Back in Belgium, he devoted himself to illustration. He took part in the exhibition of contemporary lithography at the Bibliothèque royale of Brussels in 1931. Greuell moved permanently to Paris in 1932 where he exhibited at the Salon d’Automne and at the Salon des Tuileries. His work was exhibited abroad, including Philadelphia, Los Angeles, The Hague, Berne, Warsaw and Prague. He performed portraits of dancers, actresses, musicians, landscapes of Provence, Andalusia and Venice, as well as legendary scenes and chivalry.
Born in Wildbad, Belgium, and studied at the Académie des Beaux-Arts in Brussels from 1905 to 1909, then in Paris in 1913-1914, where he studied with Louis Anquetin.