Tag Archives: catalyst

New ceramic catalyst sponge promises to turn waste organic matter into cheap biofuel, medicine

A new, ultra-efficient catalyst could pave the way towards turning various products from food waste to old tires into biofuels or medicine.

Stock photo — biofuel doesn’t actually look like this. Image credits Chokniti Khongchum.

The new material allows for efficient, low-cost recycling of low-grade organic material into valuable chemical products. Food scraps, used cooking oil, agricultural waste, or even plastic can be used in the process (even when relatively impure) can be used as part of the process.

Leftover fuel

“The quality of modern life is critically dependent on complex molecules to maintain our health and provide nutritious food, clean water, and cheap energy,” says co-lead author Professor Adam Lee from RMIT University, Australia.”These molecules are currently produced through unsustainable chemical processes that pollute the atmosphere, soil, and waterways.”

“Our new catalysts can help us get the full value of resources that would ordinarily go to waste to advance the circular economy. And by radically boosting efficiency, they could help us reduce environmental pollution from chemical manufacturing and bring us closer to the green chemistry revolution.”

Turning unwanted organic material into useful products isn’t out of our reach. Currently, however, the processes we use to do so are slow and inefficient, and the tools we have to improve on them, such as chemical catalysts or engineering solutions, are quite expensive. They also require that the raw materials used be very pure. For example, waste cooking oil needs to undergo a very energy-intensive purification process before being used for biodiesel production, as our current methods can only handle around 1-2% contaminants in their raw materials.

The new catalyst, however, can work with ingredients (‘feedstock’) comprising up to 50% contaminants. According to the authors, it’s so efficient it could also double the efficiency of our current processing methods.

The team first fabricated a porous ceramic sponge 100 times thinner than a human hair that contains several different (and specialized) active components. Feedstock molecules enter through the larger pores and undergo an initial chemical reaction, and later flow into smaller pores where final reactions take place. It’s the first catalyst that can mediate several chemical reactions in a sequence in a single particle, the authors note, which helps simplify the process and keeps costs low.

This approach, they explain, mimics the way enzymes handle complex chemical processes in living cells.

“Catalysts have previously been developed that can perform multiple simultaneous reactions, but these approaches offer little control over the chemistry and tend to be inefficient and unpredictable,” said Professor Karen Wilson, also from RMIT.

“Our bio-inspired approach looks to nature’s catalysts — enzymes — to develop a powerful and precise way of performing multiple reactions in a set sequence. It’s like having a nanoscale production line for chemical reactions – all housed in one, tiny and super-efficient catalyst particle.”

Even better, these sponges are cheap to manufacture and don’t use any rare and expensive materials like precious metals. They’re also meant to be employed in a similarly simple manner: mix feedstock such as agricultural waste with the catalysts in a large container, heat gently, and stir.

Their ease of use and low cost should make them attractive in developing countries where diesel is widely employed. Farmers, in particular, are well suited to using these catalyst sponges, as they have access to large quantities of agricultural byproducts to turn into fuel for their farms and machinery.

“If we could empower farmers to produce biodiesel directly from agricultural waste like rice bran, cashew nut and castor seed shells, on their own land, this would help address the critical issues of energy poverty and carbon emissions,” Wilson said.

The team now plans to further refine their catalyst sponges to allow for production of a greater range of final products and useful feedstock, such as producing jet fuel from forestry waste or old rubber. Until then, however, they will be hard at work scaling up production, which is currently limited to the order of a few grams.

The paper “A spatially orthogonal hierarchically porous acid-base catalyst for cascade and antagonistic reactions” has been published in the journal Nature Catalysis.

New catalyst nanoparticle turns plastic waste into high-quality hydrocarbons for oils, waxes, cosmetics

New research is looking to give plastic waste a new lease on life as quality motor oil, lubricants, detergents, or even cosmetics.

Electron micrograph of the platinum nanoparticles distributed onto perovskite nanocubes.
Image credits Northwestern University / Argonne National Laboratory / Ames Laboratory.

Let’s not beat around the bush: humanity has a plastic problem. We’re making a lot of it and we’re throwing most away after a single use. Most recycling methods available today can take some of this waste out of the environment, but they also result in cheap, lower-quality plastics than the ones going into the process, which doesn’t make them very lucrative.

In an effort to find a better way of repurposing the mounds of plastic in the wild, a group of U.S. researchers has developed a new catalyst to turn them into high-quality liquid hydrocarbons. These materials can serve as the base for other products or can be useful as-is.

