Abstract:
Certain Mannich reaction products (i.e., alkylated phenol, polyamine, and an aldehyde) are used to deactivate first row transition metal species contained in hydrocarbon fluids. Left untreated, such metals lead to decomposition resulting in the formation of gummy, polymer masses in the hydrocarbon liquid.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to the use of chelating molecules to deactivate copper species to prevent fouling in hydrocarbon fluids. 
     In a hydrocarbon stream, saturated and unsaturated organic molecules, oxygen, peroxides, and metal compounds are found, albeit the latter three in trace quantities. Of these materials, peroxides can be the most unstable, decomposing at temperatures from below room temperature and above depending on the molecular structure of the peroxide (G. Scott, &#34;Atmospheric Oxidation and Antioxidants&#34;, published by Elsevier Publishing Co., NY, 1965). 
     Decomposition of peroxides will lead to free radicals, which then can start a chain reaction resulting in polymerization of unsaturated organic molecules. Antioxidants can terminate free radicals that are already formed. 
     Metal compounds and, in particular, transition metal compounds such as copper can initiate free radical formation in three ways. First, they can lower the energy of activation required to decompose peroxides, thus leading to a more favorable path for free radical formation. Second, metal species can complex oxygen and catalyze the formation of peroxides. Last, metal compounds can react directly with organic molecules to yield free radicals. 
     The first row transition metal species manganese, iron, cobalt, nickel, and copper are found in trace quantities (0.01 to 100 ppm) in crude oils, in hydrocarbon streams that are being refined, and in refined products. C. J. Pedersen (Inc. Eng. Chem., 41, 924-928, 1949) showed that these transition metal species reduce the induction time for gasoline, an indication of free radical initiation. Copper compounds are more likely to initiate free radicals than the other first row transition elements under these conditions. 
     To counteract the free radical initiating tendencies of the transition metal species and, in particular, copper, so called metal deactivators are added to fluids. These materials are organic chelators that tie up the orbitals on the metal rendering the metal inactive. When metal species are deactivated, fewer free radicals are initiated and smaller amounts of antioxidants would be needed to inhibit polymerization. 
     Not all chelators will function as metal deactivators. In fact, some chelators will act as metal activators. Pedersen showed that while copper is deactivated by many chelators, other transition metals are only deactivated by selected chelators. 
     PRIOR ART 
     Schiff Bases such as N,N&#39;-salicylidene-1,2-diaminopropane are the most commonly used metal deactivators. In U.S. Pat. Nos. 3,034,876 and 3,068,083, the use of this Schiff Base with esters were claimed as synergistic blends for the thermal stabilization of jet fuels. 
     Gonzales, in U.S. Pat. No. 3,437,583 and 3,442,791, claimed the use of N,N&#39;-disalicylidene-1,2-diaminopropane in combination with the product from the reaction of a phenol, an amine, and an aldehyde as a synergistic antifoulant. Alone the product of reaction of the phenol, amine, and aldehyde had little, if any, antifoulant activity. 
     Products from the reaction of a phenol, an amine, and an aldehyde (known as Mannich-type products) have been prepared in many ways with differing results due to the method of preparation and due to the exact ratio of reactants and the structure of the reactants. 
     Metal chelators were prepared by a Mannich reaction in U.S. Pat. No. 3,355,270. Such chelators were reacted with copper to form a metal chelate complex which was used as a catalyst for furnace oil combustion. The activity of the copper was not decreased or deactivated by the Mannich reaction chelator. 
     Mannich-type products were used as dispersants in U.S. Pat. Nos. 3,235,484 and Re. 26,330 and 4,032,304 and 4,200,545. A Mannich-type product in combination with a polyalkylene amine was used to provide stability in preventing thermal degradation of fuels in U.S. Pat. No. 4,166,726. 
