Abstract:
An aqueous organic amine acid gas scrubbing system, particularly an aqueous N-methyldiethanolamine or diethanolamine acid gas scrubbing system having incorporated therein (1) a compound or mixture of compounds having the formula ##STR1## wherein n is an integer from 1 to 3, m is an integer from 2 to a number sufficient to yield a molecular weight of about 800, R 1 , R 2 , R 3  and R 4  are each independently selected from the group consisting of --H, --C n&#39;  H 2n&#39;  OH, --C n&#39;  H 2n&#39;+1 , --C n&#39;  H 2n&#39;  N(R 3 )R 4  wherein n&#39; is an integer from 1 to 2 and wherein R 1  -R 3  and R 2  -R 4  may be joined to form cyclic amines when n is 2; said compound being present in about 10 to about 2000 parts per million parts of treating solution; (2) copper or a copper ion yielding compound in from 0 to 1000 ppm; and (3) sulfur or a sulfur atom yielding compound in from 0 to 1000 ppm.

Description:
BACKGROUND OF INVENTION 
     Natural and synthetic gases containing acidic components such as CO 2 , H 2  S, COS, and the like, have been treated on a commercial scale with aqueous alkanolamine solutions to remove the acidic components. The severe corrosion which results from the presence of these components, particularly in the rich absorbent solution regeneration section, has necessitated keeping the concentration of the amine low, i.e., 10-30 percent generally and the loading, i.e. the amount of H 2  S/CO 2 , in the absorbent solution, low. In light of the recent energy shortage and necessity to conserve energy it would be advantageous to more heavily load the gas treating solutions with the acidic components. It would be a further advantage to employ more concentrated absorbent solutions. However to accomplish these objects it is necessary to prevent any increase in corrosion and it would be more advantageous to reduce the corrosion to less than that experienced today at the lower loadings and solution concentrations. 
     A brief review of the prior art discloses that numerous patents have taught various polyamines as corrosion inhibitors for various fluids: 
     For example, Dickson et al. in U.S. Pat. No. 3,262,791, which is representative of many patents in the corrosion inhibitor field issued to Petrolite Corporation, describes polyalkylenimines of molecular weight above 800 as useful in preventing corrosion of iron, steel and ferrous alloys when using slushing oils. The patent also suggests these polyalkylenimines as capable of imparting corrosion resistance to brines, weak inorganic acids, organic acids, CO 2 , H 2  S, etc. 
     Ting Sin Go in U.S. Pat. No. 3,819,328, also a Petrolite patent, discloses alkylene polyamines, such as ethylene diamine, to control acid corrosion in distillation columns, such as occurs in petroleum distillation columns. Preferably the alkylene polyamine is used in conjunction with a corrosion inhibitor, e.g., a film-forming corrosion inhibitor, i.e., morpholine, at regulated pH&#39;s of about 2. The corrosion of columns which have water condensers and which water has a high pH due to acidic materials such as H 2  S, HCN, CO 2 , HCl, etc. is taught to be controlled. 
     Ulrich et al. in U.S. Pat. No. 2,143,393 discloses absorbing acid gases in an aqueous solution of a polymerized alkylenimine. 
     Johnson et al. in U.S. Pat. No. 3,137,654 teach using glycines as a corrosion inhibitor in an alkanolamine solution used to absorb CO 2  from industrial gases. 
     Yeakey et al. in U.S. Pat. No. 3,829,494 teach using a water-soluble trialkanolamine in an aqueous 2-(2-aminoethoxy)ethanol gas scrubbing medium. 
     Singh in U.S. Pat. No. 3,535,260 teaches a similar result for monoethanolamine gas treating solutions. 
     The art is rife with disclosures of nitrogen containing compounds useful as corrosion inhibitors, but that only a few are commercially acceptable. It is evident to one skilled in the art operating a commercial installation that the old limitations on concentration of absorbent, loading of the absorbent solution, etc., while improved to some extent with these few commercially accepted inhibitors are lacking in ability to carry without excessive corrosion the demands for more efficient operation, higher absorbent concentrations and higher loading, brought on by the energy shortage. 
     Is is therefore an object of the present invention to provide an inhibitor for aqueous amine gas absorbing systems which will enable higher concentrations of the amine absorbent to be used as well as a higher loading of the acid gases in the absorbent with reduced corrosion. 
     These and other advantages of the present invention will be apparent to those skilled in the art from the following disclosure and claims. 
     BRIEF DESCRIPTION OF INVENTION 
     In accordance with the present invention, a gas scrubbing solution, e.g., an aqueous alkanolamine solution, particularly, diethanolamine and N-methyldiethanolamine solutions, is rendered less corrosive toward metals, particularly ferrous metal and their alloys by incorporating into the solution from about 10 to about 3000 parts of an inhibitor composition consisting essentially of (1) from 10 to 2000 ppm of a compound having the formula ##STR2## wherein n is an integer from 1 to 3, m is an integer from 2 to an integer sufficient to yield a molecular weight of about 800; each R represents an independently selected member from the group consisting of --H, --C n&#39;  H 2n&#39;  OH; --C n&#39;  H 2n&#39;+1  ; C n&#39;  H 2n&#39;  N(R 3 )R 4  ; wherein n&#39; is an integer from 1 to 2 and wherein R 1  -R 3  and R 2  -R 4  may be joined together to form cyclic amines when n&#39; is 2; (2) copper or a copper ion yielding compound in from 0 to 1000 ppm; and (3) sulfur or a sulfur atom yielding compound in from 0 to 1000 ppm. 
     Amine compounds falling within the scope of the formula set out above are for example, polyethylenimine (polyethylene polyamines) having molecular weights from about 60 to about 800 which may be mixtures of several amines, for example a commercial polyalkylene polyamine identified as EA-10 (or E-100) containing 8-9 weight percent tetraethylenepentamine, 30-35 weight percent pentaethylenehexamine, 55 weight percent hexaethyleneheptamine and the remainder branched and cyclic isomers, polyethylenimines, PEI 3 (molecular weight 300±50), PEI 6 (molecular weight about 600), EA-17 tris(aminoethyl)amine (about 90 percent branched), EA-19 pentaethylenehexamine (MW about 232), EA-15 (a mixture of 35-45 percent diethylenetriamine, 10-15 percent triethylenediamine, 5-15 percent piperazine), EA-25 (reaction product of triethylenetetramine divinylbenzene), EA-26 (a divinylbenzene-ethylvinylbenzene-diethylenetriamine mixture), EA-11 (aminoethylpiperazine-diethylenetriamine mixture), 1,2-polypropylenimine, tetraethylenepentamine, triethylenetetramine, diethylenetriamine, ethylenediamine, dihydroxyethyl ethylenediamine, and the like. 
     Copper metal or a copper ion yielding compound such as CuCO 3 , or the like may be employed. (Get scope from earlier case.) 
     Sulfur or a sulfur ion yielding compound may be present and is present in those compositions containing H 2  S, COS or other sulfur containing constituents. 
     The inhibitors are most effective in diethanolamine solutions where the H 2  S to CO 2  ratio is 10/1 to 1/10, respectively. The inhibitors reduce corrosion compared to present day inhibitors in systems containing up to 1/40 H 2  S/CO 2 , respectively. The absorbents DEA and MDEA are effectively provided with less corrosion than present day inhibitor systems with H 2  S only but the results are not as dramatic as when CO 2  is present also. 
     The alkanolamines which have been employed as absorbents for the acidic gas are the mono C 2-3  alkanolamines, such as monoethanolamine, monisopropanolamine, the dialkanol C 2-3  amines, such as diethanolamine and their N-alkyl substituted derivatives, i.e., methyl diethanolamine. The dialkanolamines show marked improvement in corrosion protection when the inhibitors of the present invention are employed. 
     DETAILED DESCRIPTION OF THE INVENTION 
     PROCEDURE 
     The laboratory data were obtained from tests run in a modified Sparkler Filter at 40 psig, at a temperature at 125° C for about 17 hours. All 1020 mild steel test specimens (which were acid etched in 5N HCl, soap washed, water and acetone rinsed and weighted) were placed in 4 oz bottles containing the prospective inhibitor and 50% diethanolamine (DEA) -50 percent water, saturated with H 2  S/CO 2  at various gas ratios. The total liquid volume in each bottle at the start of the experiment was 120 mls. At the end of the experiment, the mild steel specimens were again etched in acid (containing HCl inhibitor) washed with soap and water and acetone rinsed and weighed. The corrosion rate and percent inhibition were calculated using the before and after weighing of the mild steel specimens according to the following equations: 
     
