超临界CO_2条件下大豆油极度氢化的研究

以机榨大豆油为原料,在超临界CO_2体系中,选取Pd/C作为催化剂催化极度氢化反应,通过单因素试验,确定催化剂添加量、氢气压力、反应时间、反应温度及搅拌速度的最适量。在最优条件下制备出极度氢化大豆油的碘值为2.6 gI_2/100 g,反式脂肪酸含量为0.23%(可看作零反式脂肪酸含量),VE含量186.7 mg/kg。与常规极度氢化反应相比,反应温度降低了70℃,反应时间缩短了60 min,提高了极度氢化油的质量。Pd/C催化剂可回收重复使用6次,降低了生产成本。     

电化学氢化法制备低反式脂肪酸大豆油脂

设计了质子转移膜式电化学氢化反应器,在低温（30-75 ℃）、常压和低电流密度下实施大豆油氢化反应,反应以稀甲酸钠溶液作为介质,通过电化学方法使甲酸根离子再生并作为电化学氢化反应媒质。考察电化学氢化反应条件反应温度、机械搅拌强度、EDDAB量和溶液组成对氢化油脂脂肪酸组成、碘值、反式脂肪酸含量、异构化指数和氢化反应选择性的影响。结果表明,质子转移膜式电化学氢化法制备氢化大豆油的最适工艺参数为反应温度60 ℃,机械搅拌强度850 r/min,3.0 g EDDAB /100 g油,溶液组成0.3 g/g,在此条件下获得碘值为82.73 g I2/100 g油,TFAs含量为13.3%,酸值为0.15 mg KOH/g油,过氧化值为0.070 g/100 g油的氢化大豆油产品。与传统气体氢化工艺相比,当完成相同程度氢化时,质子转移膜式电化学氢化可使反式脂肪酸含量减少71％。     

Pd/C催化剂用于大豆油电化学氢化的研究初探

采用自制的质子转移膜式电化学氢化反应器,在低温(60℃)和常压条件下实施大豆油氢化反应,反应以稀甲酸盐溶液作为介质,以负载型贵金属钯/碳(Pd/C)作为催化剂,考察Pd/C催化剂量对氢化大豆油脂肪酸组成、碘值、反式脂肪酸、异构化指数和氢化反应选择性影响。结果表明:增加催化剂量有利于提高催化剂表面的氢浓度,提高氢化反应速率,并改变氢化反应选择性和同分异构化作用;结果还表明,Pd/C催化剂具有很好的稳定性,通过催化剂回收实验证明钯催化剂可重复使用5次,因而在工业化应用上仍具有竞争力。     

超临界CO_2状态下米糠油加氢反应的研究

在CO2超临界状态下,采用Pd/C做催化剂,对三级米糠油进行氢化反应研究,确定了最佳工艺条件:催化剂用量0.07%,反应时间40 min,温度75℃,总压力7.5 MPa,搅拌速度200 r/min。在此条件下,所得氢化米糠油的碘值为53.2 g/100 g,产品颜色为乳白色,免去了油脂脱色步骤,保留了原有的营养物质,成品中反式脂肪酸含量低,使其成为优质的人造奶油基料。     

负载型贵金属铂催化剂催化氢化大豆油的性能研究

油脂氢化是利用还原性镍等金属作为催化剂,使氢加成到三酰甘油双键上的过程。但在氢化过程中会不同程度地产生异构化产物——反式脂肪酸(TFAs)。因此学术界一直研究如何降低氢化过程中TFAs含量的方法,尤其是对催化氢化中各类催化剂的制备与性能的探究。通过制备二氧化锆(ZrO2)负载贵金属铂的催化剂,在工业条件下氢化大豆油并与雷尼镍催化剂对比其活性、反应选择性以及产生TFAs的含量。采用浸渍-还原法制备负载贵金属铂的催化剂,利用常用的表征手段如XRD、TEM、BET、ICP等对催化剂进行物理化学表征;同时在工业氢化条件下对大豆油进行催化氢化,对比各催化剂的活性、选择性以及TFAs的含量,且进一步对比氢化后油脂的品质指标如酸价、熔点。结果表明,ZrO2负载贵金属铂催化剂的活性极明显高于镍催化剂,且在碘值约为70时产生的反式酸含量为25.48 g/100 g大豆油,低于镍催化剂产生的反式酸(31.42g/100 g大豆油)。负载铂催化剂氢化后油脂的酸价稳定并且小于1.0 mgKOH/g;油脂的滑动熔点值显著上升,最终高达45.08℃。在工业氢化条件下,ZrO2负载的铂催化剂为典型的介孔材料,金属粒径小,金属分散性很好,具有高活性,低TFAs含量等优点。     