     Copper, but not iron, is effectively deactivated by metal chelators such as N,N&#39;-disalicylidene-1,2-diaminopropane. Mannich-type products, while acting as chelators for the preparation of catalysts or as dispersants, have not been shown to be copper ion deactivators. 
     DESCRIPTION OF THE INVENTION 
     Accordingly, it is an object of the inventors to provide an effective copper deactivator for use in hydrocarbon mediums so as to inhibit free radical formation during the high temperature (e.g., 100°-1000° F., commonly 600°-1000° F.) processing of the hydrocarbon fluid. It is an even more specific object to provide an effective copper deactivator that is capable of performing efficiently even when used at low dosages. 
     We have found that copper is effectively deactivated by the use of certain Mannich-type products formed via reaction of the reactants (A), (B), and (C); wherein (A) is an alkyl substituted phenol of the structure ##STR1## wherein R and R 1  are the same or different and are independently selected from alkyl, aryl, alkaryl, or arylalkyl of from about 1 to 20 carbon atoms, x is 0 or 1; wherein (B) is a polyamine of the structure ##STR2## wherein Z is a positive integer, R 2  and R 3  may be the same or different and are independently selected from H, alkyl, aryl, aralkyl, or alkaryl having from 1 to 20 carbon atoms, y may be 0 or 1; and wherein (C) is an aldehyde of the structure ##STR3## wherein R4 is selected from hydrogen and alkyl having from 1 to 6 carbon atoms. 
     As to exemplary compounds falling within the scope of Formula I supra, p-cresol, 4-ethylphenol, 4-t-butylphenol, 4-t-amylphenol, 4-t-octylphenol, 4-dodecylphenol, 2,4-di-t-butylphenol, 2,4-di-t-amylphenol, and 4-nonylphenol may be mentioned. At present, it is preferred to use 4-nonylphenol as the Formula I component. 
     Exemplary polyamines which can be used in accordance with Formula II include ethylenediamine, propylene diamine, diethylene triamine, triethylene tetramine, tetraethylene pentamine and the like, with ethylenediamine being preferred. 
     The aldehyde component can comprise, for example, formaldehyde, acetaldehyde, propanaldehyde, butrylaldehyde, hexaldehyde, heptaldehyde, etc. with the most preferred being formaldehyde which may be used in its monomeric form, or, more conveniently, in its polymeric form (i.e., paraformaldehyde). 
     As is conventional in the art, the condensation reaction may proceed at temperatures from about 50° to 200° C. with a preferred temperature range being about 75°-175° C. As is stated in U.S. Pat. No. 4,166,726, the time required for completion of the reaction usually varies from about 1-8 hours, varying of course with the specific reactants chosen and the reaction temperature. 
     As to the molar range of components (A):(B):(C) which may be used, this may fall within 0.5-5:1:0.5-5. 
     The copper deactivators of the invention may be dispersed within the hydrocarbon medium within the range of 0.05 to 50,000 ppm based upon one million parts of the hydrocarbon medium. Preferably, the copper deactivator is added in an amount from about 1 to 10,000 ppm. 
     In an even more specific aspect of the invention and one that is of particular commercial appeal, specific Mannich products are used to effectively deactivate both copper and iron. This aspect is especially attractive since iron is often encountered in hydrocarbons as a metal species capable of promoting polymerization of organic impurities. The capacity to deactivate both copper and iron is unique and quite unpredictable. For instance, the commonly used metal deactivator, N,N&#39;-disalicylidene-1,2-diaminopropane, deactivates copper, but actually activates iron under the ASTM D-525 test. 
     In this narrower embodiment of the invention, it is critical that ethylenediamine be used as the polyamine (B) Mannich component. Also, with respect to concurrent copper and iron deactivation, the molar ratio of components (A):(B)-ethylenediamine:(C) should be within the range of 1-2:1:1-2 with the (A):(B):(C) molar range of 2:1:2 being especially preferred. 
    
