纳米钯金铁三金属催化剂的制备及其对三氯乙烯的降解

在乙醇-水体系中利用硼氢化物液相还原法合成纳米铁颗粒，通过化学沉淀法将钯金粒子负载于纳米铁表面，得到纳米钯金铁(Pd-Au@Fe)三金属催化剂复合材料，采用TEM, EDS和XPS对其进行表征. 结果表明，与纳米单金属Fe0及双金属Pd@Fe相比，三金属催化剂对三氯乙烯(TCE)具有更高的降解能力. 保持催化剂加量1.4 g/L, Pd/Fe为0.35%(w), Au/Fe为1.0%(w)时，其降解15 mg/L TCE的速度最快，5 min时去除率为88.21%，表观速率常数为0.311 min-1，是相同Pd含量下Pd@Fe双金属催化剂的3.6倍. 随降解反应持续，Pd-Au@Fe的乙烯乙烷生成率及乙烯加氢转换乙烷速率均远高于双金属Pd@Fe.

Preparation of Nanoscale Pd-Au@Fe Trimetallic Catalyst Particles for the Dechlorination of Trichloroethylene

Fe0 nanoparticles were prepared through liquid phase reduction by borohydride in ethanol-water solution, nanoscale Pd-Au@Fe trimetallic catalyst was synthesized by the reduction of Pd2+ and Au3+ with Fe0 nanoparticles. The structure and morphology of synthesized powder were characterized by TEM, EDS and XPS. The Pd-Au@Fe trimetallic catalyst showed the better reductive dechlorination property for trichloroethylene (TCE) than Fe0 monometallic and Pd@Fe bimetallic one. Keeping the dosage of mass ratio of Pd to Fe at constant (0.35%) and Au to Fe at 1.0%, the removal ability of the trimetallic catalyst was the highest. After reaction for 5 min, around 88.21% of 15 mg/L TCE was removed when the catalyst dosage was 1.4 g/L. The dechlorination rate constant was 0.311 min-1, which was 3.6 times of nanoscale Pd@Fe bimetal with the same loading rate. During the degradation reaction process, the generation rate of ethylene and ethane and hydrogenation conversion rate of ethylene to ethane by Pd-Au@Fe trimetallic catalyst are far higher than those by Pd@Fe bimetallic catalyst.