| 释义 |
Raschig|ˈrɑːʃɪg, -æ-|
Also (rare) raschig.
Chem. Engin. The name of Friedrich Raschig (1863–1928), German chemist, used attrib. († or in the possessive), as Raschig process, a process developed by workers in Raschig's chemicals company in which phenol is produced by heating benzene vapour with hydrogen chloride and air over a copper-containing catalyst to yield chlorobenzene, which is then hydrolysed to form phenol; Raschig ring, a small cylindrical ring, introduced by Raschig, made of ceramic or other suitable material and used in bulk as a packing material in towers and columns for fractionation, solvent extraction, etc.
1920Chem. Abstr. XIV. 2054 Attention is directed to the advantages attained by the use of Raschig's rings as a filling material for absorption towers in the manuf. of H2SO4, HNO3, HCl, etc. 1926Ibid. XX. 2214 Raschig rings have been used advantageously for clearing of liquids, the turbid liquor being run in at the bottom of a 80-cm. layer of rings, 15 × 15 mm. 1937Discovery Sept. 282/2 Another form of acetifier contains raschig rings. 1940Chem. & Engin. News 10 Nov. 921/1 The unit, which has been in continuous operation for four months.., employs the Raschig process, a catalytic vapor-phase system for the chlorination of benzene and the hydrolysis of the chlorobenzene produced. The process, invented by Prahl and Mathes of the Raschig organization, Ludwigshafen, Germany, produces a phenol purer than U.S.P. and does so with less than 0·1 per cent of by-product. 1947Kirk & Othmer Encycl. Chem. Technol. I. 16 Raschig rings have the greatest number of applications because they provide a large effective surface of contact between the gas and the liquid phases and they have a large free volume. They are available in sizes from 1/4 to 6 in., and the usual design has a height equal to the diameter. 1959R. J. Hengstebeck Petroleum Processing xi. 265 Modern furfural extraction columns contain about 40 to 50 ft of Raschig rings, with redistribution equipment at about 5-ft intervals. 1963Economist 14 Dec. 1193/3 The ICI plant uses the Raschig process. 1972Materials & Technol. IV. viii. 309 A modification of the Dow process is the Raschig process, in which benzene is chlorinated by Cl2 generated by the catalytic oxidation of HCl with oxygen at 230° C, and HCl is recovered in the hydrolysis at 425° C, promoted by Cu catalyst without alkali. |