    
     EXAMPLES 
     The invention will now be further described with reference to a number of specific examples which are to be regarded solely as illustrative and not as restricting the scope of the invention. Comparative examples are designated with letters while examples that exemplify this invention are given numbers. 
     Testing Methods 
     Four test methods were employed to determine the deactivating ability of chelators. These were: (1) hot wire test, (2) peroxide test, (3) oxygen absorption test, and (4) ASTM D-525-80. 
     Hot Wire Test 
     I. Objective: To screen preparations according to the amount of fouling protection they exhibit. 
     II. Method Outline: Samples treated with candidate materials are placed in hot wire apparatus and electrically heated. Fouling deposits from an untreated sample are compared with those of the treatments. 
     Peroxide Test 
     The peroxide test involves the reaction of a metal compound, hydrogen peroxide, a base, and a metal chelator. In the presence of a base, the metal species will react with the hydrogen peroxide yielding oxygen. When a metal chelator is added, the metal can be tied up resulting in the inhibition of the peroxide decomposition or the metal can be activated resulting in the acceleration of the rate of decomposition. The less oxygen generated in a given amount of time, the better the metal deactivator. 
     A typical test is carried out as follows: In a 250-mL two-necked, round-bottomed flask equipped with an equilibrating dropping funnel, a gas outlet tube, and a magnetic stirrer, was placed 10 mL of 3% (0.001 mol) hydrogen peroxide in water, 10 mL of a 0.01M (0.0001 mol) metal naphthenate in xylene solution, and metal deactivator. To the gas outlet tube was attached a water-filled trap. The stirrer was started and stirring kept at a constant rate to give good mixing of the water and organic phases. Ammonium hydroxide (25 mL of a 6% aqueous solution) was placed in the dropping funnel, the system was closed, and the ammonium hydroxide added to the flask. As oxygen was evolved, water was displaced, with the amount being recorded as a factor of time. A maximum oxygen evolution was 105 mL. With metal species absent, oxygen was not evolved over 10 minutes. 
     Oxygen Absorption Test 
     In the oxygen absorption test, a metal compound, N,N-diethylhydroxylamine (DEHA), a basic amine, and a metal chelator are placed in an autoclave and 50 to 100 psig of oxygen over-pressure is charged to the autoclave. The change in pressure versus time is recorded. With only the metal compound, DEHA, and a basic amine present, absorption of oxygen occurs. A metal deactivator in the reaction will chelate the metal in such a way to inhibit the oxygen absorption. The less the pressure drop, the better the metal deactivator. 
     A typical test used 1.25 g of a 6% metal naphthenate solution, 5.6 g of DEHA, 5.6 g of N-(2 aminoethyl)piperazine, 12.5 g of heavy aromatic naphtha as solvent, and about 2 g of metal chelator. Pressure drops of from 0 to 48 psig were found over a 60 minute time period. With metal species absent, oxygen was not absorbed. 
     ASTM D-525-80 
     In the ASTM test, a sample of a feedstock known to polymerize is placed in an autoclave with a metal compound, an antioxidant, and a metal chelator. An over-pressure of 100 psig of oxygen is added and the apparatus is heated on a hot water bath to 100° C. until a drop in pressure is noted signifying the loss of antioxidant activity. The longer the time until a drop in pressure occurs, the more effective the antioxidant and/or metal deactivator. 
     EXAMPLES 
     Hot wire tests using 80 ppm of copper naphthenate as the corrosive species were undertaken with respect to several Mannich products of the invention and a commercially known metal deactivator. Results appear in Table I. 
     
