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新型非貴金屬Fe、Ni基納米催化劑的結(jié)構(gòu)調(diào)控與催化制氫性能

發(fā)布時間:2018-04-15 21:23

  本文選題:氨分解 + 氨硼烷水解; 參考:《華東理工大學》2017年碩士論文


【摘要】:氫能來源豐富、可再生和可儲存的優(yōu)點,使其成為未來替代化石燃料的理想能源之一。尋求高密度儲氫材料和研發(fā)高效非貴金屬催化劑來建立潔凈氫能系統(tǒng)已成為當前能源研究的熱點之一。氨氣和氨硼烷均具有較高的能量密度(氫密度分別為17.6wt%和19.6wt%),且易儲存運輸,故而兩種儲氫材料均成為了人們關(guān)注的對象。高效氨分解和氨硼烷水解制氫催化劑主要集中于貴金屬催化劑(如Ru、Pt),高昂的成本迫使人們開發(fā)低成本和高儲量的非貴金屬催化劑(如Fe、Ni、Co)。此外,氨分解和氨硼烷水解作為典型的結(jié)構(gòu)敏感性反應,不僅廣泛應用于潔凈能源的轉(zhuǎn)化,還可以用作模型反應體系來研究催化劑表面結(jié)構(gòu)、電子特性與催化性能之間的關(guān)系。本文以Fe、Ni基非貴金屬催化劑為研究對象,采用催化化學氣相沉積(Catalytic Chemical Vapor Deposition,CCVD)法和液相化學還原法分別制備可控形貌的Fe基催化劑和Ni基復合物催化劑,并應用于氨分解和氨硼烷水解制氫模型反應,闡明催化劑結(jié)構(gòu)和制氫反應性能的構(gòu)效關(guān)系。(1)研究了碳源分壓和納米碳纖維生長時間在CCVD過程中對Fe納米顆粒形貌調(diào)控的影響。發(fā)現(xiàn)碳源分壓較高時有利于形成長狀多面體形貌的Fe顆粒,碳源分壓較低時易形成無規(guī)則形貌的Fe顆粒。碳纖維生長時間的增長則會進一步導致Fe納米顆粒的重構(gòu)。多面體形貌的Fe納米顆粒表現(xiàn)出更高的氨分解活性。(2)比較研究了CCVD法和傳統(tǒng)浸漬法制備的Fe、Ni基催化劑的氨分解活性,發(fā)現(xiàn)兩種方法制備的催化劑活性趨勢相反。進一步結(jié)合理論計算,揭示了表面C和次表面C對Fe、Ni催化劑上氨分解性能的影響機制,發(fā)現(xiàn)其影響規(guī)律呈現(xiàn)出相反的趨勢。(3)利用化學還原法制備了 NiB非晶態(tài)合金及其載體復合物催化劑并考察其在氨硼烷水解制氫中的活性和耐久性。進一步利用N2-BET、XRD、TEM等催化表征手段分析了不同催化劑的載體效應。動力學和同位素實驗表明CNTs負載的NiB非晶態(tài)合金催化劑具有較低的活化能并且能夠促進水的活化,進而提高氨硼烷水解活性。
[Abstract]:Hydrogen rich source of renewable and storage advantages, make it become one of the ideal energy to replace fossil fuels in the future. For high density hydrogen storage materials and development of high efficiency non noble metal catalysts to establish clean hydrogen energy system has become a hotspot of current research. The energy of ammonia and ammonia borane have high energy density (hydrogen density respectively. For 17.6wt% and 19.6wt%), and easy storage and transportation, so the two kinds of hydrogen storage materials have become the object of attention. Efficient decomposition of ammonia and ammonia borane hydrolysis catalysts mainly concentrated on noble metal catalysts (Ru, Pt), the high cost of forcing people to develop low cost and non noble metal catalysts with high reserves (such as Fe, Ni, Co). In addition, the decomposition of ammonia and ammonia borane hydrolysis as a typical structure sensitive reaction, the transformation is not only widely used in clean energy, can also be used as model to study catalytic reaction system Agent surface structure, the relationship between the electronic properties and catalytic performance of Fe. In this paper, Ni based non noble metal catalyst as the research object, using catalytic chemical vapor deposition (Catalytic Chemical Vapor Deposition, CCVD) preparation of controllable morphology of Fe catalyst and Ni composite catalyst respectively, preparation method and liquid phase chemical reduction method. And applied to the decomposition of ammonia and ammonia borane hydrolysis hydrogen production model reaction. The relationship between structure and hydrogen production catalyst performance (1). To clarify the effects of carbon source growth time on the morphology of Fe nanoparticles in the regulation process of CCVD pressure and nano carbon fiber. It is found that the carbon source pressure is high to Fe the particles formed long shaped polyhedron morphology, carbon source at low pressure to form Fe particles of irregular shape. The growth of carbon fiber growth time would lead to the reconstruction of Fe nanoparticles. The morphology of polyhedral Fe nanoparticles Exhibit higher ammonia decomposition activity. (2) a comparative study of the CCVD method and traditional impregnation method to prepare Fe, Ni based catalysts for ammonia decomposition activity, found that the catalyst activity trend of two kinds of preparation methods of the contrary. Further according to the theoretical calculation, reveals the surface and sub surface of C C Fe, Ni catalyst ammonia decomposition performance influence mechanism, the influencing law showed the opposite trend. (3) preparation of NiB amorphous alloy and carrier complex catalyst were investigated in ammonia borane by hydrolysis of the activity and durability by chemical reduction method. The further use of N2-BET, XRD, TEM and other characterization methods of effect of different carrier catalyst the analysis of the catalyst. The kinetic and isotopic experiments show that CNTs supported NiB amorphous alloy catalyst has low activation energy and can promote the activation of water, and then improve the ammonia borane hydrolysis activity.

【學位授予單位】:華東理工大學
【學位級別】:碩士
【學位授予年份】:2017
【分類號】:O643.36;TQ116.2

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