以第一原理計算探討非均相催化反應:乙醇氧化反應及乙醇氧化蒸氣重組反應

First-Principles Calculations of Heterogeneous Catalytic Reaction: Ethanol Oxidation Reaction and Oxidative Steam-Reforming Reaction

鄭弘昇(Zheng Hong-Sheng)

指導教授 ： 王禎翰

國立臺灣師範大學/理學院/化學系/碩士(2019年)

https://doi.org/10.6345/NTNU201900085

摘要

本篇論文運用密度泛函理論（DFT）計算來探討乙醇非均相催化反應，其中包括燃料電池中於陽極反應的乙醇氧化反應（Ethanol Oxidation Reaction, EOR），以及應用於產生氫氣的乙醇氧化蒸汽重整反應（Oxidative Steam -Reforming Reaction of Ethanol, OSRE）。
在EOR的研究中，我們模擬了三元金屬PtSnM催化劑（M = Ag，Co，Cu，Pd，Rh）來進行計算。計算結果發現，EOR的活性可以透過金屬M與表面上的含氧物質（OCS）來增強，並來幫助乙醇進行脫氫反應。此外，具有較高親氧性的金屬M利用電荷分佈的分析可以發現更容易有效的抓取H。因此，於PtSnM催化劑中PtSnAg表現出最佳的EOR活性。
在OSRE的研究中，我們研究了Rh（111）表面上的催化反應，以及吸附了O *和OH *的催化反應，以研究氧氣和水兩種關鍵試劑的影響。計算結果表明，氧氣環境下O *可有效地將乙醇脫氫為乙氧基，以提高OSRE的催化效率。此外，氧氣環境下的O *可以有效降低C-Hα解離能障形成吸附乙醛，改變其反應途徑及副產物選擇性，且在水環境下的OH *顯示出與氧氣環境下的O *具有一致的反應結果。

關鍵字

密度泛函理論計算 ； 乙醇氧化反應 ； 乙醇氧化蒸氣重組反應 ； 催化劑PtSnM ； 催化劑Rh

並列摘要

Our present study employed Density Functional Theory（DFT）calculation to examine ethanol related heterogeneous catalyst, including ethanol oxidation reaction（EOR）, the anodic reaction in fuel cell apply and oxidation steam reforming reaction（OSR）, in the application for hydrogen production.
In the study of EOR, we model the ternary PtSnM catalyst（M=Ag, Co, Cu, Pd, Rh）. The computation result found that EOR activity can be enhanced by oxygen containing species（OCS）on surface the additive M , to extract H in the oxidative dehydrogenation step. Also, the additive M with higher oxophilicity can grab the H easier according to the charge distribution. Thus, PtSnAg demonstrates the best EOR activity dene to the lowest oxophilicity of Ag.
In the study of OSRE, we examine the catalytic reaction on Rh（111）surface, as well as that covered with adsorbed O* and OH* to investigate the effects from oxygen and water the two key reagents. The computation result found that surface O* can effective dehydrogenate ethanol to ethoxy to enhance the catalytic efficiency of OSRE. Also, surface O* can better reduce the activation barrier for C-Hα dissociation forming adsorbed acetaldehyde. Thus, alter the reaction route and side product selectivity. Surface OH* shows similar catalytic behavior with moderate efficiency.

並列關鍵字

Density Functional Theory ； ethanol oxidation reaction ； ethanol oxidative steam-reforming reaction ； catalyst PtSnM ； catalyst Rh

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