發(fā)布時間：2018-04-10 03:33

  本文選題：甲烷重整制氫　切入點：構(gòu)效關(guān)系　出處：《南昌大學》2017年碩士論文

【摘要】：隨著全球經(jīng)濟的飛速發(fā)展,煤碳和石油等化石能源消耗速度加快,但其儲量有限,終將枯竭。此外,化石類燃料的不潔使用導致日益嚴重的環(huán)境污染,人類生存環(huán)境惡化。甲烷是天然氣和頁巖氣的主要成分,相比煤碳和石油類石化能源更清潔,且來源豐富。甲烷重整是實現(xiàn)甲烷高值轉(zhuǎn)化的主要途徑之一,其中甲烷水蒸氣重整制氫是目前工業(yè)用氫的主要來源,全世界約有1/2的氫氣通過該方法制取。Ni基催化劑因其初始活性高且價格低廉,被廣泛用于甲烷重整制氫。但目前工業(yè)上使用的Ni基催化劑在高溫反應條件下易積碳、活性Ni物種易聚集并最終導致Ni基催化劑失活。因此,本論文在深入理解甲烷重整反應機理的基礎上,從調(diào)變催化劑載體結(jié)構(gòu)和控制Ni顆粒尺寸等角度出發(fā),設計制備了含不同A位或B位離子的A_2B_2O_7燒綠石型復合氧化物載體,負載Ni用于甲烷重整制氫。主要內(nèi)容和成果總結(jié)如下:第一部分:設計制備了B位為Zr離子但A位含不同稀土離子的Ln_2Zr_2O_7載體負載Ni用于甲烷水蒸氣重整制氫。XRD和Raman結(jié)果表明,當A位離子依次為La~(3+),Pr~(3+),Sm~(3+)和Y~(3+)時,A、B位離子半徑比r_(A3+)/r _(Zr4+)逐漸減小,Ln_2Zr_2O_7復合氧化物從嚴整的燒綠石結(jié)構(gòu)(La_2Zr_2O_7),逐漸轉(zhuǎn)變?yōu)闊o序的燒綠石結(jié)構(gòu)(Pr_2Zr_2O_7和Sm_2Zr_2O_7),直至形成無序度很高的缺陷的螢石結(jié)構(gòu)(Y_2Zr_2O_7),導致Ln_2Zr_2O_7結(jié)構(gòu)中氧離子的無序性程度增大,流動性提高。H_2-TPR結(jié)果表明,活性組分Ni和無序性程度更大的Ln_2Zr_2O_7載體間的相互作用更強,從而導致Ni的分散度以及活性Ni物種的熱穩(wěn)定性更高。具有缺陷螢石結(jié)構(gòu)的Y_2Zr_2O_7載體具有最多的活潑氧物種。因此,Ni/Y_2Zr_2O_7催化劑表現(xiàn)出了最高的反應活性、穩(wěn)定性和抗積碳性能。第二部分:設計制備了A位為Y離子但B位含不同金屬離子的Y_2B_2O_7載體負載Ni用于甲烷重整制氫。XRD和Raman結(jié)果表明,當B位離子依次為Ti~(4+)、Sn~(4+)、Zr~(4+)、Ce~(4+)時,A、B位離子半徑比r_(Y3+)/r _(B4+)逐漸減小,Y_2B_2O_7復合氧化物從穩(wěn)定的燒綠石結(jié)構(gòu)(Y_2Ti_2O_7),逐漸轉(zhuǎn)變?yōu)闊o序的燒綠石結(jié)構(gòu)(Y_2Sn_2O_7),直至形成無序度很高的缺陷的螢石結(jié)構(gòu)(Y_2Zr_2O_7和Y_2Ce_2O_7)。XPS結(jié)果表明,與Ni/Y_2Zr_2O_7和Ni/Y_2Ce_2O_7相比,Ni/Y_2Ti_2O_7和Ni/Y_2Sn_2O_7催化劑上具有更多的表面氧物種。H_2-TPR結(jié)果表明,與Ni/Y_2Zr_2O_7和Ni/Y_2Ce_2O_7催化劑相比,Ni或Ni_2Sn_3活性組分與Y_2Ti_2O_7和Y_2Sn_2O_7載體間具有明顯更強的相互作用,從而將活性組分緊緊的錨定在載體表面并抑制其聚集,因此導致該兩催化劑上活性金屬比表面積更大、熱穩(wěn)定性更好。還原態(tài)Ni/Y_2Sn_2O_7催化劑上形成了Ni_3Sn_2物種,該物種顯著提高了催化劑的抗積碳性能但明顯犧牲了活性,因而限制了其工業(yè)應用前景。綜上所述,Ni/Y_2Ti_2O_7催化劑表現(xiàn)出了最高的活性、穩(wěn)定性和抗積碳性能。
[Abstract]:With the rapid development of the global economy, fossil energy consumption, such as coal and oil, has been accelerated, but its reserves are limited and will eventually dry up.In addition, the unclean use of fossil fuels leads to increasingly serious environmental pollution and deterioration of human living environment.Methane is a major component of natural gas and shale gas, cleaner and more abundant than coal and petroleum petrochemicals.Methane reforming is one of the main ways to realize the high value conversion of methane, in which steam reforming of methane is the main source of hydrogen for industrial use.About 1 / 2 of the hydrogen produced by this method is widely used in methane reforming for hydrogen production due to its high initial activity and low cost.However, at present, Ni based catalysts used in industry tend to deposit carbon at high temperature, and active Ni species tend to accumulate and lead to deactivation of Ni based catalysts.Therefore, on the basis of deep understanding of the mechanism of methane reforming reaction, from the point of view of adjusting the catalyst structure and controlling the size of Ni particles, the A_2B_2O_7 pyrochlore complex oxide carrier containing different A-site or B-site ions was designed and prepared.Supported Ni