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固相合成高性能c轴导向的片状多级孔分子筛
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摘要
ZSM-5分子筛骨架中含有平行于b轴方向的直孔道和平行于a轴方向的正弦孔道~[1]。其中,直孔道和正弦孔道的长度对ZSM-5分子筛催化剂的传质和择形性有重要影响~[2]。本文首次在固相合成体系中,采用一步法成功制备出c轴定向生长的片状ZSM-5分子筛。经过XRD、SEM、N2吸附脱附等多种手段表征,表明产品的XRD图谱符合ZSM-5的特征峰,且结晶度高,存在介孔。本文通过调整尿素的添加量,可实现对晶体c轴长度的控制。较短b轴的片状ZSM-5分子筛催化剂有利于缩短客体分子的传质路径,减少积碳生成,从而提高催化剂反应寿命。甲醇制汽油(MTG)结果表明:片状多级孔ZSM-5表现出最佳的催化性能。该催化剂在甲醇质量空速(WHSV)为1 h~(-1)、反应温度370°C、纯甲醇进料的条件下,具有长达900h的反应寿命及63.8%的高汽油组分选择性。
ZSM-5 zeolite with excellent shape selectivity is widely used in methanol to gasoline(MTG) reaction around the world,due to its uniform micropore structure with sinusoidal channels in[100]and straight channels of in[010].Herein,hierarchical sheet-like ZSM-5 zeolites with controllable c-Axis length were developed under one-pot solvent-free route in the presence of urea.High crystallinity,long c-axis and short b-axis and hierarchical pores of ZSM-5 zeolites were synthesized successfully.Moreover,MTG reactions exhibited complete methanol conversion,high C_5~+ selectivity of 63.8%and long life time of 900 hrs at 370℃ with a methanol WHSV of 1.0 h~(-1).
引文
[1]Olson,D.H.;Kokotailo,G.T.;Lawton,S.L.;Meier,W.M.J.Phys,Chem.1981,85:2238.
    [2]Yan,Liu.;Xiaozhao,Zhou.;Xiangju,Meng.;Fengshou,Xiao.ChemCatChem.2013,5:1517

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