Patent Publication Number: US-2006005464-A1

Title: Alkyl ethanolamine and biocide combination for hydrocarbon based fuels

Description:
This application is a continuation in part of U.S. application Ser. No. 10/886,866 filed Jul. 8, 2004. 
    
    
     FIELD OF THE INVENTION  
      The present invention relates to additives for systems of hydrocarbon fuels containing water. More particularly, the present invention relates to biocidal treatments for water-hydrocarbon based fuel emulsions and hydrocarbon based fuels, such as diesel or biodiesel systems containing water. The treatment comprises at least one biocidal alkyl ethanolamine agent or a combination of a biocidal agent and at least one alkyl ethanolamine.  
     BACKGROUND OF THE INVENTION  
      The performance of hydrocarbon based fuels such as diesel fuels, gasoline and kerosene can be favorably modified by the addition of performance enhancing additives such as water (emulsified fuel), emulsifiers, biocides, pH modifiers, detergents, etc. Two areas of current commercial interest are the formulation of emulsified diesel fuel and the use of plant derived diesel fuel alternatives known as biodiesel. In diesel engines, the high temperatures reached during combustion may increase the tendency for the production of nitrogen oxides (NO x ) and sulfur oxides (SO x ).  
      Nitrogen oxides are formed via the reaction of atmospheric nitrogen and oxygen in the combustion chamber and, to a far lesser extent, from oxidation of organic nitrogen species in the fuel. The rates at which various NO x  type species form are related to combustion temperature, and it has been found that a small reduction in flame temperature can result in a large reduction in the production of nitrogen oxides.  
      One approach to lowering flame temperature is to inject water into the combustion chamber. This method allows for existing fuels to be used as is, but it requires costly and complicated changes in engine design. As an alternative, one may use fuels that comprise an emulsion of both water and traditional petrodiesel (derived from a petroleum refining process) and/or biodiesel fuel (derived from transesterification of plant or animal derived triglycerides). One problem that exists in such water-hydrocarbon based fuel emulsions is the growth of microorganisms that utilize the mostly hydrocarbon based fuel as a nutrient. Such microorganisms or microbes will tend to grow in the water phase, but they can also become dispersed in the hydrocarbon fuel phase leading to degradation of the hydrocarbon fuel. In the case of biodiesel, microorganisms can grow in the pure fuel with just the traces of water naturally present as a contaminant (typical water specification for biodiesel is 50 ppm). All such contamination or degradation can cause sludge formation that clogs fuel filters and other engine components.  
      In addition to the growth of microorganisms or microbes in water-hydrocarbon based fuel emulsions and/or biodiesel type fuels, similar problems arise in other water-hydrocarbon based fuel interface situations. For example, hydrocarbon based fuels are frequently exposed to a layer of water in large storage and/or transportation vessels. The interface between the water and hydrocarbon product becomes a breeding ground for microorganisms and microbes.  
      U.S. Pat. No. 3,883,345 disclosed the use of a bactericidal agent such as an alkyl pyridinium or picolinium halide to inhibit microorganism related sludge in fuel oils.  
      UK patent number 1,325,913 discloses the use of a condensation product of an aliphatic aldehyde such as formaldehyde and a primary or secondary alkanolamine such as diethanolamine to control microorganisms in hydrocarbon fuels.  
      U.S. Pat. No. 6,607,566 discloses a method for producing a highly stable aqueous fuel emulsion. The fuel emulsion can include corrosion inhibitors including alkanolamines for pH control as well as biocides.  
