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用尿素-硝酸盐燃烧法制备了一系列的负载于HZSM-5上的CuO-ZnO-Al2O3纳米复合材料(CZA/HZSM-5)。研究了燃料与氧化物的比率对所合成的复合材料的理化性质的影响。用TGA/DTG,FTIR和XRD等研究了尿素-硝酸盐凝胶的热分解和煅烧粉体的相演变过程。FESEM结果表明在燃烧过程中燃料的用量对CZA/HZSM-5的性质有重大影响。CuO和ZnO的晶粒首先随尿素量的增加而增大,然后随尿素量的增加而减小。CuO和ZnO的相对结晶度随燃料量的增加表现为非单调趋势。随着燃料与硝酸盐的比率的增加,CZA/HZSM-5不仅形貌变得超细和均一,而且表面孔隙率也显著增加。FTIR结果表明HZSM-5的结构甚至在负载了CuO-ZnO-Al2O3纳米粒子后也未被破坏,而且在CuO和ZnO与HZSM-5之间还有表面的键合。TGA/DTG结果指出燃烧合成法是一种由若干过程组合起来的方法,例如前驱体的热分解和前驱体间的放热反应等。另外,提出了CuO-ZnO-Al2O3负载在HZSM-5上的生成机理。
A series of CuO-ZnO-Al2O3 nanocomposites (CZA / HZSM-5) supported on HZSM-5 were prepared by urea-nitrate combustion. The effect of the ratio of fuel to oxide on the physico-chemical properties of the composites was investigated. The thermal decomposition of urea-nitrate gel and the phase evolution of the calcined powder were investigated by TGA / DTG, FTIR and XRD. FESEM results show that the amount of fuel used during combustion has a significant effect on the properties of CZA / HZSM-5. The crystal grains of CuO and ZnO firstly increased with the increase of urea amount, then decreased with the increase of urea amount. The relative crystallinity of CuO and ZnO showed a non-monotonic trend with the increase of the amount of fuel. As the ratio of fuel to nitrate increased, CZA / HZSM-5 not only became ultrafine and uniform in morphology but also significantly increased surface porosity. The FTIR results showed that the structure of HZSM-5 was not destroyed even after loading CuO-ZnO-Al2O3 nanoparticles, and there was also surface bonding between CuO and ZnO and HZSM-5. TGA / DTG results indicate that combustion synthesis is a combination of several processes, such as thermal decomposition of precursor and exothermic reaction between precursors. In addition, the mechanism of CuO-ZnO-Al2O3 loading on HZSM-5 was proposed.