以非熱電漿處理CuO/ZnO/Al2O3觸媒應用於合成氣合成甲醇之研究; Plasma-treated CuO/ZnO/Al2O3 Catalyst for Methanol Synthesis from Syngas

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Title:	以非熱電漿處理CuO/ZnO/Al2O3觸媒應用於合成氣合成甲醇之研究;Plasma-treated CuO/ZnO/Al2O3 Catalyst for Methanol Synthesis from Syngas
Authors:	阮亮凱;Liang-Kai Juan
Contributors:	環境工程研究所
Keywords:	生質能;替代燃料;合成氣液化;非熱電漿;經電漿處理觸媒;甲醇;Methanol (MeOH);Biomass energy.;Alternative fuel;Syngas liquefaction;Nonthermal plasma;Plasma-treated catalyst
Date:	2009-06-09
Issue Date:	2009-09-21 12:19:23 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	甲醇為許多化學品合成之原料，近來更被視為優良能量載體，就甲醇合成程序而言，善用觸媒可降低反應所需活化能並增進反應速率。非熱電漿技術於觸媒之結合或應用乃近十年方興起之研究領域，目前國際學術界利用此新穎技術於轉化合成氣為甲醇之研究尚未得見。在傳統共沈澱法之觸媒製備過程包括：沉澱、洗滌、過濾、烘乾、鍛燒、及還原等步驟，本研究在觸媒製備過程中引入一個特殊過程：『電漿處理』，將其插入上述鍛燒製備程序之前後、或用其取代鍛燒程序，並以此觸媒在高壓高溫下進行合成氣轉化甲醇之實驗，研究重點在於瞭解電漿處理觸媒之可行性。本研究所測試的觸媒包括：商用、未經電漿處理、經氧氣電漿處理和經氫氣電漿處理等觸媒。商用及未經電漿處理觸媒經催化實驗結果顯示，本研究所自行製備之觸媒具有較高活性；比較有無氧氣電漿處理(鍛燒前)之結果顯示，可降低最佳活性溫度，於235℃、40 atm條件下，提升甲醇選擇率及產率，同時亦降低了副產物的選擇率；以氫氣電漿處理來取代鍛燒之觸媒，CO轉化率高達97%，但主要產物並非甲醇而是CO2及CH4，其活性已經截然不同。針對了電漿處理氣氛及程序做更進一步的探討，結果發現在鍛燒前氫氣電漿處理及鍛燒後氧氣電漿處理，其甲醇選擇性及甲醇產率都低於未經電漿處理；反之，鍛燒前氧氣電漿及鍛燒後氫氣電漿處理，皆優於未經處理觸媒之甲醇選擇性及甲醇產率。經由XRD、ICP及比表面積量測，證實以非熱電漿處理可輔助觸媒，分解前驅物的特性、較大之比表面積及經電漿處理過後可具有較小氧化銅顆粒。此外，以電漿處理CuO/ZnO/Al2O3觸媒具有低耗能特性，所需電量僅為11 kJ/g-cat.。綜合而言，本研究證實以非熱電漿處理確實可修飾觸媒的表面特性，但並非其所改變之特性完全有利於轉化合成氣為甲醇，乃必須慎選電漿處理方法以利觸媒催化反應，反之亦可能導致相反之結果。 In recent years, nonthermal plasma has been utilized as a novel technique to enhance the activity of catalyst. The study applied this novel technique to the preparation of the catalyst for methanol synthesis Such study has yet reported so far. The main objective of this study is to investigate the feasibility of using nonthermal plasma to modify the performance of methanol synthesis catalyst. In terms of methanol synthesis by catalysis, the catalyst is generally prepared via coprecipitation, and consists of precipitation, washing, filtration, drying, calcination and reduction. In this study, plasma treatment can be applied before/after calcination or used to replace calcinations. A variety of catalysts have been experimentally tested in this study, i.e., commercial, self-made (without plasma treatment), O2-plasma-treated, and H2-plasma-treated catalysts. The experimental results indicate the self-made catalyst could achieve better performance than the commercial one. On the other hand, the treatment of O2 plasma (before calcination) could shift the optimum temperature for methanol synthesis from 255oC to 235oC and increase the selectivity of MeOH at the same time. As for the H2-plasma-treated (replace calcination) catalyst, although the best CO conversion rate obtained in this study is as high as 97%, the main products are CO2 and CH4 instead of the desired product, MeOH. As a further study on applying different plasma treatments and processes, it reveals that the selectivity and the yield of MeOH from H2-plasma-treated catalyst before calcinations and O2-plasma-treated catalyst after calcinations are lower than that of self-made catalysts. That is to say, the selectivity and yield of MeOH from H2-plasma-treated catalyst before calcinations and O2-plasma-treated catalyst after calcinations are better than that of self-made catalysts. To get insights into the influence of plasma treatment on the physical and chemical properties of the catalyst, the measurements of XRD, ICP and surface area are also conducted in this study. The results indicate that the plasma treatment could decompose the precursors of the active components. Moreover, after plasma treatment, larger surface area and smaller CuO grain size could be achieved as well. Besides, it is worth noticing that the energy required for the treatment of Cu/ZnO/Al2O3 catalyst is only 11 kJ/g-cat, which is economically competitive. In conclusion, it has been demonstrated in this study that the plasma treatment could alter the physical and chemical properties of the catalyst. However, the alteration is not always beneficial for methanol synthesis. Therefore, one should be careful in selecting the background gas of plasma so that the plasma treatment process is beneficial to catalyst performance.
Appears in Collections:	[Graduate Institute of Environmental Engineering ] Electronic Thesis & Dissertation

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