Preparation, Modification Of Ag/TS-1 And Its Catalytic Properties On The Gas-Phase Epoxidation Of Propylene

Propylene oxide (PO) is a kind of very important chemical feedstock in organic chemicalengineering. It is widely used for the producing of polyurethane, surfactant and resins. Today,propylene oxide is mainly manufactured via chlorohydr in process or Halcon process. However,the pollutions to the environments in the former process and high investments & lots ofby-products in the latter are the main drawbacks of the two industrial processes. Gas phasepropylene epoxidation for the production of PO attracts much interest for its friendly to theenvironments and mild operation conditions.In this article, gas-phase propylene epoxidation with hydrogen and air feed stock catalyzed byAg/TS-1 prepared by deposition- precipitation method with KOH or NaOH is investigated. Firstthe Ag/TS-1 is synthesized by different precipitators like K₂CO₃ (aq), KOH, NaOH, et. al. Theeffect of different precipiators on the gas-phase propylene epoxidation over Ag/TS-1,Effect ofprecipitator(KOH) concentration and Ag loading on the gas-phase propylene epoxidation overAg/TS-1 is discussed. Second, Ag/TS-1 is synthesized by precipitator of NaOH(aq),then modifiedby alkali metals carbonate like K₂CO₃, Rb₂CO₃, Cs₂CO₃. The effect of different alkali metals on thegas-phase propylene epoxidation over Ag/TS-1 is discussed too. Furthermore the effectual silverspecies is discussed in this article. The conclusions is gained as follow:First: Alkali KOH and NaOH are good precipitators for preparation of Ag/TS-1 catalyst. Thegas-phase propylene epoxidation over Ag/TS-1 with KOH as precipitator is better than NaOH andK₂CO₃. It represent a good stability.Second: Ag loading is important to the gas-phase propylene epoxidation over Ag/TS-1 withKOH as precipitator. When the Ag loading is 1 wtï¼…, the reactive outcome is best.Third: Precipitator concentration is important to the gas-phase propylene epoxidation overAg/TS-1 with KOH as precipitator. When the precipitator concentration is 0.05mol/L, the reactiveoutcome is best.Last: Ag/TS-1 is synthesized by precipitator of NaOH(aq), then modified by alkali metalscarbonate like K₂CO₃, Rb₂CO₃,Cs₂CO₃. The stability of gas-phase propylene epoxidation ismeliorative, especially K₂CO₃ is the best modifier.