         corrosion rate/yr = (534 W/DAT) 
    
     where W = weight loss in mg; D = density of specimen in gm/cc; A = area in square inches; and T = exposure in hours. ##EQU1## 
     Each of the following tables tabulate the experiments conducted and the results obtained in a single series of tests. The corrosion rate for the uninhibited, blank tests was run for each series to enable a direct comparison to be made with the other tests run in that series. 
     
                                           TABLE I__________________________________________________________________________50% DEA H.sub.2 S/CO.sub.2 9/I                       Corrosion                             PercentCOmpound         PPM PPM                   PPM Rate MPY                             Inhibition__________________________________________________________________________ 1. Blank                   31.54 2. Blank                   31.78 3. Blank                   31.32 4. CuCO.sub.3   100        14.09 55.3 5.  &#34;           100        12.84 59.3 6.  &#34;           1000       9.70  69.3 7.  &#34;           1000       10.09 68.0 8. CuCO.sub.3 + 10 cc MEA.sup.(1)            100        5.48  82.6 9.  &#34;           100        4.38  86.110.  &#34;           1000       4.69  85.111.  &#34;           1000       4.78  84.912. CuCO.sub.3 + 10 cc MEA.sup.(1) + S°            100    100 5.55  82.413.  &#34;           100    100 5.24  83.414.  &#34;           1000   100 4.69  85.115.  &#34;           1000   100 4.55  85.616.  &#34;           100    1000                       4.71  85.117.  &#34;           100    1000                       6.65  78.918. S°           100 36.48 -15.619. &#34;                   100 33.82 -7.220. 10 cc MEA.sup.(1)       33.11 -4.921.  &#34;                      30.84 2.222. PEI 6.sup.(2)            100        4.06  87.123.  &#34;           100        4.22  86.624.  &#34;           1000       2.82  91.125.  &#34;           1000       2.04  93.5__________________________________________________________________________ .sup.(1) MEA - monoethanolamine .sup.(2) PEI 6 - polyethylenime molecular weight about 600 
    
     RESULTS 
     Observation of data from 6 tests shows compounds PEI 6, CuCo 3  + 10 cc MEA, E-100, and E-100 + CuCO 3  + S° as very good protectors of mild steel specimen in 50 percent aqueous DEA solutions and an H 2  S/CO 2  environment. Passivation was observed from 84 percent to 96 percent inhibition. E-100 offers protection at concentrations as low as 1 ppm with 74 percent inhibition; and with the addition of CuCO 3  + S° an additive effect is seen with passivation around 96 percent to 97 percent. 
     