Liquidizing the assets

“Our team is delighted to have discovered this new technology that will help us get ahead of the mounting issue of plastic waste accumulation,” said Kenneth Poeppelmeier, a paper co-author from Northwestern University.

“Our findings have broad implications for developing a future in which we can continue to benefit from plastic materials, but do so in a way that is sustainable and less harmful to the environment and potentially human health.”

The upcycling method relies on a new catalyst the team developed. It is constructed from perovskite nanocubes studded with platinum nanoparticles. Perovskite was chosen because it remains stable under high temperatures and pressures, and is also a very good material for energy conversion (perovskite is the main material used for several types of solar panels). To deposit nanoparticles onto the nanocubes, the team used atomic layer deposition, a technique developed at Argonne National Laboratory that allows precise control of nanoparticles.

Under moderate pressure and temperature conditions, the catalyst breaks down plastics into high-quality liquid hydrocarbons. The team explains that these substances could be used in motor oil, lubricants, or waxes, or further processed to make ingredients for detergents and cosmetics.

It’s the first plastic recycling or upcycling method that is able to reach this end product. Commercially-available catalysts today generate lower quality products with many short hydrocarbons, which are of limited usefulness. Classic melt-and-reprocess recycling results lower-value plastic that is not as structurally strong as the original material.

Plastics are so resilient because on an atomic level, they have a lot of carbon atoms linked to other carbon atoms — and this chemical bond is very strong (has a lot of energy). As a rule of thumb, it takes a greater amount of energy than that contained in a bond to break it. There aren’t many things in nature that can completely break down plastic, but there are enough sources of energy to degrade it into microplastics. Given that we produce around 380 million tons of plastic yearly, and that over 75% is thrown away after one use (ending up in waterways and the ocean), it adds up to a lot of microplastics.

“There are certainly things we can do as a society to reduce consumption of plastics in some cases,” said Aaron D. Sadow, a scientist in the Division of Chemical and Biological Sciences at Ames Laboratory and the paper’s co-lead author. “But there will always be instances where plastics are difficult to replace, so we really want to see what we can do to find value in the waste.”

The team says that their approach produces far less waste than comparable processes, and virtually no emissions compared to recycling methods that involve melting plastic.

The paper “Upcycling Single-Use Polyethylene into High-Quality Liquid Products” has been published in the journal ACS Central Science.

Storing solar energy: Researchers pave the way for artificial photosynthesis

A team of US and Chinese researchers has developed a new, dual-atom catalyst to serve as a platform for artificial photosynthesis.

Image credits: Department of Energy.

Solar energy has become increasingly cheaper and more effective, but the problem of energy storage still plagues renewables. Harnessing solar energy is a lofty goal, but being able to store and distribute it when it’s cloudy or dark is what researchers are striving for.

In a way, it’s like artificial photosynthesis. Just like plants convert light energy into chemical energy that can later be released to fuel their activities, scientists want to store solar energy in a way that can be used later on.

“Our research concerns the technology for direct solar energy storage,” said Boston College Associate Professor of Chemistry Dunwei Wang, a lead author of the report. “It addresses the critical challenge that solar energy is intermittent. It does so by directly harvesting solar energy and storing the energy in chemical bonds, similar to how photosynthesis is performed but with higher efficiencies and lower cost.”

Image in public domain.

Wang and his colleagues have developed a catalyst (a substance that causes a chemical reaction to occur but is not itself involved in the reaction) that greatly enables this process. Essentially, the technique uses water, carbon dioxide, and solar energy to produce energy that can be routinely stored and then sent through the power grids.

Most catalysts are single-atom, with few teams ever exploring “atomically dispersed catalysts,” which feature two atoms. Wang and his colleagues synthesized a two-atom iridium heterogeneous catalyst, using methods that are relatively facile and cheap. The catalyst exhibited an outstanding stability and high activity toward water oxidation — an essential process in natural and artificial photosynthesis.

The team confirmed the structure and performance of the catalyst through X-ray measurements, using Lawrence Berkeley National Laboratory’s Advanced Light Source. The results were so good they impressed even Wang, who was surprised by the simplicity and durability of the catalyst, as well as the high activity toward the desired reaction of water oxidation.

He says that for the first time, we’re getting a glimpse of the full potential of such catalysts, adding a much-needed innovation in the renewable energy ecosystem.

“[Researchers wondered] what the smallest active and most durable heterogeneous catalyst unit for water oxidation could be. Previously, researchers have asked this question and found the answer only in homogeneous catalysts, whose durability was poor. For the first time, we have a glimpse of the potential of heterogeneous catalysts in clean energy production and storage.”

