The invention provides a preparation method of a Cu / SiO2 catalyst modified by Na salt and application of the preparation method. The catalyst obtained by the preparation method can significantly improve the selectivity of
cyclopropane in propylene epoxidation reaction, and the catalyst cost is low. The preparation method comprises the following steps that (1) a carrier is acidified, specifically,SiO2 is placed into an inorganic acid
aqueous solution, condensing and refluxing are conducted for 6-48 h, then filtering and washing are conducted to be neutral, and
drying is conducted; (2) a Cu / SiO2 sample is prepared, specifically, a precursor compound of Cu is dissolved in water, the acidified SiO2
solid is added, stirred and mixed, then a precipitant
aqueous solution is added dropwise into the mixture, a mixed
system is subjected to
precipitation reaction at 70-130 DEG C, the obtain
solid sample is washed to be neutral, and the Cu / SiO2 sample is obtained after
drying; and (3) the Cu / SiO2sample is placed into an
aqueous solution of a Na salt
accelerant, stirring is conducted for 0.5-5 h at 20-60 DEG C, then evaporating is conducted to be dry, and then
drying is conducted.