纳米镍的制备及氢化大豆油的分析

以液相还原法制备纳米镍催化剂,并通过X-射线衍射、扫描电子显微镜、粒径分析及N2吸附脱附等手段对催化剂进行表征。结果表明：纳米镍催化剂比表面积为42.35?m2/g,平均粒径为30.0?nm,孔容为0.029?cm3/g,表面附着表面活性剂使其成球性和分散性较好,有利于催化剂活性的提高。纳米镍氢化一级大豆油的活性是雷尼镍的2.01?倍,当氢化油脂碘值约为90?g?I/100?g时,纳米镍催化剂的亚油酸选择性为0.51,反式脂肪酸异构化的选择性为0.35,氢化油脂的反式脂肪酸相对含量较雷尼镍的低10.79%。     

超临界CO_2氢化大豆油工艺优化及动力学分析

以自制Ni-Ag/SBA-15为催化剂,在超临界CO_2条件下对氢化大豆油的工艺进行研究,其最佳工艺条件为CO_2压力8.0 MPa、氢气分压3.40 MPa、氢化温度100℃、催化剂用量0.20%、搅拌速率300 r/min、氢化时间90 min,产品碘值为86.0 g I_2/100 g,反式脂肪酸(trans fatty acids,TFAs)含量为11.7%;利用氢化动力学方程,运用MATLAB软件编辑运算程序,研究超临界CO_2氢化大豆油的反应速率与选择性,与常规状态下氢化进行比较,发现超临界CO_2状态氢化反应速率较快,且对亚麻酸及亚油酸有更好的氢化选择性。同时,在超临界CO_2条件下进行氢化,氢化大豆油产品中的TFAs和硬脂酸含量更低,分别为11.7%和9.4%。     

固体聚合物电解质大豆油氢化反应器中膜电极制备条件的研究

利用固体聚合物电解质氢化反应器,在60℃和常压条件下氢化大豆油。对固体聚合物电解质氢化反应器的核心关键部件膜电极的制备条件进行了优化研究。膜电极最佳制备条件为使用RuO_2为阳极催化剂,40%Pt/C为阴极催化剂,催化剂的载量均为0.6 mg/cm~2,其中阳极和阴极黏合剂占催化层总质量的30%,膜电极最佳热压压力为2 MPa。利用优化条件下制备的膜电极获得了碘值为110 g I/100 g油、反式脂肪酸仅为1.55%的氢化大豆油。     

植物油脂水解工艺及不饱和脂肪酸组成研究

研究了碱性水解小桐子油脂制备脂肪酸的较佳工艺条件：油水比（g/g）为2：1,乙醇-水比（v/v）为2：1,皂化时间1.5h、温度70℃,在该条件下脂肪酸得率、酸值和碘值的平均值分别为：98.25%、203.67mgKOH/g和109.89g/100g。采用桐油、光皮油、棕榈油和大豆油等植物油脂考察了该工艺的原料适用程度,该水解工艺条件下各种油脂制备所得的脂肪酸得率和酸值都接近98%和199mgKOH/g。采用GC-MS分析五种植物油脂脂肪酸组成和含量,其不饱和脂肪酸含量依次为：桐油（94.88%）〉大豆油（84.07%）〉光皮油（81.90%）〉小桐子油（77.84%）〉棕榈油（77.19%）;其中多价不饱和脂肪酸含量次序为桐油（85.36%）〉大豆油（58.01%）〉棕榈油（56.81%）〉光皮油（55.31%）〉小桐子油（42.16%）。大豆油、棕榈油、光皮油和小桐子油四种植物油脂脂肪酸成分基本相同,主要是亚油酸、7,10-十八碳二烯酸、油酸。桐油中脂肪酸组成与其他植物油脂有较大区别,含大量三价不饱和脂肪酸,其主要成分有油酸（9-十八烯酸）13.83%、8,11-十八碳二烯酸24.37%、亚麻酸（9,12,15-十八碳三烯酸和6,9,15-十八碳三烯酸）60.01%。     

两种Pricat镍催化剂对大豆油氢化中固脂和反式酸含量的影响

研究了两种Prieat镍催化刺在大豆油氢化过程中对固脂和反式酸含量的影响。结果表明，9908型催化荆适合油脂的选择性氢化，而9910型则适合植物油的极度氢化。详细探讨了9908型催化刺在不同氢化温度、氢气压力以及催化荆浓度下对氢化油固体脂肪含量以及反式脂肪酸的影响。结果表明，温度对氢化反应的异构化影响较大，氢气压力和催化剂浓度对异构化的影响相对较小。     

负载型贵金属钯-氧化铝催化剂用于大豆油选择氢化

通过对大豆油的选择氢化实验 ,就各反应条件如温度、反应时间、催化剂负载量对贵金属催化剂的选择氢化催化活性的影响及催化剂回收利用进行了考察 ,初步确定适合工业化大豆油选择氢化的工艺条件 ,并对如何降低氢化过程中生成的反式烯酸做了初步的探讨。     

超临界CO2 条件下大豆粉末磷脂氢化工艺优化

为提高大豆粉末磷脂产品的储藏稳定性,对大豆粉末磷脂在CO2 超临界状态下的氢化工艺进行深入研究。采用Pd/C 作催化剂,无水乙醇与二氯甲烷(1:3,V/V)为溶剂,进行加氢反应。最终确定了最佳工艺条件：催化剂用量4%、反应时间60min、总压力10.5MPa、反应温度70℃、搅拌速度250r/min。所得氢化大豆粉末磷脂的色泽淡黄,碘值27.81g I2/100g,稳定性较好。     

Quantitative determination of conjugated linoleic acids in hydrogenated vegetable oils using refractive index

Conjugated linoleic acid contents in hydrogenated vegetable oils were differentially determined using refractive indices when the iodine value could not be used. The refractive indices of soybean oil, cottonseed oil, and corn oil varied linearly with changes of linoleic acid contents of individual oils with determination coefficients of 0.91, 0.98, and 0.98, respectively. The refractive index can be used as a simple and fast method for control of the hydrogenation process of vegetable oils to obtain a desired conjugated linoleic acid content without fatty acid compositional analysis.     

