Pt/TiO2-ZrO2觸媒於四氫萘氫化反應的抗硫性研究

Sulfur Tolerance on Hdrogenation of Tetralin over Pt/TiO2-ZrO2

李雅玲(Ya-Ling Lee)

指導教授 ： 王奕凱

國立清華大學/工學院/化學工程學系/碩士(2010年)

摘要

此研究使用0.1 wt% Pt/Al2O3 與Pt/TiO2-ZrO2觸媒，在bench scale固定床反應器內進行氫化反應，其溫度為200-250 ℃、壓力為450 psi、H2/HC=6。由四氫萘的擬一次反應式求得反應速率常數，來比較氫化活性。結果顯示Pt/TiO2-ZrO2觸媒在含硫及不含硫條件下，均擁有較高的氫化活性。我們改變硫含量，由0 ppm 至50 ppm，發現反應速率常數和硫含量成反比，藉由Langmuir-Hinshelwood 模型，我們解釋現象並進一步求得硫的吸附平衡常數，Pt/TiO2-ZrO2與Pt/Al2O3的平衡常數分別為7×106 和2×107。另外在含硫條件下仍遵守亞倫尼亞 (Arrhenius) 方程式，由含硫及不含硫條件下的外顯活化能 (Apparent Activity Energy)，我們進一步求得硫的吸附熱(Heat of adsorption of sulfur)，Pt/TiO2-ZrO2與Pt/Al2O3的吸附熱分別為-19.4 kJ/gmol和-41.0 kJ/gmol。相對反應速率常數顯示Pt/TiO2-ZrO2觸媒擁有較高的抗硫性，由硫的吸附平衡常數與硫的吸附熱可以得知，吸附於擔載TiO2-ZrO2的白金的硫較容易脫附。可能因為其TiO2-ZrO2擔體的酸性引發白金的缺電子性，以及擔體可產生較多溢流的氫。此外，Pt/TiO2-ZrO2在15 ppm含硫進料進行反應時，產物中含硫量不到1 ppm，顯示其不但擁有高抗硫性還有脫硫的功能。

關鍵字

氫化反應 ； 抗硫性 ； TiO2-ZrO2 ； 吸附熱 ； 白金

並列摘要

Hydrogenation of tetralin over Pt/Al2O3 and Pt/TiO2-ZrO2 were executed in a bench scale fixed bed reactor under 160-270 °C and 450 psi in the presence or absence of sulfur compounds in feed. The activity was compared by the rate constant of hydrogenation of tetralin, which was considered to follow a first-order kinetic model. In the range of sulfur content from 0 ppm to 30 ppm, the rate constant (kS) inversely proportion to the sulfur content (CS) was observed. Thus, a method to obtain sulfur adsorption equilibrium (KS) was developed by Langmuir-Hinshelwood model. The sulfur adsorption equilibrium constant of Pt/TiO2-ZrO2 and Pt/Al2O3 were 7×106 and 2×107, respectively. Moreover, the heat of adsorption of sulfur could be obtained from the apparent activity energy in the presence and absence of sulfur. The heat of adsorption of Pt/TiO2-ZrO2 and Pt/Al2O3 were -19.4 and -41.0 kJ/gmol, respectively. The results showed that the sulfur desorbed easier while platinum supported on TiO2-ZrO2. Meanwhile, less than 1 ppm sulfur was detected in the product of hydrotreating a 15 ppm S feedstock over Pt/TiO2-ZrO2. These results suggest that Pt/TiO2-ZrO2 exhibits not only a high sulfur tolerance hydrogenation catalyst but also possesses the desulfurization ability.

並列關鍵字

hydrogenation ； sulfur tolerance ； TiO2-ZrO2 ； heat of adsorption ； platinum

參考文獻

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參考文獻