核殼式PtSn觸媒催化正丁烷脫氫反應之研究

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Title:	核殼式PtSn觸媒催化正丁烷脫氫反應之研究
Other Titles:	The study of core-shell PtSn catalyst for n-butane dehydrogenation
Authors:	游哲瑋 YU, TSE-WEI
Contributors:	李國禎 LI, KUO-TSENG 化學工程與材料工程學系
Keywords:	正丁烷;脫氫反應;核殼式觸媒 n-butane;dehydrogenation;core-shell catalyst
Date:	2018
Issue Date:	2018-11-07T04:32:09Z (UTC)
Abstract:	本研究結合化學還原法與Stober method製備核殼式PtSn@SiO2觸媒，並利用此觸媒催化正丁烷之脫氫反應，SiO2殼層可以防止金屬燒結、降低丁烷脫氫中裂解反應與異構化的發生，在觸媒製備中改變TEOS濃度(0.047M~0.0059M)來影響SiO2的厚度及改變Pt/Sn金屬莫耳比，來找出最佳的觸媒製備條件，結果以TEOS濃度為0.0118M，PtSn莫耳數比1:1的觸媒為最佳。使用PtSn@SiO2(0.0118M TEOS)觸媒於525℃~620℃下進行4小時正丁烷脫氫反應，發現在反應溫度為600℃，當連續反應時間為10分鐘時，有最佳丁烷轉化率62.48%，丁烯選擇率與產率分別為81.56%與50.96%。正丁烷脫氫反應過程中會產生焦碳堆積於觸媒表面，造成觸媒催失活，PtSn@SiO2(0.0118M TEOS)觸媒於600℃進行四小時反應失活速率為0.0029(min-1)，為了讓觸媒恢復催化效果，必須進行觸媒再生，再生一次後觸媒進行丁烷脫氫反應較新鮮觸媒之催化效果較差，但反應再生二次以上之觸媒維持著相同之催化性能，代表觸媒能再生使用。將PtSn@SiO2(0.0118M TEOS)觸媒於不同溫度下反應，進行動力學分析，正丁烷脫氫可視為一級反應，其活化能為72.51kJ/mole。本研究使用之PtSn@SiO2觸媒以熱場發式電子顯微鏡(FE-SEM)、能量散佈分析儀(EDS)、表面積與孔洞分析儀(BET)、X光繞射儀(XRD)、程溫還原(TPR)、穿透式電子顯微鏡(TEM)及感應耦合電漿原子發射光譜分析儀(ICP-AES)進行觸媒分析，進而了解觸媒物理特性與催化性能的關聯性。 This study combined chemical reduction method and Stober method for preparing core-shell PtSn@SiO2 catalysts and used the catalysts to catalyze n-butane dehydrogenation to butenes. SiO2 shell can prevent metal sintering, and reduce side reactions (cracking and isomerization) in n-butane dehydrogenation. In catalyst preparation, different TEOS concentrations were used to change the shell thickness of SiO2. We also changed Pt/Sn metal mole ratio to find the best catalyst compositions. Experimental results showed that the catalyst with TEOS concentration of 0.0118M and Pt/Sn metal mole ratio of 1:1 had the best performances in butane dehydrogenation. The PtSn@SiO2(0.0118M TEOS) catalyst was tested in the temperature range of 525℃ ~620℃ for 4hr. When temperature was 600℃ and time of stream was 10min, n-butane conversion was 62.48%, butene selectivity and yield were 81.56% and 50.96%, respectively.N-butane dehydrogenation produce coke deposition on the catalyst surface, which cause catalyst deactivation. The catalyst deactivation rate constant at 600℃ was 0.0029min-1. Catalyst was regenerated in order to resume its catalytic activity. We regenerated the catalyst several times. Catalyst activity reduced for the first time reuse, but remained essential constant after that, which implies that the catalyst can be regenerated and reused many times.PtSn@SiO2(0.0118M TEOS) catalyst was tested at several different temperatures to determine its n-butane dehydrogenation kinetic. N-butane dehydrogenation was assumed as the first order reversible reaction, the reaction rate constants and activation energy (72.51kJ/mole) were calculated.In order to understand the relationship between catalyst physical properties and their catalytic performance in n-butane dehydrogenation, PtSn@SiO2 catalysts were characterized with FE-SEM, EDS, BET, XRD, TPR, TEM and ICP-AES.
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