aspearin1
Chemical
- Nov 5, 2002
- 391
We have a process here that uses the Amberlyst 15 cation exchange beads (Rohm-Haas) as a catalyst for esterification. Recent testing on the beads indicated a metal fouling of them. More specifically defined by a yellowing of titration.
To test the beads, a sample mass (6g) is flushed with 500mL DI water and later flushed with 4% Na2SO4 to strip remaining H+ ions off the beads and into solution. A titration is performed on samples of this solution with .1N NaOH and Phenolphthalein indicator.
Normally when I run this test on a lab scale the titrant remains clear until BOOM, pink. However, when running the test on process beads, the solution gradually became yellower before settling on a pinkish peach. Much different than normal. My best guess is that a metal is being stripped from the beads and is reacting with NaOH and Phenolphthalein to produce the yellow color. Can anyone hazard a guess as to what this metal might be?
To test the beads, a sample mass (6g) is flushed with 500mL DI water and later flushed with 4% Na2SO4 to strip remaining H+ ions off the beads and into solution. A titration is performed on samples of this solution with .1N NaOH and Phenolphthalein indicator.
Normally when I run this test on a lab scale the titrant remains clear until BOOM, pink. However, when running the test on process beads, the solution gradually became yellower before settling on a pinkish peach. Much different than normal. My best guess is that a metal is being stripped from the beads and is reacting with NaOH and Phenolphthalein to produce the yellow color. Can anyone hazard a guess as to what this metal might be?