GB2279347A - Urea derivatives and their use in treating water - Google Patents

Urea derivatives and their use in treating water Download PDF

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Publication number
GB2279347A
GB2279347A GB9412413A GB9412413A GB2279347A GB 2279347 A GB2279347 A GB 2279347A GB 9412413 A GB9412413 A GB 9412413A GB 9412413 A GB9412413 A GB 9412413A GB 2279347 A GB2279347 A GB 2279347A
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urea
water
boiler
substituted
groups
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GB9412413A
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GB2279347B (en
GB9412413D0 (en
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Roger Liddle Jefferson
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C275/00—Derivatives of urea, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups
    • C07C275/04—Derivatives of urea, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups having nitrogen atoms of urea groups bound to acyclic carbon atoms
    • C07C275/06—Derivatives of urea, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups having nitrogen atoms of urea groups bound to acyclic carbon atoms of an acyclic and saturated carbon skeleton
    • C07C275/10—Derivatives of urea, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups having nitrogen atoms of urea groups bound to acyclic carbon atoms of an acyclic and saturated carbon skeleton being further substituted by singly-bound oxygen atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C275/00—Derivatives of urea, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups
    • C07C275/04—Derivatives of urea, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups having nitrogen atoms of urea groups bound to acyclic carbon atoms
    • C07C275/06—Derivatives of urea, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups having nitrogen atoms of urea groups bound to acyclic carbon atoms of an acyclic and saturated carbon skeleton
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
    • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
    • C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
    • C23F11/14—Nitrogen-containing compounds
    • C23F11/141—Amines; Quaternary ammonium compounds
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
    • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
    • C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
    • C23F11/14—Nitrogen-containing compounds
    • C23F11/148—Nitrogen-containing compounds containing a nitrogen-to-nitrogen bond
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
    • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
    • C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
    • C23F11/14—Nitrogen-containing compounds
    • C23F11/149—Heterocyclic compounds containing nitrogen as hetero atom

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)

Abstract

A method of treating water comprises the step of adding to the water in the boiler at least one substituted urea of the following general formula (I): <IMAGE> wherein R1 and R2 are the same or different and are selected from groups having the formula R3NH-, wherein R3 is an aliphatic, cycloaliphatic or aromatic group, and which may be substituted, R4N-, wherein R4 is a cycloaliphatic group, which may include oxygen or nitrogen in its ring, and NH2=N-.

