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Direct observation of catalytic reaction of high temperatures by IR spectroscopy

红外光谱直接观察高温催化反应

基本信息

批准号：
11640600
负责人：
NOMURA Junko
金额：
$ 2.18万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11640600/
关键词：
High temperature reations catalyst IR spectroscopy FFIR Solid Surface Adosorbed Species

项目摘要

Although IR method has been widely used for the modeling of mechanisms and active sites of catalytic reactions, the limited observation conditions have suppressed the clarification of authentic mechanisms of commercialized high temperature catalytic reactions (HTCR). This study subjects to establish the IR method for the observation of HTCR, and the system is used for the detailed consideration of mechanisms of HTCR, which have been changing.In 1999, adjustment of IR beam path together with construction of flow system and proper IR cell were established. This system was used from 2000 for the observation of 1) methanol oxidation over molybdenum catalysts supported on various oxides, and 2) isomerization of n-heptane over Pt loaded Hβ zeolites. For the reaction 1), methanol adsorbed forming methoxides on supports and was oxidized to formaldehyde by oxygen flow. No reaction of methoxides proceeded in the absence of molybdenum, indicating that molybdenum is the active site for oxygen activation, which is the rate determining step.The gasoline refining process, the reaction 2), suffers the cracking side reaction of hydrocarbon isomerization. Based on this background, comparison of highly active and selective catalyst with poorly effective catalyst was considered. From results of both catalytic performance and observation of surface species, Pt loading and hydrogen co-flow were found to be effective to suppress the formation of dehydrated compounds such as coke and polyolefins. Isotope experiments further reveal that hydrogen (H and D) exchange of surface species was rapid on the active catalyst, and that all the active species were in equilibrium in the steady state reaction. In summary, the system established in this study was regarded as a powerful tool for the observation of HTCR, and therefore is further applied for other reactions hereafter.

虽然红外光谱方法已被广泛用于催化反应机理和活性中心的模拟，但有限的观察条件阻碍了对商业化高温催化反应(HTCR)真实机理的澄清。本研究旨在建立用于HTCR观察的红外方法，该系统用于详细考虑HTCR发生变化的机理。1999年，我们调整了红外光路，建立了流动系统和合适的红外池。该系统从2000年开始用于观察1)不同氧化物负载的钼催化剂上的甲醇氧化和2)正庚烷在负载铂的H-β分子筛上的异构化反应。在反应1)中，甲醇吸附在载体上形成甲氧化物，并在氧气的作用下被氧化成甲醛。在没有钼的情况下，甲醇不发生反应，表明钼是氧活化的活性中心，这是反应速度的决定步骤。汽油精制过程中，反应2)经历了烃类异构化的裂化副反应。在此背景下，对高效、选择性催化剂和低效催化剂进行了比较。从催化剂的催化性能和表面物种的观察，发现铂负载和氢气并流对焦炭和聚烯烃等脱水化合物的形成具有有效的抑制作用。同位素实验进一步表明，活性催化剂表面物种的氢(H和D)交换速度很快，所有活性物种在稳态反应中处于平衡状态。综上所述，本研究建立的体系被认为是观察HTCR的有力工具，因此可以进一步应用于以后的其他反应。