担载羰基铂金属簇催化剂的研究—脱羰活化过程

INVESTIGATION ON SUPPORTED [Pt_3(CO)_6]_5 [N(C_2H_5)_4]_2 CATALYST-THE PROCESS OF ACTIVATION THROUGH DECARBONYLATION

用红外光谱(IR)及程序升温分解-质谱(TPDE-MS)联用技术研究了[Pt_3(CO)_6]_5[N(C_2H_5)_4]_2/Al_2O_3簇负载型催化剂的脱羰活化过程。IR结果表明,[Pt_3(CO)_6]_5^(2-)在真空中羰基随温度升高而脱除,180℃时脱除干净,其中线式羰基配位体的吸-脱附是可逆的,而桥式羰基配位体的吸-脱附是不可逆的。TPDE-MS结果表明,该络合物的分解基本可分为两部分,在140-220℃首先发生羰基脱除反应,随着温度的升高,在约220℃—410℃的范围内络合物的配体[N(C_2H_5)_4]^+也发生了分解。该络合物在H_2气流中的分解比在Ar气流中较易进行。经480℃氢还原处理后络合物羰基的脱除及配体的分解都已基本完成。

The decarbonylation of alumina supported[Pt_3(CO)_6]_5[N(C_2H_5)_4]_2 complex was investigated by infrared spectroscopy(IR),and temperature-programmed decomposition(TPDE)combined with mass spectroscopy(MS)(TPDE-MS).The IR Spectra showed that the decarbonylation of[Pt_3(CO)_6]_5^(2-)proceeded gradually under evacuation as the temperature in creused and was completed at 180℃.During the decarbonylation of the complex,the process of adsorption-desorption for the linearly coordinated ligands was reversible,but that for the bridging ligands was not.The TPDE-MS results indicated that the decomposition of[Pt_3(CO)_6]_5[N(C_2H_5)_4]_2 complex might be divided into two stages.Firstly the decarbonylation of the complex occurs at temperatures about 140-220℃ and secondly,the decomposition of[N(C_2H_5)_4]^+ ligand takes place at temperatures between 220℃ and 440℃.The experimental data also showed that the complex decomposes more easily in H_2 than in Ar.The decarbonylation of the complex and the decomposition of the ligand are almost complete at 480℃ in H_2