介孔結(jié)構(gòu)鐵鈷硅酸鹽復合材料的可控制備及催化性能研究
發(fā)布時間：2018-10-15 17:59
【摘要】：具有核殼結(jié)構(gòu)的納米復合材料的性質(zhì)比單組分材料的性質(zhì)優(yōu)異,因此在催化、填料、多功能涂層材料以及藥物載體、生物醫(yī)藥等諸多方面有著廣泛的應用和發(fā)展前景。過渡金屬催化劑因熱穩(wěn)定性高、原料廉價易求,所以常用于催化硝基苯液相加氫生產(chǎn)苯胺。本論文的研究成果總結(jié)如下:1.介孔硅酸鐵微球的水熱合成及表征。在水熱條件下,采用犧牲模板界面反應法,合成了具有中空結(jié)構(gòu)的介孔硅酸鐵微球,并對合成過程進行了初步的研究。研究發(fā)現(xiàn):不同的堿性環(huán)境會影響產(chǎn)物的形貌和物相組成,非堿性環(huán)境下會生成棒狀的氧化鐵。當反應物硅鐵摩爾比為1:2時得到的水熱產(chǎn)物為尺寸均一的銀耳狀花球。隨著反應時間的延長,水熱產(chǎn)物由核殼微球變?yōu)榭招奈⑶颉Ｒ虼?可以通過控制反應時間來調(diào)整產(chǎn)物的微觀結(jié)構(gòu),合成具有核殼或空心結(jié)構(gòu)的硅酸鐵。硅酸鐵空心球的比表面積為142.2 m2/g,且具有介孔結(jié)構(gòu)。2.介孔Fe/SiO_2的制備及催化性能研究。將介孔硅酸鐵空心微球在氫氣氣氛下,保持600°C還原3 h,得到介孔Fe/SiO_2催化劑,還原前后微球的尺寸和形貌沒有很大變化,仍保持空心結(jié)構(gòu)。將Fe/SiO_2用于硝基苯液相加氫制備苯胺,考察Fe/SiO_2的催化活性,研究表明:提高反應溫度有利于硝基苯轉(zhuǎn)化為苯胺,加快催化反應的速度,節(jié)省反應時間。當催化溫度為100 °C時,時間為5 h時即可達到平衡,硝基苯的轉(zhuǎn)化率為75%,苯胺的選擇性是83%;Fe/SiO_2催化劑的催化性能隨水熱反應時間的延長而提高,在水熱反應時間達到24 h時,產(chǎn)物是空心球結(jié)構(gòu),比表面積更大,催化效果更好。3.Fe-Co/SiO_2的水熱-還原合成及催化性能。在180 °C下反應12 h得到了具有介孔結(jié)構(gòu)的海膽狀堿式硅酸鈷空心微球,在氫氣氣氛下被完全還原為介孔Co/SiO_2空心微球,還原前后樣品的形貌沒有較大變化,比表面積分別是382.78 m2/g,158.25 m2/g。將Co/SiO_2用于催化硝基苯液相加氫制備苯胺,表現(xiàn)出較高的催化活性。當鐵鈷摩爾比為2:1,堿性水熱環(huán)境下得到了尺寸均一、形貌穩(wěn)定的鐵鈷硅酸鹽復合微球。研究發(fā)現(xiàn):升高水熱反應溫度能夠加快反應速度,但溫度過高會導致中空結(jié)構(gòu)不穩(wěn)定而發(fā)生坍塌。水熱產(chǎn)物被氫氣還原為介孔Fe-Co/SiO_2中空微球,比表面積較大,有利于物質(zhì)的傳輸并發(fā)揮催化活性,由于雙金屬的協(xié)同效應,使得鐵鈷復合催化劑的催化性能比單一金屬催化劑的催化性能更好。
[Abstract]:The properties of nanocomposites with core-shell structure are better than that of single-component materials, so they are widely used and developed in catalysis, packing, multifunctional coating materials, drug carriers, biomedicine and so on. Because of its high thermal stability and cheap raw materials, transition metal catalysts are often used to catalyze the liquid phase hydrogenation of nitrobenzene to produce aniline. The research results of this paper are summarized as follows: 1. Hydrothermal synthesis and characterization of mesoporous iron silicate microspheres. Mesoporous ferric silicate microspheres with hollow structure were synthesized by sacrificial template interface reaction under hydrothermal conditions. It is found that the morphology and phase composition of the product will be affected by different alkaline environment, and the rod-like iron oxide will be formed in non-alkaline environment. When the molar ratio of silicon to iron was 1:2, the hydrothermal product was a uniform Tremella flower ball. With the increase of reaction time, the hydrothermal products changed from core-shell microspheres to hollow microspheres. Therefore, the microstructure of the product can be adjusted by controlling the reaction time to synthesize ferric silicate with core-shell or hollow structure. The specific surface area of iron silicate hollow spheres is 142.2 m2 / g and has mesoporous structure. Preparation and catalytic properties of mesoporous Fe/SiO_2. The mesoporous iron silicate hollow microspheres were reduced to 600 擄C for 3 h in hydrogen atmosphere, and the mesoporous Fe/SiO_2 catalyst was obtained. The size and morphology of the mesoporous Fe/SiO_2 microspheres did not change greatly before and after reduction, and the hollow structure was maintained. Fe/SiO_2 was used in liquid phase hydrogenation of nitrobenzene to prepare aniline. The catalytic activity of Fe/SiO_2 was investigated. The results showed that increasing the reaction temperature was beneficial to the conversion of nitrobenzene to aniline, accelerating the rate of catalytic reaction and saving the reaction time. When the catalytic temperature is 100 擄C, the reaction time is 5 h, the conversion rate of nitrobenzene is 75, the selectivity of aniline is 83% Fe / SiO2 catalyst, and the catalytic performance of the catalyst increases with the prolongation of hydrothermal reaction time, and when the hydrothermal reaction time reaches 24 h, the selectivity of aniline increases with the increase of hydrothermal reaction time. The product is hollow sphere structure with larger specific surface area and better catalytic effect. Hydrothermal reduction synthesis and catalytic performance of 3.Fe-Co/SiO_2. The basic cobalt silicate hollow microspheres with mesoporous structure were prepared at 180 擄C for 12 h. The microspheres were completely reduced to mesoporous Co/SiO_2 hollow microspheres in hydrogen atmosphere. The morphology of the samples did not change significantly before and after the reduction, with a specific surface area of 382.78 m2 / g ~ 158.25 m ~ (2 / g), respectively. Co/SiO_2 was used to catalyze the hydrogenation of nitrobenzene to aniline in liquid phase and showed high catalytic activity. When the molar ratio of iron and cobalt is 2: 1, the Fe-Co silicate composite microspheres with uniform size and stable morphology are obtained in alkaline hydrothermal environment. It is found that the reaction rate can be accelerated by increasing the hydrothermal reaction temperature, but the hollow structure will collapse due to the instability of the hollow structure when the temperature is too high. Hydrothermal products were reduced by hydrogen to mesoporous Fe-Co/SiO_2 hollow microspheres with large specific surface area, which was conducive to the transport of materials and played a catalytic activity, due to the synergistic effect of bimetallic materials. The catalytic performance of Fe-Co composite catalyst is better than that of single metal catalyst.
