镍基纳米催化剂的制备及其在加氢反应中稳定性的研究
发布时间：2018-07-26 20:25
【摘要】：催化加氢作为原子经济性反应的代表,符合绿色化学化工的理念,是近年来国内外研究的热点之一。催化剂是催化反应的核心所在,因此,高效催化剂的开发在催化加氢反应的研究中占有重要的地位。针对贵金属催化剂存在的价格昂贵等问题,本文采用廉价易得的过渡金属镍为主催化活性组分,制备了一系列的镍基纳米催化剂用于加氢反应,重点考察了溶剂、载体及催化剂结构对催化剂活性和稳定性的影响。首先,采用化学还原法来制备纳米NiB非晶态合金催化剂,考察了不同溶剂对镍基催化剂在肉桂酸加氢反应中性能的影响,发现以甲醇和叔丁醇为溶剂时,催化剂具有最佳的活性,肉桂酸的转化率达到98.9%,氢化肉桂酸的选择性达到100%。与此同时,当以叔丁醇为溶剂时,在加氢反应过程中催化剂的活性组分流失最少。然后,通过浸渍-还原法制备了负载型NiB非晶态合金催化剂,考察了不同载体负载的镍基催化剂(NiB/γ-Al_2O_3、NiB/SiO2、NiB/TiO2)在肉桂酸加氢反应中的活性和稳定性,发现载体γ-Al_2O_3具有较好的分散活性组分的作用。NiB/γ-Al_2O_3催化剂在叔丁醇作溶剂时表现出了较好的稳定性,随着套用次数的增加,催化剂的活性逐渐增加,反应三次后肉桂酸的转化率为75.0%,氢化肉桂酸的选择性依然是100%。这可能是因为催化剂在载体孔道中的活性组分随着反应的进行而不断暴露所致。最后,通过改进的St?ber-自组装法制备一种新型可磁分离的核壳结构镍基纳米催化剂Ni-Ca@mSiO2。该催化剂在二苯甲酮的选择性加氢反应中显示出了良好的活性和选择性。在最佳反应条件下,二苯甲酮的转化率达到96.1%,二苯甲醇的选择性为94.9%。透射电子显微镜(TEM)和二氧化碳程序升温脱附(CO2-TPD)测试结果表明碱土金属钙的添加不但有利于提高活性组分镍的分散度,并且能调节催化剂的酸碱性,抑制目标产物二苯甲醇的脱水,使该催化剂在二苯甲酮选择性加氢制备二苯甲醇的反应中同时具有高活性和高选择性。此外,使用后的催化剂可利用外部磁场有效分离,且循环使用四次后活性基本无变化,证明该催化剂还具有不错的稳定性。
[Abstract]:As the representative of atomic economic reaction, catalytic hydrogenation accords with the idea of green chemistry and chemical engineering, and it is one of the hot research topics at home and abroad in recent years. Catalyst is the core of catalytic reaction, so the development of high activity catalyst plays an important role in the study of catalytic hydrogenation. In view of the expensive price of noble metal catalysts, a series of nickel based nanocatalysts were prepared for hydrogenation by using cheap and readily available transition metal nickel as the main active component. The effect of support and structure on the activity and stability of the catalyst. First of all, nanocrystalline NiB amorphous alloy catalysts were prepared by chemical reduction method. The effects of different solvents on the performance of nickel based catalysts in the hydrogenation of cinnamic acid were investigated. It was found that methanol and tert-butanol were used as solvents for the hydrogenation of cinnamic acid. The catalyst has the best activity, the conversion of cinnamic acid reaches 98.9 and the selectivity of hydrogenated cinnamic acid reaches 100. At the same time, when tert-butanol was used as solvent, the catalyst lost the least active component during hydrogenation. Then, the supported NiB amorphous alloy catalysts were prepared by impregnation-reduction method. The activity and stability of NiB/ 纬 -Al _ 2O _ 3NiB / Sio _ 2NiB / TIO _ 2 catalyst supported on different supports in the hydrogenation of cinnamic acid were investigated. It was found that the carrier 纬 -Al2O3 had a better effect on dispersing active components. NiB / 纬 -Al _ 2O _ 3 catalyst exhibited better stability when tert-butanol was used as solvent, and the activity of the catalyst gradually increased with the increase of application times. After three reactions, the conversion of cinnamic acid was 75.0 and the selectivity of hydrogenated cinnamic acid was 100. This may be due to the continuous exposure of the active components of the catalyst in the carrier channels with the reaction. Finally, a novel core-shell structure Ni-CamSiO _ 2 catalyst with magnetic separation was prepared by improved Stnber-self-assembly method. The catalyst showed good activity and selectivity in the selective hydrogenation of benzophenone. Under the optimum reaction conditions, the conversion of benzophenone reached 96.1 and the selectivity of dibenzyl alcohol was 94.9. The results of transmission electron microscope (TEM) (TEM) and temperature programmed desorption (CO2-TPD) of carbon dioxide show that the addition of alkaline earth metal calcium can not only improve the dispersion of nickel, but also adjust the acidity and basicity of the catalyst. The catalyst has high activity and selectivity in the selective hydrogenation of benzophenone to dibenzyl alcohol. In addition, the catalyst can be effectively separated by external magnetic field, and the activity of the catalyst can not change after four cycles, which proves that the catalyst has good stability.
