固體超強酸/鹼觸媒提升生質柴油生產技術之研究

Enhancement of Production Technology for Biodiesel Using Solid Super Acidic/Basic Catalysts

許嘉威(Chia-Wei Shu)

指導教授 ： 林錕松

元智大學/工程學院/化學工程與材料科學學系/碩士(2013年)

https://doi.org/10.6838/YZU.2013.00290

摘要

由於地球暖化的議題受到越來越多的關注，所以如何將植物油轉酯化成生質柴油變得相當重要。生質柴油為一普遍之生質能，其性質與傳統石化柴油相近以及有效降低NOx與SOx，又能和石化柴油混合使用，亦具有無毒、生物可分解、成分中不含硫化物和芳香族類等優點，因此為目前為重要的替代能源之一。
本研究主要目的在完成開發奈米固體超強酸觸媒(SO42-/ZrO2/Al2O3 catalysts)及完成開發奈米固體超強鹼觸媒(Na/NaOH/Al2O3 catalysts與KF/CaO–Fe3O4 catalysts)最佳合成方法、觸媒特性鑑定及觸媒量化生產技術之最佳操作條件，並探討其酯化與轉酯化效率。
在儀器分析方面，本研究使用XRD、TGA、FE-SEM、HR-TEM、 N2 adsorption、FTIR、ESCA以及XAS進行分析，XRD分析部分，固體超強酸觸媒SO42-/ZrO2/Al2O3分析中發現本研究所呈現之晶型以四方晶(Tetragonal)結構為主，而該結構在文獻中會增加其產率；固體超強鹼觸媒KF/CaO–Fe3O4的XRD分析部分，則發現KCaCO3F該結構會使結構脆弱，也是導致觸媒在造粒上困難度上升原因；接著是固體超強鹼觸媒Na/NaOH/Al2O3部分，發現晶型中有NaAlO2及NaOH存在，使得觸媒在吸濕特性上大幅上升；於TGA分析中利用溫度的提升了解固體超強酸觸媒SO42-/ZrO2/Al2O3、固體超強鹼觸媒KF/CaO–Fe3O4以及固體超強鹼觸媒Na/NaOH/Al2O3中物質斷鍵溫度，已判斷其成分、接著利用FE-SEM以及HR-TEM了解其外觀與微結構分析，固體超強酸觸媒SO42-/ZrO2/Al2O3主要以12 nm之四方體柱狀結構，固體超強鹼觸媒KF/CaO–Fe3O4為具有一鐵磁中心Fe3O4之結構，固體超強鹼觸媒Na/NaOH/Al2O3則為直徑約11 nm之群聚性結構，並且表面有明顯之水狀物質；BET分析中顯示，固體超強酸觸媒SO42-/ZrO2/Al2O3為一非多孔觸媒，固體超強鹼觸媒KF/CaO–Fe3O4為一中孔結構之觸媒，固體超強鹼觸媒Na/NaOH/Al2O3則也為非多孔洞型觸媒；FTIR分析中則著重於固體超強酸觸媒SO42-/ZrO2/Al2O3之路易士酸(Lewis acid)與布朗斯特酸(Br#westeur057#nsted acid)，在固體超強鹼觸媒KF/CaO–Fe3O4、固體超強鹼觸媒Na/NaOH/Al2O3，本研究也藉由FTIR分析了解固體超強鹼觸媒Na/NaOH/Al2O3之吸濕性高於固體超強鹼觸媒KF/CaO–Fe3O4；最後ESCA以及XAS部分在於分析其軌域及價態，藉由該分析了解Zr於固體超強酸觸媒SO42-/ZrO2/Al2O3中為Zr4+及Zr2+，同時固體超強鹼觸媒KF/CaO–Fe3O4中Fe3O4也可表示為Fe2O3‧FeO。
由於基本要求條件為常溫常壓下進行，其中固體超強酸觸媒SO42-/ZrO2/Al2O3於常溫常壓下行酯化反應，如需轉酯化反應，則需高溫高壓下進行；而固體超強鹼觸媒Na/NaOH/Al2O3與固體超強鹼觸媒KF/CaO–Fe3O4並不需高溫高壓下進行轉酯化反應，故本研究將於常溫常壓下進行固體超強鹼觸媒Na/NaOH/Al2O3與KF/CaO–Fe3O4 catalysts的轉酯化效率測試；酯化效率結果發現，市售固體超強酸觸媒Amberlyst 15在3 hr就可達到將近100%的Free fatty acid去除率，Amberlyst IR120效果最差，固體超強酸觸媒SO42-/ZrO2/Al2O3居中，接著做不同濃度硫酸以及不同煅燒溫度FFA去除率測試顯示，固體超強酸觸媒SO42-/ZrO2/Al2O3於煅燒溫度329℃以及1.5M硫酸為最適化條件，而固體超強鹼生質柴油產率發現，固體超強鹼觸媒Na/NaOH/Al2O3的生質柴油產率高於固體超強鹼觸媒KF/CaO–Fe3O4，對於縮短製造生質柴油的時間有著顯著的幫助，但由於其高吸濕缺陷，本研究將重心放於固體超強鹼觸媒KF/CaO–Fe3O4之最適化條件，經由生質柴油產率確認，25 wt% KF與煅燒溫度600℃為固體超強鹼觸媒KF/CaO–Fe3O4最適化條件。

