應用銅/二氧化鋯觸媒於糠醛與異丙醇之催化轉移氫化反應：表面化學與活性位點之研究

Catalytic Transfer Hydrogenation of Furfural with Isopropanol over Copper/Zirconia Catalyst: A Study of Surface Chemistry and Active Site

簡正奇(Cheng-Chi Chien)

指導教授 ： 游文岳

國立臺灣大學/工學院/化學工程學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202102661

摘要

本研究目標使用醇類作為液態氫源，研發異相觸媒透過催化轉移氫化(catalytic transfer hydrogenation, CTH)反應，將生質衍生物轉換成高值化的化學品。我們以含浸法製備不同Cu擔載量的Cu/ZrO2觸媒，探討Cu/ZrO2觸媒在糠醛與異丙醇反應生成2-甲基呋喃上的CTH表現。程溫規劃還原(temperature-programmed reduction, TPR)鑑定顯示，在低Cu擔載量時，有較高比例的高分散CuOx顆粒。程溫規劃表面反應(temperature-programmed surface reaction, TPSR)及原位擴散反射紅外線光譜(in-situ diffuse reflectance infrared Fourier transform spectroscopy, in-situ DRIFTS)結果顯示，未擔載Cu的ZrO2主要催化異丙醇進行脫水反應生成丙烯和水；ZrO2擔載Cu後，主要催化異丙醇進行脫氫反應生成丙酮和氫氣，較有利於CTH反應。丙酮的脫附溫度隨Cu擔載量增加而降低。由於丙酮的脫附為反應限制型脫附，所以此觀察顯示增加Cu擔載量有利於異丙烷氧基(IPA反應中間體)在較低的溫度下脫氫。CTH活性測試結果顯示，在低Cu擔載量及較低反應溫度條件下，糠醛可初步氫化得到糠醇(furfuryl alcohol)；而增加Cu擔載量及提升反應溫度，則可使糠醇進行進一步的氫解產生2-甲基呋喃。綜合觸媒鑑定和反應測試結果，我們認為在ZrO2表面高分散的Cu顆粒為催化糠醛與異丙醇進行轉移氫化反應生成2-甲基呋喃的主要活性位點。

關鍵字

催化轉移氫化 ； 銅觸媒 ； 二氧化鋯 ； 糠醛 ； 異丙醇 ； 程溫規劃表面反應

並列摘要

This research is aimed at developing efficient heterogeneous catalysts for catalytic transfer hydrogenation (CTH) of renewable biomass derivatives into value-added chemicals using alcohols as the liquid hydrogen sources. In this work, Cu/ZrO2 with various Cu loadings was prepared by impregnation, characterized, and evaluated their catalytic performance for producing 2-methylfuran from the reaction of furfural with isopropyl alcohol (IPA). Temperature-programmed reduction with H2 (H2-TPR) characterization show that a higher proportion of highly-dispersed Cu oxide particles are present on ZrO2 with a lower Cu loading. Temperature-programmed surface reaction (TPSR) and in-situ diffuse reflectance infrared Fourier transform spectroscopy (in-situ DRIFTS) indicate that Cu-free ZrO2 mainly catalyze IPA dehydration as indicated by the production of propene; the conversion of IPA switches into dehydrogenation to form acetone over Cu/ZrO2, which is favorable for IPA-assisted CTH. It is found that with the increase of Cu loading, the desorption temperature of acetone decreases, which indicating that the isopropoxide (i.e., surface intermediate of IPA) could decompose at lower temperatures since the desorption of acetone is reaction-limited. CTH reaction testing reveals that under the conditions with lower Cu loading and lower reaction temperatures, the main product is furfuryl alcohol. The increase of Cu loading and elevation of reaction temperature could promote the IPA dehydrogenation, thus facilitating the hydrogenolysis of furfuryl alcohol to form 2-methylfuran. Combining catalyst characterizations and activity tests, we suggest that the highly-dispersed Cu particles on ZrO2 surface are the active sites responsible for the 2-methylfuran production from the transfer hydrogenation from furfural with IPA.

並列關鍵字

catalytic transfer hydrogenation ； Cu catalyst ； ZrO2 ； furfural ； isopropyl alcohol ； temperature-programmed surface reaction

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