                       TABLE I______________________________________            Molar            Ratio   Concentration                                CokeDeactivator      A:B:C   Used (ppm)  (mg)______________________________________1.  Blank            --      --        7.52.  p-t-butyl        2:1:2   350       0    phenol-ethylenediamine    (EDA)-paraformaldehyde    (PF)3.  p-nonylphenol-EDA-PF                4:1:4   220       3.1                        220       2.9                        400       1.5                        800       14.  P--nonylphenol-EDA-PF                2:1:2   220       2.6                        400       1.95.  p-dodecylphenol-EDA-PF                4:1:4   520       06.  MD*              --      200       0______________________________________ *MD -- N,N&#39;--disalicylidene1,2-cyclohexanediamine 
    
     Oxygen tests (using 1.6M mols Cu) were undertaken. Results are reported in Table II. 
     
                       TABLE II______________________________________         Molar Ratio                    ConcentrationDeactivator   A:B:C      Used, mMols Δ P______________________________________Blank         --         --          48, 49MD                       2.5           7.5p-nonylphenol-EDA-PF         2:1:2      0.8         17, 48*                    1.1         17                    2.3          5p-nonylphenol-EDA-PF         4:1:4      1.0         21                    2.0          6______________________________________ *Probable leak in autoclave 
    
     Additional oxygen tests were also undertaken with various Mannich products of the invention and comparative materials with varying metal species as indicated. Results appear in Table III as follows: 
     
                       TABLE III______________________________________                     mgs of      Deactivator    Deacti- mL O.sub.2Metal Species      (Molar Ratio)  vator   in 5 min.______________________________________Cu Naphthenate      Blank          --      105, 105, 105                             (in 15 sec.)      PC-TETA-PF (2:1:2)                     100     0      PC-TETA-PF (2:1:2)                     100     0      PC-EDA-PF (2:1:2)                     100     0      PC-EDA-PF (2:1:2)                     100     14      90% NP-EDA-PF  100     13, 10      (2:1:2)Fe Naphthenate      Blank          --      31, 30, 30(old source)      PC-TETA-PF (2:1:2)                     100     0, 20      PC-TETA-PF (2:1:2)                     100     30      PC-EDA-PF (2:1:2)                     100     0      90% NP-EDA-PF  100     0      (2:1:2)Fe Naphthenate      Blank          --      68, 65, 68(new source)      PC-TETA-PF (2:1:2)                     100     100      PC-TETA-PF (2:1:2)                     100     84, 91      PC-TETA-PF (2:1:2)                     200     82      PC-EDA-PF (2:1:2)                     100     87      PC-EDA-PF (2:1:2)                     100     82, 84      PC-EDA-PF (2:1:2)                     200     22      90% NP-EDA-PF  100     32, 32      (2:1:2)      90% NP-EDA-PF  200     3, 4      (2:1:2)(Prod. batch)      NP-EDA-PF (2:1:2)                     100     29      MD             100     81, 86FeCl.sub.3 Blank          --      65(in water) 90% NP-EDA-PF  100     5      (2:1:2)      MD             100     44FeCl.sub.3 in water      Blank          --      25, 20(next day) 90% NP-EDA-PF  100     11      (2:1:2)      MD             100     0Fe II Acetate      Blank          --      0in water   Blank          --      30   using      90% NP-EDA-PF  100     26   20 mL      (2:1:2)      MD             100     100  H.sub.2 O.sub.2Fe in halogen-      Blank          --      105, 105ated hydrocarbon                  (in 15 sec.)(Prod. batch)      NP-EDA-PF (2:1:2)                     100     105 (60 sec.)(Prod. batch)      NP-EDA-PF (2:1:2)                     200     21(Prod. batch)      NP-EDA-PF (2:1:2)                     400     20      PC-EDA-PF (2:1:2)                     200     12      MD             100     105 (40 sec.)      MD             200     105 (40 sec.)Co Naphthenate      Blank          --      47      90% NP-EDA-PF  100     0      (2:1:2)      MD             100     21Ni Octanoate      Blank          --      22      90% NP-EDA-PF  100     4      (2:1:2)      MD             100     9V Naphthenate      Blank           0      21      90% NP-EDA-PF  100     0      (2:1:2)      MD             100     0Cr Naphthenate      Blank           0      5      90% NP-EDA-PF  100     0      (2:1:2)      MD             100     0______________________________________ PC = paracresol TETA = triethylenetetramine PF = paraformaldehyde EDA = ethylenediamine NP = nonylphenol MD = N,N&#39;--disalicylidene1,2-diaminocyclohexane 
    
     Table III indicates that the para-cresol TETA PF compounds deactivated copper but not iron. In contrast, the P-cresol EDA-PF compounds deactivated both copper and iron. The MD activates iron naphthenate and acetate and appears to slightly deactivate some other forms of iron. The MD appears to slightly deactivate Co and Ni as well as V and Cr. Overall, the NP-EDA-PF Mannich product is more efficacious than MD. 
     EXAMPLE A 
     The reactivity of copper and iron were determined by the peroxide, oxygen absorption test, and ASTM test described above. Results are shown in Table IV. 
     