【学位授予单位】：河北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36
本文编号：2147196
[Abstract]:As the representative of atomic economic reaction, catalytic hydrogenation accords with the idea of green chemistry and chemical engineering, and it is one of the hot research topics at home and abroad in recent years. Catalyst is the core of catalytic reaction, so the development of high activity catalyst plays an important role in the study of catalytic hydrogenation. In view of the expensive price of noble metal catalysts, a series of nickel based nanocatalysts were prepared for hydrogenation by using cheap and readily available transition metal nickel as the main active component. The effect of support and structure on the activity and stability of the catalyst. First of all, nanocrystalline NiB amorphous alloy catalysts were prepared by chemical reduction method. The effects of different solvents on the performance of nickel based catalysts in the hydrogenation of cinnamic acid were investigated. It was found that methanol and tert-butanol were used as solvents for the hydrogenation of cinnamic acid. The catalyst has the best activity, the conversion of cinnamic acid reaches 98.9 and the selectivity of hydrogenated cinnamic acid reaches 100. At the same time, when tert-butanol was used as solvent, the catalyst lost the least active component during hydrogenation. Then, the supported NiB amorphous alloy catalysts were prepared by impregnation-reduction method. The activity and stability of NiB/ 纬 -Al _ 2O _ 3NiB / Sio _ 2NiB / TIO _ 2 catalyst supported on different supports in the hydrogenation of cinnamic acid were investigated. It was found that the carrier 纬 -Al2O3 had a better effect on dispersing active components. NiB / 纬 -Al _ 2O _ 3 catalyst exhibited better stability when tert-butanol was used as solvent, and the activity of the catalyst gradually increased with the increase of application times. After three reactions, the conversion of cinnamic acid was 75.0 and the selectivity of hydrogenated cinnamic acid was 100. This may be due to the continuous exposure of the active components of the catalyst in the carrier channels with the reaction. Finally, a novel core-shell structure Ni-CamSiO _ 2 catalyst with magnetic separation was prepared by improved Stnber-self-assembly method. The catalyst showed good activity and selectivity in the selective hydrogenation of benzophenone. Under the optimum reaction conditions, the conversion of benzophenone reached 96.1 and the selectivity of dibenzyl alcohol was 94.9. The results of transmission electron microscope (TEM) (TEM) and temperature programmed desorption (CO2-TPD) of carbon dioxide show that the addition of alkaline earth metal calcium can not only improve the dispersion of nickel, but also adjust the acidity and basicity of the catalyst. The catalyst has high activity and selectivity in the selective hydrogenation of benzophenone to dibenzyl alcohol. In addition, the catalyst can be effectively separated by external magnetic field, and the activity of the catalyst can not change after four cycles, which proves that the catalyst has good stability.
【学位授予单位】：河北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36
【参考文献】
相关期刊论文 前2条
1 李辉;马春景;李和兴;;Ni-Co-B非晶态合金催化肉桂醛常压加氢制3-苯丙醛的研究[J];化学学报;2006年19期
2 李同信;高大彬;;非晶态合金催化剂研究进展[J];石油化工;1991年12期
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