Au-Pd/ZrO2双金属纳米催化剂光催化Ullmann偶联反应

摘要

Zirconia supported bimetallic gold-palladium photocatalysts were prepared through sodium borohydride reduction. The prepared samples were characterized by means of XRD,TEM, UV-Visible diffuse reflectance spectrum(UV-Vis DRS) and ICP-MS. Under visible-light irradiation, the optimal reaction conditions of the Ullmann coupling reaction of bromobenzene to diphenyl were studied. It was indicated that,the introduction of both Au and Pd had little effect on the structure of the ZrO2 support,and Au and Pd were dispersed on ZrO2 in the form of spherical particles with the particle size of less than 8 nm. Under the optimal conditions of visible light irradiation with the intensity of 1.7×10-2 W/cm2,reaction time 3 h,reaction temperature (35±3)℃ and 5 mL isopropyl alcohol as solvent,50 mg Au-Pd/ZrO2 as catalyst(w(Au) +w(Pd) 3％ andm(Au):m(Pd) 2:1) and 1.0 mmol KOH as alkali,the yield of biphenyl could reach 98.0％.%采用NaBH4还原法制备了Au-Pd/ZrO2双金属纳米催化剂.采用XRD,UV-Vis DRS,TEM,XPS,ICP-MS等手段对催化剂试样进行了表征.在温和条件下通过可见光照射,探索了该催化剂对溴苯Ullmann偶联反应的适宜条件.表征结果显示,Au和Pd的引入对载体ZrO2的结构几乎没有影响,Au和Pd以球形颗粒分散在ZrO2载体上,粒径均小于8 nm.实验结果表明,在可见光照射下,反应时间3 h、反应温度(35±3)℃、5.0 mL异丙醇为溶剂、50 mg Au-Pd/ZrO2为催化剂(w(Au)+w(Pd)=3％且m(Au):m(Pd)=2:1)、1.0 mmol KOH为碱、光强1.7×10-2 W/cm2的条件下,溴苯Ullmann偶联反应效果最佳,联苯产率可达98.0％.