油脂和脂肪酸加氢高活性催化剂的研究

【作者】 陈凌霞；

【导师】 刘寿长；

【作者基本信息】 郑州大学 ， 物理化学， 2001， 硕士

【摘要】 天然油脂加氢改性在食品工业上具有广泛用途，如椰油加氢后得到的硬脂可替代可可脂及作为人造奶油的原料。另外通过对油脂中的碳碳双键加氢，使其中的不饱和脂肪酸脂转变为饱和的硬脂酸脂，由此可制备大量使用的工业原料—硬脂酸。这些都涉及到油脂的催化加氢，因此研究制备高活性的工业加氢催化剂具有重要的意义。 对于油脂加氢催化剂，国内外已进行了大量的研究，其中铜镍二元催化剂和单元镍催化剂是主要的研究方向。对于食用油脂加氢，主要采用单元镍催化剂，这种催化剂活性高，且加氢后的油脂在室温储存期间具有高度的抗氧化稳定性。而铜镍催化剂也具有原料价格低，活性高等优点。油脂加氢催化剂的制备方法很多，活性组分前体也有多种存在形式。对于负载型催化剂，载体的晶体结构、表面积及孔分布都会对催化剂的活性和加氢产物产生影响，因此，选择合适的制备方法及适宜的载体，控制适当的制备条件，是制备高活性工业加氢催化剂的关键问题。本论文采用改进的化学混合法及沉淀法，分别以硅藻土和二氧化硅为载体，以甲酸镍和碱式碳酸镍（铜）为活性组分前体，制备了高活性的工业加氢催化剂。其中沉淀法制备的Ni催化剂，活性很高，具有工业应用价值，可望替代进口催化剂。1．化学混合法制备Ni/SiO₂催化剂。制备条件：由Na₂SiO₃或水玻璃过阳离子交换树脂，制得可溶性二氧化硅，浓度控制在3.9％左右，pH=7。甲酸镍溶液浓度为0.15mol/L，二者混合搅拌后，凝胶陈化，用乙醇置换其中的水分，凝胶粉碎铺展快速烘干后可制得高比表面积的Ni/SiO₂催化剂。研究了催化剂在制备过程中，凝胶后处理方法、镍含量、甲酸镍浓度，硅胶浓度和pH值以及干燥方式对催化剂活性的影响。操作条件： 140～150C，氢压1．OMPa，反应90min。研究了压力，时间及催化剂浓 度的影响。由椰油加氢，WijS法测定产物gMA来评价催化剂活性，通过 TGoTA、XRD、BET比表面、红外光谱等手段对催化剂进行了表征。 结果表明，化学混合法制备的NVSIOZ体系活性组分高驸，催化剂比表 面大，活性组分与载体的作用较强，催化剂加氢后除熔点升高外油脂的 其它性质没有改变，是一种高活性的油脂碳碳双键加氢的催化剂。 Z沉淀法制备N帷藻土催化剂。制备脓：将NISO。6H20配咸稀溶液 和硅藻土（预处理：用浓盐酸浸泡1－2d，不断更换酸液直到酸液不再变 黄，再用蒸馏水洗至中性，烘干）搅拌混合 10～20Wu，然后在搅拌下慢 慢滴加 N32CO3溶液，至州值为 8刃后再搅拌 l刁h，滤出沉淀，洗净 SO／－，于 110C左右烘干。此时镍以碱式碳峻盐的形式负载在硅藻土上， 加入过量甲酸反应3h，使其转换为甲酸镍。洗涤，烘干，筛分。研究了 制备抓对催化剂镍含量与加氢活性的影响。操作脓：140J℃，氢 压1．OMPa，反应90Inin。由椰油加氢评价催化剂活性，并通过TG－DTA、 XRD、BET比表面、红外光谱等手段对催化剂进行了表征。 3．沉淀法制奋CUN1催化剂。制备条件：水玻璃经离子交换法制备出载 体 SIOZ．将 CZSO4．SHZO及NISO4．6HZO同时溶于蒸馏水中，以 NdiCO3 溶液为沉淀剂，并流沉淀。同时加入 SIOZ（控制 CZ－NilsiOZ＝l．5：l为 佳），搅拌6O分钟并控制水浴温度的℃，老化一定时间后抽滤，水洗 至无 SO／－，烘干，研磨后焙烧sh；250C下通氢氮混合气还原 1．sh，通 氮气冷却后取出。用豆油加氢评价活性。研究了焙烧温度和SIOZ加入量 对催化剂活性的影响。操作条件：180－200C，氢压 0．ZMPa；反应 60min。 结果表明：加入一定量的 SIOZ可大大提高催化剂的活性。 4．沉淀法制备 Ni催化剂。制备条件：将 NISO。6H。O或 Ni(NO＊ 2石HZO 溶液与 NMCO3溶液并流沉淀，力。N一定量的 SIOZ(NV SIO2＝3：1为佳L 1 在 65 C水浴中搅拌 60分钟，老化一定时间后抽滤，水洗至无 SO4‘”，烘 干，研磨后焙烧 sh，300℃下通氢氮混合气还原 l．sh，通氮气冷却至室 温后，氮气氛保护下倒入硬化油中，搅拌均匀，冷却固化。用豆油加氢 评价其活性。操作条件：180－－200C，氢压 0．ZMPa，反应 60min。研究 了氢化时间、氢化温度、氢化压力、催化剂浓度等对活性的影响。用3OlD、 红外光谱等对催化剂进行表征。 5．催化剂的活性比较。分别在相同条件下，用椰油和豆油力。氢，比较了 化学混合法制备的NilsiOZ、沉淀法制备的Nt藻土、CuNi、单元M 四种催化剂的活性。在相同条件下与作者研制的催化剂进行了比较。对 于椰油加氢，在较高Ni含量条件下，自制的四种催化剂活性与进口的三 种催化剂活性相当；对于豆油加氢，催化剂浓度按工业用量，结果表明 沉淀法?更多还原