大豆油氢化反应釜数值模拟及工艺优化

以一级大豆油为液相、Pt/C催化剂为固相,釜体为圆柱体,釜体高度为180 mm,内径为120 mm,液面高度为130 mm,利用FIUENT软件对大豆油氢化反应釜进行液固两相数值模拟,发现倾斜式搅拌桨距反应釜底部高度80 mm、桨叶直径40 mm、搅拌速率300 r/min时流体流动及催化剂分布最佳,并以模拟的主要参数制备了高压反应釜。高压反应釜内一级大豆油添加量90.0 g、Pt/C催化剂添加量0.15%(m/m),充入8 MPa的CO2气体,后充入H2保持反应釜内总压为12 MPa,通过优化得出最佳反应温度97℃、反应时间87 min、搅拌速率285 r/min时,氢化后大豆油的碘值为79.50 g I2/100 g,说明模拟准确,为展示大型设备油脂氢化过程提供理论依据。     

Effects of Alcohol Type and Amounts on Conjugated Linoleic Acid Formation During Catalytic Transfer Hydrogenation of Soybean Oil

ABSTRACT: Effects of alcohol type and amount on formation of conjugated linoleic acids (CLAs) in soybean oil were studied during catalytic transfer hydrogenation with a nickel catalyst and an alcohol as a hydrogen donor. Identification and quantification of CLA isomers in the oil were done by 100-m cyano-capillary column gas chromatography. Butanol and propanol showed the highest activity for the formation of CLAs, followed by ethanol and methanol. As the amount of ethanol in the reaction system increased from 0% to 2.5%, CLA formation increased. At the level of 2.5%, CLA formation decreased. CLA compositions in soybean oils were also affected by hydrogenation time and alcohol amount. Catalytic transfer hydrogenation with alcohol has an advantage over classic hydrogenation with a gaseous hydrogen in that soybean oil, with an extremely low level of t-C_18:1 but high level of CLAs, could be produced.     

Ni catalyst promotion of a Cis-selective Pd catalyst for canola oil hydrogenation

A Ni catalyst was added to a cis-selective Pd catalyst in an attempt to further improve the Pd catalyst's cis-selectivity and activity for canola oil hydrogenation. The system was tested under reaction conditions known to be suitable for cis-selective hydrogenation with the Pd catalyst (50 ppm Pd, 70 °C, and 5.2 MPa). Although inactive on its own under these conditions, the addition of 100 ppm Ni increased the hydrogenation activity (from 2.12 to 2.49 10⁻² min⁻¹). Further addition of Ni up to 1000 ppm resulted in no further improvements in activity. The trans isomer contents of the oils hydrogenated with Pd and the Pd/Ni systems were similar. The level of conjugated dienes decreased rapidly during hydrogenation with both Pd alone and with the Pd/Ni combination and no changes in conjugation were detected in the presence of the Ni catalyst alone. The increased activity of the Pd/Ni system over Pd alone was attributed to adsorption of catalyst poisons from the oil by Ni.     

Non-thermal dielectric barrier discharge plasma hydrogenation for production of margarine with low trans-fatty acid formation

A novel technique for palm oil hydrogenation with very low trans-fatty acid formation using non-thermal dielectric barrier discharge (DBD) plasma with parallel-plate configuration has been successfully demonstrated. This green technique does not require catalyst and is highly environmental-friendly. With 15% H₂: 85% He mixed carrier gas concentration ratio and initial 31 °C (rising to 50 °C due to plasma), after 4 h of plasma hydrogenation, iodine value (IV) was reduced from 60.89 to 48.39 and detected trans-fat was 1.44%. This represents trans-fat generation rate of only 0.07% per % decrease in IV, which is about 6.12 times lower than a conventional method relying on high temperature, high pressure and catalyst. About 8 h was required to produce margarine with texture closest to commercial margarines. Acid value (AV) reduced from 0.47 to 0.27%, or 43% reduction, after 12–20 h of treatment, significantly indicating that plasma hydrogenation can also help extend shelf life of oil or margarine. Large portion of DBD plasma hydrogenated palm oil can, thus, be mixed with palm olein and interesterified palm oil to produce margarine with overall trans-fatty acid content no higher than regulatory requirement. Continuous production scheme was presented. This novel plasma hydrogenation technique offers promising possibility for commercial utilization by edible oils industry.