Since the discovery of ZSM-5 molecular sieves as a promising catalyst material, the synthesis of ZSM-5 has been investigated in great detail. In the first synthesis of ZSM-5,tetrapropylammonium(TPA) was used as the te...Since the discovery of ZSM-5 molecular sieves as a promising catalyst material, the synthesis of ZSM-5 has been investigated in great detail. In the first synthesis of ZSM-5,tetrapropylammonium(TPA) was used as the templating agent. However, the industrial manufacture and application of ZSM-5 molecular sieves arc limited because TPA, the templating agent, is expensive. In the attempt to search for a suitable substitute for TPA,展开更多
Nano hierarchical mesoporous ZSM-5 catalysts were prepared with cationic dimethyldiallyl ammonium chloride acrylamide copolymer（PDDA） as a soft second template. Using ZSM-5 catalyst as a matrix,Zn/ZSM-5 catalysts we...Nano hierarchical mesoporous ZSM-5 catalysts were prepared with cationic dimethyldiallyl ammonium chloride acrylamide copolymer（PDDA） as a soft second template. Using ZSM-5 catalyst as a matrix,Zn/ZSM-5 catalysts were also obtained by the wet impregnation method. The effect of the PDDA amount and Zn loadings on the properties of the catalysts,including crystallinity,morphology,textural properties,acid nature and catalytic activity in MTG reaction,was investigated by XRD,FESEM,TEM,Nitrogen adsorption–desorption isotherms and NH3-TPD method,respectively. The MTG reaction was performed in a fixed bed reactor,and the result revealed that the nano hierarchical ZSM-5 catalyst prepared with a PDDA/Si molar ratio of 0.070 possesses longer stable phase of 70 h with a liquid hydrocarbon selectivity of 29.8%.Zn/ZSM-5 catalyst with a Zn/ZSM-5 ratio of 0.07 wt.% shows the highest liquid hydrocarbon selectivity,reaching 62.5%.展开更多
Hierarchical ZSM-5 zeolite was hydrothermally synthesized by a novel silicone quaternary ammonium salt surfactant as a mesopore director.The crystallinity and the morphology of sample were characterized by X-ray diffr...Hierarchical ZSM-5 zeolite was hydrothermally synthesized by a novel silicone quaternary ammonium salt surfactant as a mesopore director.The crystallinity and the morphology of sample were characterized by X-ray diffraction(XRD),field-emission scanning electron microscope(FE-SEM),and transmission electronic microscope(TEM).Results indicated that the prepared ZSM-5 zeolites had good crystallinity,ellipsoid structure morphology and rough surface.Moreover,the pore size was enlarged to about 4 nm measured by nitrogen sorption,which indicated positive function of the synthesized template.展开更多
ZSM-5 zeolites with similar St/Al ratio were synthesized successfully using various templates [n- butylamine （BTA）, tetrapropylammonium bromide （TPABr） and no template （NT）] under hydrothermal conditions, The sa...ZSM-5 zeolites with similar St/Al ratio were synthesized successfully using various templates [n- butylamine （BTA）, tetrapropylammonium bromide （TPABr） and no template （NT）] under hydrothermal conditions, The samples were characterized by XRD, SEM, Py-IR and BET surface area measurements in order to understand the template eiTects and the differences between the ZSM-5 santples. The synthesis of ZSM-5 with organic templates was relatively easier than those with inorganic templates and withnut template. SEM results revealed that ZSM-5 synthesized with different templates had different morphologies in similar particle size. Toluene disproportiortation reaction was carried out over the catalyst samples to evaluate the catalytic properties. The results have shown that large crystals which have a correspondingly small external surface showed a high para-xylene selectivity, and the amount of C9^＋ and C5^＋ was much less than that obtained from zeolite with small crystals.展开更多
Syntheses of ZSM-5 zeolites from R-SiO2-Al2O3-H2O-HF(R = diethylamine and ethylenediamine, respectively) were investigated by using the hydrothermal crystallization. The large single crystals of ZSM-5 containing dieth...Syntheses of ZSM-5 zeolites from R-SiO2-Al2O3-H2O-HF(R = diethylamine and ethylenediamine, respectively) were investigated by using the hydrothermal crystallization. The large single crystals of ZSM-5 containing diethylamine and ethylenediamine were synthesized. The ZSM-5 precursors were characterized by means of X-ray powder diffraction, scanning electron microscopy, thermal analysis and electron microprobe analysis. The analysis result of aluminium distribution shows that the interior aluminium content of large crystals of ZSM-5 zeolites is rather low.展开更多
