James HOLM / Swaminathan RAMESH
Catalytic Thermal Depolymerisation
( Plastic to Diesel )
Catalytic Thermal Depolymerisation
( Plastic to Diesel )
https://www.sciencedaily.com/releases/2017/04/170403083052.htm
Ridding
the oceans of plastics by turning the waste into valuable
fuel
Billions of pounds of plastic waste are littering the world's oceans. Now, a Ph.D. organic chemist and a sailboat captain report that they are developing a process to reuse certain plastics, transforming them from worthless trash into a valuable diesel fuel with a small mobile reactor. They envision the technology could someday be implemented globally on land and possibly placed on boats to convert ocean waste plastic into fuel to power the vessels.
The researchers will present their results today at the 253rd National Meeting & Exposition of the American Chemical Society (ACS).
A sailor for 40 years, James E. Holm says he has watched the sea and coastline become more and more polluted. "A few years ago, I was sailing through the Panama Canal, and when I stopped at an island on the Atlantic side, I was stunned by the amount of plastic covering the beach. I thought if I had a chance to do something about it, I should."
His partner, Swaminathan Ramesh, Ph.D., was driven by the desire and excitement of searching for a new "killer idea" with the power to change the world. Ramesh took early retirement in 2005 from BASF after 23 years as a research chemist and began looking for new opportunities. Ramesh formed EcoFuel Technologies and coupled his chemical knowledge with Holm's concerns about plastic wastes and ocean pollution. In the meantime, Holm had formed Clean Oceans International, a nonprofit organization.
They sought to optimize a technology that can use waste hydrocarbon-based plastics as a feedstock for valuable diesel fuel. Their goal was to rid the world of plastic waste by creating a market for it.
For years, Ramesh explains, pyrolysis technologies have been used to break down or depolymerize unwanted polymers, such as plastic wastes, leaving a hydrocarbon-based fuel. But the process usually calls for complex and costly refining steps to make the fuel useable.
Ramesh set out to change the game and developed a metallocene catalyst deposited on a porous support material that, coupled with a controlled pyrolysis reaction, yields diesel fuels directly without further refining. It is also cost-effective on a small scale, runs at lower temperatures and is mobile.
"The catalyst system also allows us to perform the pyrolysis as a continuous-feed process and shrink the footprint of the whole system," Ramesh says. "We can scale the capacity to handle anywhere from 200 pounds per 10-hour day to 10,000 or more pounds per 10-hour day. Because of its small size, we also can take the technological process to where the plastic wastes are." The whole system can fit in a 20-foot shipping container or on the back of a flat-bed truck, Holm says.
The next step, they say, is to show the technology works well and that it can create a useable drop-in diesel fuel. They will soon conduct a demonstration project for the government of the city of Santa Cruz, California. Officials there are interested in implementing the technology to address waste plastics that currently cannot be recycled, as well as to formulate diesel fuel the city can use for its vehicles, Holm adds.
"If we can get people around the world to pick this up and use it to shift waste plastics to fuel and make money, we are winning," Holm says. "We can even eliminate plastic waste before it gets to the oceans by creating value for it locally on a global basis."
A catalyst for recycling a plastic chosen from polyethylene, polypropylene, polystyrene, and combinations thereof includes a porous support having an exterior surface and at least one pore therein, a depolymerization catalyst component comprising a metallocene catalyst disposed on the exterior surface of the porous support, and a reducing catalyst component disposed in the at least one pore. The exterior surface of the porous support comprises less than 10 parts by weight of the reducing catalyst component based on 100 parts by weight of the depolymerization catalyst component as determined using Energy Dispersive X-Ray Spectroscopy (EDS). Moreover, the reducing catalyst component comprises a transition metal selected from the group of iron, nickel, palladium, platinum, and combinations thereof. The at least one pore in the porous support has an average pore size of 10 Angstroms.
RELATED APPLICATIONS
This application is the National Stage of International Patent Application No. PCT/US2012/071334, filed on Dec. 21, 2012, which claims priority to and all the advantages of U.S. Provisional Patent Application Ser. No. 61/630,894, filed Dec. 21, 2011, which is expressly incorporated herein by reference in its entirety.
FIELD OF THE DISCLOSURE
The present disclosure generally relates to a method for recycling a plastic. More specifically, the present disclosure relates to a method of recycling the plastic in the presence of a catalyst including a depolymerization catalyst component and a reducing catalyst component.
