Joint research project

Supported bimetallic AuCu and AuAg catalysts in selective alcohol (benzyl alcohol, glycerol) oxidation reactions: Au/Cu(Ag) atomic ratio, Au/Cu(Ag) structure and support effects

Project leaders
Claudio Evangelisti, Andrea Beck
Agreement
UNGHERIA - HAS (MTA) - Accademia Ungherese delle Scienze
Call
CNR/HAS (MTA) 2016-2018
Department
Chemical sciences and materials technology
Thematic area
Chemical sciences and materials technology
Status of the project
New

Research proposal

Heterogeneous catalysis represents the key to ''green chemistry''. Indeed a decreasing pollution from chemical and refining processes can be forecast by atomically tailoring the structure of active sites in order to convert reactants directly to products without generating by-products that typically end up as harmful emissions or as wastes. In particular of selective oxidation catalytic processes using molecular oxygen thus producing minimal by-product, are highly desirable in order to replace expensive and environmentally unfriendly stoichiometric reactions.
In this field the importance of structural features of metal nanoparticles and nanostructured systems to the performance of catalysts has stimulated wide efforts to develop methods for their synthesis and characterization, making this area of study an integral part of nanoscience.
Gold-based catalysis is an environmentally and economically viable process for producing a wide range of useful chemicals from alcohols. Furthermore, as the large international research activity on the field also demonstrated, the efficiency of gold can be enhanced by modification with a second metal, by proper choice of support, using suitable additives. For understanding the role of different structural properties, effect of the different additives on activity, selectivity, stability, accidental inhibiting phenomena, and for optimization of the different parameters further systematic studies are needed. The proposed project is in line with all these.
In the Hungarian team, supported Au-Ag and Au-Cu bimetallic catalyst were recently studied in glucose and benzyl alcohol oxidation. The bimetallic and corresponding monometallic catalysts were typically prepared by sol immobilisation methods and characterized by transmission electron microscopy (TEM, HRTEM), UV-vis, XPS, FTIR spectroscopy, XRD, TPR, TPO. Synergetic effect was observed in Au-Ag/SiO2 system (Au/Ag>2 molar ratio) both in glucose and benzyl alcohol oxidation. When Cu is used to modify Au catalyst (Au/Cu=1) a positive synergism on both Al2O3 and SiO2 supports was observed only in benzyl alcohol oxidation.
The Italian team is involved in the preparation of gold-based bi/trimetallic catalysts since a long time using both sol and solvated metal atoms deposition (SMAD) methods. They are particularly involved in the design of Au catalyst for the selective alcohol oxidation and developed great experience in polyols oxidations. They were one of the first groups demonstrating that alloying gold to other metals, synergistic effect can be obtained acquiring advantages in both selectivity and durability of the catalysts.
The knowledge and the experience of the two groups will be merged in the present project that will be based on the application of AuAg or AuCu bimetallic catalysts mainly in glycerol oxidation with the aim to direct and improve the selectivity of the reaction toward valuable products (tartronic, mesoxalic acids, dihydroxyacetone). Indeed, these bimetallic systems have not been much studied in glycerol oxidation according to the literature. Only few reports deal with AuCu and AuAg catalysts in glycerol oxidation and glycerol electrooxidation, respectively.
In the proposed collaboration different methodologies for preparing truly bimetallic (alloyed or cluster in cluster type) catalyst such as sol techniques, SMAD or galvanic replacement will be employed. Particular attention will be paid to their characterisation by combination of different techniques, such as TEM, HRTEM, UV-vis, XPS, FTIR spectroscopy, XRD, TPR, TPO in order to determine the real structure of the metal nanoparticles and their dispersion as a function of the internal metal ratio (0.1

Research goals

Hungarian and Italian teams have similar scientific background on catalysis but different expertise of application. Therefore they can share very easily their experience with benefit for both of them. Therefore from this cooperation it could be expected a step forward in the application of bimetallic gold based catalysts.
The main task of the project is to produce a highly selective and durable catalyst for glycerol oxidation tailored for targeted high-value products, namely dihydroxyacetone and meso-oxalic acid, able to operate with oxygen as the oxidant. Indeed only the use of environmentally friendly oxidant could make the processes sustainable and alternative to stoichiometric or enzymatic processes.
Another aim of the project is to establish a direct correlation between the bimetallic particle structures and composition and their activity/selectivity in dependence of the support and the substrate. This study will allow a wider application of the catalyst and promote design of new, targeted catalytic materials.
At the same time, another relevant objective is to establish long-term linkages between CNR-ISTM, Italy and MTA, Hungary for further extensive international collaborations possibly leading to formulate common research project ideas and to apply for international or EU research grants.

Last update: 17/07/2024