                       TABLE IV______________________________________Reactivity (Averages) for Metal NaphthenatesWith No Metal Chelators AddedTest     Units   No Metal Copper                           Manganese                                   Iron______________________________________Peroxide mL of   0/10 min 105/0.5                           105/2 min                                   15/5 min    O.sub.2 /min     minOxygen Abs    psig/hr  0       48    --       5ASTM     min     55       22    --      49______________________________________ 
    
     Each of these tests show the same results, namely, copper is the more active catalyst and iron is much less active, although iron is still an active catalyst for promoting oxidation reactions. Manganese is between copper and iron in reactivity as evidenced in the peroxide test. 
     EXAMPLE B 
     The Table IV tests above were repeated, but this time with N,N&#39;-disalicylidene-1,2-diaminocyclohexane (DM) present (Table V). 
     
                       TABLE V______________________________________Reactivity (Averages) by Test Method for Metal NaphthenatesWith N,N--disalicylidene-1,2-diaminocyclohexane (DM)           Amt of    No          Man-Test    Units   Chelator  Metal Copper                                 ganese                                       Iron______________________________________Peroxide   mL      100    mg   0     15/5.0                                   105/0.3                                         90/5   O.sub.2 /minOxygen  psig/hr 0.5    g    0     14.5  --    --AbsASTM    min     123    ppm  56    52    --    27______________________________________ 
    
     Comparing Example A and Example B shows that catalytic activity of the copper was reduced (deactivated) by the N,N-disalicylidene-1,2-diaminocyclohexane, but that of iron and manganese were increased (activated). 
     EXAMPLE 1 
     A series of products were prepared by reacting p-nonylphenol, ethylenediamine, and paraformaldehyde in xylene. For the 2-1-2 product, 110 g (0.5 mol) of nonylphenol, 15 g (0.25 mol) of ethylenediamine, 16.5 g (0.5 mol) of paraformaldehyde, and 142 g of xylene were charged to a 3-necked flask fitted with a condenser, a thermometer, and a stirrer. The mixture was slowly heated to 110° C. and held there for two hours. It was then cooled to 95° C. and a Dean Stark trap inserted between the condenser and the flask. The mixture was heated to 145° C., during which time water of formation was azeotroped off--9 mL was collected--approximately the theoretical amount. The mixture was cooled to room temperature and used as is. 
     EXAMPLE 2 
     The 4-1-4, 1-1-2, and 2-1-2 products from Example 1 were evaluated in the peroxide test (Table VI) and in the Oxygen Absorption test (Table VII). 
     
                       TABLE VI______________________________________Peroxide Test Data for p-Nonylphenol-EDA-FormaldehydemL of Oxygen Evolved in 5.0 Min.  Copper         IronMgs Chelator    4-1-4    1-1-2  2-1-2  4-1-4                                1-1-2  2-1-2______________________________________500      10       7      7*     7    11, 0  0*100      50       13**   3      5    10**   6______________________________________ *600 mgs **125 mgs 
    
     
                       TABLE VII______________________________________Oxygen Absorption Data for p-Nonylphenol-EDA-Formaldehyde Change in Pressure Over 60 MinutesWith Copper           Pressure ChangeGrams Chelator    2-1-2   4-1-4______________________________________2.0               17      214.0               3.5, 4.5                      6______________________________________ 
    
     In this example, it can be seen that at very high levels of any ratio all products work. But as treatment is decreased to more cost effective levels, the 2-1-2 product is more effective for copper and all ratios are effective for iron. 
     These products are effective iron deactivators in contrast to N,N-disalicylidene-1,2-diaminocyclohexane, an iron activator. 
     EXAMPLE 3 
     A series of products prepared by reaction of p-dodecylphenol, EDA, and formaldehyde as in Example 1 were tested in the peroxide test (Table VIII). 
     
                       TABLE VIII______________________________________Peroxide Test Data for p-Dodecylphenol-EDA-FormaldehydemL of Oxygen Evolved in 5.0 Min.  Copper         IronMgs Chelator    4-1-4    1-1-2  2-1-2  4-1-4                                1-1-2  2-1-2______________________________________500       8        5      5*    7     6      7*100      100      80     21     3    10     7______________________________________ *450 mgs 
    
     As above, at high treatment levels all products show efficacy. However, at lower treatment levels, the 2-1-2 molar ratio product is superior for copper and all are similar for iron. 
     The next two examples further illustrate the efficacy of the invention. 
     EXAMPLE 4 
     The 1-1-2 and 2-1-2 products from the reaction of p-t-octylphenol, EDA, and formaldehyde were prepared as in Example 1 and tested in the peroxide test (Table IX). 
     
