改性镍铝催化剂氧化零价汞及抗氨干扰机理

Hg^(0) oxidation of modified Ni-Al catalysts and its anti-ammonia interference mechanism

采用尿素水解法制备NiAlO和NiAlMO(M=Zn、Ba、Mn、La、Cr)催化剂用于Hg^(0)催化氧化研究.结果表明,在NH_(3)存在时,NiAlZnO催化剂展现出最好的Hg^(0)氧化活性,250℃时Hg^(0)的转化率超过80%,并在350℃达到最高(90%).Raman和XPS结果显示,Zn掺杂构成Ni-O-Zn固溶体,引起NiAlZnO催化剂的Jahn-Teller畸变,使催化剂产生大量的氧空位,促进O_(2)的活化,提高了催化剂的表面化学吸附氧含量.H_(2)-TPR和Hg^(0)-TPD结果表明,Zn的掺杂能提高催化剂的氧化还原性和Hg^(0)的吸附量,使催化剂在NH_(3)存在时依然保持高的Hg^(0)吸附性能.NH_(3)-TPD和NH_(3)-DRIFT证实Zn掺杂为催化剂引入新的Hg^(0)吸附位点(B酸位点).因此,NiAlZnO催化剂展现出优异的Hg^(0)氧化活性和抗NH_(3)干扰性能.

NiAlO and NiAlMO(M=Zn、Ba、Mn、La、Cr)catalysts were prepared to evaluate the efficiency of Hg^(0) oxidation of NiAlZnO catalyst using urea hydrolyzation,Raman and XPS experiments,etc.The results indicate that NiAlZnO catalyst exhibited the highest Hg^(0) oxidation activity in the presence of NH_(3) and the Hg^(0) oxidation efficiency of NiAlZnO catalyst was above 80%at 250℃and reached 90% at 350℃.Doping Zn enabled the NiAlZnO catalyst to form Ni-O-Zn solid solution and generate Jahn-Teller distortions which could increase the content of surface chemisorbed oxygen and promote the activation of O_(2),and thus increase the surface chemisorption oxygen content of catalyst.The incorporation of Zn could improve the redox and Hg^(0) adsorption performance of NiAlZnO catalyst,even in the presence of NH_(3).NH_(3)-TPD and NH_(3)-DRIFT experiments also proved that the addition of Zn introduced the new Hg^(0) adsorption site(B acid site)for NiAlZnO catalyst.Obviously,NiAlZnO catalyst can greatly promote Hg^(0) oxidation and possesses the resistance to NH_(3) interference.