Description

Title: Boiler treatment and novel compounds therefor DESCRIPTION This invention concerns boiler treatment and novel compounds therefor.
In order to treat boiler systems, typically made of mild steel, including steam supply and condensation return lines to prevent corrosion of metal parts, it is necessary to maintain the system at an alkaline pH, typically of the order of 8.5 to 10.5. Conventionally sodium hydroxide has been added to boiler systems to maintain alkalinity. Sodium hydroxide has been added directly to the system, as part of a so-called congruent phosphate treatment or hidden as sodium slippage from a non-polished demineralisation plant.
The purpose of adding any alkali is to provide free hydroxyl ions in solution. If derived from sodium hydroxide the free hydroxyl ions are formed upon dissociation of the hydroxyl ions upon dissolution of the sodium hydroxide in the boiler water. However, because sodium hydroxide is non-volatile it does not readily pass into the condensate return system leaving it vulnerable to corrosion.
An alkaline pH regime not only maintains mild steel in its least corrosive state but also fixes any carbon dioxide gas by converting it to bicarbonate ions.
This is especially important in condensate return lines where dissolved carbon dioxide (carbonic acid) promotes corrosion of mild steel.
Another disadvantage with sodium hydroxide is that it is a hazardous material to handle whether solid or in aqueous solution. Furthermore, free sodium hydroxide is not desirable in boilers associated with combined heat and power plant and/or boilers associated with turbines.
Therefore, a suitable replacement or alternative for sodium hydroxide has been sought. Some amines have been found to be suitable, being both thermally stable and volatile, these amines can increase pH values of the boiler water and in the steam supply and condensate return lines.
There are two conflicting requirements for an amine to be used in a boiler system. Firstly the amine must exhibit as high a degree of ionisation as possible in order to produce hydroxyl ions in water. The higher the dissociation constant, the more effective will be the amine as a hydroxyl ion provider. In this context the most common amine, namely ammonia, has the highest dissociation constant. Most amines are, however, only partially dissociated in water so that practically only a few amines can be used in boiler treatment. Secondly, the amine should have a suitable partition coefficient i.e. its distribution between the liquid and vapour phases of water is desirably such that the amine will be spread throughout a boiler system to protect all parts thereof. In most systems, however, there is always some water phase present as a thin condensing film on inside surfaces of steam pipes.Therefore, because ammonia is so soluble in water, it is quickly removed from the steam phase leaving the rest of the system unprotected.
In general, amines with lower molecular weights have better dissociation constants but amines with higher molecular weight have better partition coefficients but become increasingly less volatile and have in general poorer dissociation constants.
One amine that has been found to be suitable for use in boiler treatment is 2-amino-2-methylpropanol, which has a good balance of dissociation constant and partition coefficient. However, its partition coefficient and boiling point favours condensing out earlier in a complex condensate system, so that it is usually blended with cyclohexamine.
Unfortunately amines have an unpleasant odour, typically of rotting fish, and are generally hazardous to handle. Because they are alkaline on dissolution in water, the materials used for constructing storage tanks, pipes and pumps has to be chosen carefully.
Aqueous solutions of amines tend to give off gas when in storage and the alkaline gases given off are very toxic.
Because of their alkaline nature it is difficult to blend amines with other boiler chemicals.
One object of this invention is to provide a method of treating boilers to maintain alkalinity which does not suffer from the above-mentioned disadvantages.
According to this invention there is provided a method of treating water boilers comprising the step of adding to the water in the boiler at least one substituted urea of the following general formula(I)
wherein R1 and R2 are the same or different and are selected from groups having the formula R3NH-, wherein R3 is an aliphatic, cycloaliphatic or aromatic group and which may be substituted, R4N-, wherein R4 is a cycloaliphatic group, which may include oxygen or nitrogen in its ring, and NH2=N-.
R1 and R2 may be straight or branched chain aliphatic groups.
R1 and/or R2 may be substituted by one or more hydroxyl groups.
Examples of suitable urea compounds for use in the method of the invention include the following: Dimethyl urea Diethyl urea
2-aminomethyl propanol cyclohexamine urea
Di 2-amino-2-methyl propanol urea
Di-cyclohexamine urea
Di-2-amino-2-methyl propane urea
2-amino-2-methyl propane cyclohexamine urea
Morpholine based ureas
where R is any group R1 or R2 as hereinbefore defined Di-C19 amine urea
It is believed that many of the ureas of the general formula (I) are novel and the invention therefore encompasses any novel compound of the general formula (I). In particular, the invention provides ureas of the general formula (I) wherein R1 and R2 are as defined above but excluding R1 and R2 being the same when they are methyl or ethyl groups.
Ureas for use in or of the invention may be prepared in any suitable way, including the following: 1) By addition of an acid such as sulphuric or hydrochloric acid to a single amine or a mixture of amines to form an amine salt, followed by reaction thereof with a cyanate, such a potassium cyanate to form a mono-substituted urea which reacts with excess amine salt to form the di-substituted urea; 2) By reaction between one or more amines and carbon dioxide at elevated temperatures and pressures; 3) By reaction of one or more amines with carbonyllchloride; 4) By reaction of primary amines with urea in a mixture of acetic acid and alcohol.
The preferred compounds for use in the invention are solids which are soluble in water or a mixture of water and an organic solvent such as, for example, 2propanol. It is preferred that a solution of one or more preferred compounds be added to boiler water or blended with other boiler treatment materials in carrying out the method of the invention. Typically other boiler treatment materials include, for example, filming amines and volatile organic oxygen sealers, such as hydrocarbazide or ascorbic acid. In that way a single boiler treatment solution may be provided.
The method of the invention operates by hydrolysis of the substituted urea of the general formula (I) in a boiler to convert it to one or two amines depending on whether it is a simple or mixed substituted urea with release of carbon dioxide. The following formula is an example of the hydrolysis reaction:
The resultant amine or amines can then perform the required function of maintaining an alkaline pH value in the boiler system. By using a mixed substitute urea, i.e. where R1 and R1 are different, two different amines may be produced in the boiler system which have different dissociation constants and partition coefficients, so that one amine may be active in liquid phase areas of the boiler system, whereas the other may be active in steam phase areas of the boiler system.
For example, a substituted urea wherein R1 is
and R2 is C6H1NH will produce 2-amino-2-methyl-1-propanol and cyclohexylamine in a boiler system The 2-amino-2 methyl-1-propanol favours the liquid phase to protect the boiler itself, whereas cyclohexylamine will remain longer in the steam phase to protect steam supply and condensate lines.
Some amines which have desirable properties for boiler treatment are not considered to be practical for use because of other properties. For example, 2-amino2-methyl propane has a higher dissociation constant than 2-amino-2-methyl propanol but has a much lower boiling point (650C compared to 1650C) and so is not suitable for longer term on-site storage. By producing a substituted urea which will hydrolyse to 2-amino-2methyl propane, that amine can be used in boiler treatment without the storage difficulty.
It may also be possible to produce novel mixed functional compounds wherein one substituent of the urea is an amine group and the other is a hydrocarbazide to provide both a neutralising amine and an oxygen scavenger upon hydrolysis in a boiler. See, for example, the following formula:
In general advantages of the present invention include the following: 1) The substituted ureas may be non-volatile; 2) The substituted ureas may be safer and easier to handle; 3) Different boiler treatment materials may be blended into a single treatment; 4) Otherwise unsuitable amines may be used; 5) Possibility of producing novel mixed functional compounds wherein one substituent of the urea is an amine group and the other is a hydrocarbazide to provide both a neutralising amine and an oxygen scavenger upon hydrolysis in a boiler.
6) Possibility of producing novel mixed substituted ureas which will hydrolyse to produce two different amines.
This invention will now be further described by means of the following Example.
Example Di-2-amino-2-methyl propanol urea was prepared in the following manner. An equivalent weight of sulphuric acid was added to 2-amino-2-methyl propanol to form an amine sulphate. The amine sulphate was then reacted with potassium cyanate and excess water boiled off under vacuum. Removal of water caused precipitation out of potassium hydrogen sulphate to form a mono substituted urea. That was then reacted with excess amine sulphate to form the di-substituted urea, which was extracted using dry 2-propanol. Boiling off the 2propanol left the di-substituted urea as a white powder.
Hydrochloric acid may be used in place of sulphuric acid and a mixture of amines may be used to obtain a mixed substituted urea.

