GTI Computational Modeling Tools to Accelerate New Metal-Organic Framework Membrane Technology for Gas Separations

Computational modeling tools developed at the Georgia Institute of Technology could accelerate development of a new type of membrane technology that will boost the efficiency of energy-related gas separations. The tools will help researchers identify the best candidate materials for use in new metal-organic framework (MOF) membranes now under development.
MOF membranes offer an alternative to more energy intensive processes for separating gases such as carbon dioxide, methane, nitrogen and hydrogen. The technology has generated significant interest because of the broad range of crystalline structures that can be synthesized, but development of new MOF membranes is still at an early stage.
“Metal-organic framework membranes will be useful for doing large-scale energy-related separations in an efficient way. We are trying to accelerate their development to help move the world’s energy economy toward a more sustainable path,” said David Sholl, a professor in the Georgia Tech School of Chemical and Biomolecular Engineering. “A lot of chemists are interested in developing these metal-organic frameworks, and we hope to provide a new approach to designing the membranes.”
A publication on the use of atomically detailed calculations for designing metal-organic framework membranes was recently cited by ScienceWatch as its “fast-breaking paper in engineering” for February 2010. Details of the work were published in the journal Industrial Engineering Chemical Research in January 2009. The research was funded in part by the National Science Foundation (NSF).
Metal-organic framework materials are nanoporous crystals that combine metal-organic complexes with organic linkers to create highly porous frameworks. They offer advantages such as high surface area, porosity, low density and both thermal and mechanical stability – all important for separation membranes.
There are many possible material combinations that could be used in the membranes. By comparing such properties as binding strength and flow rates, the computational modeling could give researchers a way to rapidly identify the materials that will work best in high-volume industrial applications.
“The extra challenge with using metal-organic frameworks is that there are literally thousands of different materials that could be considered for use,” said Sholl, who is a Georgia Research Alliance eminent scholar in energy sustainability. “This is where computational modeling really helps. We are doing the materials screening problem computationally to guide us in attacking the actual fabrication problem experimentally.”
Sholl hopes the technique will narrow the list of candidate materials from thousands down to as few as 10. Researchers would then fabricate the membranes and test them in real-world conditions.
“If we were testing all of these in the lab without the computational guidance, it’s unlikely that we would ever choose the right material,” he said. “The biggest challenge for making a new membrane is that it really requires a lot of work to make a functioning device. Even if we know exactly what material to use, there is a very long development path.”
At Georgia Tech, Sholl’s modeling group is working with experimentalists such as Sankar Nair and Christopher Jones – both professors in the School of Chemical and Biomolecular Engineering – to produce prototype membranes for evaluation.
“The big push right now is to make some devices and get test data,” Sholl said. “In particular, we want to do this within a technology framework that we know can scale up to real-world industrial levels quickly.”
In addition to colleagues at Georgia Tech, the group is also working with industrial partners to help ensure that the membranes work in industrial conditions.
“If we can go from the idea in the academic lab to a serious field test within five years, that would be a real success,” said Sholl, who holds the Michael Tennenbaum Family Chair in the School of Chemical and Biomolecular Engineering. “We can’t afford for this to take 25 years because there is a need for this technology now.”
The new membrane technology could be used to address environmental issues such as removal of carbon dioxide from stack gases of coal-burning facilities in a cost-effective way. The technology could also make it economically attractive to use natural gas supplies that are contaminated with carbon dioxide, potentially expanding supplies of that fuel.
The researchers, including graduate student Seda Keskin, have modeled how the membrane technology would operate in separating methane from carbon dioxide, hydrogen from carbon dioxide, nitrogen from carbon dioxide, hydrogen from methane, nitrogen from hydrogen and methane from nitrogen.
“The common thread of this work is that we are interested in very large scale, large volume applications that can only be economical with very low energy input,” Sholl added.

