鎳基納米催化劑的制備及其在加氫反應中穩(wěn)定性的研究
發(fā)布時間：2018-07-26 20:25
【摘要】：催化加氫作為原子經濟性反應的代表,符合綠色化學化工的理念,是近年來國內外研究的熱點之一。催化劑是催化反應的核心所在,因此,高效催化劑的開發(fā)在催化加氫反應的研究中占有重要的地位。針對貴金屬催化劑存在的價格昂貴等問題,本文采用廉價易得的過渡金屬鎳為主催化活性組分,制備了一系列的鎳基納米催化劑用于加氫反應,重點考察了溶劑、載體及催化劑結構對催化劑活性和穩(wěn)定性的影響。首先,采用化學還原法來制備納米NiB非晶態(tài)合金催化劑,考察了不同溶劑對鎳基催化劑在肉桂酸加氫反應中性能的影響,發(fā)現(xiàn)以甲醇和叔丁醇為溶劑時,催化劑具有最佳的活性,肉桂酸的轉化率達到98.9%,氫化肉桂酸的選擇性達到100%。與此同時,當以叔丁醇為溶劑時,在加氫反應過程中催化劑的活性組分流失最少。然后,通過浸漬-還原法制備了負載型NiB非晶態(tài)合金催化劑,考察了不同載體負載的鎳基催化劑(NiB/γ-Al_2O_3、NiB/SiO2、NiB/TiO2)在肉桂酸加氫反應中的活性和穩(wěn)定性,發(fā)現(xiàn)載體γ-Al_2O_3具有較好的分散活性組分的作用。NiB/γ-Al_2O_3催化劑在叔丁醇作溶劑時表現(xiàn)出了較好的穩(wěn)定性,隨著套用次數(shù)的增加,催化劑的活性逐漸增加,反應三次后肉桂酸的轉化率為75.0%,氫化肉桂酸的選擇性依然是100%。這可能是因為催化劑在載體孔道中的活性組分隨著反應的進行而不斷暴露所致。最后,通過改進的St?ber-自組裝法制備一種新型可磁分離的核殼結構鎳基納米催化劑Ni-Ca@mSiO2。該催化劑在二苯甲酮的選擇性加氫反應中顯示出了良好的活性和選擇性。在最佳反應條件下,二苯甲酮的轉化率達到96.1%,二苯甲醇的選擇性為94.9%。透射電子顯微鏡(TEM)和二氧化碳程序升溫脫附(CO2-TPD)測試結果表明堿土金屬鈣的添加不但有利于提高活性組分鎳的分散度,并且能調節(jié)催化劑的酸堿性,抑制目標產物二苯甲醇的脫水,使該催化劑在二苯甲酮選擇性加氫制備二苯甲醇的反應中同時具有高活性和高選擇性。此外,使用后的催化劑可利用外部磁場有效分離,且循環(huán)使用四次后活性基本無變化,證明該催化劑還具有不錯的穩(wěn)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/ 緯 -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 緯 -Al2O3 had a better effect on dispersing active components. NiB / 緯 -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.
【學位授予單位】：河北大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O643.36
本文編號：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/ 緯 -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 緯 -Al2O3 had a better effect on dispersing active components. NiB / 緯 -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.
【學位授予單位】：河北大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O643.36
【參考文獻】
相關期刊論文 前2條
1 李輝;馬春景;李和興;;Ni-Co-B非晶態(tài)合金催化肉桂醛常壓加氫制3-苯丙醛的研究[J];化學學報;2006年19期
2 李同信;高大彬;;非晶態(tài)合金催化劑研究進展[J];石油化工;1991年12期
，本文編號：2147196
本文鏈接：http://sikaile.net/kejilunwen/huaxue/2147196.html
教材專著
