Müller became a member of the executive committee in July 2011. His responsibilities included Environment Safety & Health Affairs, Innovation Excellence, and the Business Units Catalysis & Energy, Emulsions, Detergents & Intermediates, and Oil & Mining Services.
Until 31 March this year, he was a member of the managing board of Süd-Chemie AG Munich, Germany, a role he initially took up in 2007.