     SUMMARY OF THE INVENTION  
      US Patent Application Publication number U.S. 2003/0162845 A1 discloses the use of de-activatable biocides in hydrocarbonaceous products.  
      The present invention relates to a treatment for water-hydrocarbon based fuel system, which provides in part, biocidal control. More particularly, the present invention relates to the addition of a combination of a biocide and at least one alkyl ethanolamine to a water-hydrocarbon based fuel system to inhibit microbiological activity. In hydrocarbon based fuel systems, contact with water either intentionally or through contamination can result in undesirable biological activity. The microbiological activity can result in degradation of the fuel, sludge formation, undesirable odor generation, etc. The use of biocidal agents in such systems is known. The present inventors have discovered that the addition of a combination of a biocidal agent and at least one alkyl ethanolamine to such systems results in unexpected increased biocidal activity. The combination of the present invention can allow a reduction in the amount of biocide necessary to achieve a given level of control. The alkyl ethanolamine, in addition to enhancing the activity of the biocide, also can provide pH control for the system. Such pH control can reduce possible corrosion problems. The favorable impact of the amine is particularly important in the plant-derived fuels known generically as biodiesel.  
      The biocidal agent-alkyl ethanolamine treatment of the present invention can be employed in combination with conventional additives for hydrocarbon fuel systems containing water such as water-hydrocarbon emulsion systems and/or non-emulsion fuels containing or contaminated with small amounts of water. Conventional additives can include emulsifiers, detergents, pH adjusting agents, etc. The treatment of the present invention can be employed in systems containing hydrocarbon based fuels such as diesel fuel, gasoline, kerosene, heating oils, etc. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Formulated hydrocarbon fuels in general and emulsified hydrocarbon fuels in particular are prone to degradation via microbiological contamination or attack. In hydrocarbon fuel systems where water is present, microorganism growth can occur at the water-hydrocarbon interface. The microorganism can degrade the quality of the hydrocarbon, cause undesirable odors and cause sludge formation. The treatment of such systems with biocidal control agents is known. The present inventors discovered that the efficacy of biocidal agents in such systems could be enhanced through the addition of alkyl ethanolamines. As used herein, biocide or biocidal agent refers to any substance that kills or inhibits the growth of microorganisms such as bacteria, molds, slimes, fungi and the like.  
      In hydrocarbon fuel systems where water is present as a contaminant, the water or aqueous phase can comprise between 0.01% and 25% by weight of the system. Such water contamination can result from condensation in large storage or transportation vessels. In addition, such contamination can result from non-exclusive use of storage tanks. In addition to water-hydrocarbon fuel systems resulting from contamination, such systems may be formed intentionally. For example, the formation of water-diesel fuel emulsions to control NO x  and SO x  emissions is known. The use of additives including biocides in such systems is known.  
      The present inventors have discovered that the combination of an alkyl ethanolamine and a biocide in such systems significantly enhances the efficacy of the biocide. The use of the combination of the present invention allows for a decrease in the amount of biocide needed to provide a desired level of control, or an increase in the level of biocidal control without an increase in the amount of biocide employed.  
      The alkyl ethanolamines of the present invention are of the formula: 
 
