Nickel Insitute - Nickel Alloys in Organic Acids & Related Compounds

interest from a corrosion standpoint. The Reppe process prepares the ester from acetylene, carbon monoxide and alcohol. This reaction is conducted in an acid medium with nickel chloride present. As a consequence, corrosion in the reaction area can be very high. Table LXXXI shows data obtained in a reaction to prepare ethyl acrylate by this procedure. Note that the liquid contains over two per cent hydrochloric acid along with free acrylic acid. Among the alloys tested, only HASTELLOY alloys B and C-276 appear to offer good corrosion resistance in this environment. Once the ester is removed from the reaction medium, the conventional materials of construction for recovery of the ester can be employed.

and accompanying equipment. In general, the vapor from the reactor is no worse than that described for the ethyl acrylate process. However, the first distillation column in the recovery chain can experience severe corrosion in the base, and the use of nickel-base molybdenum-chromium- iron alloys and other highly corrosion-resistant materials should be evaluated for use in this area. As described before, conditions in the recovery system are not severe. The austenitic stainless steels are used for the vast majority of the equipment. Again, adequate attention should be given to the possible detrimental introduction of chlorides or other foreign species into the streams. One other method of preparing ethyl acrylate is of

TABLE LXXVIII

Field Exposure of Alloys in Fatty Acid Esterifications

Exposure 1–On agitator shaft in liquid of kettle during esterification of C 12 -C 18 fatty acids with alcohols + 0.25% H 2 SO 4 at 100 ºC (212 ºF) for 33 days. Exposure 2–In liquid of kettle near head during esterification of fatty acids (myristic present) with alcohols (isopropanol present) with sulfuric acid at approximately 110 ºC (230 ºF) for 82 days. Exposure 3–Liquid and vapor phase of a kettle (liquid velocity ca. 16 ft/sec) for 18 days during glyceryl esterification, amidation and sulfurization of tall oil.

Corrosion Rate

1

2

3*

Liquid

Liquid

Liquid

Vapor

Alloy

mm/y

mpy

mm/y

mpy

mm/y

mpy

mm/y

mpy

.16 .03 .15 .08 .01

6.2 1.1 5.8 3.1 0.4

.23

9

<.03

<1

Type 304 Stainless Steel Type 216 Stainless Steel Type 316 Stainless Steel Type 317Stainless Steel CARPENTER alloy 20Cb-3 ACI CN-7M Cast Alloy INCOLOY alloy 825 INCONEL alloy 600 INCONEL alloy 625 HASTELLOY alloy G HASTELLOY alloy B JESSOP JS-700 MONEL alloy 400 HASTELLOY alloy C-276 NITRONIC ** 50

.51

20

–

–

–

–

–

–

.05

2

<.03

<1

.51

20

– –

– –

– –

– –

–

– 4 – – – – – – – – 4 – 6 – – –

.10

–

–

<.03

<1

<.03

<1

– – – – – – – –

.02 .01

0.9 0.4

– –

– –

– –

– –

–

–

.13

5

<.03

<1

.25

10

.02 .01 .01 .09 .05

0.7 0.4 0.5 3.7 2.0

– –

– –

– –

– –

<.03

<1

<.03

<1

.18

7

.15

6

–

–

–

–

– – –

– – _

.56 .97

22 38

.30 .36

12 14

.10

Nickel 200 Copper Titanium

–

– –

– –

– –

– –

.15

.01

0.3

– – –

– –

– –

.33 .15

13

.15 .30

16 12

30% Nickel Cast Iron

Ni-Resist Type 1

6

*Reference 30 **Trademark of Armco Steel Corporation

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