本文關鍵詞： 一步法 玉米秸稈活性炭 催化劑 動力學 氫氣　出處：《青島科技大學》2015年碩士論文　論文類型：學位論文

【摘要】：隨著化石能源的日益枯竭和環(huán)境污染的不斷加重,可持續(xù)清潔能源-氫氣的開發(fā)受到世界各國的高度關注。氫能是未來的理想能源,可以通過燃燒得到熱能,同時也可作為燃料電池原料轉(zhuǎn)化為電能。然而氫氣在儲存和運輸方面的不便,使其在燃料電池方面的應用受到很大的限制。硼氫化鈉水解制氫技術由于其供給速率快、生產(chǎn)純度高、釋放條件溫和、產(chǎn)物對環(huán)境無污染等優(yōu)點引起國內(nèi)外研究者的廣泛關注。催化劑的制備是硼氫化鈉溶液發(fā)生水解制氫反應的核心技術。相比于貴金屬催化劑的價格昂貴、儲量有限等缺點,非貴金屬Co-基催化劑以其優(yōu)良的性能,成為近幾年來研究的熱點。催化劑的催化性能不僅與催化劑的基本組成有關,還與催化劑的形態(tài)結構緊密相關,而催化劑的制備方法正是造成其結構差異的主要原因之一。因此,針對國內(nèi)外Co-基催化劑的制備需求,尋求制備方法簡單、價格低廉且性能高效的Co-基催化劑是當前需要解決的關鍵問題。本文采用一步法簡單、高效制備了玉米秸稈活性炭Co-基制氫催化劑。玉米秸稈活性炭的活化過程與催化劑的高溫焙燒過程相結合,一方面減少單元操作,節(jié)省焙燒過程能耗；另一方面增強了載體與活性組分之間的相互作用,使催化劑的催化活性得以改善。主要研究內(nèi)容和研究結果如下：1、通過一步法制備了玉米秸稈活性炭Co-基制氫催化劑,考察了其催化硼氫化鈉溶液水解反應的產(chǎn)氫性能,優(yōu)化了一步法制備工藝條件(炭化溫度、炭化時間、活化溫度、活化時間),并考察了催化劑的穩(wěn)定性。研究結果表明,炭化-活化相結合的制備工藝使得Co-基催化劑催化硼氫化鈉的產(chǎn)氫性能改善。所述催化劑的最佳制備工藝為：400℃炭化1h,800℃活化2 h,平均產(chǎn)氫速率為1715.2mL·min-1·g-1,瞬時產(chǎn)氫速率最高達2952 mL·min-1·g-1。經(jīng)11次循環(huán)使用后,催化活性仍保持初始活性的51%,具有較高的循環(huán)穩(wěn)定性,可循環(huán)用于硼氫化鈉水解制氫。2、通過一步法引入助劑Fe和Mn元素制備成雙組分催化劑,并對引入其助劑的作用方式進行了探討分析。結果表明：(1)添加Fe、Mn后,催化劑的平均產(chǎn)氫速率均增至1784 mL·min-1·g-1,尤其是Co-Mn/AC催化劑,其瞬時產(chǎn)氫速率高達3040 mL·min-1·g-1.(2)助劑Fe、Mn的加入使活性組分在載體表面的團聚現(xiàn)象明顯減少,活性組分鑲嵌到活性炭的孔道內(nèi),抑制了活性相的流失。(3)助劑Fe的引入使得在20=44.2°處的特征峰向低角度略有偏移,Fe固溶于Co,晶格發(fā)生畸變,引起晶格常數(shù)的變化,活性點位增多。(4)助劑Mn的引入使得催化劑中活性組分的晶粒尺寸相比于Co、Co-Fe更小,活性組分的尺寸越小,越具有較大的表面原子比和較高的比表面積,從而提高其催化性能。3、對玉米秸稈活性炭Co/AC催化劑催化硼氫化鈉水解體系下的反應動力學進行詳細的分析,得到此催化劑的反應活化能為50.2 KJ·mmol-1,其表觀水解產(chǎn)氫速率動力學方程的表達式為：r=Ae-50200/(RT)[catalyst]0.48[NaOH]0.49[NaBH4]1.16當NaBH4的濃度小于10wt.%；而當NaBH4的濃度大于10wt.%時,則有r=Ae-50200/(RT)[catalyst]0.48[NaOH]0.49[NaBH4]1.16。
[Abstract]:With the increasing depletion of fossil energy and the worsening of environmental pollution and sustainable development of the clean energy hydrogen is highly concerned by all countries in the world. Hydrogen is an ideal energy in the future, through the combustion heat, but also can be used as fuel cell materials into electricity. However, hydrogen storage and transportation in the inconvenience. The application in fuel cells is limited. Hydrolysis of sodium borohydride due to the supply rate, the production of high purity, the release of mild conditions, attention product without pollution to the environment caused by domestic and foreign researchers. The preparation of catalyst is the core technology of sodium borohydride solution by hydrolysis reaction. Compared to the noble metal catalysts are expensive, disadvantages of limited reserves, non noble metal Co- catalyst for its excellent performance, has become a hot research topic in recent years. Catalytic The catalytic performance of the agent not only basic composition and catalyst, are closely related with the morphological structure of the catalyst, and the catalyst preparation method is one of the main causes of structural differences. Therefore, in view of the domestic and foreign Co- based catalyst preparation requirements for the preparation method is simple, inexpensive and Co- based catalyst high performance is the key problem to be solved. This paper uses a simple step, corn stalk activated carbon Co- based catalysts were prepared. High efficiency corn stalk active