改进型XC502低压甲醇合成催化剂的研究 Ⅱ.催化剂的活性位

采用ＸＰＳ－Ａｕｇｅｒ、ＸＲＤ和ＦＴＩＲ等方法，对５组分Ｃｕ－Ｚｎ－Ａｌ－Ｍ１－Ｍ２改进ＸＣ５０２铜基低压甲醇合成催化剂进行了表征。ＸＰＳ－Ａｕｇｅｒ结果表明，ＸＣ５０２催化剂出现主峰为３３６．４ｅＶ（Ｃｕ＋），而Ｃｕ－Ｚｎ－Ａｌ催化剂主峰为３３４．９ｅＶ（Ｃｕ０）；ＸＲＤ结果表明，两种工作态催化剂比氧化态新增峰的２θ分别为３６．５°（Ｃｕ＋）和４３．３°（Ｃｕ０），ＸＣ５０２催化剂这两峰的强度比Ｉ３６．５／Ｉ４３．３是Ｃｕ－Ｚｎ－Ａｌ催化剂的２．１倍，说明工作态ＸＣ５０２催化剂单位Ｃｕ０中的Ｃｕ＋含量比Ｃｕ－Ｚｎ－Ａｌ催化剂多；ＦＴＩＲ谱显示，ＸＣ５０２和Ｃｕ－Ｚｎ－Ａｌ两种工作态催化剂新增波数分别为６２２ｃｍ－１和６２７ｃｍ－１的振动峰，此新增峰可能是Ｃｕ＋－Ｏ或Ｃｕ＋－Ｏ－Ｚｎ２＋的振动峰。改进型铜基甲醇合成催化剂的活性位可能是Ｃｕ０－Ｃｕ＋－Ｏ－Ｚｎ２＋／Ａｌ２Ｏ３－ＭＯｘ。

Study of a modified low pressure copper based catalyst XC502 for methanol synthesis

pectroscopic　characterization　of　the　active　site　of　a　modified　low　pressure　copper based　catalyst　XC502,　prepared　by　adding　a　small　amount　of　metal　oxides　of　the　VI　B　and　VB　groups　to　a　Cu Zn Al catalyst　for　methanol　synthesis,　is　carried　out　by　XPS Auger,　XRD　and　FTIR.　The　main　peaks　are　detected　by　XPS Auger　to　be　336.4eV(Cu+)　and　334.9eV(Cu0)　on　the　surfaces　of　XC502　and　the　Cu Zn Al　catalyst,　respectively.　The　XRD　result　shows　that　two　new　peaks　appear　at　2θ=36.5°(Cu+)　and　43.3°(Cu0)　for　those　functioning　catalysts,　but　I36.5/I43.3　of　XC502　is　twice　as　large　as　that　of　the　Cu Zn Al　catalyst,　showing　that　the　surface　of　the　functioning　XC502　catalyst　has　higher　Cu+/Cu0　ratio　and　valence　stability　than　those　of　the　Cu Zn Al　catalyst.　By　applying　FTIR　spectroscopy,　bands　at　622　cm-1　and　627cm-1　are　observed　on　the　functioning　XC502　and　Cu Zn Al　catalysts,　respectively,　and　the　band　may　be　assigned　to　Cu+ O Zn2+　bond　vibration.　In　light　of　the　above　results,　it　is　suggested　that　the　active　site　on　the　functioning　XC502　copper based　catalyst　for　methanol　synthesis　at　low　pressure　is　probably　　Cu0 Cu+ O Zn2+/Al2O3 MOx.