SURFACE REACTIVITY OF ZSM-5 ZEOLITES IN INTERACTION WITH KETONES AT AMBIENT-TEMPERATURE (A FT-IR STUDY)
SURFACE REACTIVITY OF ZSM-5 ZEOLITES IN INTERACTION WITH KETONES AT AMBIENT-TEMPERATURE (A FT-IR STUDY)
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DOI：
10.1016/0144-2449(91)80355-4
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发表时间：
1991-01-01
期刊：
影响因子：
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通讯作者：
NOVAKOYA, J
中科院分区：
文献类型：
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作者：
KUBELKOVA, L;CEJKA, J;NOVAKOYA, J
利用红外光谱研究了丙酮、丙酮-d6、二乙基酮、二丙酮醇和二甲氧基氧化物在常温下在HZSM-5、脱羟基HZSM-5和NaZSM-5分子筛上形成的表面配合物。光谱学。研究发现，在酮类中，C=O键受桥接羟基的干扰比受电子接受位、Al和Na离子的干扰大得多，而且这种影响对碱性较强的二乙基酮比对丙酮更大。桥接羟基导致质子化酮的形成。与二乙基酮相反，质子化的丙酮通过与物理吸附的分子反应而醛化，形成二丙酮醇，二丙酮醇在室温下立即脱水成强吸附的二甲氧基。丙酮在NaZSM-5的空腔中不发生反应，但二丙酮醇的脱水很容易发生，很可能是由于小浓度存在的Al Lewis位点的影响。
Surface complexes formed at ambient temperature from acetone, acetone-d6, diethyl ketone, diacetone alcohol, and mesityl oxide on HZSM-5, dehydroxylated HZSM-5, and NaZSM-5 zeolites were studied using FTi.r. spectroscopy. It was found that the C=O bond in ketones is perturbed far more by the bridging hydroxyls than by electron-accepting sites, Al and Na ions, and that this effect is greater for the more basic diethyl ketone than for acetone. The bridging hydroxyls cause the formation of protonated ketones. In contrast to diethyl ketone, protonated acetone is aldolized by the reaction with the physisorbed molecule to form diacetone alcohol, which is immediately dehydrated to strongly adsorbed mesityl oxide at room temperature. Acetone does not react in the cavities of NaZSM-5, but dehydration of diacetone alcohol occurs readily, most probably due to the effect of Al Lewis sites present in small concentrations.