                       TABLE IX______________________________________Peroxide Test Data for p-t-Octylphenol-EDA-FormaldehydemL of Oxygen Evolved in 5.0 Min.      Copper          IronMgs Chelator 1-1-2  2-1-2      1-1-2                               2-1-2______________________________________500           7      0         9    20, 0125          --     7, 0       --    7100          13     --         7    -- 63          --     105        --   10______________________________________ 
    
     EXAMPLE 5 
     The p-t-butylphenol-EDA-formaldehyde products were prepared as in Example 1 and tested in the peroxide test (Table X). 
     
                       TABLE X______________________________________Peroxide Test Data for p-t-Butylphenol-EDA-FormaldehydemL of Oxygen Evolved in 5.0 Min.             Copper  IronMgs Chelator      2-1-2   2-1-2______________________________________320               5       5100               3       5______________________________________ 
    
     EXAMPLE 6 
     Deactivation of manganese is achieved by the compounds of the invention. Again, the 1-1-2 compounds also deactivate manganese but not as well as the 2-1-2 compounds (Table XI). 
     
                       TABLE XI______________________________________Peroxide Test on Manganese NaphthenatemL of Oxygen Evolved in 5.0 Min.Phenol          mgs    mL______________________________________None            --     104/2 min.*t-Butyl 2-1-2  1000   14*t-Butyl 2-1-2   500   47*Nonyl 1-1-2    1000   41______________________________________ *Compounds formed from phenolEDA- and PF. 
    
     EXAMPLE 7 
     The p-alkylphenol-TETA-formaldehyde products were prepared as in Example 1 and tested in the peroxide test (Table XII). 
     
                       TABLE XII______________________________________Peroxide Test Data for p-alkylphenol-TETA-FormaldehydemL of Oxygen Evolved in 5.0 Min.             MgsAlkyl     Ratio   Chelator     Copper                                Iron______________________________________Nonyl     2-1-2   440          5     16Nonyl     2-1-2    88          14    23Dodecyl   2-1-2   500          3     27Dodecyl   2-1-2   100          25    32Dodecyl   1-1-2   500          0     74Dodecyl   1-1-2   100          7     73______________________________________ 
    
     This example shows that TETA in place of EDA provides a good copper deactivator, but an iron activator. 
     EXAMPLE 8 
     Mixtures of polyamines can be used in the preparation of the Mannich products, prepared as in Example 1 and tested in the peroxide test (Table XIII). 
     
                       TABLE XIII______________________________________Peroxide Test Data for p-Alkylphenol-EDA-TETA-Formaldehyde mL of Oxygen Evolved in 5.0 Min.              MgsAlkyl     Ratio    Chelator    Copper                                Iron______________________________________Nonyl     1-.5-.5-2              500          9    39Nonyl     1-.5-.5-2              100          7    46Dodecyl   1-.5-.5-2              500         11    33Dodecyl   1-.5-.5-2              100         50    11______________________________________ 
    
     This example shows that mixtures of polyamines give good copper deactivators and iron activators. 
     EXAMPLE 9 
     The dialkylphenol-polyamine-formaldehyde products were prepared as in Example 1 and tested in the peroxide test (Table XIV). 
     
                       TABLE XIV______________________________________Peroxide Test Data for 2-1-2 Ratio 2,4-Dialkylphenol-Polyamine-Formaldehyde mL of Oxygen Evolved in 5.0 Min.              MgsAlkyl    Polyamine Chelator     Copper                                 Iron______________________________________t-Butyl  EDA       500          105   18t-Amyl   EDA       500          96     0t-Butyl  DETA      500           0    50t-Butyl  TETA      500          17    100*t-Amyl   TETA      500           0    87______________________________________ *mL of oxygen was evolved in 30 seconds DETA = diethylenetriamine 
    
     This example shows that copper deactivation occurs with all of the products, although better deactivation occurs with DETA and TETA. Iron is activated by the DETA and TETA materials and deactivated or not effected by EDA materials. 
     Reasonable variations and modifications which will be apparent to those skilled in the art can be made without departing from the spirit and scope of the invention.