【Abstract】 The hydrogenation of natural oils and fatty acids has been widely used in chemical and food industry, for example, the stearin obtained from coconut oil can substitute cocoa grease or is used as raw material of margarine. In addition, by the means of hydrogenation of Carbon-Carbon double bonds in oil, stearin, a kind of industrial raw material used in a large amount, can be prepared. All of these processes involve the catalysis hydrogenation. Therefore, the study of the preparation of high active catalysts for hydrogenation is of great significance. Many studies of catalysts for hydrogenation of oils and fatty acids have been made, in which Cu-Ni bibasic catalyst and Ni unitary catalyst are the two mainstreams. For the food industry, the Ni unitary catalyst is mainly adopted because of its high activity, and the hydrogenation products is of high anti-oxidation stability during their storage at room temperature. However, the Cu-Ni bibasic catalyst is also of such advantages as low cost and high activity. There are a lot of preparation methods of the catalysts which active component precursors also have many forms. For the supported catalyst, the crystal structure of supports, the surface area and pore distribution of the catalysts, have influences on hydrogenation activities and hydrogenation products. Thus, suitable preparation method and appropriate supports is the key to prepare industrial catalyst with high activity. In this paper, the catalysts have been prepared by using precipitation method and chemical mixing procedure. In these catalysts, the Ni unitary catalyst prepared by precipitation method exhibits very high activity. Characterization of the catalysts also has been made. Some main conclusions are as follows: 1. NiISiO2 catalyst prepared by chemical mixing procedure. Preparation conditions: Silica sol is obtained by ion exchange with sodium or water glass flowing through positive ion resin, controlled silica concentration 3.9%, pH 7 and formic nickel concentration 0.1 5mol.U? agitated for lh, made the sol gelatinized, washed by ethanol finally .The gel was dried quickly. NiISiO2 with high surface area is obtained. Operation conditions : 140-450 ; hydrogen pressure, 1.0 Mpa; reaction time, 90 mm. XRI), IR etc. show that Ni!Si02 is of high dispersity, high surface area. The interaction between active component and the support is observed. ? Hydrogenation products maintain oil’s physical character except its melting ? point being enhanced. The catalyst is of high activity for hydrogenation of carbon -carbon double bonds. 2. Nildiatomite catalyst prepared by precipitation Preparation condition: A solution of N1SO4.6H20 and diatomite is agitated for I 0?0 mm, added Na2CO3 solution into the above solution until the pH value becomes 8---9, agitated for 1-3 h. The obtained solid which is basic carbonate nickel is filtered ,washed and dried at 110 . In order to transfer the basic carbonate nickel into formic nickel, superfluous formic acid is added to the solids, reacting for 3 h, then washed dried and sieved. Operation conditions: 140 502; hydrogen pressure, 1 .OMpa; reaction time, 90 mm. Physical and chemical characterization of the catalysts was carried out by means of atomic adsorption, activity and BET surface area measurement, X更多还原