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首页> 外文期刊>Catalysis science & technology >Methane-to-methanol conversion over zeolite Cu-SSZ-13, and its comparison with the selective catalytic reduction of NOx with NH3
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Methane-to-methanol conversion over zeolite Cu-SSZ-13, and its comparison with the selective catalytic reduction of NOx with NH3

机译：在沸石Methane-to-methanol转换Cu-SSZ-13,与选择性的比较催化还原氮氧化物和氨

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The direct conversion of methane into methanol is considered as one of the holy grails in hydrocarbon chemistry and recently it was found that small pore zeolites, such as Cu-SSZ-13, Cu-SSZ-16 and Cu-SSZ-39, are active for this process. Here, we propose a reaction mechanism based on spectroscopic evidence for the methane-to-methanol reaction over Cu-SSZ-13 (Si/Al = 20). Using in situ FT-IR and operando UV-vis-NIR DRS, performed on a series of different Cu-ion-exchanged SSZ-13 zeolites, both a mono-nuclear site or a dimeric copper active site are consistent with the observations of this study. These proposed active site(s) are characterized by a nu(OH) at similar to 3654 cm(-1) and a charge transfer (CT) transition at similar to 29000 cm(-1). We have further evidence to complete the full catalytic cycle to methanol, including the formation of the reaction intermediate Cu(CH3)(H2O), which is characterized by overtone transitions, i.e., a 2 nu(OH) at similar to 4200 cm(-1) and a 2 nu(OH) at similar to 5248 cm(-1). We found that increasing the pre-oxidation temperature from 450 degrees C to 550 degrees C resulted in a 15% increase in methanol production, as well as a concomitant increase of the 29000 cm-1 CT transition. Furthermore, Cu-exchanged SSZ-13 zeolites, which perform well in the NH3-SCR reaction at 200 degrees C (the low temperature regime), also show a high activity in the methane-to-methanol reaction and vice versa, leading us to believe that this material has a similar if not the same active site for both the catalytic reduction of NO and the stepwise reaction towards methanol.
机译：直接甲烷转化为甲醇视为的圣杯之一碳氢化合物的化学和最近发现小毛孔沸石,Cu-SSZ-13等Cu-SSZ-16 Cu-SSZ-39,是活跃的的过程。基于光谱的证据在Cu-SSZ-13 methane-to-methanol反应(Si / Al = 20)。UV-vis-NIR DRS,进行一系列的不同Cu-ion-exchanged SSZ-13沸石,mono-nuclear网站或二聚的铜活跃网站的观察是一致的研究。以类似于3654年的ν(哦)厘米(1)和电荷转移(CT)过渡29000厘米(1)相似。完成完整的甲醇催化循环,包括反应的形成中间铜(CH3) (H2O)为特征泛音的转换,即2ν(哦)类似于4200厘米(1)和2ν(哦)相似5248厘米(1)。pre-oxidation温度在450摄氏度550摄氏度导致增加了15%甲醇生产,以及伴随的增加的29000 cm - 1 CT过渡。此外,Cu-exchanged SSZ-13沸石,在200年的NH3-SCR反应表现良好度(低温政权),也显示高methane-to-methanol活动反应,反之亦然,我们相信这种材料也有类似的如果不一样的的催化还原活性部位没有,逐步对甲醇的反应。

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