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本文着重考察了在相同条件下用不同有机胺合成DG分子筛的物化性质和催化反应性能。实验表明,用不同胺合成的DG分子筛均为ZSM-5型分子筛。用它们制成HDG催化剂后,用于甲苯歧化、间二甲苯异构化及烷烃裂化反应时均具有择形催化性能。除二乙胺合成的DG分子筛外,其它DG分子筛用于甲苯歧化反应均具有选择地生成对二甲苯的性能;各种DG分子筛对于甲苯歧化和间二甲苯异构化反应均有抑制二甲苯歧化生成三甲苯的能力;对于正己烷和3-甲基戊烷混合物裂化反应则是优先裂解正己烷。在合成DG分子筛时,原料中SiO_2和Al_2O_3分子比不同,生成分子筛的SiO_2/Al_2O_3及物化性质和催化性能也不同。随着SiO_2/Al_2O_3降低,分子筛的憎水性能和选择吸附对二甲苯的性能降低。用于甲苯歧化反应时,催化剂活性增加,而选择性、歧化率降低。此外随着SiO_2/Al_2O_3降低,催化剂总酸度和强酸中心数目增加,另一方面DG分子筛SiO_2/Al_2O_3变化对其晶体结构特性,如骨架密度等影响不大。
In this paper, the physicochemical properties and catalytic properties of DG zeolites synthesized with different organic amines under the same conditions were investigated emphatically. Experiments show that, with different amine synthesis of DG molecular sieves are ZSM-5 zeolite. After they are used to make HDG catalyst, they have the shape-selective catalytic properties for toluene disproportionation, m-xylene isomerization and alkane cracking. In addition to the DG molecular sieve synthesized by diethylamine, other DG molecular sieve used in the toluene disproportionation reaction can selectively generate p-xylene performance; all kinds of DG zeolite toluene disproportionation and m-xylene isomerization reaction are inhibited disproportionated xylene The ability to generate trimethylbenzene; the cracking of n-hexane and 3-methylpentane blends preferentially cleave n-hexane. In the synthesis of DG molecular sieve, the raw materials in different molecular ratio of SiO_2 and Al_2O_3, the molecular sieve generated SiO_2 / Al_2O_3 and the physical and chemical properties and catalytic performance are also different. With the decrease of SiO 2 / Al 2 O 3, the hydrophobic property of the molecular sieve and the selectivity of p-xylene decreased. For the toluene disproportionation reaction, the catalyst activity increases, while the selectivity, disproportionation rate decreases. In addition, with the decrease of SiO 2 / Al 2 O 3, the total acidity and the number of strong acid sites in the catalyst increased. On the other hand, the change of the molecular structure of SiO 2 / Al 2 O 3 did not affect the crystal structure, such as the skeleton density.