A natural CXN zeolite (stilbite, type code-STI) discovered in China was modified with +4NH exchange by using ammonium salt and calcinations (procedure I), or with +4NH exchange followed by treatment with acid (procedu...A natural CXN zeolite (stilbite, type code-STI) discovered in China was modified with +4NH exchange by using ammonium salt and calcinations (procedure I), or with +4NH exchange followed by treatment with acid (procedure II). The coordination state of Si and Al atoms in the framework, the property of ion exchange, and the adsorption of the H-STI zeolite samples prepared by different modification procedure were investigated with XRD, EDX, 29Si and 27Al MAS NMR, Ag+ ion exchange and N2 adsorption. The results of the investigations indicate that different procedure of the modification made variety on the distribution of the framework Si atoms and Al atoms, the content of non-framework aluminum, and the blocking channels and the shielding effect to the positions of the exchangeable cations. The H-STI zeolite prepared by the procedure II possesses high ion exchange capacity, open and perfect pore system, and high thermal stability.展开更多
采用离子交换和焙烧等方法,对我国CXN天然沸石(STI型)进行改性.应用化学分析,粉末XRD,TG/DTA,^(27)Al MAS NMR,^(29)Si MAS NMR,低温N_2吸附等方法表征相关的结构、离子交换等性质.CXN沸石的晶胞组成Na_(0.2)Mg_(0.1)Ca_(8.4)[Al_(17.2)...采用离子交换和焙烧等方法,对我国CXN天然沸石(STI型)进行改性.应用化学分析,粉末XRD,TG/DTA,^(27)Al MAS NMR,^(29)Si MAS NMR,低温N_2吸附等方法表征相关的结构、离子交换等性质.CXN沸石的晶胞组成Na_(0.2)Mg_(0.1)Ca_(8.4)[Al_(17.2)Si_(54.8)O_(144)]·65H_2O,属富钙型.经离子交换脱出Ca^(2+)后的沸石在焙烧过程中伴随有骨架脱铝,骨架的热稳定性已由原样的500℃以下提高到700℃以上.交换改性后的沸石,呈现反映该沸石微孔特性的Ⅰ型氮吸附等温线.展开更多
文摘A natural CXN zeolite (stilbite, type code-STI) discovered in China was modified with +4NH exchange by using ammonium salt and calcinations (procedure I), or with +4NH exchange followed by treatment with acid (procedure II). The coordination state of Si and Al atoms in the framework, the property of ion exchange, and the adsorption of the H-STI zeolite samples prepared by different modification procedure were investigated with XRD, EDX, 29Si and 27Al MAS NMR, Ag+ ion exchange and N2 adsorption. The results of the investigations indicate that different procedure of the modification made variety on the distribution of the framework Si atoms and Al atoms, the content of non-framework aluminum, and the blocking channels and the shielding effect to the positions of the exchangeable cations. The H-STI zeolite prepared by the procedure II possesses high ion exchange capacity, open and perfect pore system, and high thermal stability.
文摘采用离子交换和焙烧等方法,对我国CXN天然沸石(STI型)进行改性.应用化学分析,粉末XRD,TG/DTA,^(27)Al MAS NMR,^(29)Si MAS NMR,低温N_2吸附等方法表征相关的结构、离子交换等性质.CXN沸石的晶胞组成Na_(0.2)Mg_(0.1)Ca_(8.4)[Al_(17.2)Si_(54.8)O_(144)]·65H_2O,属富钙型.经离子交换脱出Ca^(2+)后的沸石在焙烧过程中伴随有骨架脱铝,骨架的热稳定性已由原样的500℃以下提高到700℃以上.交换改性后的沸石,呈现反映该沸石微孔特性的Ⅰ型氮吸附等温线.
