Tag Archives: petroleum

Gold, palladium team up to clean up chemical-making process.

 

Kesavan, L, R Tiruvalam, MH Ab Rahim, MI bin Saiman, DI Enache, RL Jenkins, N Dimitratos, JA Lopez-Sanchez, SH Taylor, DW Knight, CJ Kiely and GJ Hutchings. 2011. Solvent-free oxidation of primary carbon-hydrogen bonds in toluene using Au-Pd alloy nanoparticles. Science http://dx.doi.org/10.1126/science.1198458.

 


Jun 07, 2011

 

2011-0606audreyshand
Audrey Moores
Chemists report a cleaner way to produce a much-used compound called benzylbenzoate.

A team of researchers have cleaned up the process to produce a versatile compound – called benzylbenzoate – that kills disease-causing mites, stabilizes fragrances and is a building block for pharmaceuticals. Benzylbenzoate is made from toluene – a cheap and readily available chemical in crude oil. The new process applies oxygen gas and toluene to a material made of carbon and tiny particles of metals gold and palladium. No solvents are used, and no waste byproducts are generated. The finding is also important because it is a stepping stone to a method to convert natural gas into a useful fuel like methanol.

 

 

Context

Adding an oxygen atom to a molecule – called oxidation – in a controlled fashion is a long sought but challenging goal of chemistry. The procedure is important because most molecules used in industrial and consumer applications have unique properties due to the exact position on the molecule of specific groups of atoms – their chemical functional groups. Many of these functional groups are oxygen based.

For example, introducing one oxygen atom would convert methane – the main component of natural gas and an abundant resource – into methanol, which could be used as a liquid fuel. While simple on paper, the actual transformation is challenging. It often leads to more than one oxygen attaching and ultimately, to the complete burning of methane into carbon dioxide.

More generally, the chemical industry heavily relies on molecules that contain oxygen at key positions. They are used as bulding blocks to make other chemicals. Among them, benzyl alcohol, benzaldehyde, benzoic acid and benzylbenzoate have important economical impacts. They constitute starting points in the manufacture of important products, such as pharmaceuticals, dyes, solvents, perfumes, plasticizers, preservatives and flame retardants.

But, harmful chemicals are needed to make this family of molecules. The process starts with a simple, carbon-based molecule called toluene. Toluene is a component of crude oil. Its transformation currently requires harsh processes involving chlorinated chemicals, acidic solvents or toxic metals. The process has very poor yields (around 15 percent) and generates copious quantities of waste.

Alternatives starting with biomass are desirable and intensely researched, but to date, no alternative process exists to create this important family of compounds.

Current research on oxidation reactions focuses on three key points. First, any required additive needs to be solid to ease separation. Second, the oxygen atom introduced should preferably come from oxygen gas present in air, as opposed to more wasteful or toxic sources. Third, the process must be very efficient – that is, yield a lot of material– and selective – create only one molecular product and thus limit separating the wheat – what’s wanted – from the chaff – what’s not – after the reaction.

What did they do?

The research team from the United Kingdom and the United States exposed toluene to oxygen at 160 degrees Celcius and 10 bars of oxygen – equivalent to 10 times normal atmospheric pressure – for two days. Under these conditions, a very small fraction – 2.9 percent – of toluene was converted into a mixture of benzaldehyde, benzoic acid and a small quantity of the desired benzylbenzoate.

Then, they tested several materials for their ability to improve the reaction. One was gold nanoparticles deposited onto titania, because it actively promotes oxidation of alcohols and carbon monoxide.

Gold nanoparticles deposited onto carbon – similar to porous charcoal – was also tested.

In another approach, they deposited tiny particles of gold and palladium inside the carbon pores. In this setting, gold and palladium form an alloy that has unique properties, different from both pure gold and pure palladium.

They also varied the proportion of gold and palladium in the system and measured how it was impacting the chemical process.

Each system was analyzed using two criteria: 1) conversion – the number of toluene molecules transformed – and 2) selectivity – Did one toluene transform into one or several kinds of molecules?

What did they find?

The gold and palladium nanoparticles on the porous carbon offered the best materials to spur the difficult reaction that transforms toluene to benzylbenzoate.

About half of the toluene was converted with this media. The process was very selective – 94.3 percent of the product was benzylbenzoate. This process required 6,500 times less metal than toluene.

The authors then tried to improve toluene conversion by altering the amount of metal. By adding more metal – 1,650 times less metal than toluene – they reached a conversion of 94.4 percent.

Researchers found that the other materials were not as good. Gold nanoparticles on titania did not perform well despite its other successes. Gold alone on carbon was not very active, either.