R X NH Z (CH 2 CH 2 OH) Y  
 
 wherein R is C 3  to C 18  alkyl or isoalkyl group, X and Y are 1 or 2, Z is 0 or 1, X+Y is not greater than 3, when X or Y is 2 than Z is 0 and when X is 2 the R groups are the same or different C 3  to C 18  alkyl or isoalkyl groups. Preferred alkyl ethanolamines include butyl diethanolamine, Butylaminoethanol, dibutylaminoethanol and diisopropylaminoethanol. The alkylamine ethoxylate can be added to water-hydrocarbon based fuel systems at treatment concentrations from about 100 to 8000 parts per million (ppm) and preferably at treatment concentrations of from about 1000 to 5000 ppm. 
 
      The alkyl ethanolamine is added to a water-hydrocarbon based fuel system in combination with a biocide. The biological control agent can include triazines, thiazolinones, halogenated compounds, thiocyanates, carbamates, pyrithiones, quaternary ammonium compounds, aldehydes, heterocyclic compounds, soluble metal ions and reactive alkylating agents. A preferred biocide is a 78.5% 1,3,5-(2-hydroxyethyl)-s-triazine solution in water available as GROTAN® from Troy Chemicals. Other suitable biocides may comprise benzoisothiazolone such as Proxel DB20, a 20% suspension of benzoisothiazolone available from Avecia, and the like. The biocide can be added in concentrations from about 100 to over 2000 ppm. However, to minimize potential adverse environmental impact, it is preferred to use lower levels of biocide. In the combination of the present invention, biocide concentrations of from about 100 ppm to about 1500 ppm have been found to be effective. In cases wherein the biological challenge is minimal, the alkyl ethanolamines of the present invention may be used as the sole biological control agent.  
      The biocide-alkyl ethanolamine combination of the present invention, in addition to providing enhanced biocidal control also will provide pH control in water-hydrocarbon based fuel systems. The alkyl ethanolamine component of the present invention can provide pH control that inhibits corrosion in hydrocarbon based fuel systems containing water. The treatment combination of the present invention can be employed in concert with other system additives such as emulsifiers, detergents, pH adjusting agents, etc.  
      The present invention will be further described by the following non-limiting examples.  
     EXAMPLES  
     Example 1  
      A 324 well microtiter plate was employed to evaluate the growth of a microorganism common to water-hydrocarbon based fuel systems,  Pseudomonas Aeruginosa  (ATCC27853) in with a variety of amines at varying concentrations. The testing employed Trypticase Soy Broth (TSB) as a growth medium and 25 m molar tris (trihydroxymethylmethylamine) as a buffer. The test duration was 24 hours at pH 8.5.  
      The amines tested were alkyl ethanolamines: butyldiethanolamine (BDEA), butylaminoethanol (BAE), tert-butylaminoethanol (TBAE) and diisopropylaminoethanol (DIPAE). Alkyl alkanolamines, 2-methyl-2-amino-1-propanol (AMP),) and diglycolamine (DGA) were also tested. The biocide was GROTAN® available from Troy Chemicals of New Jersey. Table I summarizes the test results. The entries in Table 1 are averages of at least four replicate runs for each test.  
                                           TABLE 1                                      GROTAN   GROTAN   GROTAN   GROTAN   GROTAN   GROTAN           0 ppm   100 ppm   250 ppm   500 ppm   1000 ppm   2000 ppm                                                     Bacteria/   0.97   1.19   1.21   0.88   0.36   0.39       media                                                                         Plus   2000   4000   2000   4000   2000   4000   2000   4000   2000   4000   2000   4000       Amine   ppm   ppm   ppm   ppm   ppm   ppm   ppm   ppm   ppm   ppm   Ppm   ppm               BDEA   0.67   0.45   0.52   0.67   0.72   0.51   0.79   0.30   0.32   0.28   0.33   0.33       DIPAE   0.59   0.46   0.56   0.42   0.52   0.41   0.52   0.28   0.31   0.28   0.35   0.36       BAE   0.37   0.49   0.49   0.35   0.45   0.32   0.35   0.25   0.30   0.29   0.36   0.36       AMP   0.72   1.12   0.72   0.72   0.72   0.69   0.72   0.39   0.31   0.30   0.35   0.37       TBAE   0.67   0.55   0.72   0.58   0.69   0.59   0.83   0.34   0.30   0.28   0.35   0.36       DGA   0.76   0.68   0.71   0.70   0.70   0.69   0.76   0.36   0.32   0.29   0.34   0.36                  
 
      The data in Table I shows that the alkyl ethanolamines BAE, BDEA and DIPAE provide an enhancement in the biocidal effect of GROTAN® that is not seen in alkyl alkanolamines AMP and DGA.  
     Example 2  
      A culture of mixed enteric bacteria ( klebsiella pneumoniae, Proteus vulgarus, Citrobacter  sp.,  Escherichia coli ) at pH=9.0 in TSB (trypticase soy broth) media mixed with emulsified oil was prepared. A biocide, GROTAN® {78.5% 1,3,5-(2-hydroxyethyl)-s-triazine solution in water} as sold by Troy Chemicals (Florham Park, N.J.) was added at varying concentrations to the culture in combination with 2500 ppm of one of the four alkanolamines, N-butylaminoethanol (BAE), diethanolamine (DEA), diglycolamine (DGA) or 2-amino-2-methyl-1-propanol (AMP). Optical density measurements were taken every 15 minutes over a 24 hour time period (total of 96 data points). The maximum growth slope was calculated by taking the 10 contiguous data points that result in the highest growth slope (units of OD per time) over the 24 hour period. Those 10 data points were subjected to a least squares linear fit to calculate the maximum growth slope. Table 2 summarizes the maximum growth slopes for these tests.  
                               TABLE 2                       [Biocide]   BAE   DEA   DGA   AMP                                                        1650   ppm   0.0515   0.117   0.0725   0.069       650   ppm   0.082   0.466   0.1955   0.32       0   ppm   0.2   0.723   0.796   1.065                  
 
