Periodic Reporting for period 3 - 3D-FABRIC (3D Flow Analysis in Bijels Reconfigured for Interfacial Catalysis)
Période du rapport: 2022-06-01 au 2023-11-30
Solvents provide the liquid media for countless chemical processes involving immiscible reagents, forming the basis to produce pharmaceuticals, detergents, pesticides, polymers, fuels and many other chemicals. On the downside, solvents contribute up to 50% of the energy employed in industrial reactions. 6.5 million tons of alcohol based organic solvents were employed worldwide in 2013 alone. The separation of products and catalysts from solvents and solvent-recycling significantly increases investment and operational costs of chemical plants. Without solvents, chemical reactions of immiscible reagents take place in biphasic mixtures (emulsions). Besides being more energy efficient, solvent-free biphasic processes often have the advantage of combining reaction and separation in one step (phase transfer catalysis). Classical examples are the Shell higher olefin process with annually over 1 megatons production of linear alpha olefins or the Ruhrchemie/Rhône-Poulenc process for the hydroformylation of propene with an annual production of over 6 megatons aldehydes. However, chemical reactions in emulsions are typically based on batch processing, limiting the economic productivity. Continuous flow reactors for biphasic reactions are highly desirable for the uninterrupted production of high value added chemicals.
Within the project 3D-FABRIC, we investigate continuous flow chemistry of immiscible reagents within nanostructured materials. We aim at developing catalytic nanomaterials that enable reaction and separation of chemicals in a single step during continuous flow operation. To this end, a sponge like material called the bijel is employed. The bijel is a structure that is half solid and half liquid. Bijels are composed of intertwined oil and water channels of only a few hundred nanometers in size. The channels are held in place by a rigid scaffold of densely-packed nanoparticles. The small channel sizes and nanoparticles provide the bijel with a large internal surface area, ideal for the intimate exchange of immiscible reactants and products during chemical reactions. Moreover, the channels in the bijel enable the continuous in- and outflow of reactants and products. Last, the nanoparticle scaffold can be functionalized to act as a catalyst for chemical reactions.
The three main objectives of 3D-FABRIC are (a) the synthesis of bijels with well-defined structure-function relationships, (b) the mechanical reinforcement of bijels and (c) the continuous flow synthesis of specialty chemicals in the bijel. By achieving these goals, we will introduce a scalable technology for the sustainable synthesis of biofuels, specialty chemicals and pharmaceuticals in the chemical industry.
Within the project 3D-FABRIC, we investigate continuous flow chemistry of immiscible reagents within nanostructured materials. We aim at developing catalytic nanomaterials that enable reaction and separation of chemicals in a single step during continuous flow operation. To this end, a sponge like material called the bijel is employed. The bijel is a structure that is half solid and half liquid. Bijels are composed of intertwined oil and water channels of only a few hundred nanometers in size. The channels are held in place by a rigid scaffold of densely-packed nanoparticles. The small channel sizes and nanoparticles provide the bijel with a large internal surface area, ideal for the intimate exchange of immiscible reactants and products during chemical reactions. Moreover, the channels in the bijel enable the continuous in- and outflow of reactants and products. Last, the nanoparticle scaffold can be functionalized to act as a catalyst for chemical reactions.
The three main objectives of 3D-FABRIC are (a) the synthesis of bijels with well-defined structure-function relationships, (b) the mechanical reinforcement of bijels and (c) the continuous flow synthesis of specialty chemicals in the bijel. By achieving these goals, we will introduce a scalable technology for the sustainable synthesis of biofuels, specialty chemicals and pharmaceuticals in the chemical industry.
During the first 2 ½ years of the project, we have made significant progress towards the realization of the three project objectives. For objective (a) we have advanced the bijel synthesis method to fabricate continuous channel networks of submicrometer dimensions. Our work has created knowledge about the mechanisms controlling bijel synthesis with silica and alumina nanoparticles. We show how the nanostructured bijel is formed via the self-assembly of nanoparticles during the demixing of oil and water. These findings are general and can be transferred to a broad range of bijel building blocks. Within objective (b), we have developed two different methods to reinforce the bijel. The first method combines bijels of different mechanical properties into composite structures with enhanced mechanical strength and flexibility. For the second method we impregnate the bijel with a chemical that binds the nanoparticles strongly together, similar to mortar in a brick wall. Also within objective (ii), we have discovered a method to flow liquids through the bijel. To this end, a electrical voltage is applied across the bijel, dragging water through the microscopic channels. For objective (c) we have shown for the first time continuous flow liquid-liquid extraction within the bijel.
Our progress on the bijel synthesis technique has resulted in bijels with the highest internal surface areas yet reported in the literature. The low cost of the commercially available raw materials for bijel fabrication and the continuous production technique enable the mass production of this versatile new material. The reinforcement techniques developed during 3D-FABRIC is not only useful for bijels, but can be employed to combine a variety of materials such as hydrogels, emulsions or polymers into composite materials with features greater than the sum of their individual parts. We also show for the first time the convective flow of liquids through bijels. The potentials to flow liquids through the bijel has already been envisioned in the seminal publication on bijels in 2005, but has never been experimentally demonstrated until now. Last, we have introduced continuously operated liquid-liquid extraction within bijels, leveraging their potentials for separations in the chemical industry.
These important findings now pave the way for continuous molecular separations and catalysis in the bijel. We plan to develop additional bijel synthesis methods with different catalytic building blocks. Moreover, we will further investigate bijel reinforcement techniques with polymers to obtain highly stable and strong bijels for technological applications. These bijels will have tailored permeabilities for reactive separations during continuous flow chemistry. We will design lab-scale catalytic bijel flow reactors and investigate the structure function relationships for different chemical reactions including hydrolysis, epoxidation and esterification. The flow through chemistry will be analyzed by confocal microscopy, computer simulations and analytical techniques to enable a deep understanding of the time dependent 3-dimensional transport phenomena occurring during catalysis in the bijel.
These important findings now pave the way for continuous molecular separations and catalysis in the bijel. We plan to develop additional bijel synthesis methods with different catalytic building blocks. Moreover, we will further investigate bijel reinforcement techniques with polymers to obtain highly stable and strong bijels for technological applications. These bijels will have tailored permeabilities for reactive separations during continuous flow chemistry. We will design lab-scale catalytic bijel flow reactors and investigate the structure function relationships for different chemical reactions including hydrolysis, epoxidation and esterification. The flow through chemistry will be analyzed by confocal microscopy, computer simulations and analytical techniques to enable a deep understanding of the time dependent 3-dimensional transport phenomena occurring during catalysis in the bijel.