"合成酸官能化中孔洞二氧化矽奈米粒子做為可回收式固體催化劑應用於果糖-5-羥甲基糠醛(HMF)-2,5-二甲基呋喃(DMF)的序列式生質轉換"

Abstract

近年來由於石油短缺的問題，使得人們對於替代能源的需求日漸益增，因此本研究致力果糖、5-羥甲基糠醛(5-Hydroxymethyl furfural, HMF)至生質燃料─2,5-二甲基呋喃(2,5-dimethylfuran, DMF)的製備。在許多生質燃料中，2,5-二甲基呋喃(DMF)因其所具有的優異性質，例如高能量密度、高效配送、易儲存、高安全係數等特點，使2,5-二甲基呋喃(DMF)成為最具有吸引力及發展潛力的生質燃料。 本研究首先合成出三種不同酸官能化的中孔洞二氧化矽奈米粒子(mesoporous silica nanoparticles, MSNs)，由於中孔洞二氧化矽奈米粒子(MSNs)具有高比表面積及易表面改質等特點，因此本研究以此材料作為反應的異相固態觸媒。本研究共將三種酸官能基成功嫁接於中孔洞二氧化矽奈米粒子(MSNs)上，同時利用X光繞射儀(X-ray diffraction, XRD)、掃描式電子顯微鏡(scanning electron microscopy, SEM)、穿透式電子顯微鏡(transmission electron microscopy, TEM)、氮氣吸/脫附孔隙儀(nitrogen adsorption/desorption isotherms)等儀器進行材料鑑定，並將這些帶有磺酸根、羧酸根和亞磷酸根的中孔洞二氧化矽奈米粒子(MSNs)分別以S-MSN、C-MSN、P-MSN表示。實驗結果顯示在四氫呋喃(tetrahydrofuran, THF)系統、反應溫度75°C及反應時間15小時的條件下，S-MSN和C-MSN分別有助於果糖至5-羥甲基糠醛(HMF)、5-羥甲基糠醛(HMF)至2,5-二甲基呋喃(DMF)的轉化反應。因此，本研究利用這兩種固態催化劑(S-MSN和C-MSN)有效地進行果糖-5-羥甲基糠醛-2,5-二甲基呋喃的序列式反應，其最佳2,5-二甲基呋喃產率可達69 mol %。 此外，本研究也以系統性的方式進行5-羥甲基糠醛(HMF)至2,5-二甲基呋喃(DMF)反應路徑的探討。由上述結果可知本研究所合成的酸官能化中孔洞二氧化矽奈米粒子可作為有效的反應催化劑，同時並顯示出酸官能化中孔洞二氧化矽奈米粒子在生質轉換的應用潛力。

Due to strong demand for green and economical alternatives to traditional fossil fuels, this study is focused on the production of 2,5-dimethylfuran (DMF) converted from fructose or 5-hydroxymethylfurfural (HMF). In many biomass-derived liquid fuels, 2,5-dimethylfuran (DMF) is the most attractive one because of its excellent properties such as high energy density, efficient distribution, easier storage, and higher safety coefficient. In this study, we synthesized several acid-functionalized mesoporous silica nanoparticles (MSNs) as solid heterogeneous catalysts because of several advantages of MSNs including high surface area and easy surface functionalization. Three acid-functionalized MSNs (i.e. sulfonic acid, carboxylic acid and phosphoric acid for S-MSN, C-MSN and P-MSN, respectively) were synthesized and characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherms and so on. It was found that S-MSN and C-MSN exhibited the highest efficiency for fructose-to-HMF and HMF-to-DMF, respectively, conversion in tetrahydrofuran (THF) system under mild conditions (75 °C, 15 hr). Therefore, we utilized these two catalysts to achieve efficient and subsequent fructose-to-HMF-to-DMF conversion with highest DMF yield of 69 mol%. The pathway of the HMF-to-DMF conversion was systematically studies. The acid-functionalized MSN materials synthesized in this study have shown potential applications as efficient catalysts for biomass conversion.