Catalysts for the lower temperature WGS reaction are commonly based on copper or copper oxide loaded ceramic phases, While the most common supports include alumina or alumina with zinc oxide, other supports may include rare earth oxides, spinels or perovskites.  A typical composition of a commercial LTS catalyst has been reported as 32-33% CuO, 34-53% ZnO, 15-33% AlO. The active catalytic species is CuO. The function of ZnO  is to provide structural support as well as prevent the poisoning of copper by sulfur. The AlO prevents dispersion and pellet shrinkage.  The LTS shift reactor operates at a range of 200–250 °C. The upper temperature limit is due to the susceptibility of copper to thermal sintering. These lower temperatures also reduce the occurrence of side reactions that are observed in the case of the HTS.  Noble metals such as platinum, supported on ceria, have also been used for LTS.