the present disclosure discloses an α - alumina carrier , comprising the elements of lanthanum and silicon both dispersed in the interior and on the surface of the carrier . the mass ratio of the element of lanthanum to the element of silicon is in the range from 0 . 1 : 1 to 20 : 1 . the inventors of the present disclosure have made extensive researches into the field of the silver catalyst and alumina carrier thereof , and added the elements of lanthanum and silicon in preparing the alumina carrier used in the silver catalyst . the carrier thus obtained contains the elements of silicon and lanthanum both in the interior and on the surface thereof , and has improved specific surface area and strength . the silver catalyst prepared with the carrier can react in a low reaction temperature and has a high selectivity in producing ethylene oxide through oxidation of ethylene .