Previously, SDSS had spectroscopically confirmed over half a million quasars with redshifts comprised between z=0.1 and z=6.5. Data Release 14 contains about 150,000 new quasars with 0.9 < z < 3.5. In addition, about 70,000 quasars have now multi-epoch spectroscopy available. The SDSS-DR14 quasar catalog (DR14Q) contains all quasars observed as part of SDSS-I/II/III/IV, based on a refined automated procedure to identify quasars, and a partial visual inspection of spectra of the remaining objects. Spectroscopic measurements, such as refined redshift, automated broad absorption line (BAL) detection or emission-line fits, and multi-wavelength photometric information are all included in DR14Q.
We recommend that you use the DR14 quasar catalog, as this catalog is the most recent one available. Previously released SDSS quasar catalogs are still available on the SAS, and are described in Pâris et al. (2017) for DR12, in Pâris et al. (2014) for DR10, and Pâris et al. (2012) for DR9. Corresponding data models for the quasar catalogs can be found here.