      The data in Table 2 shows that the bacteria growth rate can be slowed significantly with reduced levels of biocide when an alkyl ethanolamine is combined with the biocide.  
     Example 3  
      A culture of  Pseudomonas aeruginosa  (ATCC 10145) at pH=8.5 in TSB (trypticase soy broth) media was prepared. The biocide Proxel DB20 (20% suspension of benzoisothiazolone (BIT) in water), as sold by Avecia, was added at varying concentrations in combination with 1000 ppm or 2000 ppm of the alkanolamines N-butylaminoethanol (BAE), 2-amino-2-methyl-1-propanol (AMP), dibutylaminoethanol (DBAE) or n-octylaminoethanol (OAE). Optical density measurements were taken every 15 minutes over a 24 hour time period (total of 96 data points). The maximum growth slope was calculated by taking the 10 contiguous data points that result in the highest growth slope (units of OD per time) over a 24 hour period. Those 10 data points were subjected to a least squares linear fit to calculate the maximum growth slope. Table 3 summarizes the maximum growth slopes for these tests.  
                                   TABLE 3                                      AMP   BAE   DBAE   OAE                                                     1000   2000   1000   2000   1000   2000   1000   2000       BIT   ppm   ppm   ppm   ppm   ppm   ppm   ppm   ppm                                                             0   ppm   0.478   0.29   0.333   0.000   0.228   0.114   0.000   0.000       150   ppm   0.667   0.361   0.317   0.134   0.221   0.084   0.000   0.000       250   ppm   0.508   0.320   0.353   0.000   0.255   0.104   0.000   0.000       500   ppm   0.407   0.228   0.281   0.000   0.143   0.000   0.000   0.000                  
 
      The data in Table 3 shows that the bacteria growth rate can be slowed significantly with reduced levels of biocide when an alkyl ethanolamine is combined with the biocide.  
     Example 4  
      A culture of  Pseudomonas aeruginosa  (ATCC 10145), a bacteria common in water-oil systems, at pH 8.5 in Tris buffer was prepared in TSB media. Biological control agent Bronopol (2-nitro-2-bromo-1,3-propanediol) at varying concentrations in combination with alkanols BAE and AMP at 2000 ppm was added and bacteria growth monitored via optical density as in Example 3. Table 4 summarizes the maximum growth slope:  
                                       TABLE 4                                   [Bronopol]   35 ppm   25 ppm   15 ppm   5 ppm                                                                AMP (2000 ppm)   0   0   0.327   0.345           BAE (2000 ppm)   0   0   0   0.083                      
 
      The data in Table 4 shows that the bacteria growth rate can be slowed significantly with reduced levels of biocide when an alkyl ethanolamine is combined with the biocide.  
     Example 5  
      The impact of various N-alkyl alkanolamines on the control of the bacterial species  Mycobacterium smegmatis  (ATCC # 19420), a bacteria common in water-oil systems, was evaluated by measuring optical absorbance of samples treated with various concentrations of N-alkyl alkanolamines. Bacterial concentration in the experimental media, consisting of a standardized solution of clear nutrient broth (Middlebrook 7H9), amine, buffer (Tris) and water, was monitored indirectly via optical absorbance at 590 nm. The pH was adjusted initially to 8.5 with Tris buffer. An additional absorbance reading at 750 nm was used to insure that light scattering and turbidity were not adversely affecting the data. A tetrazolium dye was employed to increase the sensitivity of the optical measurement. The values reported in Table 1 are end-point optical densities in milliOD units after 72 hours. In Table 1, AMP is 2-amino-2-methyl-1-propanol, BAE is butylaminoethanol, DBAE is dibutylaminoethanol, OAE is octylaminoethanol. The first column in Table 1 gives the treatment amine concentration in parts per million by weight.  
                               TABLE 5                       [Amine] (ppm)   AMP   BAE   DBAE   OAE                                                    470   2100   2200   2000   0       940   2200   2100   2000   0       1880   2100   2000   2000   0       3750   2000   1900   1900   0       7500   1700   1700   1200   0                  
 
