本文關(guān)鍵詞： 鎳基催化劑 晶相影響 二氧化碳甲烷化 單層分散　出處：《太原理工大學》2017年碩士論文　論文類型：學位論文

【摘要】：化石燃料的燃燒排放出的大量二氧化碳(CO_2)是導致地球氣候變暖的根本原因,由此誘發(fā)了一系列的生態(tài)環(huán)境問題。因此,CO_2捕集及其資源化利用成為一個當今全球性的重要研究課題。CO_2可以作為一種重要的化工原料,用于加氫反應、碳酸酯及尿素等化學品的合成。甲烷(CH_4)作為代用天然氣的主要組成成分,在國民生產(chǎn)中占據(jù)著十分關(guān)鍵的地位,將CO_2加氫轉(zhuǎn)化為CH_4等能源產(chǎn)品具有重要的意義。因此,CO_2加氫甲烷化反應有很大的發(fā)展前景。電制氣技術(shù)(PtG)通過太陽能或者風能等新能源發(fā)電制氫,進而利用CO_2加氫反應合成CH_4,是一個重要的CO_2利用途徑。近年來,德國、日本、美國等國已經(jīng)建成多個PtG示范項目。我國應當大力發(fā)展新能源發(fā)電技術(shù)和CO_2捕獲技術(shù),大幅降低PtG技術(shù)的工藝成本,有效實現(xiàn)CO_2減排,同時緩解天然氣供應不足的問題。本論文首先合成出三種不同晶相的氧化鋯(單斜、四方、立方),采用常規(guī)浸漬法制備出Ni/ZrO_2催化劑,添加Re和W助劑,考察了各種催化劑樣品在CO_2甲烷化反應中的性能,結(jié)合表征結(jié)果,分析了氧化鋯載體晶相結(jié)構(gòu)、添加助劑對催化劑甲烷化反應性能的影響,主要研究內(nèi)容總結(jié)如下:(1)ZrO_2晶相對負載Ni的尺寸有顯著的影響,通過謝樂公式計算得到Ni/t-ZrO_2催化劑的Ni的晶粒尺寸最小(16.79 nm);(2)Ni/t-ZrO_2催化劑表面相對較多的堿性位點和氧空缺對CO_2有較強的吸附,進而生成的單齒或雙齒碳酸鹽更容易分解脫附CO_2;(3)制備出不同負載量(1-9 wt%)的Ni/t-ZrO_2催化劑,發(fā)現(xiàn)負載量為7 wt%時催化劑活性最高,此時達到金屬鎳在t-ZrO_2表面的單層分散閾值(0.388 g/g);(4)添加4 wt%的Re或W后,Ni/t-ZrO_2催化劑的CO_2轉(zhuǎn)化率略有提高,在500°C的反應條件下,CO_2轉(zhuǎn)化率大于80%,CH_4選擇性達到85%,添加助劑增加了催化劑表面的氧空缺數(shù)量,進而改善了甲烷化反應性能。
[Abstract]:A lot of CO2 emissions from fossil fuel combustion are the root cause of global warming. As a result, a series of ecological and environmental problems have been induced. Therefore, the collection of CO2 and its utilization of resources have become an important research topic in the world today. COS2 can be used as an important chemical raw material for hydrogenation reactions. Synthesis of Carbonate and Urea. Methane CH4) as the main component of alternative natural gas, it plays a key role in national production. It is of great significance to convert CO_2 hydrogenation to CH_4 and other energy products. Therefore, the hydromethanation reaction of CO_2 2 has great development prospects. Electricity gas production technology, PtG, generates hydrogen through new energy sources, such as solar or wind energy. In recent years, many PtG demonstration projects have been built in Germany, Japan, the United States and other countries. China should vigorously develop new energy generation technology and CO_2 capture technology. In this thesis, three kinds of zirconia (monoclinic, tetragonal, monoclinic, tetragonal) have been synthesized. Ni/ZrO_2 catalyst was prepared by conventional impregnation method. Re and W auxiliaries were added to the catalyst. The properties of various catalyst samples in CO_2 methanation reaction were investigated. The crystal phase structure of zirconia carrier was analyzed with the results of characterization. The effect of additives on the methanation reaction performance of the catalyst was studied. The main contents of the study were summarized as follows: the size of Ni loaded on ZrO2 crystal was significantly affected by the addition of additives. By using the Xie Lecong formula, the grain size of Ni in Ni/t-ZrO_2 catalyst is the smallest (16.79 nm). The surface of Ni / t-ZrO _ 2 catalyst has relatively more basic sites and oxygen vacancies on the surface of the catalyst, and there is a strong adsorption of CO_2 on the surface. The monodentate or bicententate carbonate can be easily separated into two groups of Ni/t-ZrO_2 catalysts with different loading amount (1 ~ 9 wt). It is found that the catalyst activity is the highest when the loading amount is 7 wt%. At this time, the monolayer dispersion threshold of nickel on t-ZrO _ 2 surface is 0.388 g / g / g ~ (4)) the CO_2 conversion of Ni / t-ZrO _ 2 catalyst increases slightly after adding 4 wt% re or W, Under the reaction conditions of 500 擄C, the selectivity of COS _ 2 conversion greater than 80% CHS _ 4 reached 85%. The addition of additives increased the number of oxygen vacancies on the surface of the catalyst and improved the methanation reaction performance.
【學位授予單位】：太原理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：X701;O643.36

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