【學位授予單位】：青島科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TB33;O643.36
[Abstract]:The properties of nanocomposites with core-shell structure are better than that of single-component materials, so they are widely used and developed in catalysis, packing, multifunctional coating materials, drug carriers, biomedicine and so on. Because of its high thermal stability and cheap raw materials, transition metal catalysts are often used to catalyze the liquid phase hydrogenation of nitrobenzene to produce aniline. The research results of this paper are summarized as follows: 1. Hydrothermal synthesis and characterization of mesoporous iron silicate microspheres. Mesoporous ferric silicate microspheres with hollow structure were synthesized by sacrificial template interface reaction under hydrothermal conditions. It is found that the morphology and phase composition of the product will be affected by different alkaline environment, and the rod-like iron oxide will be formed in non-alkaline environment. When the molar ratio of silicon to iron was 1:2, the hydrothermal product was a uniform Tremella flower ball. With the increase of reaction time, the hydrothermal products changed from core-shell microspheres to hollow microspheres. Therefore, the microstructure of the product can be adjusted by controlling the reaction time to synthesize ferric silicate with core-shell or hollow structure. The specific surface area of iron silicate hollow spheres is 142.2 m2 / g and has mesoporous structure. Preparation and catalytic properties of mesoporous Fe/SiO_2. The mesoporous iron silicate hollow microspheres were reduced to 600 擄C for 3 h in hydrogen atmosphere, and the mesoporous Fe/SiO_2 catalyst was obtained. The size and morphology of the mesoporous Fe/SiO_2 microspheres did not change greatly before and after reduction, and the hollow structure was maintained. Fe/SiO_2 was used in liquid phase hydrogenation of nitrobenzene to prepare aniline. The catalytic activity of Fe/SiO_2 was investigated. The results showed that increasing the reaction temperature was beneficial to the conversion of nitrobenzene to aniline, accelerating the rate of catalytic reaction and saving the reaction time. When the catalytic temperature is 100 擄C, the reaction time is 5 h, the conversion rate of nitrobenzene is 75, the selectivity of aniline is 83% Fe / SiO2 catalyst, and the catalytic performance of the catalyst increases with the prolongation of hydrothermal reaction time, and when the hydrothermal reaction time reaches 24 h, the selectivity of aniline increases with the increase of hydrothermal reaction time. The product is hollow sphere structure with larger specific surface area and better catalytic effect. Hydrothermal reduction synthesis and catalytic performance of 3.Fe-Co/SiO_2. The basic cobalt silicate hollow microspheres with mesoporous structure were prepared at 180 擄C for 12 h. The microspheres were completely reduced to mesoporous Co/SiO_2 hollow microspheres in hydrogen atmosphere. The morphology of the samples did not change significantly before and after the reduction, with a specific surface area of 382.78 m2 / g ~ 158.25 m ~ (2 / g), respectively. Co/SiO_2 was used to catalyze the hydrogenation of nitrobenzene to aniline in liquid phase and showed high catalytic activity. When the molar ratio of iron and cobalt is 2: 1, the Fe-Co silicate composite microspheres with uniform size and stable morphology are obtained in alkaline hydrothermal environment. It is found that the reaction rate can be accelerated by increasing the hydrothermal reaction temperature, but the hollow structure will collapse due to the instability of the hollow structure when the temperature is too high. Hydrothermal products were reduced by hydrogen to mesoporous Fe-Co/SiO_2 hollow microspheres with large specific surface area, which was conducive to the transport of materials and played a catalytic activity, due to the synergistic effect of bimetallic materials. The catalytic performance of Fe-Co composite catalyst is better than that of single metal catalyst.
【學位授予單位】：青島科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TB33;O643.36
【參考文獻】
相關(guān)期刊論文 前10條
1 楊翠英;申騰;滕弘霓;;表面活性劑模板法制備介孔材料的研究進展[J];山東科技大學學報(自然科學版);2016年06期
2 秦祖贈;栗西亮;蔣月秀;謝新玲;粟海鋒;;硝基苯氣-固相催化加氫為苯胺的實驗研究[J];實驗室研究與探索;2016年03期
3 李君瑞;李曉紅;丁s，
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