Final Report Summary - MOFCAT (Functional Metal Organic Frameworks as Heterogeneous Catalysts)
Metal organic frameworks (MOFs) are novel organic-inorganic crystalline materials, which could become a powerful and flexible family for different industrial uses within catalysis, adsorption and sensor technology, overcoming many of the limitations of seolites, the porous crystalline solids which are conventionally used as catalysts. MOFs may display extreme porosity and surface areas, and their functionalities can be tailored by using functional precursors in their preparation or by post-functionalisation using standard techniques of organic- and organometallic chemistry.
The objectives of the project were to:
1) develop reproducible and scalable synthesis procedures for known and new MOFs, and also using combinatorial techniques;
2) understand at the molecular level the interactions governing their stability, self-assembly and adsorption properties, by means of combined experimental and theoretical modelling efforts;
3) develop functionalisation routes to create MOF-based single-site catalysts for two emerging industrial processes;
4) exploit the functionalised MOFs as catalysts in two emerging industrial processes;
5) exploit Pt-functionalised MOFs as catalysts for C-H activation at moderate conditions;
6) exploit MOF materials for catalytic hydrodesulphurisation (HDS) of oil; and
7) exploit selected MOFs as adsorbent or storage media for non-condensable gases (hydrogen and methane).
The project was split into six technical work packages that have worked in parallel: All materials synthesis was carried out in WP1 (Synthesis) and WP2 (Functionalisation). In WP1, the aim was to prepare open, porous and crystalline MOFs, both non-functionalised MOFs and MOFs having specific functionalities inside the pores that later can be made into active catalysts in WP2. In WP4 (Characterisation) a deep understanding of selected materials was gained through spectroscopic analyses of the material itself and its interaction with various gaseous molecules. To complement the experimental work and obtain a full understanding of the materials, quantum chemical modelling was carried out in WP3 (modelling). In cases where potential catalysts were prepared, the catalyst would be tested in WP5 (Catalysis), while the most porous MOFs made would be evaluated for gas storage potentials in WP6 (Adsorption).
One MOF structure that was invented prior to the MOFCAT project was further studied within the project resulting in a deep understanding on the material activation and the behaviour in the presence of various gases. The CPO-27-M family, M= Ni, Mg, Co, Mn, demonstrated a very nice one-dimensional pore structure. Thermal treatment of the CPO-27M materials leads to an open porous structure where each metal atom has on open coordination site. Thus, this is one of the rare MOF materials where the reactivity and effect of the different metals can be directly compared within the same framework structure.
A second family of novel MOF materials that was developed through the MOFCAT project and that gained much attention was the zirconium based UiO-66 family. Variation of the organic linker gives an isoreticular family of ultra stable MOFs, some showing stable performance to temperatures above 400 degrees Celsius. Increasing the length of the linker make pore size and -volume larger, which is of importance if the materials should be used to store or convert molecules of larger size.
Part of the material preparation part of MOFCAT was devoted to synthesis up-scaling and particle formulation since both these aspects are of great importance when it comes to the application of these materials in real industrial processes. Both preparations of CPO-27-Ni and UiO-66 were successfully up-scaled from gram to 100 gram scale. In addition, pelletising CPO-27-Ni demonstrated only negligible reduction in pore volume and surface area.
One on the main objectives of MOFCAT was to develop novel MOFs for storage of non-condensable gases such as hydrogen and methane. Both the CPO-27-M family and the UiO-66 family could store significant amount of hydrogen at low temperature (77 K). The initial adsorption energies determined were strongly dependent on the metal of the MOF, the highest being nickel with 12.4 kJ/mol (CPO-27-Ni) which was among the highest reported for MOF adsorbents.
For the UiO-66 family, highest H2 storage capacity was obtained with the material prepared with the dicarboxylic acid biphenyl linker since this material had the highest specific surface area and pore volume.
Methane storage in the CPO-27-M materials demonstrated the same trend as with H2: a similar two step adsorption was observed due to the initial strong adsorption on the metal sites. For the CPO-27-Ni material significant storage potential was observed, exceeding the volumetric storage density at room temperature.
From quantum chemical modelling, the adsorption of methane inside the materials was analysed. The high methane storage capacity was also reproduced using pellettised CPO-27-Ni showing that real applications of MOFs for methane storage might be feasible.
