采用氨气还原法制备了 Na Y分子筛负载的 Mo Co/ Y、Mo Ni/ Y双组分氮化物催化剂 ,用 XRD和 EXAFS方法表征了样品的结构 ,并测定了其在 CH4+CO2 重整反应中的活性 .在氧化态时 ,Mo Co/ Y样品中主要存在Co Mo O4和 Co3O4两种物相 ,Mo的配位状态接近于 Co Mo O4,而 Co的配位状态更接近于 Co3O4.Mo Ni/ Y样品中主要有 Ni Mo O4和 Ni O两种物相 ,Mo的配位状态接近于 Ni Mo O4,而 Ni的配位状态可能是 Ni Mo O4和 Ni O两种化合物中 Ni配位状态的平均效果 .Ni- Mo之间的相互作用似乎比 Co- Mo相对较强 .在氮化态时 ,两种样品中Mo的配位状态较为相似 ,但既不同于 Mo O3,也不同于单组分 γ- Mo2 N.Co和 Ni的配位状态都不同于各自在氧化态下的状态 ,且都在相同的位置出现一个新强峰 .这似乎表明 Mo Co和 Mo Ni生成了结构相似的氮化物 .在CH4+CO2 重整反应中 ,氮化态 Mo Co/ Y和 Mo Ni/ Y的活性大大超过非负载单组分 γ- Mo2 N催化剂 .其中 Mo Ni/Y的活性相对更好一些 ,且活性随
The adsorption of NO on alumina supported Pd catalysts and the effect of adding Li 2O on NO adsorption have been investigated by using TPD MS method. Experimental results certify the existence of three types of surface species. The adsorptive dissociation of NO gives a relatively inactive intermediate N 2O. Its desorption amount is larger on Al 2O 3 and Pd/Al 2O 3 Li 2O than that on Pd/Al 2O 3. The adsorption intensity of N 2O is the strongest on Pd/Al 2O 3 Li 2O. The experiments of competitive adsorption of O 2 and NO reveal that the presence of O 2 has two effects: (1) the O atom sticks to the Pd site on the surface and inhibits the adsorption of NO, as well as the decomposition of NO; (2) O 2 can react with NO to form nitrite or nitrate species which can adsorb strongly on the surface. The relative efficiency of the two effects differs with temperature, and this can be applied to explain some phenomena in the adsorption of NO, and the selective catalytic reduction of NO as well.
The adsorption of CO2 and NO on supported Pd catalysts has been studied by using TPD-MS method and the adsorbed surface species were discussed based on literatures. The amount and intensity of basic sites increase when promoter Li is added, whereas the amount of basic sites decreases when Ce is added. It is found that there are three kinds of basic sites with different intensity on the catalyst surface. On sample Pd/Al2O3 and Pd/Al2O3-Li2O, large amount of CO desorption species is detected, this shows some CO2 on the surface being decomposed. There is no such effect on the sample Pd/Al2O3-CeO2. After analyzing the TPD profiles of NO adsorption on catalysts, it is found that both the NO desorption amount and the shapes of desorption peaks change remarkably when promoter Li or Ce is added. In the case of Li, the γ-peak （nitrate and nitrite species on surface） of NO desorption increases, the intermediate N2O desorbs at higher temperature. In the case of Ce, the α-peak （species on the Bronstesd acidic sites ） of NO desorption decreases, and N2O desorbs at lower temperature.