                                           TABLE II__________________________________________________________________________50% DEA H.sub.2 S/CO.sub.2 9/1                      Corrosion                            PercentCompound          PPM                PPM                   PPM                      Rate MPY                            Inhibition__________________________________________________________________________ 1. Blank                  40.91 2. Blank                  40.59 3. Blank                  39.97 4. PEI 6.sup.(1)  100     3.76  90.7 5.  &#34;             100     2.50  93.8 6.  &#34;            1000     2.09  94.8 7.  &#34;            1000     5.53  86.4 8.  &#34;            2000     5.11  87.4 9.  &#34;            2000     5.64  86.110. PEI 6.sup.(1) + CuCO.sub.3              100                1000  3.34  91.711.  &#34;             100                1000  3.23  92.012.  &#34;            1000                 100  2.29  94.313.  &#34;            1000                 100  2.82  93.014.  &#34;            1000                1000  3.12  92.315.  &#34;            1000                1000  2.82  93.016. PEI 6.sup.(1) + CuCO.sub.3 + S°             1000                 100                   1000                      3.03  92.517.  &#34;            1000                 100                   1000                      2.20  94.618.  &#34;            1000                1000                    100                      2.71  93.319.  &#34;            1000                1000                    100                      2.72  93.320. CuCO.sub.3        100  12.63 68.821.  &#34;                100  13.36 67.022.  &#34;               1000  12.42 69.323.  &#34;               1000  13.89 65.724. CuCO.sub.3 + Co(OAc).sub.2             1000                1000  11.18 72.425.  &#34;            1000                1000  10.54 74.026. PEI 6.sup.(1) + Co(OAc).sub.2             1000                1000  4.49  88.927.  &#34;            1000                1000  23.06 43.128. Co(OAc).sub.2 1000     25.37 37.329.  &#34;            1000     24.52 39.430. Co(OAc).sub.2 + S°             1000                 100  36.32 10.331.  &#34;            1000                 100  35.59 12.132. PEI 6.sup.(1) + CuCO.sub.3 + MEA 10 cc             1000                1000  2.20  94.633.  &#34;            1000                1000  2.50  93.8__________________________________________________________________________ .sup.(1) PEI 6 a polyethylenimine of molecular weight of about 600 
    
     
                                           TABLE III__________________________________________________________________________50% DEA H.sub.2 S/CO.sub.2 9/1                       Corrosion                             PercentCompound         PPM               PPM PPM Rate MPY                             Inhibition__________________________________________________________________________ 1. Blank                   31.31 2. Blank                   31.98 3. Blank                   32.12 4. CuCO.sub.3      1000     8.33 73.8 5.  &#34;              1000     8.70 72.6 6. Co(OAc).sub.2 + CuCO.sub.3 + PEI 6            1000               1000                   1000                        2.73 91.4 7.  &#34;           1000               1000                   1000                        2.57 91.9 8. E-100.sup.(1)            1000        1.99 93.7 9.  &#34;           1000        2.14 93.310. E-100 + CuCO.sub.3            1000               1000     2.73 91.411.  &#34;           1000               1000     2.21 93.012. E-100 + CuCO.sub.3 + PEI 6            1000               1000                   1000                        1.76 94.513.  &#34;           1000               1000                   1000                        2.06 93.514. Cr(NO.sub.3).sub.3            1000       25.12 21.015.  &#34;           1000       24.83 21.916. Cr(NO.sub.3).sub.3 +  KMNO.sub.4            1000               &lt;100    26.37 17.117.  &#34;           1000               &lt;100    28.00 11.918. Cd(OAc).sub.2            1000       31.98 -0.619.  &#34;           1000       31.31 1.620. Cd(OAc).sub.2 + KMNO.sub.4            1000               &lt;100    34.04 -7.021.  &#34;           1000               &lt;100    35.16 -10.522. Co(OAc).sub.2            1000       23.36 26.523.  &#34;           1000       23.86 25.0__________________________________________________________________________ .sup.(1) E-100 is a polyethylene polyamine mixture having a molecular weight of about 250-300 
    
     
                       TABLE IV______________________________________50% DEA H.sub.2 S/CO.sub.2 9/1                              Cor-  Per-                              rosion                                    cent                              Rate  Inhi-Compound        PPM    PPM    PPM  MPY   bition______________________________________ 1. Blank                          20.52 2. Blank                          19.90 3. Blank                          21.64 4. E-100.sup.(1)            100               1.88  90.9 5.  &#34;           100               1.88  90.0 6.  &#34;          1000               1.47  92.9 7.  &#34;          1000               2.02  90.2 8.  &#34;          2000               1.88  90.9 9.  &#34;          2000               1.73  91.610. E-100.sup.(1) + Co(OAc).sub.2.sup.(2)           1000   1000        3.62  82.511.  &#34;          1000   1000        1.82  91.212. E-100 + PEI 6           1000   1000        1.94  90.613.  &#34;          1000   1000        2.02  90.214. E-100 + 10 cc MEA.sup.(3)           1000               2.02  90.215.  &#34;          1000               1.53  92.616. 10 cc MEA.sup.(3)              27.69 -33.917.   &#34;                            28.66 -38.618. PEI 6.sup.(3)      1000        2.72  86.919.  &#34;                 1000        2.29  88.920. Co(OAc).sub.2      1000        14.40 30.421.  &#34;                 1000        20.66 0.122. K-437.sup.(4)           1000               12.38 40.223.  &#34;          1000               10.22 50.624. KW-12.sup.(5)           1000               9.32  54.925.  &#34;          1000               9.67  53.2______________________________________ .sup.(1) E-100 a polyethylene polyamine mixture, avg. MW 250-300 .sup.(2) Co(OAc).sub.2 cobalt acetate .sup.(3) MEA monoethanolamine .sup.(4) Commercial corrosion inhibitor for DEA and MEA manufactured by Petrolite and sold under trade name K-437 .sup.(5) Commercial corrosion inhibitor for DEA and MEA manufactured by Petrolite and sold under trade name KW-12 
    
     
                       TABLE V______________________________________50% DEA H.sub.2 S/CO.sub.2 9/1                         Corrosion                                  PercentCompound  PPM     PPM    PPM  Rate MPY Inhibition______________________________________1.   Blank                      31.782.   Blank                      41.653.   Blank                      37.264.   E-100    10                7.60     79.45.   &#34;        10                7.36     80.16.   &#34;        50                7.13     80.77.   &#34;        50                6.89     81.38.   &#34;        100               7.82     78.89.   &#34;        100     6.96 81.110.  &#34;        1000              6.89     81.311.  &#34;        1000              8.46     77.1______________________________________ 
    
