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用X射线衍射线宽法测量了各种催化剂中镍的晶粒大小,发现稀土氧化物Y_2O_3,La_3O_3Sm_2O_3及Nd_2O_3对镍的分散作用都优于Al_2O_3,SiO_2,TiO_2,MgO及Cr_2O_3。稀土氧化物还可以抑制催化剂在升高温度时镍的晶粒长大,提高其稳定性。这几种催化剂的NiO晶界移动活化能的差异不大,说明稀土氧化物对镍的分散作用是因为载于其上的镍晶粒表面自由能较低,而表面自由能的降低是由于镍与稀土氧化物之间的强相互作用(SMSI)所致。X射线能谱表明这种SMSI的实质是载体原子或原子团向镍晶粒表面晶格转移造成的。
The grain size of nickel in various catalysts was measured by X-ray diffraction line width method. It was found that the dispersive effects of rare earth oxides Y_2O_3, La_3O_3Sm_2O_3 and Nd_2O_3 are better than that of Al_2O_3, SiO_2, TiO_2, MgO and Cr_2O_3. Rare earth oxides can also inhibit the catalyst at elevated temperature nickel grain growth, improve its stability. These catalysts have little difference in the activation energy of NiO grain boundaries, indicating that the dispersion of rare earth oxides on nickel is due to the lower surface free energy of the nickel grains carried thereon and the reduction of the surface free energy due to nickel Strong interaction with rare earth oxides (SMSI). X-ray spectroscopy shows that the essence of this SMSI is the lattice shift of the carrier atoms or radicals toward the surface of the nickel grains.