was used in methane reforming to produce hydrogen.The main contents and achievements are summarized as follows: in the first part, Ni supported on Ln_2Zr_2O_7 carrier with Zr ions at position B but different rare earth ions at site A has been designed and prepared for hydrogen production by steam reforming of methane. The results of XRD and Raman show that Ni carrier supported on Ni carrier is used in steam reforming of methane to produce hydrogen.The very high defect fluorite structure of Ys _ 2Zr _ 2O _ 7 leads to an increase in the degree of disorder of oxygen ions in the Ln_2Zr_2O_7 structure.The results of enhanced fluidity. H2-TPR show that the interaction between active component Ni and Ln_2Zr_2O_7 carrier with greater disordered degree is stronger, which leads to higher dispersion of Ni and higher thermal stability of active Ni species.Y_2Zr_2O_7 carriers with defective fluorite structure have the most active oxygen species.Therefore, the Ni / Y _ 2Zr _ 2O _ 7 catalyst exhibited the highest reaction activity, stability and resistance to carbon deposition.The second part: the Ni supported on Y_2B_2O_7 carrier with Y ion at position A but different metal ions in B site was designed and prepared for reforming methane to produce hydrogen. The results of XRD and Raman showed that Ni was used in reforming methane to produce hydrogen.The results of the trapped fluorite structure, Ys _ 2Zr _ 2O _ 7 and Y_2Ce_2O_7).XPS indicate that,Compared with Ni/Y_2Zr_2O_7 and Ni/Y_2Ce_2O_7, there are more surface oxygen species. H2-TPR results show that the active components of Ni or Ni_2Sn_3 have significantly stronger interaction with Y_2Ti_2O_7 and Y_2Sn_2O_7 supports than Ni/Y_2Zr_2O_7 and Ni/Y_2Ce_2O_7 catalysts.Thus, the active components were tightly anchored on the surface of the support and inhibited their aggregation, which led to the larger specific surface area and better thermal stability of the active metals on the two catalysts.A species of Ni_3Sn_2 was formed on the reduced Ni/Y_2Sn_2O_7 catalyst. The species significantly improved the carbon deposition resistance of the catalyst, but obviously sacrificed its activity, thus limiting its industrial application prospects.To sum up, the Ni / Y _ 2TiS _ 2O _ 7 catalyst showed the highest activity, stability and anti-carbon property.
【學位授予單位】：南昌大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O643.36;TQ116.2

【參考文獻】

相關(guān)期刊論文 前2條

1 Xiuzhong Fang;Jie Lian;Kaiwen Nie;Xianhua Zhang;Yanfeng Dai;Xianglan Xu;Xiang Wang;Wenming Liu;Changqing Li;Wufeng Zhou;;Dry reforming of methane on active and coke resistant Ni/Y_2Zr_2O_7 catalysts treated by dielectric barrier discharge plasma[J];Journal of Energy Chemistry;2016年05期

2 Honggen Peng;Youhe Ma;Wenming Liu;Xianglan Xu;Xiuzhong Fang;Jie Lian;Xiang Wang;Changqing Li;Wufeng Zhou;Ping Yuan;;Methane dry reforming on Ni/La_2Zr_2O_7 treated by plasma in different atmospheres[J];Journal of Energy Chemistry;2015年04期

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本文編號：1729501