晶格氧用于甲烷部分氧化制合成气是一种甲烷转化新工艺...

晶格氧用于甲烷部分氧化制合成气是一种甲烷转化新工艺... 晶格氧用于甲烷部分氧化制合成气是一种甲烷转化新工艺，该方法考虑选择 一些合适的储氧 材料 关于××同志的政审材料调查表环保先进个人材料国家普通话测试材料农民专业合作社注销四查四问剖析材料 ，利用它们的晶格氧作为甲烷催化氧化制合成气的氧源直接 将甲烷高选择性的氧化为合成气，失去晶格氧的储氧材料可以通过空气再生重新 获得晶格氧，从而实现循环利用。与单纯的催化部分氧化法(POM)相比，该工艺采用空气代替纯氧，可以较大幅度降低合成气的生产成本；另外，该方法中采用 甲烷和空气分开进料，能有效地避免POM中存在的爆炸危险。 本论文以共沉淀法制备了系列铈基复合氧化物Ce-M-O（M＝Fe、Mn、Cu、Co），对较适合用于部分氧化甲烷制合成气的Ce-Fe-O，系统的研究了不同制备 条件以及ZrO掺杂对其性能的影响，并探讨了其部分氧化甲烷的反应机理。 2 在不同复合氧化物Ce-M-O（M＝Fe、Mn、Cu、Co）中，Ce-Fe-O显示了最好的部分氧化甲烷性能。对系列Ce-Fe-O-X（X为铈铁摩尔比，X=9/1、8/2、7/3、6/4、5/5、4/6、2/8）氧载体的研究表明，铈铁间存在着强烈的相互作用，不仅 表现在铈铁固溶体的形成，而且分散在CeO表面的FeO对复合氧化物与甲烷223的反应也有相当的影响。在与甲烷反应时，表面FeO首先转换为还原性铁物种23 Fe或FeC，该铁物种被认为是整个反应的活性位：甲烷先在活性Fe物种上的活3 化裂解生成活化碳物种和H，然后氧化铈将活化碳物种选择性氧化为CO。过高2 的铁含量不仅不利于复合氧化物活性的提高而且容易造成甲烷的完全氧化，在该 系列复合氧化物中，Ce-Fe-O-7/3显示了最好的部分氧化甲烷性能。 焙烧温度对铈铁复合氧化物的性能有较大影响，较高的焙烧温度引起较好的 结晶度对提高产物气中合成气选择性有利，但却会导致氧载体活性下降，而较低 的焙烧温度会引起较多吸附氧，进而导致CO和H选择性明显降低。800?焙烧2样品具有很好的部分氧化甲烷性能，但经长时间循环Ce-Fe-O-7/3（800）的部分 氧化甲烷性能略微降低，这主要是由CeO的烧结引起。 2 在Ce-Fe-O-7/3（800）氧载体中掺杂ZrO不仅能提高其部分氧化甲烷活性，2 而且还可以改变其对碳物种和氢物种的选择性氧化匹配性，使产物气中n (H): n 2 (CO)更接近于理论值2。更重要的是，添加ZrO可以很好地改善氧载体的抗烧2结能力和循环使用性能。 铈基复合氧化物；甲烷；晶格氧；合成气；部分氧化; Redox循环 Abstract A novel process of methane partial oxidation using lattice oxygen instead of gaseous oxidant to participate in methane partial oxidation to synthesis gas has been recently proposed．In this process a suitable oxygen storage compound (OSC) is circulated between two reactors. In one reactor, methane is oxidized to synthesis gas by the lattice oxygen of OSC, and in the other, the reduced OSC are re-oxidized by air to restore its initial state．This technology has many advantages, when compared with the partial oxidation of methane (POM). First, it can avoid the risk of explosion due to the premixed CH/O mixture within the ignition and explosion limits. Second, the 42 selectivity of desired product can be enhance, because the product is not easy to be deeply oxidized in the absence of molecular oxygen. Third, it can save oxygen supply by the cryogenic distillation of air needs additional investment and operational expense, because which does not need using pure oxygen. In this thesis, we incorporate ceria and transition metal oxides such as FeO, CuO, 23 MnOand CoO aimed at increasing the oxygen storage capacity and the oxygen 2 34 mobility in the oxygen storage compound for this redox cycle process. Their catalytic activities in the direct conversion of methane to synthesis gas in a fixed-bed reactor are investigated in the absence of gas-phase oxygen by temperature programmed surface reaction, continuous reactions, and sequential redox cycles. The Ce-Fe-O sample was found to be suitable for partial oxidation methane to synthesis gas. Then, the effect of n (Ce): n (Fe), calcination temperature and doped Zirconia on catalytic activity was measured. The OSC with good performance and the reaction mechanism between oxygen carriers and methane are desirable to be obtained. The Ce-Fe-O sample exhibits the highest selectivity to synthesis gas, and it is the best oxygen carrier among the tested Ce-M-O oxides for synthesis gas production. The phase cooperation between CeO and FeO is responsible for the better activity. 223First, the solid solution based upon ceria-ferric oxide system can enhance the lattice oxygen mobility of oxygen carrier. Second, dispersed FeO was firstly returned to 23 original state and then virtually form Fe or FeC species on the catalyst which could 3be considered as the active site for selective CH oxidation. The appearance of carbon 4formation is significant and the oxidation of carbon appears to be the rate-determining step.CeOmainly provides selective lattice oxygen which is the necessities for 2 synthesis gas production. Too high content of FeO seems to be disadvantageous to 23the catalytic activity enhancement and favor deep oxidation of methane. There is a suitable atom ratio exhibits highest degree of interaction between Ce and Fe species. Comparison of seven types of complex oxide systems Ce-Fe-O-X(X was the cerium iron Molar ratio，X=9/1, 8/2, 7/3, 6/4, 5/5, 4/6 and 2/8) made in this work, Ce-Fe-O-7/3 shows the best catalytic activity. The calcination temperature exerts an important influence to the performance of the ceria-ferric oxide system; the concerned results have shown that there exists a best temperature range which is at about 800?. A better crystallinity could improve the syngas selectivity, but actually would lead to decreased activity of oxygen carrier. After a long-term redox cycle, the selective methane oxidation performance of Ce-Fe-O-7/3(800) decreased appreciably, mainly caused by the sintering of CeO. 2 However, the oxygen storage capacity of Ce-Fe-O-7/3 (800) has not declined but increased slightly through redox cycle. It is shown that introduction of ZrO into the Ce-Fe-O-7/3 (800) framework with 2formation of cerium–zirconium solid solution strongly modifies the reduction behaviour in comparison to that seen with Ce-Fe-O-7/3 (800) alone. Moreover, it also results in more active catalysts with enhanced synthesis gas selectivity and promotes the value of n (H): n (CO) more close to 2. Remarkably, ZrOenhances the thermal 22 stability and the oxygen storage capacity of Ce-Fe-O-7/3 (800), resulting in better redox capacities for partial oxidation of methane at moderate temperatures. Key wards: Ceria-based complex oxides; Methane; Lattice oxygen; syngas; partial oxidation; Redox cycles.