Journal Reference: Yanyan Zhao el al., “Stable iridium dinuclear heterogeneous catalysts supported on metal-oxide substrate for solar water oxidation,” PNAS (2018).

Hydrogen sign.

Solar fuels just years away, propelled by breakthrough in catalyst research

New research from Caltech could bring an economically-viable solar fuel to the market in the next few years.

Hydrogen sign.

Image credits Zero Emission Resource Organisation / Flickr.

One of the holy grails of renewable energy researchers which they have been pursuing for decades, is the brewing of economically-viable solar fuel. It sounds like something you drill out of the core of a star, but in reality, it’s both much more useful and less dramatic than that: “solar fuels” are chemical compounds which can be used to store solar energy.

Most of the recent research performed in this field focused on splitting water into its constituent parts (hydrogen and oxygen) using only sunlight. It’s easy to see why — hydrogen produced this way would be a clean, cheap, easy-to-produce and generally widely-available fuel. It could be used to power solar cells, motor vehicles, or even spin the turbines of power plants. One of it’s most attractive qualities is that it would be virtually endless and produces zero emissions: the only reactionary product of a hydrogen engine (which burns the gas, i.e. combines it back with oxygen) would be plain old water.

We’re actually pretty close to having the solar fuels we so desire, the only thing we’re missing is the “cheap” part. Back in 2014, a team of Caltech researchers led by Professor Harry developed a water-splitting catalyst from layers of nickel and iron. It worked pretty well for a prototype, showing that it has potential and could be scaled-up. However, while the catalyst clearly worked, nobody knew exactly how it did so. The working theory was that the nickel layers were somehow responsible for the material’s water-splitting ability.

Catalyst model chemical structure.

Ball-and-stick model of the catalyst’s molecular structure. Iron atoms are blue, nickel is green, oxygen is shown in red and hydrogen in white.
Image credits Caltech.

To get to the bottom of things, a team led by Bryan Hunter from Caltech’s Resnick Institute created an experiment during which the catalyst was starved of water, and observed how it behaved.

“When you take away some of the water, the reaction slows down, and you are able to take a picture of what’s happening during the reaction,” Bryan says.

The experiment revealed that the spot where water gets broken down on the catalyst — called its “active site” — wasn’t nickel, but iron atoms. The results are “very different” from what researchers expected to find, Hunter says. However, that isn’t a bad thing. Our initial hypothesis was a dud, but now that we know exactly how the alloy works — meaning we won’t waste time researching the wrong avenues.

“Now we can start making changes to this material to improve it.”

Gray believes the discovery will be a “game changer” in the field of solar fuels, alerting people that iron is “particularly good” for this type of applications. As we now know what we should look for, we can go on to the next step — which is finding out how to make such processes unfold faster and more efficient, which translates to lower costs of the final fuel.

“I wouldn’t be at all shocked if people start using these catalysts in commercial applications in four or five years.”

The paper “Trapping an Iron(VI) Water Splitting Intermediate in Nonaqueous Media” has been published in the journal Joule.

Jet Fuel and Enzymes power Fuel Cell for the First Time

Researchers at University of Utah have demonstrated for the first time a working biological fuel cell that uses enzymes to convert jet fuel into electricity; all at room temperature. Fuel cells are much cleaner and efficient at producing energy than internal combustion engines – theoretically, fuel cells can be up to four times more efficient since the energy conversion is electrochemical and if hydrogen is used, the emissions are zero, nil.

Fuel cell on jet fuel

800px-Boeing_Fuel_Cell_Demonstrator_AB11

In 2008, The Boeing Fuel Cell Demonstrator achieved straight-level flight on a manned mission powered by a hydrogen fuel cell. Photo: Wikimedia Commons

A fuel cell is similar to a battery in that it has an anode, cathode, and electrolyte and creates electricity, but it uses fuel to create a continuous flow of electricity. Typically, a fuel – hydrogen, carbon monoxide, methanol etc – reacts with a catalyst, becomes ionized and reacts with oxygen at the anode. Free electron are generated in the process which flow through a circuit creating electricity. While batteries are common in mobile devices, fuel cells are typically employed in buildings where excess renewable energy is converted into chemical fuel for later use.

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This isn’t the first time that jet fuel has been used in a fuel cell. This summer, Washington State University demonstrated a solid-oxide fuel cell that runs on jet fuel to provide electrical power on commercial airplanes. The system coming off the University of Utah lab, however, works on  Jet Propellant-8 or JP-8, a kerosene-based jet fuel that is used by the U.S. military in extreme conditions such as scorching deserts or subzero temperatures. Most importantly, the fuel cell works at room temperature, as opposed to 950 degrees Fahrenheit (510 degrees Celsius) in other models, and uses enzymes – biological catalysts – instead of solid metal catalysts.