The mixture of the gold with palladium inside each nanoparticle proved essential to activity. The optimum proportion was 1 gold atom for 1.85 palladium atoms. Size mattered too, and a small size particle was critical to obtaining high conversion.

What does it mean?

In this work, researchers developed a novel material that takes oxygen from the air to transform toluene into the valuable benzyl benzoate. The material is composed of carbon, gold and palladium at specific ratios for optimum performance.

This research is very important because it brings chemists closer to defining the reaction that could convert methane from natural gas to methanol. Such a  process could allow two important developments.

First, methane is a flammable gas and is thus impractical and dangerous to use as a fuel for vehicles. Methanol, on the other side, is a liquid similar in properties to ethanol. Ethanol currently makes up a small fraction of automobile fuel sold in the United States.

Second, methanol has other important applications in the chemical industry. It is used as a solvent, as an antifreeze and as a building block for a host of commodity chemicals.

The new reaction is also remarkable because of its high yield, chemical selectivity, low waste and use of available resources. The use of a very simply reagent – oxygen gas from air – generated no waste.

The material was very convenient to use. After the reaction, the ending product separated completely from the starting material and was simply filtered off. This allows for two good things: 1) no metal or carbon ended up in the product and 2) the material can be reused in subsequent reactions. The materials was reused four times without measuring any alteration of reactivity.

The porous carbon support played an important role in the success of the reaction. The same material based on porous titania was less active. The researchers suggest the improved performance originates from the difference in surface structure between the carbon and titania based nanoparticles. They believe carbon causes the metal particles to be rougher and thus more reactive with the oxygen.

In all cases, the chemists did not detect any carbon dioxide waste. This means that the oxidation reaction – that is, adding an oxygen atom to the starting carbon, gold and palladium materials – proceeds well. Only one atom of oxygen is added, not several, which happens during complete combustion. This process affords a valuable chemical from toluene without burning toluene itself.

More development and studies are needed to turn this discovery into an industrial process.

Resources

Edwards, JK, B Solsona,E Ntainjua, AF Carley, AA Herzing, CJ Kiely, and GJ Hutchings. 2009. Switching Off Hydrogen Peroxide Hydrogenation in the Direct Synthesis Process. Science 323(5917):1037-1041.

Enache, DI, JK Edwards, P Landon, B Solsona-Espriu, AF Carley, AA Herzing, M Watanabe, CJ Kiely, DW Knight and GJ Hutchings. 2006. Solvent-Free Oxidation of Primary Alcohols to Aldehydes Using Au-Pd/TiO2 Catalysts. Science 311(5759):362-365.

Konietzni, F, U Kolb, U Dingerdissen, WF Maier. 1998. AMM-MnxSi-catalyzed selective oxidation of toluene. Journal of Catalysis 176(2):527-535.

Partenheimer, W. 1995. Methodology and scope of metal/bromide autoxidation of hydrocarbons. Catalysis Today 23(2): 69-158.

Saravanamurugan, S, M Palanichany, V Murugesan. 2004. Oxyfunctionalisation of toluene with activated t-butyl hydroperoxide. Applied Catalysis A General 273(1-2), 143-149.

Sheldon, RA, and JK Kochi. 1981. Metal-catalyzed oxidations of organic compounds. Academic Press:New York.

Chemists convert seaweed to chemicals and fuels.

Kim, B, J Jeong, S Shin, D Lee, S Kim, H-J Yoon and JK Cho.  2011.  Facile single-step conversion of macroalgal polymeric carbohydrates into biofuelsChemSusChem 3:1273-1275.
Synopsis by Evan Beach
Apr 28, 2011

An innovative idea – if adapted to a large scale – could take advantage of an abundant but so far little-used raw material to make biofuels, according to a team of green chemists in Korea. The secret ingredient: seaweed.

Many varieties of seaweeds thrive in the world’s saltwater oceans and seas. Their growth is fueled by carbon dioxide. Unlike most conventional land-based plants, it is possible to produce multiple crops in a year without requiring fertile land and fresh water.

In recent years, microalgae – which are invisible to the naked eye – have been researched and exploited for use as fuels. Mostly ignored in this boom were the macroalgae – the kind you can see with your naked eye and find at the seashore. These seaweeds usually have lower oil content and have not attracted as much attention from chemists and manufacturers.

What they lack in oil, many types of seaweeds make up for in carbohydrates. The red algae species used in the current study is almost 80 percent carbohydrates. These sugars form long chemical chains called agar.

The Korean researchers found two ways to convert the agar into useful products.

