LOW CORROSION ALKANE SULFONIC ACIDS FOR CONDENSATION REACTIONS

Abstract

The present invention relates to methods for adding an aqueous solution of alkane sulfonic acids to a reactor via a pipe or container, wherein a condensation reaction takes place after addition of the aqueous solution of alkane sulfonic acid and to methods for reducing or limiting corrosion by adding said aqueous solution to a reactor. The present invention also relates to the use of aqueous solutions of alkane sulfonic acids in the reduction or limitation of corrosion and to the use of such aqueous solutions in condensation reactions.

Claims

1-19. (canceled)

20. A method for reducing the corrosion rate of an iron-containing surface, comprising adding an aqueous solution (A) to the iron-containing surface, wherein said aqueous solution (A) comprises 80 w/w % to 99 w/w % of an alkane sulfonic acid, relative to the total weight of the aqueous solution (A).

21. The method of claim 20, wherein the alkane sulfonic acid is methane sulfonic acid.

22. The method of claim 20, wherein the surface comprising iron further comprises chrome and/or nickel.

23. The method of claim 20, wherein the aqueous solution (A) further comprises nitric acid or salts thereof.

24. The method of claim 20, wherein the iron-containing surface belongs to a reactor, pipe and/or container.

25. The method of claim 24, wherein an acid catalyzed reaction takes place in the reactor after the addition of the aqueous solution (A) into the reactor.

26. The method of claim 25, wherein the reaction is a condensation reaction.

27. The method of claim 20, wherein a temperature of the aqueous solution (A) is at least about 20 C. when contacted with the iron-containing surface.

28. The method of claim 20, wherein the method limits the corrosion rate of an iron-containing surface to a rate of max. 0.3 mm/year.

Description

EXAMPLES

[0067] The corrosion behavior of corrosive media by means of gravimetric and visual assessment of metal coupons was determined. It was tailored to the different and therefore comprised different types of coupons, media (from acidic to alkaline), test temperature (room temperature to 80 C.), potential corrosion inhibitors and test period of time.

[0068] Equipment and materials: [0069] analytical balance [0070] 125 ml beaker (PP) with screw cap, supplied by VWR (PA, USA) [0071] metal coupon 50201 mm* [0072] *see Tables 2 to 4 for steel alloys used [0073] test solution** [0074] *** see Tables 2 to 4 for aqueous acid solutions [0075] ethyl acetate for degreasing [0076] deionized water (NH.sub.3 free) to set up the test medium

[0077] Procedure: [0078] 1. The metal coupon was degreased in ethyl acetate and then rinsed with deionized water and dried. In order to avoid further contamination, the metal coupon was only touched with disposable gloves (e.g. Dermatril) after this treatment. [0079] 2. Weighing on an analytical balance. [0080] 3. The coupon was charged with 100 g of the test solution in a PP beaker and then closed. [0081] 4. The PP beaker with the coupon in the test solution was then stored at given temperatures (e.g., 40 C., 60 C., and 80 C.) [0082] 5. At predetermined time intervals 1 d, 3 d, 7 d, 14 d), the coupon was removed with forceps, rinsed, dried and weighed. In addition, visual changes of the coupon and the solution were recorded. Then the coupon was placed into the test solution again. [0083] 6. At the end of the test period, the annual corrosion was calculated. For each setting a double test was performed. [0084] 7. Calculation of the annual corrosion rate:

[00001]$\mathrm{CorrosionRate}\left[\mathrm{mm}.Math.\text{/}.Math.a\right]=\frac{\mathrm{MassLoss}.Math.10.Math.365}{\mathrm{Density}.Math.\mathrm{Area}.Math.\mathrm{Duration}}$

[0085] Mass Loss [g[

[0086] Density of metal coupon [g/cm.sup.3]

[0087] Area of metal coupon in [cm.sup.2]

[0088] Duration=Days of immersion [d] (for Tables 2 to 4: the respective values for 14 d are shown)

TABLE-US-00002 TABLE 2 Corrosion Rate 40 C. [mm/year] Aqueous Aqueous Aqueous solution with solution with solution with 70 w/w % Aqueous 94 w/w % 100 w/w % Steel alloy MSA solution with MSA and MSA according (MSA70), 94 w/w % 900 ppm (MSA100), to DIN comparative MSA nitric acid comparative EN 10088-3 example (MSA94) (MSA94 NA) example 1.4401 0.00 0.00 0.00 0.0909 1.4404 0.00 0.00 0.00 0.4125 1.4541 0.00 0.00 0.00 0.2902 1.4571 0.00 0.00 0.00 0.0888 1.4462 0.00 0.00 0.00 0.25 1.4539 0.00 0.00 0.00 0.146 1.4016 2.9197 0.00 0.00 >6.5 1.4006 1.0256 0.00 0.00 >6.5

TABLE-US-00003 TABLE 3 Corrosion Rate 60 C. [mm/year] Steel alloy according to DIN EN 10088-3 MSA70 MSA94 MSA94 NA MSA100 1.4401 0.1183 0.00 0.00 0.1587 1.4404 0.1368 0.00 0.00 0.3519 1.4541 0.5285 0.00 0.00 0.3447 1.4571 0.1616 0.00 0.00 0.1609 1.4462 0.00 0.00 0.00 1.5 1.4539 0.0013 0.00 0.00 0.25 1.4016 >6.5 0.00 0.00 >6.5 1.4006 >6.5 0.00 0.00 >6.5

TABLE-US-00004 TABLE 4 Corrosion Rate 80 C. [mm/year] Steel alloy according to DIN EN 10088-3 MSA70 MSA94 MSA94 NA MSA100 1.4401 0.7335 0.00 0.00 0.3128 1.4404 2.4652 0.00 0.00 0.9946 1.4541 2.522 0.00 0.00 0.8023 1.4571 0.9175 0.00 0.00 0.3043 1.4462 1.4391 0.0003 0.00 >6.5 1.4539 0.1931 0.0948 0.00 >6.5 1.4016 >6.5 >6.5 0.00 >6.5 1.4006 >6.5 >6.5 0.00 >6.5