Claims (12)

1. A method of treating water boilers comprising the step of adding to the water in the boiler at least one substituted urea of the following general formula (I)
wherein R1 and R2 are the same or different and are selected from groups having the formula R3NH-, wherein R3 is an aliphatic, cycloaliphatic or aromatic group and which may be substituted, R4N-, wherein R4 is a cycloaliphatic group, which may include oxygen or nitrogen in its ring, and NH2=N-.
2. A method as claimed n claim 1, wherein R1 and R2 are straight or branched chain aliphatic groups.
3. A method as claimed in claim 1 or 2, wherein R1 and/or R2 are substituted by one or more hydroxyl groups.
4. A method as claimed in claim 1, wherein the urea is selected from dimethyl urea, diethyl urea, 2aminomethyl propanol cyclyhexamine urea, di-2-amino-2methyl propanol urea, di-cyclohexamine urea, di-2-amino2-methyl propane urea, 2-amino-2-methyl propane cyclohexamine urea and morphine based ureas of the general formula
wherein R is any group R1 or R2, and di-C19 amine urea.
5. A method as claimed in any one of claims 1 to 4 wherein the at least one urea is added to the boiler water in a water based solvent.
6. A method as claimed in claim 5, wherein the solvent is water or a mixture of water and an organic solvent.
7. A method as claimed in claim 6, wherein the organic solvent is 2-propanol.
8. A method as claimed in claim 5, 6 or 7, wherein the urea solution is blended with other boiler treatment materials.
9. A method as claimed in claim 8, wherein the other boiler treatment materials include filming amines and volatile organic oxygen sealers.
10. A method as claimed in claim 9, wherein the volatile organic oxygen sealer is selected from hydrocarbazide and ascorbic acid.
11. An urea having the general formula (I)
wherein R1 and R2 are the same or different and are selected from groups having the formula R3NH-, wherein R3 is an aliphatic, cycloaliphatic or aromatic group, and which may be substituted, R4N-, wherein R4 is a cycloaliphatic group, which may include oxygen or nitrogen in its ring and NH2=N-, with the proviso that R1 and R2 and not the same when they represent methyl or ethyl groups.
12. A method of treating water boilers substantially as hereinbefore described with reference to the foregoing Example.
GB9412413A 1993-06-22 1994-06-21 Boiler treatment Expired - Fee Related GB2279347B (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0875604A1 (en) * 1997-04-17 1998-11-04 Nalco Chemical Company Substituted semicarbazides as oxygen scavengers
WO2007087099A2 (en) * 2006-01-17 2007-08-02 Johnsondiversey, Inc. Method of removing scale and acidic composition used thereof