In one, they found that agar reacts with an acid catalyst to produce a small molecule known as HMF. HMF is a valuable precursor to a variety of chemicals. To draw an analogy with petroleum refining, HMF would be considered the bio-based equivalent of a petrochemical like toluene that serves as the ultimate starting material for many commercial chemicals. The yield of HMF from the red algae was higher than expected, and this was attributed to unusual simple sugars and linkage patterns in the agar structure.

By adding a different catalyst to agar and introducing a solvent for the reaction, the yield was improved and two different chemical products were formed. Both of these chemicals are well known as biofuels and could be used as building block structures for specialty chemicals as well.

The product yields might be further improved by changing the seaweed growth conditions or even the species. Since the researchers discovered that the agar structure leads to unique reactivity, future work could take advantage of ways to tweak it towards a more favorable composition. Other combinations of catalyst and solvent could be explored as well.

What do you think? Is SynBio the next big scary thing?

The Sins of Syn Bio

How synthetic biology will bring us cheaper plastics by ruining the poorest nations on Earth.

By Jim ThomasPosted Wednesday, Feb. 2, 2011, at 10:00 AM ET

This article arises from Future Tense, a collaboration among Arizona State University, the New America Foundation, and Slate. A Future Tense conference on whether governments can keep pace will scientific advances will be held at Google D.C.’s headquarters on Feb. 3-4. (For more information and to sign up for the event, please visit the NAF Web site.)

An aerial view of rainforest. Here’s a grim prediction to chew on. This biotech craze dubbed “synthetic biology“—where hipster geeks design quirky life-forms: That technology is going to wind up costing lives—likely a lot of them. I’m not suggesting a direct kill by rogue viruses. These will be economic deaths. The dead will not be noteworthy: farmers, pastoralists, and forest dwellers who live in poor nations that depend on plant commodities. Here’s a grim prediction to chew on. This biotech craze dubbed “synthetic biology“—where hipster geeks design quirky life-forms: That technology is going to wind up costing lives—likely a lot of them. I’m not suggesting a direct kill by rogue viruses. These will be economic deaths. The dead will not be noteworthy: farmers, pastoralists, and forest dwellers who live in poor nations that depend on plant commodities.

Syn bio is feted as the next big thing, but we should be clear-eyed about what makes syn bio such a big deal and about whom it will harm. Its advocates predict that synthetic bio will lead to the “New Bioeconomy,” in which we harness biology to perform tasks now accomplished by manufacturing. Read more.

Can Green Chemistry get us out of Deepwater?

By Elizabeth Grossman and Karen Peabody O’Brien

It is now more than three months since the Deepwater Horizon rig exploded, killing 11 workers, injuring more, and unleashing its vast underwater oil gusher into the Gulf of Mexico. As this unnatural disaster continues with devastating consequences to Gulf Coast wetlands, wildlife, culture, and economy, our attention is – quite understandably – focused on the immediate. But as we hasten to rescue, repair, and restore, shouldn’t we also be thinking about what we can do to make sure this never happens again?

This question has many answers. Among them is green chemistry, the science that calls for eliminating hazards and waste at the design stage rather than at the end of the pipe – literally and figuratively. While not a magic wand, green chemistry would go a long way toward moving us away from society’s dependence on toxic petrochemicals as the basis for most manufactured materials.

Rather than preventing pollution and toxic exposures by designing products to be without inherent hazards, we’ve relied on containing, or “managing,” the risk of exposure. And risk management works… until it doesn’t. Sooner or later, it fails. Hence Bhopal. Hence toxic spills. Hence the Deepwater Horizon disaster. Accidents happen.

Historically, we’ve taken these risks and assumed the environment would successfully absorb the consequences of our industrial effluence – accidental or intentional. But clearly this is not working.

Green chemistry can change this course. It is a radical departure from the status quo, the age-old practice of valuing expedience at the expense of the environment and human health.

Green chemistry design has already created products like paint made with soy additives, pesticides made from microbes, and plastics made from orange peels. There are even green chemistry products that can break down petroleum in environmentally benign ways, products that detoxify hazardous petrochemicals and leave behind nothing more toxic than oxygen and water. Not only are these products safe for human health but who wouldn’t prefer an orange peel spill to what is happening in the Gulf?

So far, nearly 2 million gallons of chemical oil dispersants have been poured into the Gulf. Yet these EPA-approved dispersants – themselves petroleum-based products with unknown long term ecological and health impacts – are products of the kind of old thinking and outdated design that got us into this mess in the first place.

“This is an engineering miracle,” said Paul Anastas, assistant administrator for the Environmental Protection Agency’s Office of Research and Development, pointing to a photograph of the Deepwater Horizon drilling rig. “But when we define our goals, we define the consequences of our actions,” he continued in remarks to the 14th annual American Chemistry Society Green Chemistry and Engineering conference in Washington, DC, last month. “There is no doubt,” said Anastas who is also a founder of green chemistry, “that we’re on an unsustainable trajectory.”