Novel Microwave Method Produces Entirely New Line of Nanocomposites, Process Could Revolutionize Carbon Black Industry, New Catalyst to Remove Sulfur and Nitrogen from Petroleum Feedstocks such as Canadian Tar Sands

A University of Arkansas (Little Rock, AR)  scientist has developed a novel process for the conversion of biomass renewable resources materials into carbon and carbon-metal nanostructures. The method is an environmentally friendly process that may revolutionize carbon black and related industries by making use of massive quantities of by-products from the forest product industries and steer away from non-renewable resources such as natural gas, petroleum, and coal for the generation of carbon materials.

University of Arkansas (Little Rock, AR) chemistry Professor Tito Viswanathan  has developed a novel microwave method to produce carbon-metal nanocomposites. The process of synthesizing carbon and carbon-metal composites uses a microwave-assisted method to obtain nanoscale carbon-metal composites from carbon-containing precursors, such as lignins, tannins, lignosulfonates, tanninsulfonates, and their derivatives.  

The materials synthesized represent technologically diverse multifunctional materials by an extremely inexpensive and environmentally friendly process. The novel nanometal derivatives synthesized represent an entirely new line of nanocomposites with unique morphologies with potential applications in a variety of fields.    
The processes, detailed in U.S. Patent Application 20100035775,  will also allow the formation of carbides, nitrides and borides, which represent exciting new materials. Among many applications of one of the carbon-metal composites, Ni2P (Nickel phosphide) is its use as a catalyst for the removal of sulfur and nitrogen from petroleum feedstocks–a problem of extreme urgency because of the prediction of decreased Arab oil resources and increased reliance on Canadian tar sands with increased Sulfur and Nitrogen content.

The process is quick and inexpensive in comparison to the known technologies. Moreover, it represents a deviation from conventional heating source as well as raw materials, many of which are non-renewable resource based. It also allows the formation of metal nanoparticles either pristine or on carbon support with high surface area.

Additionally, the process simultaneously reduces metal ions during the process of carbonization and produces nanoparticles of both carbon and metal. The metal obtained may be a zero valent metal or one of the metal tertralides, pnictides, chalcogenides, borides or carbides depending on the reactants present during the synthetic process. The process also allows the formation of unique carbon nanostructures including nanodiamonds.

The novel methods of synthesizing carbon-metal composites includes using metal ions in the presence of an organic compound, which is one of cellulose; hydroxyalkylcellulose such as hydroxyethylcellulose, methylcellulose, carboxymethylcellulose; cyclodextrins; chitin and chitosan; starch; guar gum and polysaccharides.

Viswanathan’s novel process for synthesizing metal particles in the reducing or non-oxidizing environment generated during the microwave process  can be accomplished without the need to use reducing gases, such as H2 gas, or inert gases, such as Ar and N2 gases, during the process.  The process allows simultaneously producing carbon from lignin and reducing the metal ions, such as Ni, Cu, to elemental metal such that nanoparticles of carbon and metal are produced after dispersion.

Viswanathan,  in a further aspect, found a way of synthesizing Ni2P nanoparticles in the reducing or non-oxidizing environment generated during the microwave process without the need to use reducing gases, such as H2 gas, during the process.

Viswanathan also developed a novel method for synthesizing Cu3P and Cu2S nanoparticles in the reducing or non-oxidizing environment generated during the microwave process without the need to use reducing gases, such as H2 gas, during the process.

Viswanathan also developed a process for the preparation of carbon nanostructures as well as carbon-metal nanostructures by applying microwave radiation to a carbon-containing precursor, such as lignins, tannins, lignosulfonates, tanninsulfonates and their derivatives. The microwave radiation is applied at a frequency of 900 MHz to 5.8 GHz, or more preferably at a frequency of 2.45 GHz for a period of 30 seconds to 60 minutes, or more preferably for a period between 4 minutes and 30 minutes. The process may take place either in the presence of air, in the presence of a non-oxygenated atmosphere or in the absence of air.

