Synthesis and operando characterization of new catalysts based on metal-organic frameworks functionalized by palladium and platinum

РНФ Бугаев МОФы From 03.07.2018 01:00:00 till 30.06.2020 23:00:00
Grant holder: Aram Bugaev
Responsible: Alina Skorynina
Workers: Elizaveta Kamyshova

Metal-organic frameworks (MOFs) represent a new class of porous crystalline materials, based on the inorganic cornerstones connected via organic linkers. The possibility to vary the type of linkers and cornerstones gave rise to a great number of the obtained structures. Due to exceptionally high porosity and specific surface area, these materials can find their applications in various fields, including catalysis. However, in most of the MOFs metal atoms do not have any coordination vacancies and cannot be catalytically active themselves. In this regard, functionalization of MOFs by metal nanoparticles or single-site metal centers to combine the porosity and high surface area of MOFs with catalytic activity of metals is a problem if great scientific interest. This direction is very promising and quite new, the first works appeared only in the end of 2000s.
This project is aimed to development of new MOFs functionalized by palladium and platinum for catalytic application in hydrogenation of CO2 and C2H2. The project will involve both synthesis of new materials and their in situ and operando characterization, and computer modelling of their atomic and electronic structure. UiO-66, UiO-67 and UiO-68 structures will be chosen as the main topology of MOFs.
The synthesis will be performed by substitution of x part of standard linkers by MCl2-grafted ones, where x will be varied from 0.01 to 0.2, and M = Pd, Pt. The synthesized materials will be analyzed by laboratory techniques to prove the overall crystallinity of MOFs and successful grafting of Pd and Pt atoms into the linkers. The as synthesized materials will be then subjected to the temperature programmed reduction in the atmospheres with varied content of hydrogen. We will determine the role of the hydrogen content on the type of the resulting metal centers: small metal clusters or isolates single-site active metal centers. In the case of metal clusters, the effect of the temperature, ramp rate and the concentration x of the substituted liners on the particle size will be also investigated.
The process of formation of metal clusters and single-site active metal centers will be monitored by in situ FTIR spectroscopy, X-ray absorption spectroscopy and X-ray diffraction. Based on the obtained experimental data complemented by theoretical simulations, we will propose the mechanisms of formation of the active metal sites inside MOFs.
The obtained materials will be tested in the reaction of hydrogenation of CO2 and C2H2. The type of the catalytically active species will be determined by means of X-ray absorption spectroscopy at Pd K- and Pt L3- edges and FTIR spectroscopy with simultaneous online control of the reaction products by means of mass spectroscopy.
The main expected results are
1) synthesis of new functional materials based on the metal-organic frameworks with high catalytic activity in reaction of CO2 and C2H2 hydrogenation;
2) development of new non-destructive approach for in situ and operando characterization of the atomic and electronic structure of the functionalized metal-organic frameworks;
3) development of the stable and scalable procedure to functionalize MOFs by platinum and palladium to obtain materials with desired properties for practical applications;
4) development of the advanced approach for big data analysis and computer simulations based on the artificial intelligence and machine learning.