一种新的高活性CO氧化催化剂Ag/SBA-15(英文)

A Novel Active Catalyst Ag/SBA-15 for CO Oxidation

以SBA15为载体,采用后修饰法制备了Ag/SBA15催化剂.XRD和TEM结果表明,金属Ag粒子均匀分散于SBA15的纳米孔道中,粒子平均大小为4～5nm.同时,负载金属Ag纳米粒子后,载体的介孔结构仍然能很好地保持.CO催化氧化测试结果表明,Ag/SBA15具有很高的催化活性,120℃时就能使CO完全氧化.而在富H2气氛下,80℃时CO的转化率达到最大值(48%),此时O2的选择性为28%.高温H2还原是活化Ag/SBA15的必要步骤.

Highly dispersed metal nanoparticles on an oxide support are widely used in industrial catalysis. Generally, the activity and selectivity of a nanoparticle catalyst are strongly dependent on its size, shape and surface structure. A typical example is gold catalyst in CO oxidation, which was first developed by Haruta＇s group. Following that work, more research has been carried out to reveal the active sites of the gold catalyst and to find a more economical catalyst for CO oxidation. Very recently, Ag nanoparticles supported on SiO2 were found to be very active in the selective oxidation of CO in the presence of H2 However, in the Ag/SiO2 system, the Ag particles are very large due to the severe aggregation that occurred during the high-temperature O2 treatment. A highly dispersed Ag nanoparticle catalyst has still not been found. In this work, we used the ordered mesoporous material SBA-15 as a support and prepared highly dispersed Ag particles confined in the nanochannels. The nanocatalyst Ag/SBA-15 was found to exhibit high activity for CO oxidation.