     
                                           TABLE VI__________________________________________________________________________50% DEA H.sub.2 S/CO.sub.2 1/1                     Corrosion                           PercentCompound      PPM            PPM               PPM                  PPM                     Rate MPY                           Inhibition__________________________________________________________________________ 1. Blank                 25.27 2. Blank                 26.22 3. Blank                 24.90 4. E-100     1           6.55  74.3 5.  &#34;        1           6.62  74.0 6.  &#34;        10          5.67  77.8 7.  &#34;        10          5.08  80.0 8.  &#34;        100         1.70  93.3 9.  &#34;        100         1.62  93.610.  &#34;        1000        1.62  93.611.  &#34;        1000        1.47  94.212. CuCO.sub.3 Lot 6750         100         7.96  68.713.  &#34;        100         7.51  70.514.  &#34;        1000        6.41  74.815.  &#34;        1000        8.17  67.916. S° 100         22.62 11.217. &#34;         100         23.73  6.818. &#34;         1000        23.57  7.419. &#34;         1000        22.39 12.120. E-100 + CuCO.sub.3 + S°         1000             100  1000                     0.97  96.221.   &#34;       1000             100  1000                     0.88  96.622.   &#34;       1000            1000  1000                     1.10  95.723.   &#34;       1000            1000  1000                     1.03  95.924. CuCO.sub.3 + S°            1000  1000                     8.46  66.825.  &#34;           1000  1000                     8.10  68.2__________________________________________________________________________ 
    
     In the following tables, data is presented demonstrating the results achieved with various compounds falling within the scope of the invention as well as results obtained with closely related compounds and commercially available compositions. Abbreviations used hereinafter are set forth here to facilitate comprehension of the data. 
     
         ______________________________________AbbreviationsCode      Description______________________________________E-100     Polyethylene polyamine MW ca 250-300PEI 6     Polyethylenimine avg. MW 600EA-13     Distilled E-100EA-14     Bis(2-hydroxyethyl) piperazineVE-1      Bis(2-aminoethyl ether)EA-15     Ethyleneamine (NC2189L)EA-17     Tris(2-aminoethyl)amine     90% Branched 10% LinearEA-19     PentaethylenehexamineEA-22     Aminated Polypropylene GlycolEA-23     Dodecylamine + 2EO.sup.(1) + 4BO.sup.(2)EA-25     Triethylenetetraamine-     Divinyl Benzene     TETA-DVB PolymerEA-26     Ethylvinylbenzene (EVB)     Divinylbenzene (DVB)     Ethylvinylbenzene (EVB)     Diethylenetriamine (DETA)     PolymerEA-27     MeCl Quat, DVB-DETAEA-28     2-methyl ImidazolineEA-29     PiperazineEA-18     Dowell Corban 326EA-10     E-100DETA      DiethylenetriamineTRT3      Commercial inhibitor(KW-17)   Petrolite KW-17EA-75     Polyethylenimine (E-75)     filtered solids from E-100PEI 3     Polyethylenimine avg. MW 300TEPA      TetraethylenepentaamineRCC-9     Tetradecylalkyl pyridinium bromideFO-3      Commercial quaternary amineSH-1      70 gm MEA, 3 g CuS, 15 gm S°OA-70     Organic amine 70 a mixture of polyamines     sold by The Dow Chemical Company______________________________________ .sup.(1) EO - ethylene oxide .sup.(2) BO - 1,2-butylene oxide 
    
     The data in each of the following tables was obtained using the indicated compound(s) in the manner set forth in Example 1. 
     PROCEDURE 
     A 50 percent solution of N-methyl diethanolamine (N-MDEA) was saturated with H 2  S/CO 2  gases at a ratio of 9/1. Prospective inhibitors for N-MDEA were tested in the same manner used to test compounds for diethanolamine (DEA) inhibition. The corrosion rate and percent inhibition were determined by the same method used for DEA. 
     
                       TABLE VII______________________________________50% N-Methyl Dea H.sub.2 S/CO.sub.2 9/1                                    Per-                              Corro-                                    cent                              sion  Inhibi-Compound        PPM    PPM    PPM  Rate  tion______________________________________1.   Blank                           25.642.   Blank                           24.833.   Blank                           27.784.   EA-10 (E-100)   10              18.49 29.15.   &#34;               10              19.15 26.66.   &#34;               100             2.14  91.87.   &#34;               100             1.91  92.78.   EA-75 (E-75)    10              21.45 17.89.   &#34;               10              23.64 9.410.  &#34;               100             1.84  92.911.  &#34;               100             1.84  92.912.  PEI-3           10              2.43  90.713.  &#34;               10              2.57  90.114.  &#34;               100             1.62  93.815.  &#34;               100             2.07  92.116.  PEI-6           10              2.59  90.117.  &#34;               10              7.96  69.518.  &#34;               100             1.99  92.419.  &#34;               100             1.70  93.520.  TRT-3 (KW-17)  1000             1.92  92.621.  TRT-3 (KW-17)  1000             2.50  90.422.  TRT-3 (KW-17)   100             6.99  7.3223.  TRT-3 (KW-17)   100             4.34  83.424.  CuCO.sub.3            10        16.50 36.725.  CuCo                  10        16.79 35.626.  CuCO.sub.3 +S° 10   10   16.94 35.127.  CuCO.sub.3 +S° 10   10   18.42 29.428.  S°                  10   27.25 -4.529.  S°                  10   27.03 -3.630.  EA-10+CuCO.sub.3 +S°                10    10   10   2.28  91.331.  EA-10+CuCO.sub.3 +S°                10    10   10   2.28  91.332.  EA-75+CuCO.sub.3 +S°                10    10   10   2.59  90.133.  EA-75+CuCO.sub.3 +S°                10    10   10   2.28  91.334.  PEI-3+CuCO.sub.3 +S°                10    10   10   1.98  92.435.  PEI-3+CuCO.sub.3 +S°                10    10   10   1.91  92.736.  PEI-6+CuCO.sub.3 +S°                10    10   10   2.80  89.337.  PEI-6+CuCO.sub.3 l +S°                10    10   10   2.90  85.0______________________________________ 
    
     RESULTS AND DISCUSSION 
     The data, listed in Table VII, shows that those compounds which were effective in preventing corrosion in DEA, were just as effective in inhibiting corrosion in N-methyl DEA. At 100 ppm, the materials offered protection around 93 percent and the polyamine, CuCO 3  and S° synergistic system also showed excellent protection of mild steel. 
     
