| Number | Name | Date | Kind |
|---|---|---|---|
| 2589674 | Cook et al. | Mar 1952 | |
| 3577528 | Yonkers et al. | May 1971 | |
| 3697452 | Olson et al. | Oct 1972 | |
| 3755559 | Hewitt et al. | Aug 1973 | |
| 3849348 | Hewitt et al. | Nov 1974 | |
| 3959461 | Bailey et al. | May 1976 | |
| 4012398 | Conner et al. | Mar 1977 | |
| 4183917 | Iwao et al. | Jan 1980 | |
| 4252695 | Homma et al. | Feb 1981 | |
| 4592907 | Akimoto et al. | Jun 1986 | |
| 4673568 | Grollier et al. | Jun 1987 | |
| 4726945 | Patel et al. | Feb 1988 |
| Entry |
|---|
| Kirk-Othmer Encyclopedia of Chemical Technology, 3rd Ed, vol. 19, pp. 521-531, 1982. |