物理化学学报 >> 1994, Vol. 10 >> Issue (08): 710-715.doi: 10.3866/PKU.WHXB19940808

研究论文 上一篇    下一篇

Pt羰基簇合物在NaY内的合成机理

李光进, 郭燮贤, 藤本俊幸, 市川胜   

  1. 中国科学院大连化学物理研究所催化基础国家重点实验室,大连 116023|日本北海道大学触媒化学研究中心,札幌 060,日本
  • 收稿日期:1993-04-03 修回日期:1993-08-26 发布日期:1994-08-15
  • 通讯作者: 李光进

Mechanismic Study of the Synthesis of Intrazeolite Pt Carbonyl Clusters

Li Guang-Jin, Guo Xie-Xian, Fujimoto Toshiyuki, Ichikawa Masaru   

  1. State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chenese Academy of Sciences, Dalian 116023|Catalysis Research Center, Hokkaido University, Sapporo 060, Japan
  • Received:1993-04-03 Revised:1993-08-26 Published:1994-08-15
  • Contact: Li Guang-Jin

摘要:

利用IR,EXAFS, ~(13)CO同位素交换反应及与NO作用等手段研究了Pt羰基簇合物[Pt_3(CO)_6]~(2-)_n(n=3,4)在NaY分子筛超笼内的合成机理.在氧化样品Pt~(2+)/NaY上300-373 K的还愿羰基化过程中,首先Pt~(2+)与CO反应生成PtO(CO)物种(波数σ_(CO)=2110 cm~(-1)),然后聚集成“Pt_3(CO)_6”(σ_(CO)=2112,1896和1841 cm~(-1)),最后生成深绿色的Pt羰基簇合物Pt_(12)(CO)_(24)]~(2-)/NaY(σ_(CO)=2080,1824 cm~(-1)).“Pt_3(CO)_6”的羰基在室温下能迅速地与~(13)CO发生交换,而[Pt_3(CO)_6]~(2-)_n(n=3,4)的羰基与~(13)CO的同位素交换即使在343 K也进行得很慢,室温下,NO能逐步破坏Pt羰基簇合物的层间和层内Pt-Pt键,得到中间物种“Pt_3(CO)_6”和PtO(CO),同时在气相产生CO_2和N_2O.而由上述两中间物种出发,300-353 K温度下,在CO气氛中的还原羰基化又能可逆地得到原羰基簇合物.

关键词: 分子筛, 铂, 羰基簇合物, 13CO交换反应, EXAFS

Abstract:

The mechanism of the synthesis of platinum carbonyl clusters [Pt_3(CO)_6]~(2-)_n(n=3,4) in cages of NaY was studied by IR, EXAFS ~(13)CO exchange reaction and No interaction. The results suggest that oaldized Pt species in NaY cages reacts with CO at 300-373 K to form PtO(CO) (σ_(CO)=2110 cm~(-1)) which aggregates into "Pt_3(CO)_6"(σ_(CO)=2112, 1896 and 1841 cm~(-1)) and eventually converts into dark-green carbonyl cluster [Pt_(12)(CO)_(24)]~(2-). The carbonyl "Pt_3(CO)_6" can exchange with ~(13)CO very quickly at 298 K but the exchange reaction between ~(13)CO and intrazeolite Pt carbonyl clusters [Pt_3(CO)_6]~(2-)_n (n=3,4) proceeds slowly even at enhanced temperature such as 343 K. It is interesting to find that NO breaks successively the intra and inter-trigonal Pt-Pt bonds of the Pt_(12) carbonyl clusters (even at 298 K) and the "Pt_3(C)_6" formed is further reacted to give PtO(CO) with the formation of N_2O and CO_2 in the gas phase. Pt_(12)(CO)_(24)]~(2-) can be reversibly regenerated from the Pt subcarbonyls such as PtO(CO) and "Pt_3(CO)_6" inside NaY by reacting wich CO at 300—353 K.

Key words: Zeolites, Pt, Carbonyl clusters, 13CO exchange, EXAFS