                       TABLE VIII______________________________________50% DEA H.sub.2 S/CO.sub.2 9/1                            Corro-                                  Per-                            sion  cent                            Rate  Inhibi-Compound      PPM    PPM    PPM  MPY   tion______________________________________1.   Blank                         42.06 10.52.   Blank                         46.64 0.73.   Blank                         52.24 -11.24.   E-100 (EA-10)             1000             1.84  96.15.   &#34;            1000             1.47  96.96.   WS-1         1000             3.17  93.37.   &#34;            1000             2.80  94.08.   EA-13        1000             2.06  95.69.   &#34;            1000             2.28  95.110   EA-14        1000             53.11 -13.111.  &#34;            1000             49.73 -5.912.  EA-15        1000             6.92  85.313.  &#34;            1000             7.66  83.714.  EA-17        1000             1.99  95.815.  &#34;            1000             2.51  94.716.  EA-19        1000             2.14  95.517.  &#34;            1000             2.28  95.118.  EA-22        1000             56.36 -20.019.  &#34;            1000             56.65 -20.620.  EA-23        1000             52.30 -11.321.  &#34;            1000             47.89 -1.922.  EA-25        1000             8.91  81.023.  &#34;            1000             8.10  82.724.  EA-26        1000             7.96  83.125.  &#34;            1000             7.51  84.0EA-2926.  Piperazine   1000             29.46 37.327.  &#34;            1000             28.88 38.528.  Diethyl-enetriamine  1000             16.36 65.229.  &#34;            1000             24.17 48.630.  EA-28        1000             59.52 -26.731.  &#34;            1000             58.79 -25.132.  EA-18        1000             48.47 -3.233.  ∝     1000             48.32 -2.934.  EA-27        1000             10.16 78.435.  &#34;            1000             10.24 78.2______________________________________ 
    
     
                       TABLE IX______________________________________50% DEA H.sub.2 S/CO.sub.2 9/1                              Corro-                                    Per-                              sion  cent                              Rate  Inhibi-Compound        PPM    PPM    PPM  MPY   tion______________________________________1.   Blank                           35.95 -1.62.   Blank                           33.89 4.23.   Blank                           36.32 -2.64.   E-100            .5             6.92  80.45.   &#34;                .5             6.70  81.16.   &#34;               10              8.62  75.67.   &#34;               10              9.14  74.28.   &#34;              1000             1.10  96.99.   &#34;              1000             1.03  97.110.  CuCO.sub.3      100             11.71 66.911.  &#34;               100             11.34 67.912.  &#34;              1000             9.22  74.013.  &#34;              1000             9.72  72.514.  S°       100             26.97 23.815.  &#34;               100             29.61 16.316.  &#34;              1000             23.36 34.017.  &#34;              1000             23.73 32.918.  CuCO.sub.3 +S°                100     100     11.49 67.519   &#34;               100    100      11.27 68.120.  &#34;              1000    100      10.16 71.321.  &#34;              1000    100      10.61 70.022.  E-100+CuCO.sub.3                10     100      1.26  96.423.  &#34;               10     100      1.25  96.524.  &#34;               10    1000      1.54  95.625.  &#34;               10    1000      1.47  95.826.  &#34;              1000    100      1.18  96.727.  &#34;              1000    100      1.18  96.728.  E-100+S°                10     100      8.25  76.729.  &#34;               10     100      8.04  77.330.  &#34;               10    1000      6.92  80.431.  &#34;               10    1000      5.68  84.032.  &#34;              1000    100      1.11  96.933.  &#34;              1000    100      1.26  96.434.  E-100+CuCO.sub.3 +S°                10     100 100  1.47  95.835.  &#34;               10     100 100  1.33  96.336.  &#34;               10    1000 100  1.25  96.537.  &#34;               10    1000 100  1.33  96.338.  &#34;              1000    100 100  1.26  96.439.  &#34;              1000    100 100  1.25  96.5______________________________________ 
    
     
                       TABLE X______________________________________ 50% DEA H.sub.2 S/CO.sub.2 9/1                              Corro-                                    Per-                              sion  cent                              Rate  Inhibi-Compound        PPM    PPM    PPM  MPY   tion______________________________________1    Blank                           31.24 1.52.   Blank                           32.85 -3.63.   Blank                           31.01 2.24.   E-100           1               12.68 60.05.   &#34;               1               14.51 54.26.   &#34;               10              2.72  91.47.   &#34;               10              2.80  91.28.   &#34;              100              1.33  95.89.   &#34;              100              1.33  95.810.  CuCO.sub.3 in DEA.sup.(1)                10              14.30 54.911.  &#34;               10              14.59 54.012.  CuCO.sub.3     100              12.81 59.613.  &#34;              100              12.38 61.014.  S° in MEA.sup.(2)                10              28.14 11.215.  &#34;               10              27.33 13.816.  S°      100              24.38 23.117.  &#34;              100              24.38 23.118.  E-100+CuCO.sub.3                1      10       1.47  95.419.  &#34;               1      10       1.47  95.420.  &#34;               10     10       1.39  95.621.  &#34;               10     10       1.33  95.822.  &#34;               10    100       1.25  96.123.  &#34;               10    100       1.39  95.624.  E-100 + CuCO.sub.3 +S°                1      10   10  1.76  94.425.  &#34;               1      10   10  1.78  94.426.  &#34;               10     10   10  1.33  95.827.  &#34;               10     10   10  1.47  95.428.  &#34;               10    100   10  1.25  96.129.  &#34;               10    100   10  1.26  96.030.  &#34;               10    100  1.54 95.131.  &#34;               10    100  100  1.17  96.332.  E-100+Co(OAc).sub.2                10    100       5.16  83.733.  &#34;               10    100       8.17  74.234.  &#34;               1     100       14.51 54.235   &#34;               1     100       15.76 50.336.  E-100+Cr(NO.sub.3).sub.3                10    100       4.64  85.437.  &#34;               10    100       2.59  91.838.  &#34;               1     100       12.22 61.539.  &#34;               1     100       13.70 56.8______________________________________ .sup.(1) 10 cc 50% aqueous DEA .sup.(2) 10 cc MEA 
    
