發(fā)布時間：2018-01-26 02:43

  本文關(guān)鍵詞： 溶液燃燒合成 納米材料 鎢基材料 光催化性能 氧化物彌散強化　出處：《北京科技大學(xué)》2017年博士論文　論文類型：學(xué)位論文

【摘要】：納米鎢基材料由于其獨特的理化特性被廣泛應(yīng)用于催化、電子、航空航天、國防軍工等眾多領(lǐng)域。溶液燃燒合成是近年來發(fā)展迅速的一種制備納米材料的新的濕化學(xué)方法,具有簡便、快捷、能耗小、成本低、產(chǎn)物活性高等諸多優(yōu)點。本論文研究將低溫燃燒合成應(yīng)用于納米鎢基材料的制備。主要研究了以下幾個方面的內(nèi)容：(1)研究了燃料種類、配比等參數(shù)對燃燒反應(yīng)的過程、機理以及產(chǎn)物的結(jié)構(gòu)、形貌、物相的影響,成功通過一步燃燒法合成了單相的WO_ 3、W_(18)O_(49)。在甘氨酸、尿素/檸檬酸混合為燃料的兩種燃燒體系中,反應(yīng)過程中可形成了泡沫狀網(wǎng)絡(luò)結(jié)構(gòu),制備出直徑小于100nm,長度為5μm左右的納米針狀純相W_(18)O_(49)。單獨采用尿素作為燃料時,制備出了粒徑小于100nm顆粒狀純相WO_ 3。所制備納米氧化鎢具有優(yōu)異光催化性能,能夠在50min內(nèi)將40ppm的MB溶液降解完全。(2)通過引入摻雜元素,利用溶液燃燒法制備出摻雜氧化鎢粉體材料,可進(jìn)一步提高其光催化性能。通過在燃燒體系中引入硝酸鐵作為鐵源,首次利用溶液燃燒合成一步制備Fe~(3+)摻雜W_(18)O_(49),Fe與W_(18)O_(49)的光反應(yīng)協(xié)同作用以及摻雜造成的缺陷使其催化性能提高。在Fe~(3+)摻雜量為0.5wt%時,得到的復(fù)合粉末的光催化性能最好,能夠在30min內(nèi)將40ppm的MB溶液降解完全。通過在燃燒體系中引入葡萄糖作為碳源,利用溶液燃燒法制備出無定型C復(fù)合WO_ x粉體,在碳復(fù)合與缺陷結(jié)構(gòu)的協(xié)同作用下,C復(fù)合WO_ x粉體材料可以在40min內(nèi)將80ppm的MB溶液降解完全,并呈現(xiàn)出優(yōu)異的循環(huán)穩(wěn)定性。(3)通過在燃燒體系中引入硝酸鑭作為稀土源,首次利用溶液燃燒法制備出粒度細(xì)小、摻雜均勻的氧化鎢與稀土氧化物的復(fù)合前驅(qū)體。以該前驅(qū)體為原料,在700℃的氫氣氣氛中還原2小時,制備出粒徑為20-30nm、分散性好、氧化鑭摻雜均勻的鎢基粉末。(4)所制備氧化鑭摻雜鎢基(La_2O_3—W)粉末具有很高的燒結(jié)活性,在1500℃下燒結(jié)可達(dá)到95%以上的致密度。隨著氧化鑭含量的增加(氧化鑭含量在0～1%范圍內(nèi)),晶粒尺寸減小。隨著溫度的升高,材料的顯微硬度先上升后下降,在1500℃呈現(xiàn)出最大值。對于La_2O_3含量為1.0%樣品,在1500℃燒結(jié),材料晶粒尺寸為300～500nm,第二相粒子尺寸小于50nm,分布均勻,顯微硬度達(dá)到703HV_(0.2),力學(xué)性能優(yōu)異。
[Abstract]:Nanocrystalline tungsten based materials have been widely used in catalysis, electronics and aerospace due to their unique physical and chemical properties. Solution combustion synthesis is a new wet chemical method for the preparation of nanomaterials in recent years. It is simple, fast, low energy consumption and low cost. In this paper, low temperature combustion synthesis was applied to the preparation of nanocrystalline tungsten-based materials. The single phase WO _ 3 was successfully synthesized by one-step combustion method with the influence of the ratio and other parameters on the process, mechanism, structure, morphology and phase of the product. In the combustion systems of glycine and urea / citric acid, the foam network structure can be formed during the reaction, and the diameter is less than 100 nm. When using urea alone as fuel, the nanoscale needle-like pure phase WA18 / O _ (9) is about 5 渭 m in length. The pure phase WO _ 3 with particle size less than 100 nm was prepared. The prepared nanocrystalline tungsten oxide has excellent photocatalytic performance. The 40 ppm MB solution can be completely degraded within 50 min.) doped tungsten oxide powder materials were prepared by solution combustion method by introducing doping elements. By introducing ferric nitrate as Tie Yuan in combustion system, Fe~(3 was synthesized by solution combustion for the first time. The synergistic effect of Fe and W _ S _ (18) O _ (9) and the defects caused by doping can improve its catalytic performance. When the doping amount of Fe~(3 is 0.5 wt%. The composite powder has the best photocatalytic performance and can completely degrade 40 ppm MB solution in 30 min. Glucose is introduced as carbon source in combustion system. Amorphous C composite WO _ x powder was prepared by solution combustion method. C composite WO _ x powder can completely degrade 80 ppm MB solution in 40 min. And showed excellent cycle stability. 3) by introducing lanthanum nitrate as rare earth source in combustion system, the particle size was prepared by solution combustion method for the first time. The composite precursor doped with tungsten oxide and rare earth oxide was prepared by reducing the precursor in hydrogen atmosphere at 700 鈩，

本文編號：1464434