To change this course, said Anastas, “we need to design into our technologies the consequences to human health and the environment.”

We have the capacity to do this – to create high performance products that are both effective and environmentally benign. But until we make a real commitment to this transformation we will be limited to what Anastas called “elegant and expensive technological bandages that are inherently unsustainable.”

What would such a commitment look like?

– Every chemistry PhD student would graduate with an in-depth understanding of the environmental costs and benefits of the design choices they make. Every chemistry student would learn the biological mechanisms of toxicology. Investing in and expanding green chemistry education is key. Equipping the next generation with the tools necessary to create sustainable technologies is essential.

– Government procurement programs would use green chemistry principles to seek out the ‘greenest’ technologies. Rather than being limited to products (ranging from dispersants to carpets) that fit a standard set decades ago, government agencies would be empowered to choose and use the most environmentally innovative.

– Companies would compete to lead the transition away from chemicals of greatest concern. We are not talking about using marginally “less bad” chemicals, but about redesigning products and processes to be inherently benign and sustainable. How much smarter is it to become a market leader rather than wait for regulations to force a change?

We don’t need rocket science to prevent future Deepwater disasters. We need chemistry. And green chemistry is one of our most promising tools. Let’s deploy it to its fullest potential.

Original article at The Huffington Post

High Tech Trash

Chasing Molecules

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Boycott Big Oil? Prepare to give up your lifestyle.

Boycott Big Oil? Prepare to give up your lifestyle

By SETH BORENSTEIN
AP Science Writer

WASHINGTON (AP) — Has the oil spill in the Gulf of Mexico got you so mad you’re ready to quit Big Oil?

Ready to park the car and take up bike-riding or walking? Well, your bike and your sneakers have petroleum products in them. And sure, you can curb energy use by shutting off the AC, but the electric fans you switch to have plastic from oil and gas in them. And the insulation to keep your home cool, also started as oil and gas. Without all that, you’ll sweat and it’ll be all too noticeable because deodorant comes from oil and gas too.

You can’t even escape petroleum products with a nice cool fast-food milkshake – which probably has a petrochemical-based thickener.

Oil is everywhere. It’s in carpeting, furniture, computers and clothing. It’s in the most personal of products like toothpaste, shaving cream, lipstick and vitamin capsules. Petrochemicals are the glue of our modern lives and even in glue, too.

Because of that, petrochemicals are in our blood. more.

“Thoughtful Design Versus Reaction” by Paul Anastas

Thoughtful Design Versus Reaction

by Paul Anastas, Assistant Administrator, US EPA, Director of the Office of Research and Development

From: US EPA Science Matters

Seldom in all my years at EPA have I been more impressed by the raw effort and dedication of the people of EPA, and of course here in the Office of Research and Development, in response to the oil spill in the Gulf of Mexico.

Day in and day out I’ve been in the Emergency Operations Center where people come together to solve some of the most challenging questions the Agency has ever faced, and work to prevent a tragedy from becoming a catastrophe.

As I look around the table, I see scientists and engineers sitting down and intensely engaging with economists, attorneys, communication specialists, and community outreach experts. It is a truly integrated trans-disciplinary endeavor. It has made it even more clear to me than it had been before the importance of integrated trans-disciplinary systems thinking.

When we are faced by the type of emergency such as the tragedy in the Gulf, we recognize that it takes all talents to come together and focus like a laser.

What is also clearer to me than ever before is that it is the lack of this kind of integrated trans-disciplinary systems thinking up-front that often leads us as a society into these types of environmental crisis situations.  Thoughtful sustainable design has the potential to minimize both the potential for these types of situations to occur and to minimize the consequences when accidents do happen.  It is a classic example of invest a little now versus having to pay tremendously later.

How will our response to the tragedy unfolding in the Gulf of Mexico change how we approach EPA research, now and into the future?  By incorporating integrated trans-disciplinary design into our scientific and technical support actions, our research products will be useful and informative to those seeking to make the products, processes, and systems of the future more sustainable and to those who are reacting to the next foreseeable yet unforeseen crisis.

Our colleagues are contributing to dealing with the situation in the Gulf — spending days, nights, and weekends.  How I wish it were unnecessary for them to be working on such a terrible event.  The hope remains that as we spend our efforts on thoughtful trans-disciplinary design through our research that there will be fewer of these tragedies in the future.

More information about EPA’s response to the BP Oil spill is available on the US EPA web site:
http://www.epa.gov/bpspill/.