Dynamic Multiple Tracing with D2and C2D4in Ethylene Hydroformylation over Mn–Rh/SiO2
Dynamic Multiple Tracing with D2and C2D4in Ethylene Hydroformylation over Mn–Rh/SiO2
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Mn-Rh/SiO2 乙烯氢甲酰化反应中 D2 和 C2D4 的动态多重示踪
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
S. Chuang
中科院分区：
文献类型：
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作者：
M. Brundage;S. Chuang
摘要采用傅立叶变换红外光谱/质谱联用技术研究了Mn Rh/SiO2催化剂上乙烯加氢反应过程中氢/氘吸附物对D2和C2 D4脉冲响应的动力学行为。暴露时间的变化的催化剂的D 2和C 2 D 4脉冲显示，再吸附没有发挥显着的作用，在产品的响应;长的暴露时间允许更多的氘进入较慢的途径的d 1 -和d 2 -丙醛。来自D2和C2 D4脉冲的两个不等峰HD响应表明氢/氘吸附存在同位素效应。氘代乙烯和乙烷的快速响应可以用Horiuti-Polanyi机理描述，表明它们的中间体具有小的θ（表面覆盖度）和τ（停留时间），不能用瞬态响应的时间分辨来分辨。D1-和D2-丙醛产物显示双峰响应，这可以通过不同的氘掺入丙醛的途径来解释。第一个峰是由于吸附的酰基上的氢/氘交换和酰基氢化。第二个峰是由于吸附的烷基物种上的H/D交换，然后进行CO插入和酰基氢化。第二个峰衰变部分是由于与Si-OD的反应，如d 1 -和d 2 -丙醛和Si-OD的平行衰变所示。
Abstract Combined FT-IR/mass spectrometry was used to study the dynamic behavior of hydrogen/deuterium adsorbates in response to D 2 and C 2 D 4 pulses during ethylene hydroformylation on Mn–Rh/SiO 2 at 513 K and 0.1 MPa. Variation of exposure time of the catalyst to the D 2 and C 2 D 4 pulses revealed that readsorption did not play a significant role in the product responses; long exposure time allows more deuterium to enter the slower pathway of d 1 - and d 2 -propionaldehyde. The two-unequal-hump HD response from both the D 2 and C 2 D 4 pulses indicates the presence of an isotope effect on hydrogen/deuterium adsorption. The rapid responses of the deuterated ethylene and ethane can be described by the Horiuti-Polanyi mechanism and indicate that their intermediates have small θ (surface coverage) and τ (residence time) which cannot be resolved by the time resolution of their transient responses. The d 1 - and d 2 -propionaldehyde products show a two-hump response, which can be explained by the different deuterium incorporation pathways into the propionaldehyde. The first hump is due to hydrogen/deuterium exchange on adsorbed acyl and acyl hydrogenation. The second hump is due to H/D exchange on the adsorbed alkyl species, which then undergoes CO insertion and acyl hydrogenation. The second hump decay is partly due to the reaction with Si–OD as indicated by the parallel decay of d 1 - and d 2 -propionaldehyde and Si–OD.