“The major advance in this research is the ability to use Jet Propellant-8 directly in a fuel cell without having to remove sulfur impurities or operate at very high temperature,” says the study’s senior author, Shelley Minteer, a University of Utah professor of materials science and engineering, and also chemistry. “This work shows that JP-8 and probably others can be used as fuels for low-temperature fuel cells with the right catalysts.” Catalysts are chemicals that speed reactions between other chemicals.

Jet fuel is really hard to convert to electricity without igniting it since it contains sulfur, which can impair metal catalysts used to oxidize fuel in traditional fuel cells. Also, this highly complex fuel needs to be split into simpler components like hydrogen or carbon monoxide. Clearly, there were a lot of challenges the researchers had to overcome.

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An enzyme “cascade” of two enzymes – alkane monooxygenase and alcohol oxidase – was used to catalyze JP-8. Hexane and octane, which are chemically similar to JP-8, also were tested as fuels. The researchers found that adding sulfur to their enzymatic fuel cell did not reduce power production.

“Enzymatic fuel cells are a newer type of fuel cell, so they are not currently on the market,” says Minteer, also a professor with USTAR, the Utah Science Technology and Research economic development initiative. “However, researchers haven’t been able to use JP-8 before, because they haven’t had the enzymes to be able to oxidize JP-8.”

Now that they’ve demonstrated a working version, the researchers next plan on improving its efficiency. The findings appeared in the American Chemical Society journal ACS Catalysis.

New Catalyst converts CO2 to methanol 90 times faster than current options

Turn that frown upside down – scientists have found a way to take convert carbon dioxide (CO2) into methanol – a key commodity used to create a wide range of industrial chemicals and fuels. The catalytic system has a much higher efficiency than currently existing systems and makes it easier to get normally unreactive CO2 to participate in the reaction.

“Developing an effective catalyst for synthesizing methanol from CO2 could greatly expand the use of this abundant gas as an economical feedstock,” said Brookhaven chemist Jose Rodriguez, who led the research.

It’s even possible to envision a future where such catalysts are used to reduce the accumulation of greenhouse gas, by capturing carbon dioxide and recycling it to synthesize new fuel. This of course depends on many factors – the most important one being economic feasibility. Their work shows a good proof of concept, paving the way for future such systems to become a reality.

“Our basic research studies are focused on the science-the discovery of how such catalysts work, and the use of this knowledge to improve their activity and selectivity,” Rodriguez emphasized.

When it comes to catalysts, the problem with CO2 is that it’s not a team player – in other words, it generally has very weak interactions with other catalysts. This team used a catalyst composed of copper and ceria (cerium-oxide) nanoparticles, sometimes also mixed with titania, which ensured a remarkable CO2 reactivity. Their work revealed that the metal component of the catalysts alone could not carry out all the chemical steps to transform the CO2 into methanol, but the oxide nanoparticles worked out very well.

“The key active sites for the chemical transformations involved atoms from the metal [copper] and oxide [ceria or ceria/titania] phases,” said Jesus Graciani, a chemist from the University of Seville and first author on the paper.

The catalyst they developed converts CO2 to methanol more than a thousand times faster than plain copper particles, and almost 90 times faster than a common copper/zinc-oxide catalyst currently in industrial use. The study illustrates how the right approach (in this case, adding oxide nanoparticles) can dramatically improve results.

“It is a very interesting step, and appears to create a new strategy for the design of highly active catalysts for the synthesis of alcohols and related molecules,” said Brookhaven Lab Chemistry Department Chair Alex Harris.

Journal Reference: J. Graciani, K. Mudiyanselage, F. Xu, A. E. Baber, J. Evans, S. D. Senanayake, D. J. Stacchiola, P. Liu, J. Hrbek, J. F. Sanz, J. A. Rodriguez. Highly active copper-ceria and copper-ceria-titania catalysts for methanol synthesis from CO2. Science, 2014; 345 (6196): 546 DOI: 10.1126/science.1253057

The X-ray snapshots in the figure show the atomic arrangement of the molecule being brominated before, during, and after the reaction. Photo: Fujita et al/JACS

X-rays image atoms during chemical reactions for the first time

Since its advent some 100 years ago, crystallography has become one of the most important processes in chemical research and development. It involves bombarding a material with X-rays to produce a diffraction pattern as they reflect off the sample. The pattern can be used then to directly determine the atomic structure of the crystal. Using this technique, the structure of DNA was first obserbed, along with that of diamond, table salt, penicillin, numerous proteins, and entire viruses.