BACKGROUND
Plastics are typically made from non-renewable petroleum resources and are often non-biodegradable. In the United States, plastics are produced in amounts exceeding 115,000 million pounds annually. Plastics are used in many industries to form products for sale in both industrial and residential markets. In industrial markets, plastics are used to form packaging, insulation, construction products, etc. In residential markets, plastics are used to form bottles, containers, and the like.
Plastics such as polyethylene terephthalate (PET), high density polyethylene (HDPE), and polyvinyl chloride (PVC), have commonly accepted Recycling Codes of from 1 to 3, respectively, as developed by the American Plastics Council. These aforementioned plastics are more widely recycled and re-used than many other types of plastics. However, plastics such as polyethylenes having Recycling Codes of 2, 4, and 7, polypropylene having a Recycling Code of 5, and polystyrene having a Recycling Code of 6, can also be recycled. Yet, recycling efforts for polyethylenes, polypropylene, and polystyrene have not been maximized.
Only a small fraction of the plastics produced each year are recycled and re-used. To ease in recycling, the plastics are usually crushed, melted, and/or broken down. Plastics that are not recycled and re-used present potential environmental pollution risks when discarded, are not utilized for energy or raw materials, and contribute to an increased reliance on non-renewable petroleum resources. Traditionally, plastics are recycled according to one of two methods including open- and closed-loop recycling. Closed-loop recycling involves using the plastic as an input to make the same product again. Open-loop recycling involves using the plastic as an input to make other products. For example, open-loop recycling may be used to form diesel fuel using the plastic as an input. However, neither of these methods are particularly efficient because of the complexities involved in processing plastics of different colors, textures, and consistencies and producing other products.
One particular type of open loop recycling includes decomposition of a plastic by heating, in the absence of a catalyst, to reverse polymerize the plastic and form monomers. After the plastic is decomposed, the monomers can then be used in a variety of manufacturing or commercial processes. Traditionally, this decomposition through heating forms monomers having an inconsistent and/or unpredictable number of carbon atoms, while leaving much of the plastic unusable. Formation of monomers having unpredictable numbers of carbon atoms inhibits the monomers from being effectively recycled into other products.
Another particular type of open-loop recycling includes catalytic cracking, which improves on the decomposition of plastic by heating alone. As is known in the art, catalytic cracking involves reverse polymerizing a plastic, in the presence of a catalyst, to form monomers. Traditionally, the catalysts used in catalytic cracking procedures include classic Lewis acids such as AlCl3, metal tetrachloroaluminates, zeolites, superacids, gallosilicates, metals on carbon, and basic oxides. However, many of these catalysts are ineffective in selectively cracking the plastics to form specific monomers. Although traditional catalytic cracking is more efficient in forming monomers than simple decomposition of plastics through heating alone, many of these traditional catalysts still form monomers having an inconsistent and/or unpredictable number of carbon atoms and still leave much of the plastic unusable and un-cracked. Accordingly, there remains an opportunity to develop an improved method for recycling plastics.
SUMMARY OF THE DISCLOSURE AND ADVANTAGES
The present disclosure provides a method of recycling a plastic. The method includes decomposing the plastic in the presence of a catalyst to form hydrocarbons. The catalyst includes a porous support having an exterior surface and defining at least one pore therein. The catalyst also includes a depolymerization catalyst component disposed on the exterior surface of the porous support for depolymerizing the plastic. The depolymerization catalyst component includes a Ziegler-Natta catalyst, a Group IIA oxide catalyst, or a combination thereof. The catalyst further includes a reducing catalyst component disposed in the at least one pore.
The method of the instant disclosure tends to allow for controlled and efficient formation of specific hydrocarbons e.g. having from 4 to 40 carbons, which can be used as fuel. The method also tends to allow for increased decomposition of plastic thereby reducing reliance on, and slowing depletion of, non-renewable energy sources. The method further tends to reduce a need for new mining and drilling operations on unused land and also reduces energy expenditure associated with refining petroleum to form fuels. Still further, the method tends to reduce potential environmental pollution by allowing for the decomposition of the plastics that are discarded in landfills and by reducing runoff and soil erosion from the mining and drilling operations. The catalyst of the method tends to contribute to decomposition of the plastic and direct formation of these hydrocarbons, typically without a need for additional processing or purification. Also, the catalyst tends to be inexpensive to dispose of or recycle...