Patent Application 20100035775, FIG. 22 shows a flow diagram illustrating a synthesis process of making Ni–C composite.

Microbor to Establish First Large Scale Manufacturing Plant for Cubic Boron Nitride Nanopowder, an Ultra-Hard Material, Allianz ROSNO Taking 10% Stake

RUSNANO and Microbor, ZAO have reached agreement with Allianz ROSNO Asset Management for the latter’s participation in the Microbor Nanotech project. Allianz ROSNO will take a share of about 10 percent. The fund, created with the involvement of the Moscow Government, the Ministry for Economic Development of the Russian Federation, and private investors, has been an investor in Microbor since 2007.
In 2009 RUSNANO approved investment in the project of Microbor Nanotech, ZAO. Its total cost is $30.7 million (930 million rubles).
Microbor Nanotech, a new generation manufacturer of composite materials, will establish large-scale manufacturing of cutting instruments using an ultra-hard material—cubic boron nitride nanopowder—in the framework of Microbor, ZAO.
“We welcome the decision of Allianz ROSNO Asset Management to enter the project. RUSNANO always responds favorably when financial investors take an active role in a project,” RUSNANO Managing Director Alexander Kondrashov said.
The full production cycle will be established within the project—from synthesis of cubic boron nitride nanopowder to manufacturing the cutting instruments from the material. To date, only world-leading manufacturers produce instruments from cubic boron nitride. No company has undertaken commercial production of instruments from cubic boron nitride nanopowder.

“The expertise and international relationships that Allianz ROSNO Asset Management has acquired are going to be extremely helpful for the project’s realization,” said Microbor Nanotech Director Alexander Timofeev.
The parties expect to complete the investment during the first quarter of 2010.
According to Allianz ROSNO Asset Management Deputy Director Dmitry Vasyutinsky, execution of the agreement for participation in the project fund and the company’s later departure from the fund demonstrate that the Russian market for investments in high-technology projects can operate on internationally accepted practice.

Singapore Institute of Manufacturing Technology of A*STAR Shows Hot Roller Embossing Technique Cost Effective for Production of Microfluidic Devices

Microfluidic devices are used in a variety of life science applications but, because they are typically disposed of after a single use to avoid cross-contamination, finding a cost-effective, high-throughput method for their mass-production is vital. Now, Lip Pin Yeo from the Singapore Institute of Manufacturing Technology of A*STAR and co-workers have completed a feasibility study of the ‘hot roller embossing technique’— a method to fabricate polymer-based microfluidic chips1.
Fig. 1: The embossing of a ‘Y-mixer’ depicting the principle of fabrication of polymer-based microfluidic devices using the hot roller embossing technique.
Image Credit: © 2010 L. P. Yeo
Microfluidics are typically based on either silicon, glasses or polymers. According to Yeo, approaches based on silicon or glass are costly because the raw materials and associated manufacturing costs are expensive. Polymers, however, are widely available at low cost and are easy to process.
Commenting on the choice of fabrication method, Yeo says: “The setup cost of a roller embossing facility is much lower compared to conventional silicon and glass microfabrication facilities.” The technique is analogous to gravure printing. Two rollers are used to imprint the required pattern of microchannels on a polymer substrate that is sandwiched between them (Fig. 1).
While it is a simple method conceptually, the fidelity of the mold-to-substrate pattern transfer is strongly dependent on a multitude of process parameters, making the search for the optimum regime of operation tedious. Yeo and co-workers tackled this problem using a design-of-experiment (DOE) method, a statistical framework that is able to predict the optimal design from only a limited number of experimental runs.
The variable ‘input’ parameters in the DOE were the substrate preheat temperature, the embossing-roller temperature and the pressure applied during embossing. The output parameter to be optimized was the normalized embossing depth—the ratio between the depth of the polymer microchannel and the height of the mold protrusion—where a value of 1 signifies a perfect mold-to-pattern transfer.
The researchers conducted experimental runs with different input parameters and used the DOE method to elucidate the optimal operating regime yielding the best mold-to-pattern transfer, which they then verified by test experiments. “By operating the roller embossing process using the optimal conditions, an averaged normalized embossing depth of 0.85 can be achieved for low pattern-density mold designs,” explains Yeo. The ratio of 0.85 is in close agreement with the value predicted by the DOE.
Functional testing of fluid flow and mixing of the optimally fabricated microfluidic devices also yielded encouraging results. However, the method will benefit from further improvement. “The crucial issues will be to maintain uniform temperature and pressure distribution during the embossing process,” says Yeo.
The A*STAR affiliated authors in this highlight are from the Singapore Institute of Manufacturing Technology
Reference
  1. Yeo, L.P., Ng, S.H., Wang, Z.F., Xia, H.M., Wang, Z.P., Thang, V.S., Zhong, Z.W. & de Rooij, N.F. Investigation of hot roller embossing for microfluidic devices. Journal of Micromechanics and Microengineering20, 015017 (2010). | article