      It is clear from the data shown that OAE is markedly more effective than AMP against Mycobacteria.  
     Example 6  
      The impact of N-alkylalkanolamines on the control of the bacterial species  Mycobacterium smegmatis  (ATCC # 19420), a bacteria common in water-oil systems, was evaluated by measuring optical absorbance of samples treated with various alkyl ethanolaminesis DCHA=Dicyclohexylamine, OAE=Octylaminoethanol, ODEA=Octyldiethanolamine. Bacterial concentration was monitored indirectly via optical absorbance at 660 nm. The values reported are end-point optical densities in milliOD units after 48 hours. The media consisted of a standardized solution of clear nutrient broth (Middlebrook 7H10 with OADC supplement), amine, buffer (Tris) and water. The pH was adjusted initially to 8.5 with Tris buffer. The first column in the Table gives the amine concentration in ppm. The final two columns give data for cells that also contained 2 grams per liter of boric acid. In all cases, the values are averages of at least three replicates. The final row of the Table gives an estimate of the concentration range in which the amine in question starts to inhibit the growth of this bacterial species.  
                                   TABLE 6                                       OAE   DCHA       [Amine]               Boric   Boric       (ppm)   OAE   ODEA   DCHA   Acid   Acid                                                        0   1.13   1.13   1.13   0.925   0.925       500   0.184   0.847   1.02   0.100   1.125       1000   0.149   0.117   0.802   0.121   0.855       1500   0.213   0.260   0.995   —   —       2000   0.226   0.225   0.268   0.015   0.085       4000   0.205   —   —   —   —       MIC   &lt;500   500-1000   1500-2000   &lt;500   1000-2000       (ppm)                  
 
     Example 7  
      The impact of the N-alkylalkanolamines of Example 6 on the control of the bacterial species  Mycobacterium marinum  (ATCC # 19420), bacteria common in water-oil systems, was evaluated as described above in Example 6. Bacterial concentration in the experimental media was monitored indirectly via optical absorbance at 660 nm. The values reported are end-point optical densities in milliOD units after 72 hours. The media consisted of a standardized solution of clear nutrient broth (Middlebrook 7H10 with OADC supplement), amine, buffer (Tris) and water. The pH was adjusted initially to 8.5 with Tris buffer. The first column in the Table gives the amine concentration in ppm. In all cases, the values are averages of at least three replicates. The final row of the Table gives an estimate of the concentration range in which the amine in question starts to inhibit the growth of this bacterial species.  
                               TABLE 7                       [Amine] (ppm)   OAE   ODEA   DCHA   BAE                                                    0   0.8   0.8   0.8   0.8       400   0.4   0.6   0.6   —       800   0.4   0.4   0.6   0.7       1200   0.4   0.4   0.5   0.7       2000   0   0.1   0.4   0.6       4000   0   0   0.4   0.6       MIC (ppm)   1200-2000   1200-2000   &gt;4000   &gt;4000                  
 
     Example 8  
      The impact of N-alkylalkanolamines on the control of the bacterial species  Aureobasidium pullulans  (ATCC 12536), a bacteria common in water-oil systems, was evaluated by measuring optical absorbance of samples treated with various concentrations of N-alkyl alkanolamines. Biological control agent −50 ppm MIT/CMIT (2-methyl-4-isothiazolin-3-one/2-methyl-5-chloro-4-isothizolin-3-one) was employed in combination with the alkanols as listed previously at concentrations designated in Table 8. SAB media at pH 8.5 (Tris buffer) was employed. Table 8 summarizes measurement of end-point optical density after 24 hours and 48 hours:  
                               TABLE 8                                   End Point   24 hours   48 hours                                                        AMP (1000 ppm)   0.3   0.4           AMP (2000 ppm)   0.3   0.4           BAE (1000 ppm)   0.3   0.3           BAE (2000 ppm)   0.2   0.2           DBAE (1000 ppm)   0.3   0.4           DBAE (2000 ppm)   0.2   0.2           OAE (200 ppm)   0.1   0.1           OAE (500 ppm)   0   0                      
 
      While the present invention has been described with respect to particular embodiments thereof, it is apparent that numerous other forms and modifications of this invention will be obvious to those skilled in the art. The appended claims and this invention generally should be construed to cover all such obvious forms and modifications, which are within the true spirit and scope of the present invention.