     
                                           TABLE XI__________________________________________________________________________50% DEA H.sub.2 S/CO.sub.2 9/1                       Corrosion                             PercentCompound           PPM                 PPM                    PPM                       Rate MPY                             Inhibition__________________________________________________________________________1. Blank                    50.31 -0.62. Blank                    51.56 -3.13. Blank                    48.10 3.84. EDA Ethylenediamine               10      38.39 23.25. &#34;                10      37.79 24.46. &#34;               100      22.62 54.87. &#34;               100      24.24 51.58. TETA Triethylenetetramine               10      32.63 34.79. &#34;                10      29.91 40.210.   &#34;               100      20.32 59.3   &#34;               100      19.23 61.5   TEPA Tetraethylene pentamine               10      18.41 63.2   &#34;                10      26.52 47.0   &#34;               100      10.68 78.6   &#34;               100      12.97 74.1   PEI-3            10      2.95  94.1   &#34;                10      3.25  93.5   &#34;               100      1.47  97.1   &#34;               100      1.47  97.120.   EDA+CuCO.sub.3+S°               10                 10 10 38.46 23.1   &#34;                10                 10 10 40.22 19.5   &#34;               100                 10 10 14.59 70.8   &#34;               100                 10 10 14.22 71.6   TETA+CuCO.sub.3 +S°               10                 10 10 15.69 68.6   &#34;                10                 10 10 17.02 66.0   &#34;               100                 10 10 5.45  89.1   &#34;               100                 10 10 5.44  89.1   TEPA+CuCO.sub.3 +S°               10                 10 10 4.87  90.3   &#34;                10                 10 10 4.79  90.430.   &#34;               100                 10 10 4.27  91.5   &#34;               100                 10 10 4.27  91.5   PEI-3+CuCO.sub.3 +S°               10                 10 10 1.91  96.2   &#34;                10                 10 10 2.06  95.9   E-100+CuCO.sub.3 +S°               1 10 10 5.23  89.5   &#34;                1 10 10 4.72  90.6__________________________________________________________________________ 
    
     
                                           TABLE XII__________________________________________________________________________50% DEA H.sub.2 S/CO.sub.2 9/1                    Corrosion                          PercentCompound        PPM              PPM                 PPM                    Rate MPY                          Inhibition__________________________________________________________________________1. Blank                 29.02 -2.42. Blank                 28.07 0.93. Blank                 27.91 1.54. E-100         10      9.13  67.85. &#34;             10      10.09 64.46. &#34;            100      2.95  89.67. &#34;            100      2.87  89.98. CuCO.sub.3 in 50% DEA            10      31.68 -11.89. &#34;             10      38.97 -37.510.   &#34;             100     11.42 59.7   &#34;             100     9.43  66.7   Ni(NO.sub.3).sub.&#34;2 . 6H.sub.2 O            10      27.85 1.7   &#34;             10      28.80 -1.6   Bis(2-aminoethyl)ether           1000     14.51 48.8   &#34;            1000     15.69 44.6   E-100+CuCO.sub.3            10               10   3.83  86.5   &#34;             10               10   3.61  87.3   E-100 +CuCO.sub.3 +Ni.sup.+2            10               10                 10 3.32  88.3   &#34;             10               10                 10 3.83  86.520.   (Bis(3-aminoethyl)ether +   CuCO.sub.3   1000               10   10.76 62.0   &#34;            1000               10   10.47 63.1   &#34;            1000              100   3.68  87.0   &#34;            1000              100   4.13  85.4   TRT-3 (KW-17)           1000     2.28  91.9   &#34;            1000     1.91  93.3__________________________________________________________________________ 
    
     
                                           TABLE XIII__________________________________________________________________________50% DEA CO.sub.2 /H.sub.2 S 10/1                      Corrosion                            PercentCompound          PPM                PPM                   PPM                      Rate MPY                            Inhibition__________________________________________________________________________1. Blank                   6.782. Blank                   5.813. Blank                   6.194. EA-10 (E-100)    1      3.16  49.65. &#34;                1      3.09  50.66. &#34;               10      1.11  82.27. &#34;               10      1.18  81.18. &#34;               100     0.66  89.49. &#34;               100     0.66  89.410.   &#34;              1000     0.52  91.7   &#34;              1000     0.30  95.2   PEI-3           10      0.60  90.5   &#34;               10      0.74  88.2   &#34;              1000     0.52  91.7   &#34;              1000     0.52  91.7   TRT-3          1000     0.96  84.7   &#34;              1000     0.89  85.8   EA-10 + CuCO.sub.3 + S°              10                10  10                      0.88  86.0   &#34;               10                10   10                      1.03  83.520.   PEI-3 + CuCO.sub.3 + S°              10                10  10                      0.97  84.6   &#34;               10                10  10                      0.89  85.8   CuCO.sub.3 + S°              10                3     7.30  -16.5   &#34;               10                10    7.51  -19.9   CuCO.sub.3      10      7.15  -14.2   &#34;               10      7.00  -11.8   RCC-9 + NH.sub.4 SCN + EA-10              500                50 100   65.9   &#34;               500                50 100                      1.76  71.8   RCC-9           500     6.26  -0.0   &#34;               500     6.05  3.430.   NH.sub.4 SCN    50      6.26  -0.0   &#34;               50      6.05  3.4   RCC:9 +NH.sub.4 SCN              500                50    5.82  7.0   &#34; 500          50    5.82                      7.0   RCC-9 +NH.sub.4 SCN + EA-10              500                50  10                      2.36  62.3   &#34;               500                50  10                      1.99  68.2__________________________________________________________________________ 
    
