催化化学课件英文版2

固体催化剂的研究方法
Ⅱ 催化反应的动态监测技术
申 文 杰
2003. 1. 14
催 化 反 应 化 学 课 题 组
Catalytic Reaction Chemistry Group
多相催化研究方法
实际催化剂
合成 表征 反应
Pressure Gap
模型催化剂
真空表面 分பைடு நூலகம்技术
发展高效催化剂
探索催化反应本质
Of course life is never so simple and some quite sophisticated approaches have been developed in recent years to extract more information from these highly informative but sophisticated data matrices as will be discussed in the next article.
稳态同位素瞬态动力学--SSITKA 光谱跟踪技术
Monitoring of Reactions Mid Infrared Spectroscopy
The idea is that the characteristic peak for each compound that is IR active changes with time and this change can then be used to follow the reaction
Ian A. Fisher and Alexis T. Bell, JOURNAL OF CATALYSIS 172, 222–237 (1997)
Infrared spectra taken during exposure of Cu/SiO2 to 0.16 MPa CO2 and 0.49 MPa H2.
2.
3.
NIR. Usually multivariate calibration such as PLS and a number of related classical chemometrics methods.
EAS. Deconvolution using MLR (multiple linear regression) and pure standards, plus multivariate calibration.
attributable to methoxide species on zirconia (CH3O–Zr)
region (not shown), peaks for CO on Cu (2131, 2094,
2077 cm°1) are present at 323 K. The peak at 2131 cm°1 is gone at 373 K, while those at 2077 and 2094 cm°1 are present at all temperatures, but decrease in intensity with temperature.
Summary of main data analysis techniques
The following data analytical techniques are most common for the analysis of on-line spectroscopic data from reactions using different spectroscopies. 1. MIR and Raman. Generally conventional kinetic curve fitting of peak areas, but some deconvolution necessary if overlapping peaks.
In-SituInfrared Study of Methanol Synthesis from H2/CO2 over Cu/SiO2 and Cu/ZrO2/SiO2 It is of interest to consider the ways in which the presence of zirconia either as a support or an additive enhances the rate of methanol synthesis. zirconia promotes the rate of methanol formation occurring on the surface of Cu, or alternatively Cu promotes the synthesis of methanol over zirconia. Which of these two options offers the most plausible explanation.
Infrared spectra taken during exposure of ZrO2/SiO2 to 0.16 MPa CO2 and 0.49 MPa H2
The principal features at 323 K are those for b-HCO3–Zr (1619 cm°1) and iCO3–Zr (1442cm°1).Asmall amount of m-CO3–Zr (1382cm°1) and b-CO3– Zr (1351 cm°1(sh)) are also present. As the temperature
UV/vis spectroscopy
Raman spectroscopy
Raman spectroscopy probes have become fashionable. This technique is an alternative to MIR, but the relative intensities of bands differ in the two techniques, however, many of the same methods can be employed to analyse the data.
is increased, the concentrations of b-HCO3–Zr and i-CO3–Zr decrease and bands appear that are characteristic of b-HCOO–Zr (2974, 2892, 1565, 1386, 1369 cm°1). At 523 K bands appear at 2942, 2842, and 1463 cm°1 which are
Near Infrared Spectroscopy
One problem with NIR is that compounds often do not exhibit highly characteristic peaks, and often the changes are more subtle and in small regions of the spectrum
Materials Gap
反应动力学
引导实际催化材料的发展
催化反应动力学
建立反应速率和操作条件参数间的定量关系， 提出正确的反应机 理， 预测反应条件时的速率变化。 稳态动力学技术 瞬态动力学技术
LHHW型： 吸附---表面反应---脱附
一个或多个快速变化的状态变量 引如系统并跟踪发生的系统变化。 温度----程序升温技术 同位素示踪 产物瞬时分析技术（TPA） 瞬变应答技术（Transient Response)
Infrared spectra taken during exposure of Cu/ZrO2/SiO2 to 0.16 MPa CO2 and 0.49 MPa H2
At 323 K the spectrum is comprised of features attributable to b-HCO3–Zr (1606, 1465 cm°1), m-CO3–Zr (1490, 1383 cm°1), b-CO3–Zr (1576 cm°1), and weak features for bHCOO–Zr (2980, 2897, 1568, 1390, and 1370 cm°1). In the temperature interval of 373– 523 K b-HCOO–Zr (2980, 2897, 1568, 1389, and 1370 cm°1) becomes the dominant species. With increasing temperature the intensities of the bands for this species pass through a maximum at 423 K. At 373 K new features appear at 2966 and 2861 cm°1 due to bidentate methylenebisoxy on zirconia (b-CH2OO–Zr) (45, 47–50), and at 2944 and 2846 cm°1 due to CH3O–Zr. At 473 K bands appear at 2957 and 2856 cm°1 due to CH3O–Si. At 523 K, the features for b-CH2OO–Zr are not readily apparent.
Infrared spectra taken for Cu/SiO2 at 523 K after switching the feed from 0.65MPa H2 to 0.16 MPa CO2 and 0.49 MPa H2 at 523 K.
Temporal Resolution of Surface Species Transient spectra were obtained after switching the feed fromH2 to 3/1H2/CO2 at a total pressure of 0.65MPa while maintaining the temperature of the Cu/SiO2 catalyst at 523 K. The results are shown in Fig. 3. b-HCOO–Cu (2927,2849, 1540, 1350 cm°1), and weak features for adsorbedCO onCu(2128, 2094, 2077cm°1, not shown) form immediately upon switching and the intensities of the bands for these species remain relatively constant during the 22.6 h transient. At 2.7 min into the transient, a peak at 2959 cm°1 begins to grow in and increases in intensity during the remainder of the transient. This feature is ascribable to CH3O–Si and the companion peak at 2856 cm°1 is evidenced by the asymmetry of the peak at 2849 cm°1 (shoulder on the left). CH3O–Si is also evidenced by the shoulder at 2994 cm °1and the bending mode observable at 1464 cm°1 at longer times. These features forCH3O–Si have been observed during methanol adsorption on Cu/SiO2.