Born May 13, 1904, in Bremen. German chemist. Academician of the Academy of Sciences of the German Democratic Republic (1953). Member of the Socialist Unity Party of Germany (SED) from 1946.
Rienäcker studied at the University of Munich from 1922 to 1926. In 1936 he was appointed an extraordinary professor at the University of Göttingen. In 1942 he became a professor at Rostock University and was also named director of the university’s Institute of Inorganic Chemistry. From 1951 to 1969 he served as director of the Institute of Inorganic Catalysis, and from 1957 to 1968, as general secretary of the Academy of Sciences of the German Democratic Republic (GDR). Rienäcker was a member of the Central Committee of the SED between 1958 and 1963. In 1969 he became research director at the Central Institute of Physical Chemistry of the Academy of Sciences of the GDR.
Rienäcker has specialized in inorganic catalysis; much of his research has dealt with the mechanism of catalytic processes on metals and mixed oxides and with new methods of preparing catalysts. Rienäcker carried out a number of studies on the intensification of industrial catalytic processes. He has received the National Prize of the GDR (1955); he is a foreign member of the Academy of Sciences of the USSR (1966).