Bergius-Rheinau process

On the basis of the above methods, two classes of industrial processes have been developed, namely the Bergius-Rheinau process, based on the use of concentrated hydrochloric acid at ordinary temperatures, and the Scholler-Tornesch process, in which very dilute sulfuric acid is used at temperatures of 170-180°C (338-356°F). The latter method in an improved form is known as the Madison process, based on work done at the U.S. Forest Products Laboratory in Madison, Wisconsin. A number of modifications have been developed, including four in Japan. 

Bergius-Rheinau Process. Hydrochloric acid of about 40 to 45 percent (by weight) is produced by reinforcing recovered, weaker acid with hydrogen chloride from salt-sulfuric acid reactors, or by burning chlorine with illuminating gas. 

In the Bergius-Rheinau process the concentrated hydrochloric acid employed requires dried wood, and recovery of the acid is essential. The process gives high yields of sugars (to 65%) at high concentrations. The intermediate sugars first obtained, however, call for an extra processing step to reduce them to monomers, before fermentation or crystallization. 

The dilute sulfuric acid employed in the Madison process gives lower yield (49-55%) of sugars than the Bergius-Rheinau process, and only very dilute solutions are obtained directly. Recovery of heat is easier in the Madison process, and the acid need not be recovered. 

Bergius-Rheinau A saccharification process in which wood is hydrolyzed with concentrated hydrochloric acid to produce sugars for subsequent fermentation to ethanol. 

Udic-Rheinau A process for making sugars from wood by hydrolysis with hydrochloric acid. Operated in Germany. See also Bergius (2). 

Bergins (1) A coal liquefaction process (also called hydroliquefaction) invented in Germany in 1913 by F. Bergius and subsequently developed by IG Farbenindustrie. The inventor, together with C. Bosch, was awarded the Nobel Prize for chemistry for this invention in 1931. A pilot plant was operated at Rheinau near... 

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