【摘要】：棕櫚酸乙酯作為一種香精、香料，主要被用來(lái)作為乳化劑、生物柴油和食品添加劑等廣泛使用。但是截止目前為止，對(duì)于棕櫚酸乙酯的合成研究大多集中在化學(xué)催化法合成的水平上，生物酶法合成棕櫚酸乙酯的文獻(xiàn)鮮有報(bào)道，另外,采用SBA-15固定化脂肪酶，并用合成的固定化酶當(dāng)作催化劑合成棕櫚酸乙酯目前尚未有相關(guān)報(bào)道，屬于一種新的想法。因此本研究以棕櫚酸和乙醇為底物，利用氨基修飾后的分子篩SBA-15為載體，固定化豬胰脂肪酶，并以此復(fù)合物作為催化劑，利用可逆反應(yīng)催化合成該酯化反應(yīng)。產(chǎn)物經(jīng)分離純化后，采用紅外、紫外等手段進(jìn)行檢測(cè)，并利用酸價(jià)法計(jì)算棕櫚酸乙酯的產(chǎn)率。利用單因素實(shí)驗(yàn)，和響應(yīng)面分析法確定了棕櫚酸乙酯合成的最優(yōu)條件。本篇論文研究主要包括以下幾個(gè)方面： 第一部分：合成NH2-SBA-15。在酸性條件下，以三嵌段共聚物PEO20-PPO70-PEO20(P123)為模板劑，正硅酸乙酯當(dāng)作硅源，采用水熱法合成介孔分子篩SBA-15，并在550℃煅燒除去殘留的模板劑P123。通過(guò)甲苯和APTES(3-氨丙基-三乙氧基硅烷)對(duì)合成的SBA-15進(jìn)行氨基化修飾，即合成NH2-SBA-15,通過(guò)XRD、N2吸附-脫附、FTIR、TEM、SEM、TGA-DTA等分析手段對(duì)樣品進(jìn)行了表征。結(jié)果表明:合成的NH2-SBA-15樣品仍然具有長(zhǎng)程有序的六方孔道結(jié)構(gòu)，孔徑范圍大概在6-8nm。 第二部分，以合成的NH2-SBA-15為載體，采用共價(jià)交聯(lián)法固定化豬胰脂肪酶�？捡R斯亮藍(lán)法測(cè)定酶的負(fù)載率；采用橄欖油乳化法，進(jìn)行了酶活測(cè)定；另外，分別對(duì)游離酶和固定化酶的性質(zhì)、穩(wěn)定性進(jìn)行測(cè)定，探究和優(yōu)化了酶固定化的條件。經(jīng)過(guò)優(yōu)化分析，結(jié)果顯示,合成固定化酶的最適條件為：交聯(lián)時(shí)間4h，加酶量360mg/g載體，緩沖液pH7.5，溫度25℃，固定化酶的負(fù)載率達(dá)82.347%，固定化酶最適溫度為50℃，最適pH為7.5，最適Km為4.94%。固定化酶在重復(fù)使用6次后，剩余酶活力仍保持初始活力約70%。與游離酶相比，固定化酶具有更高負(fù)載率和更高的酶的穩(wěn)定性。 第三部分，以NH2-SBA-15為載體的固定化酶作為反應(yīng)的催化劑，以棕櫚酸和乙醇為底物，生物催化法酯化合成棕櫚酸乙酯。經(jīng)單因素分析法和響應(yīng)面分析法得出結(jié)論，最佳反應(yīng)條件為：反應(yīng)溫度55.94℃，反應(yīng)時(shí)間為6.72小時(shí)，乙醇體積為4.26ml。另外棕櫚酸1.5g，固定化酶0.1g，，水0.5ml。采用上述優(yōu)化后的工藝參數(shù)對(duì)棕櫚酸乙酯進(jìn)行酶法制備，棕櫚酸乙酯的平均產(chǎn)率約為73.5%。 我們成功合成了具有較大孔徑的分子篩NH2-SBA-15，以此分子篩為載體，交聯(lián)法固定化豬胰脂肪酶，得到的固定化酶具有良好的穩(wěn)定性，適合做非水相催化的催化劑。本實(shí)驗(yàn)以棕櫚酸和乙醇為底物，固定化酶為催化劑，通過(guò)工藝優(yōu)化合成了產(chǎn)率約為73.5%的棕櫚酸乙酯。
[Abstract]:Ethyl palmitate, as a flavor and spice, is widely used as emulsifier, biodiesel and food additive. However, up to now, most of the studies on the synthesis of ethyl palmitate have focused on the level of chemical catalytic synthesis, and the literature on the synthesis of ethyl palmitate by biological enzyme method has been rarely reported. In addition, the immobilized lipase was immobilized by SBA-15. The synthesis of ethyl palmitate using immobilized enzyme as catalyst has not been reported, so it is a new idea. Therefore, using palmitic acid and ethanol as substrates and amino modified molecular sieve SBA-15 as carrier, porcine pancreatic lipase was immobilized and the complex was used as catalyst to synthesize the esterification by reversible reaction. After separation and purification, the product was detected by IR and UV, and the yield of ethyl palmitate was calculated by acid value method. The optimum conditions for the synthesis of ethyl palmitate were determined by single factor experiment and response surface analysis. This paper mainly includes the following aspects: the first part: synthesis of NH2-SBA-15. Under acidic conditions, mesoporous molecular sieve SBA-15, was synthesized by hydrothermal method using triblock copolymer PEO20-PPO70-PEO20 (P123) as template and ethyl orthosilicate as silicon source. The residual template P123 was calcined at 550 鈩

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