Novel, highly dispersed hydrodesurfurisation (HDS) catalysts made from bimetallic MOF precursors. Some of the new MOF based highly dispersed HDS catalysts demonstrated activities close to twice that of a commercial high-surface area alumina-supported CoMo catalyst.
The objectives of the project were to:
1) develop reproducible and scalable synthesis procedures for known and new MOFs, and also using combinatorial techniques;
2) understand at the molecular level the interactions governing their stability, self-assembly and adsorption properties, by means of combined experimental and theoretical modelling efforts;
3) develop functionalisation routes to create MOF-based single-site catalysts for two emerging industrial processes;
4) exploit the functionalised MOFs as catalysts in two emerging industrial processes;
5) exploit Pt-functionalised MOFs as catalysts for C-H activation at moderate conditions;
6) exploit MOF materials for catalytic hydrodesulphurisation (HDS) of oil; and
7) exploit selected MOFs as adsorbent or storage media for non-condensable gases (hydrogen and methane).
The project was split into six technical work packages that have worked in parallel: All materials synthesis was carried out in WP1 (Synthesis) and WP2 (Functionalisation). In WP1, the aim was to prepare open, porous and crystalline MOFs, both non-functionalised MOFs and MOFs having specific functionalities inside the pores that later can be made into active catalysts in WP2. In WP4 (Characterisation) a deep understanding of selected materials was gained through spectroscopic analyses of the material itself and its interaction with various gaseous molecules. To complement the experimental work and obtain a full understanding of the materials, quantum chemical modelling was carried out in WP3 (modelling). In cases where potential catalysts were prepared, the catalyst would be tested in WP5 (Catalysis), while the most porous MOFs made would be evaluated for gas storage potentials in WP6 (Adsorption).
One MOF structure that was invented prior to the MOFCAT project was further studied within the project resulting in a deep understanding on the material activation and the behaviour in the presence of various gases. The CPO-27-M family, M= Ni, Mg, Co, Mn, demonstrated a very nice one-dimensional pore structure. Thermal treatment of the CPO-27M materials leads to an open porous structure where each metal atom has on open coordination site. Thus, this is one of the rare MOF materials where the reactivity and effect of the different metals can be directly compared within the same framework structure.
A second family of novel MOF materials that was developed through the MOFCAT project and that gained much attention was the zirconium based UiO-66 family. Variation of the organic linker gives an isoreticular family of ultra stable MOFs, some showing stable performance to temperatures above 400 degrees Celsius. Increasing the length of the linker make pore size and -volume larger, which is of importance if the materials should be used to store or convert molecules of larger size.
Part of the material preparation part of MOFCAT was devoted to synthesis up-scaling and particle formulation since both these aspects are of great importance when it comes to the application of these materials in real industrial processes. Both preparations of CPO-27-Ni and UiO-66 were successfully up-scaled from gram to 100 gram scale. In addition, pelletising CPO-27-Ni demonstrated only negligible reduction in pore volume and surface area.
One on the main objectives of MOFCAT was to develop novel MOFs for storage of non-condensable gases such as hydrogen and methane. Both the CPO-27-M family and the UiO-66 family could store significant amount of hydrogen at low temperature (77 K). The initial adsorption energies determined were strongly dependent on the metal of the MOF, the highest being nickel with 12.4 kJ/mol (CPO-27-Ni) which was among the highest reported for MOF adsorbents.
For the UiO-66 family, highest H2 storage capacity was obtained with the material prepared with the dicarboxylic acid biphenyl linker since this material had the highest specific surface area and pore volume.
Methane storage in the CPO-27-M materials demonstrated the same trend as with H2: a similar two step adsorption was observed due to the initial strong adsorption on the metal sites. For the CPO-27-Ni material significant storage potential was observed, exceeding the volumetric storage density at room temperature.
From quantum chemical modelling, the adsorption of methane inside the materials was analysed. The high methane storage capacity was also reproduced using pellettised CPO-27-Ni showing that real applications of MOFs for methane storage might be feasible.
Novel, highly dispersed hydrodesurfurisation (HDS) catalysts made from bimetallic MOF precursors. Some of the new MOF based highly dispersed HDS catalysts demonstrated activities close to twice that of a commercial high-surface area alumina-supported CoMo catalyst.
