沉淀方式对沉淀法制备Co_3O_4催化N_2O直接分解性能的影响

以Co(NO_3)_2·6H_2O为钴源,K_2CO_3为沉淀剂,采用沉淀法制备Co_3O_4催化剂,用于催化N_2O直接分解反应。利用N_2~-物理吸附、XRD、FT-IR、TEM、TPR和ICP等对其进行表征,考察沉淀方式对Co_3O_4催化剂结构及其催化性能的影响。结果表明,沉淀方式对制备的Co_3O_4催化剂织构性质、物相组成和晶粒尺寸等影响不大,但显著影响其K残留量和还原性能,进而决定催化剂直接催化分解N_2O的催化性能。反加法制得的催化剂中K残留量为1.43%,明显高于正加法,同时催化剂中Co~(3+)较正加法更易还原,因而表现出更高的催化性能。在空速10 000 h~(-1)和N_2O体积分数0.1%的条件下,反加法制备的催化剂可在280℃催化N_2O完全分解,较正加法低20℃。

Effects of precipitation ways on direct decomposition of N2O over Co3O4 catalyst prepared by precipitation method

Using Co(NO₃)₂·6H₂O as the raw material and K₂CO₃ as the precipitant,Co₃O₄ catalysts were prepared by the precipitation method. The structure and properties of the catalysts were characterized by N₂-physisorption,XRD,FT-IR,TEM,TPR and ICP.The effect of precipitation ways on the catalytic performance of the catalysts for the direct decomposition of N₂O was investigated.The results showed that the precipitation ways had no influence on the textural properties,crystalline phases and particle sizes of Co₃O₄ catalyst,but significantly affected the amount of residual K and reducibility of Co₃O₄, which determined the catalytic performance of Co₃O₄ for direct decomposition of N₂O.The amount of residual K on Co-RP catalyst prepared by reverse mode was 1.43wt%,which was higher than that on Co-NP catalyst repared by forward mode.Simultaneously,it was much easier to regenerate the active site (Co²⁺) by donating electrons to Co³⁺ over Co-RP catalyst.Under the reaction condition of N₂O volume fraction 0.1% and space velocity 10 000 h^-1, Co-RP catalyst for direct decomposition of N₂O exhibited better catalytic activity,and the conversion of 100% was obtained at 280 ℃,which was lower 20 ℃ than that over Co-NP catalyst.