The invention belongs to the technical field of
petrochemical engineering, relates to a method for preparing
epoxide in a homogeneous
system with low propylene using amount, and more specifically, relates to a method for synthesizing propylene
epoxide by using a first protonic
solvent and a second non-protonic
solvent as a mixed
solvent. An
active center is formed by the first protonic solvent, acatalyst and
hydrogen peroxide; the second non-protonic solvent can be miscible with the first protonic solvent, and the
solubility of propylene inside the mixed solvent is added; the reaction is carried out under the condition of homogeneous phase; propylene can be in contact with
hydrogen peroxide sufficiently, the
utilization rate of propylene and
hydrogen peroxide is improved, and the using amount of propylene and the
decomposition rate of
hydrogen peroxide are reduced. Simultaneously, the second non-protonic solvent has good
solubility for an
ether compound formed in the process of an epoxidation reaction, the catalyst deactivation caused by the blockage of a catalyst pore passage can be reduced, and the stable
operation time of the catalyst is prolonged effectively. Moreover, the second non-protonic solvent is introduced, the proportion of the first protonic solvent in the
system is reduced, the
ether byproduct generated in further reaction of propylene
epoxide and the first protonic solvent can be reduced, and the yield and selectivity of propylene epoxide are improved. The method has the characteristics of simple process
route, low propylene using amount, high propylene epoxide yield and selectivity and the like, and the catalyst is unlikely to inactivate.