Synthesis and characterisation of mesoporous transition metal ion modified silica-zirconia and silica-sulfated zirconia materials towards NOx catalysis

Abstract

%XoDOÕúPDQÕQDPDFÕPHWDQLOH/]H/12xELOHúLNOHULQLQWHSNLPHOerine SRWDQVL/HOROXúWXUDFDNPH]R/DSÕOÕPDO]HPHOHULWDVDUODPDNYHoDOÕúPDNWÕU$PDFD XODúPDNLoLQELUNDoKHGHIWDVDUODQPÕúWÕU%LULQFLKHGHIVOIDW (SO42-), kobalt (Co2+) ve paladium (Pd2+L/RQXNDWNÕODQGÕUÕOPÕúPH]RJ]HQHNOLVLOLFD-zirkonya oksit alt-WDúÕ LoLQX/JXQELUVHQWH]/QWHPLQLQJHOLúWLULOPHVLGLU 8/JXQNDWDOLWLN]HOOL÷HVDKLSDOWWDúODUVHQWH]DúDPDODUÕQÕQD/DUODQPDVÕYHNRPSR]LV/RQXQRSWLPL]DV/RQXLOHHOGH HGLOPLúWLUøNLQLFLKHGHILVH&R-, Pd- ve Co-Pd-silika-VOIDWODQPÕú]LUNRQ/D6L-SZr) PDO]HPHOHULQGHNREDOWYH]LUNRQ/DPLNWDUÕQÕQ12xELOHúLNOHULLOHPHWDQDUDVÕQGDNL WHSNLPHOHUHHWNLVLQLQD/GÕQODWÕOPDVÕKHGHIOHU

ABSTRACTSYNTHESIS AND CHARACTERISATION OF MESOPOROUS TRANSITIONMETAL ION MODIFIED SILICA-ZIRCONIA AND SILICA-SULFATEDZIRCONIA MATERIALS TOWARDS NOX CATALYSISOLGA SAMARSKAYAPh.D. in Chemistry6XSHUYLVRU$VVRF3URI'UgPHU'D÷Co-Supervisor: Assoc. Prof. Dr. Margarita KantchevaSeptember 2006The purpose of this work is to design and investigate mesostructured materialas a potential support for the reaction of the methane with surface NOx species.Several objectives have been pursued in achievement of the goals. The first objectiveis to develop a facile procedure for the synthesis of mesoporous silica-zirconia mixedoxide supports that are modified with the sulphate (SO42-), cobalt (Co2+) andpalladium (Pd2+) ions. The support with requisite catalytic properties was obtainedthrough the adjustment of the synthetic steps and optimisation of the composition.The second objective is to explore the effect of cobalt and zirconia loading in thereaction of the NOx species with methane over the Co-, Pd-, and Co-Pd-silica-sulphated zirconia (Si-SZr).A one-pot synthesis procedure has been developed to prepare the mesoporoussilica-zirconia (Si-Zr), Si-SZr supports and the supermicroporous Co(II) incorporatedSi-SZr catalysts with a wide range of zirconia loadings. Introduction of the Co(II)active sites by various post-synthesis methods leads to the modification of the surface,whereas the direct (co-precipitation) techniques have provided the modification ofboth surface and bulk of the supports. The palladium ions were introduced by theconventional impregnation methods onto the calcined solid materials. The detailedanalysis of the materials has revealed that the silica and zirconia are well mixed in theframework, whereas the cobalt and sulphate ions are uniformly dispersed on theinternal surface of the silica-zirconia supports.The materials prepared in this thesis possess sufficient stability, requisitecatalytic properties, as well as good Brønsted and Lewis acidity. However, the highcobalt loading renders the catalytic performance of the Pd-Si-SZr catalysts. Amongthe investigated catalysts, the interaction of the NOx species with the CH4 takes placeat the lowest temperature over the Co-, Pd-, Co-Pd-supported zirconia rich (Zr/Si =28) Si-SZr catalysts.Key words: Mesostructure, Mesoporous Silica-Zirconia, Mesoporous Silica-Sulphated Zirconia, Co-preciapitation, Impregnation, Surface Modification, Co(II),Pd(II), NOx Catalyst, Interaction of NOx with the Methane.