Study On Synthesis Of DME From Methanol In Slurry Reactor

In the present, the contradiction among resources environment, populationincreases, and economic development become acute. And China is rich in coaland lack in oil and gas, so it is important to find a new clean energy carrier fromour energy resources especially coal. Dimethyl ether (DME) has attracted moreattention as an alternative diesel fuel recently due to its high cetane number, lowNO_x emission, near-zero smoke and less engine noise. In our previous work, anovel preparation method named complete liquid-phase technology aimed forslurry catalysts was suggested. And hybrid catalyst which was prepared by thistechnology was used in the synthesis of DME from CO, The XRDcharacterization has found that boehmite but noγ-Al₂O₃ exists in these catalysts.For this reason, it is concluded that in these catalysts, the substance that plays arole in methanol dehydration is boehmite but notγ-Al₂O₃. So in this paper, weinvestigated methanol dehydration in slurry phase by using a slurry catalystprepared by the complete liquid-phase technology, and compared catalyticperformance of the slurry catalyst with that of commercialγ-Al₂O₃ andboehmite.The slurry catalysts were characterized by XRD, N₂ adsorption, NH₃-TPDand XPS and evaluated in the synthesis of dimethyl ether (DME) frommethanol in slurry reactor. The experimental results come to followingconclusions:(1) The main phase of slurry catalyst is boehmite, and it is a better methanoldehydration catalyst.The Activity of slurry catalyst correspond to that ofγ-Al₂O₃, but DME selectivity of the preceding is better.(2) The activity of slurry catalyst reach to the best after 6～12 days reaction, and it increases as reaction time is prolonging.(3) The results show thatγ-Al₂O₃ appears in catalyst after reaction, and theamount of it is increasing when reaction time is prolongecl. Soγ-Al₂O₃ isrelated to activity promotion.(4) Boehmite samdwich structure has no obvious change afterγ-Al₂O₃ appears.(5) Activity of catalyst is better when boehmite sol is well prepared, obviouslyproperty of moist sol affects catalitical activity.