天然油脂加氢镍基纳米催化剂的研究

发布时间：2018-01-19 09:53

  本文关键词： 镍 催化剂 油脂加氢 纳米碳酸钙 载体　出处：《江南大学》2015年硕士论文　论文类型：学位论文

【摘要】：油脂加氢技术是在催化剂的作用下,氢气与脂肪酸甘油酯中的不饱和键反应,使其达到饱和,形成硬化油;后硬化油经水解等过程制备得硬脂酸。硬脂酸在日化、医药和食品加工等行业有着广泛应用。催化剂是油脂加氢技术的关键之一,直接决定硬化油/硬脂酸的质量和性能,且对成本影响也很大。因此研究高活性,低成本的加氢催化剂是油脂行业和催化剂领域的主要发展趋势。本文重点研究了使用纳米碳酸钙作催化剂载体制备的一种负载型镍基催化剂,对其表征并研究它对棕榈油加氢的催化性能,主要内容如下:(1)考察了多种不同载体对催化剂活性的影响。纳米碳酸钙在工业上廉价易得;本文将工业级的纳米碳酸钙用作催化剂载体,研究表明纳米碳酸钙作载体制备的镍基催化剂对油脂的加氢效果达到工业要求水平。打破了多孔型材料作催化剂载体的常规。(2)在提高活性方面,分别考察了活性组分的制备方法、负载量、制备条件等对催化剂活性的影响。结合产物碘值及XRD对催化剂的表征。结果显示,制备方法选择沉淀法要优于络合沉淀法和浸渍法。通过TG、H2-TPR、XRD、TEM等表征手段并结合产物碘值对以纳米碳酸钙作催化剂载体制备油脂加氢催化剂的条件进行了优化,研究表明,选择Na2CO3作沉淀剂,活性组分金属盐Ni(NO3)2溶液浓度为0.5 mol/L,镍负载量为30 wt%,沉淀温度为65℃,环境p H值调至8左右,在350℃下焙烧2 h;然后,设定H2流速为30~40 m L/min,在400℃下还原2 h,所制备的催化剂催化活性最高。然后,以产物碘值为依据,考察了氢化工艺条件的影响,确定工艺条件为:催化剂用量0.7‰,反应温度200℃,H2压力2.0 Mpa,反应2 h时油脂产物碘值最低,转化率最高,催化剂加氢效果最好。(3)研究了添加金属促进剂对催化剂活性的影响,分别用沉淀法制备了多种负载型二元镍基催化剂。结合产物碘值和H2-TPR、XRD等表征手段,确定添加Al和Co作促进剂均可提高催化剂活性,最佳促进剂选择Al,且当n(Ni):n(Al)=6:1时原料棕榈油碘值可由原来的32.14 g I2/100 g降低至0.33 g I2/100 g,转化率达到98.97%。对棕榈油加氢反应结果表明,以上优化条件下制得的催化剂,活性高,性能稳定,基本达到工业进口催化剂水平,且相对成本较低,具有良好应用前景。
[Abstract]:The technology of oil hydrogenation is that hydrogen reacts with unsaturated bond in fatty acid glycerol ester under the action of catalyst to make it saturated to form hardened oil. Stearic acid is prepared by hydrolysis of post-hardened oil. Stearic acid is widely used in daily chemical, pharmaceutical and food processing industries. Catalyst is one of the key technologies of oil hydrogenation. The quality and performance of hardened oil / stearic acid are directly determined, and the cost is also greatly affected. Therefore, the study of high activity. Low cost hydrogenation catalyst is the main development trend in oil industry and catalyst field. This paper focuses on a supported nickel based catalyst prepared with nanometer calcium carbonate as catalyst carrier. The main contents are as follows: (1) the effects of different supports on the catalytic activity of the catalyst were investigated. Nano-calcium carbonate is cheap and easy to obtain in industry. In this paper, industrial nanometer calcium carbonate was used as catalyst support. The results showed that the hydrogenation efficiency of the nickel based catalyst prepared on the support of nanometer calcium carbonate was up to the standard of industrial requirement, which broke with the conventional method of porous material as the catalyst carrier, and improved the activity of the catalyst. The effects of preparation method, loading amount and preparation conditions on the activity of the catalyst were investigated respectively. The catalyst was characterized by iodine value of the product and XRD. The preparation method is better than complex precipitation method and impregnation method. The conditions of preparing oil hydrogenation catalyst with nanometer calcium carbonate as catalyst carrier were optimized by means of TEM and iodine number of product. The results showed that Na2CO3 was chosen as precipitant. The concentration of active component metal salt Ni(NO3)2 solution is 0.5 mol / L, the nickel loading amount is 30 wts, the precipitation temperature is 65 鈩，

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