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  本文關(guān)鍵詞：多相催化過程中催化劑表面吸附層的介尺度行為　出處：《中國科學(xué)院大學(xué)(中國科學(xué)院過程工程研究所)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 多相催化 非平衡 吸附層結(jié)構(gòu) 介尺度 競爭中協(xié)調(diào)

【摘要】：在多相催化反應(yīng)過程中,反應(yīng)物和生成物可以在催化劑表面上形成復(fù)雜的吸附層結(jié)構(gòu),這些結(jié)構(gòu)對多相催化的宏觀表現(xiàn)有著重要影響。目前描述多相催化反應(yīng)過程主要有三種模型,分別是宏觀模型、微觀模型和介觀模型。忽略這種結(jié)構(gòu),采用平均化的處理方式,往往造成嚴重偏差,這是目前宏觀模型的主要缺陷;而直接描述原子、分子過程的微觀模型又包含了太多的冗余信息,以致巨大的計算開銷都難以達到實際需要的時空規(guī)模。雖然通過局部覆蓋度修正動力學(xué)速率的介觀模型引入結(jié)構(gòu)對動力學(xué)行為的影響,但其仍然采用局部平均化的分析方法,并未擺脫宏觀模型的本質(zhì)缺陷,因此,這樣的介觀模型仍未準確反映結(jié)構(gòu)對體系的影響。在氣-固流態(tài)化系統(tǒng)的研究中,能量最小多尺度(EMMS)模型已被證明可以有效關(guān)聯(lián)不同尺度。由此提出的EMMS原理認為,復(fù)雜系統(tǒng)的穩(wěn)定性條件可以表示為主導(dǎo)機制間競爭中的協(xié)調(diào),復(fù)雜系統(tǒng)的穩(wěn)態(tài)可能描述為不同主導(dǎo)機制所對應(yīng)狀態(tài)之間的組合。依據(jù)EMMS原理的指導(dǎo),本論文通過準確刻畫催化劑表面吸附層結(jié)構(gòu)的介尺度關(guān)鍵特征,將這些特征與相關(guān)的主導(dǎo)機制進行關(guān)聯(lián),以相互競爭的主導(dǎo)機制之間的協(xié)調(diào)關(guān)系證明穩(wěn)定性條件的存在,為介尺度模型的建立奠定了良好的基礎(chǔ)。通過本論文的研究可以發(fā)現(xiàn),動力學(xué)因素對催化劑表面吸附層結(jié)構(gòu)有著重要的影響,聯(lián)立穩(wěn)定性條件和守恒方程的介尺度模型是關(guān)聯(lián)宏觀與微觀,高效、準確地考慮介尺度結(jié)構(gòu)影響的有效途徑。本論文回答了催化劑表面吸附層結(jié)構(gòu)是什么,為什么要考慮吸附層結(jié)構(gòu),如何表征吸附層結(jié)構(gòu)以及不同的吸附層結(jié)構(gòu)對應(yīng)的主導(dǎo)機制是什么四個問題。依據(jù)此思路,本論文可以分為四章,分別為緒論、基于LH機理的A-B模型、基于LH機理的A-B2模型以及結(jié)論和展望。第一章緒論部分對本論文的研究背景以及基本思路進行闡述,詳細解釋了催化劑表面吸附層結(jié)構(gòu)對宏觀動力學(xué)行為的影響,并對已有模型的優(yōu)缺點進行了比較。第二章和第三章是本論文的主體,分別在不同的體系,A-B體系和A-B2體系,研究了動力學(xué)因素對催化劑表面吸附層結(jié)構(gòu)的影響,并提煉出不同相對應(yīng)的主導(dǎo)機制,說明主導(dǎo)機制競爭中的協(xié)調(diào)作用賦予了催化劑表面吸附層結(jié)構(gòu)的動力學(xué)特征。同時,由于解離作用的影響,在第三章中還詳細對比了不同體系間動力學(xué)因素對吸附層結(jié)構(gòu)影響的差異性,完整的闡述了不同體系間動力學(xué)因素對吸附層結(jié)構(gòu)動力學(xué)行為的共性與差異性。第四章結(jié)論與展望分為兩部分,分別對本論文進行了全面的總結(jié),并對之后進一步的工作進行了展望。
[Abstract]:In the course of catalytic reactions, the reactants and products can be formed in the complex structure of the adsorption layer on the surface of the catalyst, has an important impact on macroeconomic performance of these structures on heterogeneous catalysis. The description of heterogeneous catalytic reactions are mainly three kinds of models are macro model, microscopic model and mesoscopic model. Ignore this structure, using the average of the treatment, often cause serious error, which is the main defect of macro model at present; and direct description of atomic and molecular processes, the microscopic model also contains a lot of redundant information, so that the huge computational overhead are difficult to meet the actual needs of the temporal and spatial scale. Although the influence of mesoscopic model correction of dynamic rate coverage through the partial introduction of structure on dynamic behavior, but it is still using the analysis method of partial averaging, nature did not get rid of the defects of the macro model, therefore, this Not like the mesoscopic model accurately reflects the influence of structure on the system. In the study of gas-solid fluidization system, energy minimization multi-scale (EMMS) model has been proved to be effective in different scales. The principle that EMMS Association proposed the stability conditions of complex systems can be represented as the dominant mechanism in the coordination of competition steady state, complex systems can be described as the dominant mechanism corresponding to different combination between states. According to the EMMS principle, this paper describe the adsorption characteristics of meso scale key layer structure of the catalyst surface, the correlation mechanism leading to these characteristics and the stability conditions that to coordinate the relationship between leading competing mechanism the existence of established for the meso scale model has laid a good foundation. Through the research of this paper can be found that the dynamics on the catalyst surface adsorption layer. Structure has an important influence, mesoscale model of simultaneous stability conditions and conservation equations associated with macro and micro, efficient and effective way to accurately consider the impact of meso scale structures. This thesis answers the catalyst surface adsorption layer structure is what, why should we consider the adsorption layer structure, leading to different structure and characterization of adsorption layer the adsorption layer structure of the corresponding mechanism is what four questions. Based on this idea, this paper can be divided into four chapters, namely the introduction, the A-B model based on LH mechanism, LH mechanism and A-B2 model based on the conclusion and prospect. The first chapter elaborates on the research background and basic ideas, detailed explanation the influence of adsorption layer structure on the macro dynamic behavior of the catalyst surface, and the advantages and disadvantages of the existing model are compared. The second chapter and the third chapter is the main body of this paper, respectively Different system, A-B system and A-B2 system, studies the dynamic factors influencing adsorption layer structure on the surface of the catalyst, and extract the dominant different corresponding mechanism, coordination mechanism of leading role in the competition with the catalyst surface adsorption layer structure characteristics. At the same time, due to the effect of dissociation, in the third chapter also a detailed comparison of the differences between different systems of dynamic factors influence the adsorption layer structure, a full description of the similarities and differences of adsorption layer structure dynamic behavior of dynamic factors between different systems. The conclusion and Prospect of the fourth chapter is divided into two parts, respectively in this thesis is summarized, and the further the work is prospected.

【學(xué)位授予單位】：中國科學(xué)院大學(xué)(中國科學(xué)院過程工程研究所)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O643.36

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