Strong Electrostatic Adsorption for the Optimization of Bimetallic Catalysts

The aim of this thesis is to investigate and optimize the rational synthesis of supported bimetallic catalysts. The main body of this work focuses on the use of simple techniques and common elemental precursors to maximize the interaction between a promoter and catalytic metal. This is achieved through the use of Strong Electrostatic Adsorption (SEA). Special attention to the surface charging parameters of mixed oxide supports as a function of solution pH can create a driving force to selectively adsorb a precursor complex onto a single phase of a binary mixture. In Chapter 1, we present a brief introduction on the relevance of studying the fundamentals of catalyst preparation and the strong electrostatic adsorption method that can be extended to CEDI and bimetallic synthesis. Chapter 2 gives all the details of the chemical and experiments I have done in this study. In Chapter 3 we discovered a simple way to increase metal dispersion in supported metal catalysts. From the RPA model we can determine the optimal pH to synthesize highly dispersed noble metal particles. Chapters 4 provide an optimized preparation for preparing Pt-Re/C supported bimetallic catalyst. From ICP, XPS, TPR and chemisorption characterization techniques we are able to determine that Dry Impregnated (DI) would lead to a more randomly dispersed particles than SEA method. Glycerol reforming reactivity measurements also gave us key insight to the effect of strong interaction between Pt and Re. Chapter 5 focuses on the preparation of supported Ir-Pd catalysts with core-shell nano-structure. We successfully synthesized bimetallic catalyst Ir-Pd/C at optimal pH initial 1.94 with strong metal interaction via SEA method. From the EDXS point analysis, we can determine there is strong metal-metal interaction based on the preparation procedure. Clearly, the SEA preparation method provides a unique basis for the addition of a second metal to increase its interaction with the active metal through simple adjustments of the preparation procedure, like precursor and solution pH. Further characterization and reactivity measurement with regard to preparation method are suggested. From this thesis work we can concluded that the SEA method lead to a selective adsorption of metal precursor onto the desired phase. Also can lead to highly disperse active metal particles on the surface of the support. By focusing on the intrinsic principles of catalyst preparation, this technique can be applied to a wide array of catalytic materials to increase the interaction between two metals to help improve the reactivity and selectivity for special catalytic reactions.