     
                       TABLE XIV______________________________________70% DEA H.sub.2 S/CO.sub.2 9/1                            Corro-                       sion cent                            Rate  Inhibi-Compound      PPM    PPM    PPM  MPY   tion______________________________________1.   Blank                         28.44 1.72.   Blank                         29.38 -1.63.   Blank                         28.96 -0.14.   E-100         .5              13.78 52.45.   &#34;             .5              15.18 47.56.   &#34;             10              12.23 57.77.   &#34;             10              11.86 59.08.   &#34;            1000             1.76  93.99.   &#34;            1000             10.53 63.610.  PEI-6          1              24.17 16.511.  &#34;              1              24.39 15.712.  &#34;             10              12.81 55.713.  &#34;             10              12.38 57.214.  &#34;            1000             1.84  93.615.  &#34;            1000             1.76  93.916.  CuCO.sub.3 in MEA              10              21.29 26.417.  &#34;             10              27.26 5.818.  CuCO.sub. 3   100             9.36  67.619.  &#34;             100             9.66  66.620.  &#34;            1000             5.52  80.921.  &#34;            1000             5.45  81.222.  PEI-6+CUCO.sub.2              10     100      2.44  91.623.  &#34;             10     100      2.15  92.624.  &#34;            1000    100      1.55  94.625.  &#34;            1000    100      1.54  94.726.  &#34;             10    1000      1.76  93.927   &#34;             10    1000      1.63  94.428.  E-100+CuCO.sub.3              10     10       10.82 62.629.  &#34;             10     10       1.92  93.430.  &#34;            1000    10  1.33 95.431.  &#34;            1000    10       1.47  94.9______________________________________ 
    
     
                       TABLE XV______________________________________50% MDEA CO.sub.2 /H.sub.2 S 50/1                              Corro-                                    Per-                              sion  cent                              Rate  Inhib-Compound        PPM    PPM    PPM  MPY   ition______________________________________1. Blank                           8.54   0.32. Blank                           8.54   0.33. Blank                           8.62  -0.64. EA-10        10                 0.66  92.35. EA-10        10                 1.03  87.96. EA-10        100                0.89  89.67. EA-10        100                0.88  89.88. EA-10        1000               0.81  90.69. EA-10        1000               0.81  90.610. EA-10 + CuCO.sub.3 + S°°           10     10     10   1.33  84.511. EA-10 + CuCO.sub.3 + S°           10     10     10   1.33  84.512. CuCO.sub.3 + S°           10     10          6.12  28.613. CuCO.sub.3 + S°           10     10          6.62  22.714. CuCO.sub.3  10                 7.44  13.215. CuCO.sub.3  10                 6.55  23.516. FO-3        1000               5.82  32.117. FO-3        1000               3.32  61.318. FO-6        1000               6.49  24.319. FO-3        1000               6.55  23.520. RCC-9       500                6.18  27.921. RCC-9       500                5.45  36.422. NH.sub.4 SCN           50                 5.97  30.323. NH.sub.4 SCN           50                 6.10  28.824. RCC-9 + NH.sub.4 SCN           500    50          5.01  41.525. RCC-9 + NH.sub.4 SCN           500    50          4.13  51.926. FO-3 + NH.sub.4 SCN           1000   50          3.25  62.127. FO-3 + NH.sub.4 SCN           1000   50          5.00  41.628. RCC-9 + NH.sub.4 SCN +  EA-10         500    50     10   2.44  71.529. RCC-9 + NH.sub.4 SCN +  EA-10         500    50     10   3.83  55.330. RCC-9 + NH.sub.4 SCN +  EA-10         500    50     100  1.18  86.231. RCC-9 + NH.sub.4 SCN +  EA-10         500    50     100  0.73  91.532. RCC-9 + NH.sub.4 SCN +  EA-10         500    50     1000 0.89  89.633. RCC-9 + NH.sub.4 SCN +  EA-10         500    50     1000 0.66  92.334. FO-3 + NH.sub.4 SCN +  EA-10         1000   50     10   1.84  78.535. FO-3 + NH.sub.4 SCN +  EA-10         1000   50     10   1.84  78.536. FO-3 +  SCN +  EA-10         1000   50     100  0.96  88.837. FO-3 + NH.sub.4 SCN +  EA-10         1000   50     100  0.96  88.8______________________________________ 
    
     
                       TABLE XVI______________________________________30% MEA H.sub.2 S/CO.sub.2 9/1                              Corro-                                    Per-                              sion  cent                              Rate  Inhib-Compound        PPM    PPM    PPM  MPY   ition______________________________________1. Blank                           23.80  4.22. Blank                           24.97 -0.53. Blank                           25.79 -3.84. E-100        10                 10.24 58.85. E-100        10                 8.69  65.06. E-100        100                6.55  73.67. E-100        100                6.78  72.78. E-75         10                 10.84 56.49. E-75         10                 10.39 58.210. E-75        100                6.19  75.111. E-75        100                6.70  73.012. PEI-3       10                 4.42  82.213. PEI-3       10                 4.71  81.014. PEi-3       100                2.51  89.915. PEI-3       100                2.65  89.316. PEI-6       10                 7.73  68.917. PEI-6       10                 8.17  67.118. PEI-6       100                6.26  74.819. PEI-6       100                4.64  81.320. TRT-3       1000               7.37  70.321. TRT-3       1000               8.32  66.522. E-100 + CuCO.sub.3 + S°           10     10     10   4.19  83.123. E-100 + CuCO.sub.3 + S°           10     10     10   4.13  83.424. E-75 + CuCO.sub.3 + S°           10     10     10   3.98  84.025. E-75 + CuCO.sub.3 &#34;+ S°           10     10     10   3.32  86.726. PEI-3 + CuCO.sub.3 + S°           10     10     10   5.01  79.827. PEI-3 + CuCO.sub.3 + S°           10     10     10   5.97  76.028. PEI-6 + CuCO.sub.3 + S°           10     10     10   3.01  87.929. PEI-6 + CuCO.sub.3 + S°           10     10     10   2.65  89.330. CuCO.sub.3 + S°                  10     10   13.04 47.531. CuCO.sub.3 + S°                  10     10   14.30 42.5______________________________________ 
    
