Located at the South Pole, the IceCube Neutrino Observatory is the world largest neutrino telescope, instrumenting one cubic kilometre of Antarctic ice at a depth between 1450m to 2450m. In 2013 IceCube reported the first observations of a diffuse astrophysical high-energy neutrino flux. Although in the meantime the collaboration has detected more than 50 high energy neutrino events, the origin of these neutrinos is still not identified. Blazars, a subclass of Active Galactic Nuclei and one of the most powerful classes of objects in the universe, have long been considered plausible sources of high energy neutrinos. This scenario can be examined using stacking methods testing the correlation between IceCube neutrinos and catalogs of hypothesized sources. Here the results of stacking analyses using three different blazar catalogs will be presented. The analyses are performed on 7 years of through-going muon data, recorded by IceCube between 2008 and 2015.