多成份吸附系統的建立與分析應用測試

在本研究中我們將一套自建的常壓流動式吸附實驗系統改裝為可以測量多成份吸附行為的系統，以在近似於觸媒工業應用條件下探討觸媒表面的吸附行為，經由單成份吸附實驗中以TCD與質譜儀同時進行偵測，以確認實驗的準確性，實驗得知本實驗系統準確度在0.04 mmole之內。而在實驗方法的分析過程中發現step和integral法實驗步驟都可獲得相似的實驗結果。在TiO2上的氫氣和苯混合氣吸附實驗得知，由於氫氣得存在會使的苯的吸附等溫線形式由Type IV變為 Type V，顯示氫氣環境下苯在TiO2上的吸附強度更弱，而苯和環己烷混合氣的吸附實驗得知環己烷並不影響苯的吸附形式，對於苯、甲苯的吸附實驗結果得知甲苯在吸附量及吸附強度上都高於苯，在苯和甲苯混合氣的競爭吸附也得知在苯的環境下會使的甲苯吸附量降低及吸附強度較單獨成份時弱。在Pt powder上的吸附實驗可知，苯、甲苯皆屬於強的不可逆吸附，而在表面上的分子吸附可能不是如真空吸附文獻中所述的苯環平行於吸附表面，而可能是呈傾斜角度，而吸附的同時會有脫氫的發生，比例約是4.0510-3( molar ratio )。對於苯和甲苯混合氣的競爭吸附也得知在苯的環境下並不影響甲苯的吸附行為，而吸附的同時也會產生脫氫的情形。

關鍵字

氧化鈦；鉑粉末；吸附

並列摘要

In this study, a built-in-lab was modified flow-type adsorption system for multicomponent adsorption experiment such that the adsorption behaviors near industrial reaction conditions could be examined. Similar results obtained by the TCD and the Mass spectrometry detection for one-component adsorption experiments confirm the capability of the system. and the accuracy of uptake measured with this system was found better than 0.04 mmole. Besides, both the step and the integral experimental procedures showed very similar results, with the latter capable of resolving irreversible and reversible uptakes. Hydrogen and Cyclohexane would not adsorption on TiO2, as observed in one- component adsorption experiment, Benzene and Toluene both reversibly adsorption on TiO2 with the latter showing higher uptake at similar partial pressure condition. The pressure of Cyclohexane showed no effect on the Benzene adsorption isotherm on TiO2; However, the pressure of 500 torr H2 reduced Benzene uptake @ lower Benzene partial pressure but not at higher partial pressure; thus, the Benzene isothermwas changed from type IV to Type V. In the competitive adsorption between Benzene and Toluene over TiO2 the Benzene adsorption isotherm was not changed significantly but the Toluene isotherm was shifted to lower uptake values. Although the estimated adsorption constant for both Benzene and Toluene were lower that measured in the one-component experiment. The relative ratio of their adsorption constant was not changed. Benzene and Toluene adsorption over Pt powders were mostly irreversible; the Toluene showed higher uptake than Benzene under similar partial pressure condition. However, the estimated monolayer coverages showed that the average cross sectional area were much smaller than the van der Waal cross sectional area of the ring; therefor, the adsorption of Benzene or Toluene on Pt powder may not be flat lying. Besides, dehydrogenation occurred concurrently which Benzene and Toluene adsorption on Pt powder; the estimated evolved Hydrogen show nearly 0.004 molar ratio to the Benzene or Toluene uptake. In the competitive adsorption between Benzene and Toluene, the Toluene isotherm was not affected by the presence of Benzene but the Benzene isotherm was changed.

並列關鍵字

TiO2 ； Pt powder ； Adsorption

國際替代計量

多成份吸附系統的建立與分析應用測試

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