CAJ | 학술논문

采用原位红外和原位显微Raman光谱技术及XPS、吡啶(Py)吸附的漫反射UV谱、Py-TPD、CO2-TPD等方法对含氟稀土基催化剂上甲烷氧化偶联(OCM)反应活性氧物种、催化剂表面酸碱性进行了考察．在O2预处理和/或工作条件下的SrF2/La2O3，SrF2/Nd2O3．LaOF，BaF2/LaOF和BaF2/CeO2等催化剂上原位观测到超氧物种(O-2)，并在其中前4种催化剂上检测到O-2物种与CH4反应生成的气相C-2H4，CO2和表面碳酸盐等OCM反应主、副产物．这些结果为O-2是相应催化剂上OCM反应的活性氧物种首次提供了直接的光谱证据．研究结果还表明，催化剂的OCM反应性能与其表面酸碱性的强弱并无简单的对应关系．采用原位时间分辨红外光谱和原位显微Raman光谱技术对SiO2和γ-Al2O3负载的Rh、Ru催化剂上甲烷部分氧化(POM)制合成气反应的研究表明，由CH4直接氧化生成CO和H2是RhRh/SiO2上POM反应的主要途径，而燃烧-重整机理是Ru/γ-Al2O3和Ru/SiO2上CO和H2生成的主要途径，反应条件下催化剂表面氧(O2-)物种浓度的差异很可能是导致这两种催化剂体系上POM反应机理不同的主要原因，其本质可能源于Rh和Ru对氧的亲合力的不同．
채용원위홍외화원위현미Raman광보기술급XPS、필정(Py)흡부적만반사UV보、Py-TPD、CO2-TPD등방법대함불희토기최화제상갑완양화우련(OCM)반응활성양물충、최화제표면산감성진행료고찰．재O2예처리화/혹공작조건하적SrF2/La2O3，SrF2/Nd2O3．LaOF，BaF2/LaOF화BaF2/CeO2등최화제상원위관측도초양물충(O-2)，병재기중전4충최화제상검측도O-2물충여CH4반응생성적기상C-2H4，CO2화표면탄산염등OCM반응주、부산물．저사결과위O-2시상응최화제상OCM반응적활성양물충수차제공료직접적광보증거．연구결과환표명，최화제적OCM반응성능여기표면산감성적강약병무간단적대응관계．채용원위시간분변홍외광보화원위현미Raman광보기술대SiO2화γ-Al2O3부재적Rh、Ru최화제상갑완부분양화(POM)제합성기반응적연구표명，유CH4직접양화생성CO화H2시RhRh/SiO2상POM반응적주요도경，이연소-중정궤리시Ru/γ-Al2O3화Ru/SiO2상CO화H2생성적주요도경，반응조건하최화제표면양(O2-)물충농도적차이흔가능시도치저량충최화제체계상POM반응궤리불동적주요원인，기본질가능원우Rh화Ru대양적친합력적불동．
Active oxygen specie and surface acid/base properties of fluoride-containing rare earth-based catalysts for methane oxidative coupling (OCM) reaction were studied using in situ IR and in situ microprobe Raman spectroscopies, XPS, UV spectra of pyridine (Py) adsorption, Py- and CO2-TPD. O-2 species was detected over O2 and/or CH4/O2 pretreated SrF2/La2Oa, SrF2/Nd2O3, LaOF, BaF2/LaOF and BaF2/CeO2 catalysts at OCM reaction temperature, and the reactions between O-2 species and CH4 to form C2H4 and corresponding side-products of OCM reaction such as CO2 and surface carbonate were observed over SrF2/La2O3, SrF2/Nd2O3, LaOF, BaF2/LaOF catalysts. These results, for the first time, provide direct spectroscopic evidences which suggest that O-2 is the active oxygen species for OCM reaction over the corresponding catalysts. It is also found that the surface basicity is not always a requisite attribute for a good OCM catalyst. The results of in situ time-resolved FTIR and in situ microprobe Raman spectroscopic characterizations on the partial oxidation of methane (POM) reaction indicate that direct oxidation of CH4 to synthesis gas is the main pathway of POM reaction over Rh/SiO2 catalyst, while the combustion-reforming scheme is the dominant pathway of synthesis gas formation over Ru/γAl2Oa and Ru/SiO2 catalysts. The significant difference in the reaction schemes of POM reaction over SiO2 and γ-A12O3 supported Rh and Ru catalysts may be related to the difference in surface concentration of oxygen species (O2-) over the catalysts under the reaction conditions mainly due to the difference in oxygen affinity of the two metals