Epoxidation Of Propylene Over Modified TS-1 Zeolite Catalysts In Fixed-bed Reactor

In this article,the micro-TS-1 is modified by dilute tetrapropylammonium hydroxide (TPAOH)aqueous solution.The effect of modification conditions on the catalytic properties of TS-1 samples is investigated,including modification time,modification temperature and the ratio of micro-TS-1 and modification agent.The activity of the TS-1 samples is evaluated by using epoxidation of propylene as the test reaction.Then the reaction conditions such as temperature,space velocity of propylene,concentration of H₂O₂,concentration of ammonia, length/diameter radio(L/D radio)of the catalyst bed,particle size of the catalyst are optimized.A 1500 h reaction shows that the strip TS-1 modified by TPAOH exhibited good stability in epoxidation of propylene.Finally,we use an accelerated decay reaction in lab to simulate the coking process of PO to obtain the deactivated strip TS-1 catalyst.With the deactivated strip TS-1 catalyst used as research objects,the effect of dilute H₂O₂ regeneration on the catalytic performance of deactivated catalysts is studied.The conclusions are gained as follows:(1)The optimal modification conditions of TPAOH are as follows:100 g TS-1:100 ml TPAOH aqueous solution(0.05 mol/l),modification temperature 170℃,modification time 48h.(2)The suitable reaction conditions are as follows:reaction temperature 45℃,space velocity of propylene 0.6 h(-1),concentration of H₂O₂ 1.1 mol/l,concentration of ammonia 0.4 mmol/l,length/diameter radio(L/D radio)of the catalyst bed 11,particle size of the catalyst 1 mm×1 mm.(3)Dilute H₂O₂ regeneration reaction conditions are as follows:regeneration temperature 80℃,washed by CH₃OH,6 h,1.5%H₂O₂ wash 12 h,washed by reaction liquid(containing 4 mmol/l NH₄OH),1 h.The activity of the regenerated catalyst can be recovered basically, but the stability of the regenerated catalyst is lower than the fresh catalyst.