 200 ml/min. The reaction was completed in 9.7 minutes. The reaction rate with treated catalyst is faster than that with untreated catalyst.
It was 11.4 times faster.

Claims (1)

[Claims] 1. A method for selectively producing a secondary amine and a primary amine by combining a tertiary amine or a secondary amine with oxygen or an oxygen-containing gas under reaction conditions in the presence of an activated carbon catalyst, comprising: using an activated carbon catalyst from which oxides have been removed, and the secondary amine of the starting material is N-phosphonomethyl secondary amine or N-carboxymethyl secondary amine, and the tertiary amine of the starting material is N- A method characterized in that it is a phosphonomethyl tertiary amine or an N-carboxymethyl tertiary amine. 2. The method of claim 1, wherein the secondary amine is prepared from a tertiary amine. 3. The method of claim 2, wherein the tertiary amine is an N-phosphonomethyl tertiary amine. 4 The tertiary amine is N-(phosphonomethylimino)
4. The method of claim 3, wherein the diacetic acid is diacetic acid. 5 N-phosphonomethylglycine is produced,
The method according to claim 4.