Eindhoven University Receives Grants to Explore Nanotechnology for Microelectronics and Bone Growth

Two Eindhoven University of Technology researchers will receive a Vici grant from NWO, the Dutch organization for scientific research. With his grant of $2 million (1.5 million Euros), Nico Sommerdijk will explore the mechanisms of bone growth. Erwin Kessels will work on new nanotechnology that will be used in products.

Erwin Kessels (l) and Nico Sommerdijk.

In 2009, associate professor Nico Sommerdijk published an article on biomineralization that made the cover of the respected journal Science. He found that certain nanoclusters are the most important building blocks in the growth of shells and bones.
With the NWO grant, Sommerdijk (department of Chemical Engineering and Chemistry) will now focus on the formation of bone. He explains, “So far we have been working with calcium carbonate, the material shells are made of. We will focus now on calcium phosphate, the material bones are made of. We hope to be able to understand and mimic the process of bone formation and growth by replacing the biological molecules with polymers.”
One of the goals of the project is to be able to make bone replacement materials. But Sommerdijk is already looking beyond that. “By understanding the processes of nature, we may be able to come up with totally new materials that no one has previously thought of.”
For his research, Sommerdijk uses a unique electron microscope, of which there is only one in the world; the TU/e cryoTitan, manufactured by FEI Company. This machine can make 3D images on the nano scale of processes in fluids, by freezing the samples extremely quickly.
Production on an atomic scale
Nanotechnology is widely regarded as one of the most promising future technologies. But little nano research is aimed at preparing this technology for real production. Erwin Kessels, associate professor in the department of Applied Physics of TU/e, will use his Vici grant to close the gap between lab research and the industrial production of, for instance, solar cells and new nano-electronics.
An example of such a gap is carbon nanotubes, says Kessels. “Research has shown that they are suited for all kinds of electronic applications. But producing nanotubes with the exact right properties is a process that we cannot control well enough yet. Usually a large number of nanotubes are made, from which the suitable one is selected.” While that may be enough for research purposes, it is certainly not enough for industrial production. Kessels says, “We still need a lot of research before we will be able to take a demo version to an industrial and reliable production process.”
Kessels’ work is about the growing of ultra thin layers, just a couple of atoms in thickness. The state of the art in the microelectronics industry is that layers are deposited that completely cover a surface, from which tiny patterns are then etched. Kessels hopes to omit that step, and to deposit nanostructures without etching at all. A first case may be a transistor made of a carbon nanotube, to which the electrodes are attached directly. At the same time, the 36-year old researcher wants to control the material properties on an atomic scale, for maximum performance of the products made this way. For instance, products like solar panels with a higher efficiency.
NWO Vici grants are aimed at researchers who received their PhDs a maximum of fifteen years ago. The Vicis enable grantees to start their own research groups. In 2009 the TU/e also had two of thirty Vici grants. In 2008, three Eindhoven researchers were granted Vicis.