Systems and methods for producing propylene using an MTBE synthesis raffinate are disclosed. An MTBE synthesis raffinate stream first passes through a molecular sieve to separate n-butane and isobutane from the rest of C4 hydrocarbons of the MTBE synthesis raffinate. The 1-butene in the rest of C4 hydrocarbons of the MTBE synthesis raffinate is then isomerized to form 2-butene. Therefore, the concentration of 2-butene in the subsequent propylene production process increases due to the separation of n-butane and isobutane and the isomerization of 1-butene, resulting in an improved reaction rate and reaction efficiency for propylene production.