文摘Since the discovery of ZSM-5 molecular sieves as a promising catalyst material, the synthesis of ZSM-5 has been investigated in great detail. In the first synthesis of ZSM-5,tetrapropylammonium(TPA) was used as the templating agent. However, the industrial manufacture and application of ZSM-5 molecular sieves arc limited because TPA, the templating agent, is expensive. In the attempt to search for a suitable substitute for TPA,
基金supported by the National Natural Science Foundation of China (grant no.21201130)Foundation of State Key Laboratory of Coal Conversion,China (J14-15-603)+1 种基金China Scholarship Council (CSC no.:201406895017)Shanghai Education Commission Innovation Project (14YZ016)
文摘Nano hierarchical mesoporous ZSM-5 catalysts were prepared with cationic dimethyldiallyl ammonium chloride acrylamide copolymer（PDDA） as a soft second template. Using ZSM-5 catalyst as a matrix,Zn/ZSM-5 catalysts were also obtained by the wet impregnation method. The effect of the PDDA amount and Zn loadings on the properties of the catalysts,including crystallinity,morphology,textural properties,acid nature and catalytic activity in MTG reaction,was investigated by XRD,FESEM,TEM,Nitrogen adsorption–desorption isotherms and NH3-TPD method,respectively. The MTG reaction was performed in a fixed bed reactor,and the result revealed that the nano hierarchical ZSM-5 catalyst prepared with a PDDA/Si molar ratio of 0.070 possesses longer stable phase of 70 h with a liquid hydrocarbon selectivity of 29.8%.Zn/ZSM-5 catalyst with a Zn/ZSM-5 ratio of 0.07 wt.% shows the highest liquid hydrocarbon selectivity,reaching 62.5%.
基金National Natural Science Foundation of China(No.21676053)
文摘Hierarchical ZSM-5 zeolite was hydrothermally synthesized by a novel silicone quaternary ammonium salt surfactant as a mesopore director.The crystallinity and the morphology of sample were characterized by X-ray diffraction(XRD),field-emission scanning electron microscope(FE-SEM),and transmission electronic microscope(TEM).Results indicated that the prepared ZSM-5 zeolites had good crystallinity,ellipsoid structure morphology and rough surface.Moreover,the pore size was enlarged to about 4 nm measured by nitrogen sorption,which indicated positive function of the synthesized template.
文摘ZSM-5 zeolites with similar St/Al ratio were synthesized successfully using various templates [n- butylamine （BTA）, tetrapropylammonium bromide （TPABr） and no template （NT）] under hydrothermal conditions, The samples were characterized by XRD, SEM, Py-IR and BET surface area measurements in order to understand the template eiTects and the differences between the ZSM-5 santples. The synthesis of ZSM-5 with organic templates was relatively easier than those with inorganic templates and withnut template. SEM results revealed that ZSM-5 synthesized with different templates had different morphologies in similar particle size. Toluene disproportiortation reaction was carried out over the catalyst samples to evaluate the catalytic properties. The results have shown that large crystals which have a correspondingly small external surface showed a high para-xylene selectivity, and the amount of C9^＋ and C5^＋ was much less than that obtained from zeolite with small crystals.
文摘Syntheses of ZSM-5 zeolites from R-SiO2-Al2O3-H2O-HF(R = diethylamine and ethylenediamine, respectively) were investigated by using the hydrothermal crystallization. The large single crystals of ZSM-5 containing diethylamine and ethylenediamine were synthesized. The ZSM-5 precursors were characterized by means of X-ray powder diffraction, scanning electron microscopy, thermal analysis and electron microprobe analysis. The analysis result of aluminium distribution shows that the interior aluminium content of large crystals of ZSM-5 zeolites is rather low.