     
                       TABLE XVII______________________________________50% N-Methyl DEA H.sub.2 S/CO.sub.2 9/1                              Corro-                                    Per-                              sion  cent                              Rate  Inhib-Compound        PPM    PPM    PPM  MPY   ition______________________________________1. Blank                           25.64 1.72. Blank                           24.83 4.83. Blank                           27.78 -6.54. E-100        10                 18.49 29.15. E-100        10                 19.15 26.66. E-100        100                2.14  91.87. E-100        100                1.91  92.78. E-75         10                 21.45 17.89. E-75         10                 23.64 9.410. E-75        100                1.84  92.911. E-75        100                1.84  92.912. PEI-3       10                 2.43  90.713. PEI-3       10                 2.57  90.114. PEI-3       100                1.62  93.815. PEI-3       100                2.07  92.116. PEI-6       10                 2.59  90.117. PEI-6       10                 7.96  69.518. PEI-6       100                1.99  92.419. PEI-6       100                1.70  93.520. TRT-3       1000               1.92  92.621. TRT-3       1000               2.50  90.422. TRT-3       100                6.99  73.223. TRT-3       100                4.34  83.424. CuCO.sub.3         10          16.50 36.725. CuCO.sub.3         10          16.79 35.626. CuCO.sub.3 + S°                  10     10   16.94 35.127. CuCO.sub.3 + S°                  10     10   18.42 29.428. S°                 10   27.25 -4.529. S°                 10   27.03 -3.630. E-100 + CuCO.sub.3 + S °           10     10     10   2.28  91.331. E-100 + CuCO.sub.3 + S°           10     10     10   2.28  91.332. E-75 + CuCO.sub.3 + S°           10     10     10   2.59  90.133. E-75 + CuCO.sub.3 + S°           10     10     10   2.28  91.334. PEI-3 + CuCO.sub.3 + S           10     10     10   1.98  92.435. PEI-3 + CuCO.sub.3 + S°           10     10     10   1.91  92.736. PEI-6 + CuCO.sub.3 + S°           10     10     10   2.80  89.337. PEI-6 + CuCO .sub.3 + S°           10     10     10   3.90  85.0______________________________________ 
    
     
                       TABLE XVIII______________________________________50% MDEA CO.sub.2 /H.sub.2 S 10/1                              Corro-                                    Per-                              sion  cent                              Rate  Inhib-Compound        PPM    PPM    PPM  MPY   ition______________________________________1. Blank                           20.192. Blank                           20.633. Blank                           19.514. EA-10        10                 1.54  92.35. &#34;            10                 2.44  87.96. &#34;            1000               1.25  93.87. &#34;            1000               1.25  93.88. PEI-3        10                 1.25  93.89. &#34;            10                 1.41  93.010. &#34;           1000               0.30  98.511. &#34;           1000               1.11  94.512. EA-10 + CuCO.sub.3 + S °           10     10     10   1.17  94.213. &#34;           10     10     10   1.03  94.914. PEI-3 + CuCO.sub.3 + S °           10     10     10   1.03  94.915. &#34;           10     10     10   1.18  94.116. CuCO.sub.3 + S °                  10     10   11.13 44.717. &#34;                  10     10   10.90 45.818. CuCO.sub.3         1000        7.14  64.519. &#34;                  1000        7.59  62.320. SH-1        1000               10.16 49.521. &#34;           1000               10.68 46.922. EA-18       1000               19.22 4.423. &#34;           1000               18.35 8.824. EA-24.sup.(1)           1000               1.33  93.425. &#34;           1000               1.25  93.826. FO-3        1000               7.52  62.627. &#34;           1000               7.81  61.228. RCC-9       500                8.98  55.329. &#34;           500                8.69  56.830. RCC-9 + NH.sub.4 SCN           500    50          9.06  54.931. &#34;           500    50          8.77  56.432. RCC-9 + NH.sub.4 SCN +  EA-10         500    50     10   5.97  70.333. &#34;           500    50     10   6.26  68.934. &#34;           500    50     1000 1.55  92.335. &#34;           500    50     1000 1.10  94.5______________________________________ .sup.(1) Union Carbide polyamine D 
    
     
                       TABLE XIX______________________________________40% MIPA H.sub.2 S/CO.sub.2 9/1                              Corro-                                    Per-                              sion  cent                              Rate  Inhib-Compound        PPM    PPM    PPM  MPY   ition______________________________________1. Blank                           14.73 2.22. Blank                           15.25 -1.33. Blank                           15.18 -0.84. E-100        1000               3.24  78.55. &#34;            1000               3.17  78.96. E-75         1000               4.05  73.17. &#34;            1000               4.05  73.18. PEI-3        1000               1.18  92.29. &#34;            1000               1.70  88.710. PEI-6       1000               3.25  78.411. &#34;           1000               3.32  78.012. KW-17       1000               6.49  56.913. &#34;           1000               5.74  61.814. CuCO.sub.3  1000               2.80  81.415. &#34;           1000               2.95  80.416. CuCO.sub.3 in 50% DEA           10                 12.89 14.317. &#34;           10                 12.52 16.8______________________________________ 
    
     
                       TABLE XX______________________________________50% DEA H.sub.2 S/CO.sub.2 /COS 8/1/1                              Corro-                                    Per-                              sion  cent                              Rate  Inhibi-Compound        PPM    PPM    PPM  MYP   ition______________________________________1. Blank                           47.89 -0.02. Blank                           47.74 0.33. Blank                           48.03 -0.34. E-100        1000               1.39  97.15. E-100        1000               1.47  96.96. E-75         1000               1.47  96.97. E-75         1000               1.69  96.58. PEI-3        1000               1.17  97.69. PEI-3        1000               1.17  97.610. PEI-6       1000               1.55  96.811. PEI-6       1000               1.99  95.812. TRT-3       1000               2.06  95.713. TRT-3       1000               2.14  95.514. OA-70       2000               33.67 29.715. OA-70       2000               35.35 26.216. CuCO.sub.3 in DEA + S°           10     10          59.52 -24.317. CuCO.sub.3  in DEA + S°           10     10          66.60 -39.118. CuCO.sub.3  1000               8.70  81.819. CuCO.sub.3  1000               8.04  83.220. E-100 + CuCO.sub.3 + S°           10     10     10   3.24  93.221. E-100 + CuCO.sub.3 + S°           10     10     10   2.81  94.122. E-100       10                 19.23 59.823. E-100       10                 16.58 65.424. PEI-3       10                 2.59  94.625. PEI-3       10                 2.95  93.826. PEI-3 + CuCO.sub.3 + S°           10     10     10   2.20  95.427. PEI-3 + CuCO.sub.3 + S°           10     10     10   2.21  95.428. 1,2-polypropyleneimine           1000               7.96  83.429. 1,2-polypropyleneimine           1000               7.22  84.9______________________________________