From 1901 to 1909 he was head of the laboratory at Leprince & Siveke, where conducted investigations of the properties of fats and oils. In 1901 Normann heard about
Paul Sabatier publishing an article, in which Sabatier stated that only with vaporizable organic compounds it is possible to bind
catalytic hydrogen to fluid tar oils. Normann investigated and disproved Sabatier's assertion. He was able to transform liquid
oleic acid into solid
stearic acid by the use of catalytic
hydrogenation with dispersed nickel. This was the precursor of
saturated fat hardening. On 27 February 1901 Normann invented what he called fat hardening, which was the process of producing saturated fats. On 14 August 1902 the German Imperial patent office granted patent 141,029 to the Leprince & Siveke Company, and on 21 January 1903 Normann was granted the British patent, . During the years 1905 to 1910 Normann built a fat hardening facility in the Herford company. In 1908 the patent was bought by
Joseph Crosfield & Sons Limited of
Warrington, England. From the autumn of 1909 hardened fat was being successfully produced in what in a large scale plant in Warrington. The initial year's production was nearly . When
Lever Brothers produced a rival process Crosfield took them to court over patent infringement, which Crosfield lost. From 1911 to 1922, Normann was scientific director of
Ölwerke Germania (Germania Oil Factory) in
Emmerich am Rhein, which was established by the Dutch
Jürgens company. From 1917, Normann built a fat hardening factory in
Antwerp for the
margarine company
SAPA Societe anonyme des grasses, huiles et produits africaines, which operated in
India. He served as technical director by order of the
Belgian Colonial Society. On 25 April 1920 he filed for German patent 407180
Verfahren zur Herstellung von gemischten Glyceriden (Procedure for the production of mixed glycerides), which was approved on 9 December 1924. On 26 June 1920 the
Firma Oelwerke Germania and Dr Wilhelm Normann filed for German patent 417215,
Verfahren zur Umesterung von Fettsaurestern. (Procedure for the transesterification of fatty esters), which was approved on 27 September 1925. From 1924 to 1927 Normann was a consultant for fat hardening facilities for foreign companies. On 30 October 1926 Normann and the Volkmar Haenig & Comp, Metallochemische Werk Rodlebe company filed for German patent 564894, for
Elektrisch beheizter Etagenroester (Electrically heated esters), approved 24 November 1932. On 14 May 1929 he applied for German patent 582266,
Verfahren zur Darstellung von Estern (Procedure for the representation of esters), which was approved on 11 August 1933. ==Personal life==