Crystallography works for only still structures, yet if Makoto Fujita at the University of Tokyo is correct, then a refined process can be used to image atomic arrangements as chemical reactions happen in real time. This means nothing short of crystallography 2.0 – similar to the technological jump from still photography to motion picture video recording.

Fujita and colleagues studied how a catalyst – a molecule that accelerates a chemical reaction without actually reacting with the elements involved in it – called palladium worked its magic in a reaction where it accelerates the attachment of a bromine atom to a larger molecule. This reaction was carried out in a solution, however modern crystallography can not provide snapshots of atomic structures of molecules moving in a solution. The researchers thus had to employ a trick.

The X-ray snapshots in the figure show the atomic arrangement of the molecule being brominated before, during, and after the reaction. Photo: Fujita et al/JACS

The X-ray snapshots in the figure show the atomic arrangement of the molecule being brominated before, during, and after the reaction. Photo: Fujita et al/JACS

The scientists trapped the catalyst and reacting molecules in a cage, before taking X-ray snapshots during the reaction. This proved to be key for their experiments since it made the molecules still for enough time to allow X-ray imaging capture. This helped Fujita and colleagues better explain and determine how the palladium catalyst played its part in the said reaction. Most importantly, however, the experiment demonstrates a new way to use crystallography to image the structure of changing compounds.

Findings appeared in the Journal of American Chemical Society.

Surface chemistry diagram of the studied reaction. (c) Hirohito Ogasawara/SLAC National Accelerator Laboratory

Seeing a reaction in real-time using the world’s most powerful X-ray laser

Physicists at the U.S. Department of Energy’s (DOE) SLAC National Accelerator Laboratory, once home to the longest particle accelerator for nearly fifty years, have used the world’s most powerful X-ray laser to distinguish at an atomic level the mechanisms of reaction of a catalyst in action. This unprecedented view will help scientists develop cleaner and more efficient energy sources, while also furthering our understanding of how various catalysts work.

A catalyst, be it synthetic, organic or simply a metal, is basically a substance that is used to enhanced the rate of a chemical reaction. For a reactant to form into a product it  always needs to reach an activation energy for it to transform through the chemical reaction. Some reactants take a long time to become products, while others simply don’t have the means to do so by themselves. This is where catalysts come into play that speed up a reaction by changing the specific structures of the reactant molecules; this alteration causes reactant molecules to collide with each other in order to release energy or product. It’s worth noting that scientists sometimes use negative catalysts to slow down rates of reaction.

Surface chemistry diagram of the studied reaction. (c)  Hirohito Ogasawara/SLAC National Accelerator Laboratory

Surface chemistry diagram of the studied reaction. (c) Hirohito Ogasawara/SLAC National Accelerator Laboratory

Using the world’s most powerful X-ray laser,  the Linac Coherent Light Source (LCLS), in conjunction with computerized simulations, physicists  looked at a simple reaction in a crystal composed of ruthenium, a catalyst that has been extensively studied, in reaction with carbon monoxide gas. First the crystal was zapped using a conventional laser, which as expected caused the carbon monoxide molecules to break away. Using the high-power X-ray laser pulses that can reveal at an atomic level what’s going on in a chemical reaction through all its stages, at ultrafast timing, the researchers found that the carbon monoxide molecules were temporarily trapped in a near-gas state, all while still interacting with the catalyst.

“We never expected to see this state,” said Anders Nilsson, deputy director for the Stanford and SLAC SUNCAT Center for Interface Science and Catalysis and a leading author in the research,. “It was a surprise.”

Moreover, an unexpected event was observed: a high share of molecules trapped in this state for far longer than what was anticipated, raising new questions about the atomic-scale interplay of chemicals that will be explored in future research.

It’s also worth noting that the same LCLS X-ray laser was used by researchers at SLAC to heat a lump of matter at over 2 million degrees Fahrenheit – hotter than the sun’s corona.

Catalysts are widely employed today in the chemical industry, ranging from food to energy sources. The latter is of specific interest to scientists since more efficient catalysts mean a higher energy output and a cleaner environment. Most modern cars, for instance, employ catalytic converters in their exhaust that turn flue gases into less toxic compounds.

By bettering our understanding of how catalysts work, using methods such as those employed for the present study that allow observations at ultrafast time scales and with molecular precision, scientists may be able to develop cheaper and more efficient synthetic fuels or more efficient and cleaner technology.

The findings were reported in the journal Science. The five minute long video below illustrates how the LCLS laser works – definitely worth your time.