carbon activation process and catalyst calcination process combined with a reduction of unit operation, save the energy consumption in the process of roasting; enhances the interaction between the carrier and the the active components on the other hand, the catalytic activity of the catalyst was improved. The main research contents and results are as follows: 1, through one step preparation activity of maize straw Carbon Co- based catalyst for hydrogen production, hydrogen production performance of the catalytic hydrolysis of sodium borohydride solution was investigated, the preparation condition optimization (one-step carbonization temperature, carbonization time, activation temperature, activation time), and the stability of the catalyst was investigated. The results show that the carbon - activated preparation process combination the performance of Hydrogen Production Catalyzed by Co- catalyst boron sodium hydride. The best preparation process for the catalyst: 400 C 800 C 2 1H carbonization, activation of H, the average hydrogen production rate of 1715.2mL - min-1 - g-1, the instantaneous hydrogen production rate of up to 2952 mL - min-1 - g-1. after recycling 11 times after the catalytic activity remains the initial activity cycle 51%, high stability, can be recycled for hydrolysis of sodium borohydride.2, additive Fe and Mn elements for preparing two-component catalyst by one-step method is introduced, and the introduction of the additives was analyzed by the way Analysis. The results showed that: (1) add Fe, Mn, the average hydrogen production rate of catalyst was increased to 1784 mL - min-1 - g-1, especially Co-Mn/AC catalyst, the instantaneous hydrogen production rate of up to 3040 mL - min-1 - g-1. (2) Mn agent Fe, adding the active component was significantly reduced at the reunion the phenomenon of the surface of the carrier, active component embedded into the activated carbon pore, inhibited the loss of active phase. (3) the introduction of additives of Fe makes the characteristic peak at 20=44.2 DEG to the low angle slightly offset, Fe dissolved in the Co lattice distortion caused by the variation of lattice constants, active sites increased. (4) the introduction of additives of Mn makes the grain size of the active component in the catalyst compared to Co, Co-Fe is smaller, the smaller the size of the active component, has the larger surface atomic ratio and high surface area, so as to improve the catalytic performance of.3 catalytic boron corn stalk activated carbon Co /AC hydrogenation catalyst sodium and water The disintegration reaction kinetics system. A detailed analysis, the catalyst reaction activation energy is 50.2 KJ - mmol-1, the apparent expression of hydrolysis hydrogen production rate kinetics equation is: r=Ae-50200/ (RT) [catalyst]0.48[NaOH]0.49[NaBH4]1.16 when NaBH4 was less than 10wt.%; and when the concentration of NaBH4 is higher than 10wt.%, while r=Ae-50200/ (RT) [catalyst]0.48[NaOH]0.49[NaBH4]1.16.

【學位授予單位】：青島科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TQ116.2;TQ426

【參考文獻】

相關期刊論文 前1條

1 郭林,吳波,莊亞輝,李前樹,朱鶴孫;鈷氧化物納米催化劑的制備及對N_2O的分解[J];環(huán)境科學學報;1998年05期

，

本文編號：1479344