關鍵字

生質柴油 ； 酯化反應 ； 轉酯化反應 ； 固體超強鹼觸媒 ； 固體超強酸觸媒 ； 游離脂肪酸

並列摘要

The global warming has gained increased concerns, so the transformation of vegetable oils to biodiesel as bioenergy becomes more important. Biodiesel can mix with petro-diesel at any ratio and has lower amounts of NOx and SOx polluting emissions than fossil fuel. It has advantages such as low emissions, biodegradable, non-toxic, and better lubricity.
In this research, the purpose is the synthesis of complete solid super-acidic SO42-/ZrO2/Al2O3, solid super-basic Na/NaOH/Al2O3, and solid super-basic KF/CaO–Fe3O4 catalysts in optimal condition. In addition, this research investigates the efficiency of esterification and transesterification.
In the instrumental analysis, several experimental techniques were used; such as XRD, TGA, FE-SEM, HR-TEM, N2 adsorption, FTIR, ESCA and XAS. XRD patterns indicate that solid super-acidic SO42-/ZrO2/Al2O3 catalysts main structure has tetragonal phase. The XRD pattern of solid super-basic KF/CaO–Fe3O4 catalyst shows KCaCO3F peak, the newly formed crystal phase is favorable for weakening the catalytic activity and stability of the catalyst. The XRD pattern of solid super-basic Na/NaOH/Al2O3 catalysts shows NaAlO2 and NaOH peaks. This result makes the catalyst increased hygroscopic properties. TGA displays the thermal stability of solid super-acidic SO42-/ZrO2/Al2O3, solid super-basic KF/CaO–Fe3O4 and solid super-basic Na/NaOH/Al2O3 catalysts. We also analyzed appearance and microstructure by FE-SEM and HR-TEM. Solid super-acidic SO42-/ZrO2/Al2O3 catalysts are mainly composed of tetragonal columnar structure, solid super-basic KF/CaO–Fe3O4 catalysts have a ferromagnetic center, and solid super-basic Na/NaOH/Al2O3 catalysts have cluster structure. From N2 adsorption analysis it can be seen that solid super-acidic SO42-/ZrO2/Al2O3 and solid super-basic Na/NaOH/Al2O3 catalysts have non-porous structure, but solid super-basic KF/CaO–Fe3O4 catalysts have meso–porous structure. In FTIR analysis, we have focused on Lewis acid and Br#westeur057#nsted acid distribution on solid super-acidic SO42-/ZrO2/Al2O3, moreover, we also have investigated the solid super-basic Na/NaOH/Al2O3 and KF/CaO–Fe3O4 catalyst’s hygroscopicity. From ESCA and XPS analysis, we have confirmed that Zr valence in the solid super-acidic SO42-/ZrO2/Al2O3 catalysts are Zr4+ and Zr2+, and Fe3O4 also can be exprseeed as Fe2O3‧FeO.
In this research, we have performed the esterification of methanol and soybean oil to synthesize biodiesel by packing solid super-acidic SO42-/ZrO2/Al2O3 catalysts in a self-designed reactor. The reaction was carried out under atmospheric pressure and room temperature. After esterification reaction, we also performed the esterification of methanol and soybean oil to synthesis biodiesel by packing solid super-basic Na/NaOH/Al2O3 and KF/CaO–Fe3O4 catalysts in the same reactor. The esterification experiment results showed that SO42-/ZrO2/Al2O3 catalyst has higher removal efficiency of free fatty acid than Amberlyst IR120 catalyst. The results of biodiesel yield testing, solid super-basic Na/NaOH/Al2O3 catalyst has higher biodiesel yield than solid super-basic KF/CaO–Fe3O4 catalyst. This is helpful to shorten the process time. According to the removal efficiency and biodiesel yield testing, we found that 1.5M sulfuric acid and 329℃ calcination temperature was the optimum condition for solid super-acidic SO42-/ZrO2/Al2O3 catalyst, and the 600℃ calcination temperature and 25 wt% KF were the optimum condition for solid super-basic KF/CaO–Fe3O4 catalyst.

並列關鍵字

biodiesel ； esterification ； transesterification ； solid super-acidic catalysts ； solid super-basic catalysts ； free fatty acid

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