采用过氧化氢调节反应条件,在水热体系中合成了新型的勃姆石纳米管,经520℃焙烧2h后,晶型由AlOOH转化为γ-Al2O3;采用XRD、氮吸附、TEM等对合成的纳米管进行表征.结果表明,合成的γ-Al2O3纳米管长约300nm,外径20nm,比表面积达到230m2/g以上.以此为载体,采用等体积浸渍法用Cu(NO3)2溶液制备出不同Cu含量的催化剂Cu-nanotubes-w(w-质量分数),考察了Cu负载量、不同载体、O2体积分数以及SO2对CH4催化还原NO的影响.当Cu的负载量为7%时,其催化活性最佳,在600℃时NO转化率达90%;以γ-Al2O3纳米管为载体的催化剂比以传统的γ-Al2O3为载体的催化剂显示出更优越的低温(<500℃)催化活性;O2的体积分数小于0.25%时,其对NO的转化率影响很小,而当O2的体积分数高于0.25%时,反应则向有利于CH4转化的方向进行;Cu-nanotubes催化剂显示出了一定的抗硫性能.%A new type of tubular material, boehmite nanotube, was prepared by adjusting reaction condition with H2O2 in hydrothermal synthesis system. The nanotubes were characterized by XRD, nitrogen absorption and TEM etc. XRD results showed that the A1OOH nanotubes converted to 7-alumina nanotubes upon calcination at 520 ℃ for 2 h. The nanotubes were about 300 nm in length with outer diameter of 20 nm, as recorded on TEM. BET surface area of the ~γ-Al2O3 nanotubes was higher than 230 mVg. Γ-Al2O3 nanotubes were used as catalyst carriers by impregnating Cu(NO3)2 solution with different Cu content for the titled reaction. The influences of the amount of Cu, different carriers, O2 concentration and SO2 on the selective catalytic reduction of NO were studied. The results indicated that the ~γ-Al2O3 nanotubes loaded with 7% Cu possessed the highest activity which could reach 90% at 600 Xl; Further, the catalysts with nanotubes as carrier showed more active catalytic performance at low temperature (bellow 500 'C) than those non-nano scale carrier fabricated based on alumina. Oxygen at low concentration (less than 0. 25% (cp)) showed little effect on the conversion of NO while it improved the methane conversion when the concentration of O2 was higher than 0. 25% ; the Cu-nanotubes catalyst also showed sulfur-resistant property.
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