氨浓度对氨蒸发法制备Pd-Cu/凹凸棒土催化剂常温CO氧化性能的影响

Effect of ammonia concentration on the catalytic activity of Pd-Cu supported on attapulgite clay prepared by ammonia evaporation in CO oxidation at room temperature

以凹凸棒土(APT)作载体,采用氨蒸发法制备了Pd-Cu/APT催化剂,以CO氧化为探针反应,在连续流动微反应装置上,考察了初始氨浓度对催化剂CO常温催化氧化性能的影响。通过N2-physisorption、XRD、FT-IR、TEM和H2-TPR等手段对催化剂的结构和性质进行了表征。结果表明,在较低或过高氨浓度条件下,制备的PdCu/APT中Cu物种均主要以Cu O为主,仅有少量Cu2(OH)3Cl;适宜的氨浓度有利于稳定Cu2(OH)3Cl物相的形成,其薄片状的形貌特征、良好的分散状态以及与Pd物种间较强的相互作用,显著提高了CO催化氧化性能。在空速6 000 h-1、CO体积分数1.5%、水蒸气体积分数3.3%的反应条件下,Pd-Cu/APT催化剂表现出优异的CO室温催化氧化活性和稳定性。

With attapulgite clay（ APT） as support,the Pd-Cu / APT catalysts were prepared by an ammonia evaporation method and characterized by N2-physisorption,XRD,FT-IR,TEM and H2-TPR. The effect of ammonia concentration on the catalytic performance of Pd-Cu / APT in CO oxidation at room temperature was investigated in a fixed-bed continuous flowmicroreactor. The results showed that Cu O appears as the main Cu species in the Pd-Cu / APT catalysts prepared with over lowor over high ammonia concentration,whereas the quantity of Cu2（ OH）3Cl phase is much less. However,a proper concentration of ammonia is of benefits to forming stable Cu2（ OH）3Cl species in Pd-Cu /APT; owing to its high dispersion,nano-platelet morphology and strong interaction with Pd species,the presence of stable Cu2（ OH）3Cl can significantly promote the catalytic performance of Pd-Cu / APT in CO oxidation. Under a gas hourly space velocity（ GHSV） of 6 000 h- 1for a feed stream containing1. 5% CO and 3. 3% water,the Pd-Cu / APT catalyst exhibits excellent activity and stability in CO oxidation even at room temperature.