Tetrahydrofuran from Caustic-Washed Furan Hydrogenated over Nickel on Kieselguhr (Banford and Manes, du Pont, US 2,846,449)

Furan from furfural carries a little carbon dioxide and water that distilling does not remove, and they hold back the hydrogenation. Banford and Manes washed the furan with dilute potash first; then nickel on kieselguhr turned nearly all of it into tetrahydrofuran. Result: tetrahydrofuran, conversion raised from 85-90 % to 97 %. Source: Banford and Manes, US 2,846,449 (du Pont, 1958), Example 1. Not given: how the THF is drawn off. Picture drawn by Youblob.