贵金属铱对氨分解用镍基催化剂的促进作用研究  

Promoting effects of iridium on nickel based catalyst in ammonia decomposition

作　　者：韩雪[1] 储伟[1] 倪平[1] 罗仕忠[1] 张涛[2] 

机构地区：[1]四川大学化学工程学院,四川成都610065 [2]中国科学院大连化学物理研究所,辽宁大连116023

出　　处：《燃料化学学报》2007年第6期691-695,共5页Journal of Fuel Chemistry and Technology

基　　金：国家自然科学基金重大项目(205903603);国家教育部新世纪优秀人才基金(NCET-05-0783)。

摘　　要：用湿式浸渍法制备了不同贵金属质量分数的镍-铱双金属催化剂,以氨分解为模型反应对其催化性能进行考察。结果表明,贵金属铱的添加提高了10%Ni/γ-Al2O3的低温活性。在铱的质量分数不高于1%时,氨分解反应活性随铱质量分数的增加出现最大值(相应的Ir质量分数为0.7%),对应的10%Ni-0.7%Ir/γ-Al2O3催化剂在400℃时,氨分解率为43.55%,较单组分的Ni催化剂高40.0%。用H2-TPR、H2-TPD、BET和XRD表征方法对催化剂进行了表征。结果表明,Ir与活性组分Ni之间存在协同作用。铱的添加促进了活性组分的分散、减小了镍的晶粒尺寸,且增加了催化剂活性位的数量,从而提高了催化剂的氨分解性能。Nickel-iridium bimetallic catalysts with different iridium contents were prepared by the wet impregnation method. Their catalytic performances in ammonia decomposition were investigated. The results illustrated that the activity of nickel catalyst in ammonia decomposition at low temperature (300 ℃ to 450 ℃) was significantly enhanced by adding iridium to the catalyst. A maximum ammonia conversion was observed with the iridium content being 0.7%. At 400 ℃, the ammonia conversion over 10%Ni-0.7%Ir/γ-Al2O3 catalyst was 43.55%, which was 40.0% higher than that on the corresponding catalyst without iridium. X-ray diffraction (XRD) suggested that the addition of iridium provided a better dispersion of active nickel species. Temperature programmed reduction (H2-TPR) profiles demonstrated that there was a synergetic effect between iridium and nickel, and adding iridium to the catalyst may reduce the interaction between the active species and support. Temperature programmed desorption (H2-TPD) indicated that 10%Ni-0.7%Ir/γ-Al2O3 catalyst had more active sites than the corresponding 10%Ni/γ-Al2O3.

关 键 词：贵金属铱 镍基催化剂 氨分解反应 低温活性 

分 类 号：TQ032.4[化学工程]