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB962253A (en) * 1960-04-05 1964-07-01 Pennsalt Chemicals Corp Novel antioxidants and antiozonants
GB1243591A (en) * 1968-01-22 1971-08-18 Inst Francais Du Petrole Process for carbonylating amines
GB1424871A (en) * 1972-03-28 1976-02-11 Ciba Geigy Ag Carbamide-formaldehyde condensation products, their manufacture ans use
GB1451720A (en) * 1973-04-21 1976-10-06 Basf Ag Mixtures of methylol monoalkyl ureas and their butyl ethers
GB1489699A (en) * 1974-03-07 1977-10-26 Wuelfing J Process for the production of 1,3-dialkyl and di-(alkoxyalkyl)ureas
EP0010256A2 (en) * 1978-10-16 1980-04-30 BASF Aktiengesellschaft Process for preparing symmetric 1,3-disubstituted ureas
GB2190670A (en) * 1986-05-24 1987-11-25 Basf Ag Inhibitors against corrosion by CO2 and H2S in water-in-oil emulsions
GB2233973A (en) * 1989-07-21 1991-01-23 Shell Int Research Coproduction of alkylureas and anilines

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB962253A (en) * 1960-04-05 1964-07-01 Pennsalt Chemicals Corp Novel antioxidants and antiozonants
GB1243591A (en) * 1968-01-22 1971-08-18 Inst Francais Du Petrole Process for carbonylating amines
GB1424871A (en) * 1972-03-28 1976-02-11 Ciba Geigy Ag Carbamide-formaldehyde condensation products, their manufacture ans use
GB1451720A (en) * 1973-04-21 1976-10-06 Basf Ag Mixtures of methylol monoalkyl ureas and their butyl ethers
GB1489699A (en) * 1974-03-07 1977-10-26 Wuelfing J Process for the production of 1,3-dialkyl and di-(alkoxyalkyl)ureas
EP0010256A2 (en) * 1978-10-16 1980-04-30 BASF Aktiengesellschaft Process for preparing symmetric 1,3-disubstituted ureas
GB2190670A (en) * 1986-05-24 1987-11-25 Basf Ag Inhibitors against corrosion by CO2 and H2S in water-in-oil emulsions
GB2233973A (en) * 1989-07-21 1991-01-23 Shell Int Research Coproduction of alkylureas and anilines

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0875604A1 (en) * 1997-04-17 1998-11-04 Nalco Chemical Company Substituted semicarbazides as oxygen scavengers
US5904857A (en) * 1997-04-17 1999-05-18 Nalco Chemical Company 4-alkyl and aryl semicarbazides as oxygen scavengers
WO2007087099A2 (en) * 2006-01-17 2007-08-02 Johnsondiversey, Inc. Method of removing scale and acidic composition used thereof
WO2007087099A3 (en) * 2006-01-17 2008-02-21 Johnson Diversey Inc Method of removing scale and acidic composition used thereof

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Publication number Publication date
GB2279347B (en) 1997-01-15
GB9412413D0 (en) 1994-08-10
GB9312881D0 (en) 1993-08-04

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Effective date: 20010621