Many of the promising technologies currently under development can reduce energy consumption or get carbon in areas such as biotechnology, computer science, nanotechnology, materials science, etc. While not all things will prove viable, only a small amount of funding With training, many people can help solve the great challenges of this planet.
One such solution is emerging from a new approach to industrial separations at the Massachusetts Institute of Technology Department of Chemical Engineering, where Professor Zachary Smith is working on new polymer membranes that greatly reduce energy use in chemical separations. He is also conducting further studies to improve the performance of polymer films in nanoscale metal-organic frameworks (MOFs).
Joseph R Mares (1924) Zachary Smith, Assistant Professor of Chemical Engineering Career Development. Source: David Sella
'We not only make and analyze materials from the fundamentals of transportation, thermodynamics, and reactivity, but we begin to apply this knowledge to create models and design new materials that have never before been available,' Smith said 'It is exciting to think about it from the lab to the mass production and its impact on society.'
Smith often communicates with industry experts with insights into separation technologies and so far the agreement has remained legally binding, despite the withdrawal of the United States from the 2015 Paris climate agreement. The chemical and petrochemical industries, which are primarily concerned by Smith, are beginning to feel the pressure of reducing emissions. The separate heating and cooling towers require considerable energy and are expensive to construct and maintain, so the industry is also looking for ways to reduce costs.
Smith said industrial processes in the chemical and petrochemical industries consume one-quarter to one-third of total U.S. energy, while industrial separation accounts for half of the energy consumed, and about half of the energy used for separation comes from rectification, which A process requires extreme heat, either in the case of cryogenic distillation or even more energy-intensive extreme cooling.
'It takes a lot of energy to boil and reboil the mixture and it's less efficient because it requires phase transitions,' said Smith. 'Membrane separation techniques can avoid these phase transitions and use less energy. Defective, you can cast them into selective 100 - nm thick films that cover a football field.
However, there are still many difficulties. Membrane separation is only used for a small part of the industrial gas separation process because polymer membranes are often inefficient and can not match distillation performance, "Smith said." Current membranes do not provide adequate production The amounts (called fluxes) are used for high volume applications and their chemical and physical properties are not stable when using more aggressive feed streams.
Most of these performance problems are due to phenomena that the polymer tends to be amorphous or entropic. "Polymers are easy to machine to form useful geometries, but the distance the molecules can travel through the polymer film changes over time." Smith Said. 'It's hard to control the free volume inside the porous state.'
To meet this challenge, Smith Laboratory is trying to add nanoscale features and chemistry to polymers to achieve finer-grained separations, the most demanding optional separation dimension of only a fraction of molecules, Smith said, New materials can 'absorb' one molecule and reject another. '
In an effort to create higher-throughput and higher-selectivity polymer membranes, Smith's team is now re-engineering the novel polymer-template ordered structures developed at MIT laboratories into traditionally amorphous, amorphous polymers, Explained, "Then, we used a nanoscale pocket for post-synthesis to create a diffusion path."
Despite many of the technical success of Smith Laboratories, the throughput required to achieve high volume applications remains a challenge, which complicates the issue as the chemical and petrochemical industries use more than 200 different types of distillative separation processes However, it is also an advantage that when introducing new technologies, researchers can look for niches instead of trying to change the industry overnight.
'We are looking for the most influential targets,' said Smith. 'Our thin film technology covers a small area so you can use them in remote areas or offshore platforms.'
Films have been used to separate nitrogen from the air due to the small size and light weight of the film, and nitrogen is then used to lubricate the fuel tank to avoid bursting. In remote natural gas wells membranes are also used to remove carbon dioxide and have been used in some Great petrochemical applications (such as hydrogen removal) find the right place.
Smith's goal is to expand to cryogenic distillation column equipment, which requires huge energy to produce extreme cooling in the petrochemical industry, including the separation of ethylene - ethane, nitrogen - methane and air.Many plastic consumer goods are made of ethylene As a result, reducing the cost of energy in the manufacturing process can bring huge benefits.
'By cryogenic distillation, not only do you want to separate molecules of similar size and similar thermodynamic properties,' said Smith: "Distillation towers can reach 200 or 300 feet in height with very high flow rates, so separation can cost as much as billions of dollars to keep the vacuum And the energy required to operate the system at -120 degrees Celsius is huge.
Other potential applications for polymer membranes include finding other ways to remove carbon dioxide from nitrogen or methane or to separate different types of paraffin or chemical feedstock, Smith said.
Carbon capture and storage is also a potential area of application, he said: 'If today's economic drivers for carbon dioxide capture, then carbon capture will be multiplied by a maximum of 10 times the membrane We can make a sponge-like material that absorbs carbon dioxide , And effectively separate it in order to pressurize it and store it underground.
One challenge when using polymeric membranes in gas separation is that the polymer is usually made of hydrocarbons.Smith said: 'If your polymer contains the same type of hydrocarbon components, then the polymer you are trying to separate will Swelling, dissolving or losing separation.We would like to introduce non-hydrocarbon components such as fluorine into the polymer so that the membrane interacts better with the hydrocarbon-based mixture. "
Smith is also trying to add MOFs (metal-organic framework compounds) to the polymer.MOFs formed by joining metal ions or metal clusters with organic linkers not only solve the hydrocarbon problem, but also solve the problem of entropy disorder.
'MOFs materials allow you to create one, two, or permanently porous three-dimensional crystal structures,' said Smith. 'A teaspoon of MOFs has a soccer field with so much internal surface area so you can choose the inner surface of a functionalized MOFs Sexually binding or rejecting certain molecules, it is also possible to define the shape and geometry of the pores to allow one molecule to pass and the other to be rejected.
Unlike polymers, MOFs structures do not usually change shape, so voids remain more permanent over time, and Smith said: "They do not degrade through the aging process, as some polymers do. The challenge we face is how One of the ways we are working to incorporate crystalline materials into films that can be made into films is to disperse the MOFs into the polymer as nanoparticles, which allows you to take full advantage of the efficiency and productivity of MOFs while retaining MOFs. "
One potential advantage of incorporating MOFs to enhance polymer films is process enhancement: bundling different separation or catalysis processes in a single step for greater efficiency.Smith said: 'You might consider combining a process that separates the gas mixture and allows the mixture to be simultaneously MOFs for catalytic reactions Some MOFs can also act as cross-linkers instead of using polymers that are directly cross-linked together You can create the connection between MOFs particles dispersed in a polymer matrix that will be created for separation More stability.
Due to their porous nature, MOFs are likely to be used to 'capture hydrogen, methane and, in some cases, even to capture carbon dioxide,' said Smith. 'High absorption can be achieved if the correct type of sponge-like structure is made However, finding a material that can selectively bond one of these components with a very high capacity is a challenge.
A similar MOFs application fuels hydrogen or natural gas to cars, Smith said: "Using porous materials in a fuel tank allows you to hold more hydrogen or methane.
Smith warns that MOFs studies can take decades to produce results, but there is still a long way to go in his laboratory polymer research and is expected to have a business solution in the next five to 10 years.
He said: 'This study may be a real game changer.'