Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A New Catalyst for Ethanol Made from Biomass

03.08.2011
Researchers potentially find a renewable path to fuel additives, rubber and solvents

Researchers in the Pacific Northwest have developed a new catalyst material that could replace chemicals currently derived from petroleum and be the basis for more environmentally friendly products including octane-boosting gas and fuel additives, bio-based rubber for tires and a safer solvent for the chemicals industry.

To make sustainable biofuels, producers want to ferment ethanol from nonfood plant matter such as cornstalks and weeds. Currently, so-called bio-ethanol's main values are as a non-polluting replacement for octane-boosting fuel additives to prevent engine knocking and as a renewable replacement for a certain percentage of gasoline. To turn bio-ethanol into other useful products, researchers at the Department of Energy's Pacific Northwest National Laboratory and at Washington State University have developed a new catalyst material that will convert it into a chemical called isobutene. And it can do so in one production step, which can reduce costs.

Reported by researchers in the Institute for Integrated Catalysis at PNNL and in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering at WSU, the findings appeared July 21 in the Journal of the American Chemical Society.

"Isobutene is a versatile chemical that could expand the applications for sustainably produced bio-ethanol," said chemical engineer Yong Wang, who has a joint appointment at PNNL in Richland, Wash. and at WSU in Pullman, Wash., and leads research efforts at both institutions.

In addition, this catalyst requires the presence of water, allowing producers to use dilute and cheaper bio-ethanol rather than having to purify it first, potentially keeping costs lower and production times faster.

No Z-Z-Z for the Weary

An important key to unlocking renewables to replace fossil fuel products is the catalyst. A catalyst is a substance that promotes chemical reactions of interest. The catalytic converter in a car, for example, speeds up chemical reactions that break down polluting gases, cleaning up a vehicle's exhaust.

The PNNL and WSU researchers were trying to make hydrogen fuel from ethanol. To improve on a conventional catalyst, they had taken zinc oxide and zirconium oxide and combined both into a new material called a mixed oxide -- the zinc and the zirconium atoms woven through a crystal of oxygen atoms. Testing the mixed oxide out, PNNL postdoctoral researcher Junming Sun saw not only hydrogen, but -- unexpectedly -- quite a bit of isobutene (EYE-SO-BEW-TEEN).

Hydrogen is great, but isobutene is better. Chemists can make tire rubber from it or a safer solvent that can replace toxic ones for cleaning or industrial uses. Isobutene can also be readily turned into jet fuel and gasoline additives that up the octane -- that value listed on gas pumps that prevents an engine from knocking -- such as ETBE.

Sun Shines

No one had ever seen a catalyst create isobutene from ethanol in a one-step chemical reaction before, so the researchers realized such a catalyst could be important in reducing the cost of biofuels and renewable chemicals.

Investigating the catalyst in greater depth, the researchers examined what happened when they used different amounts of zinc and zirconium. They showed that a catalyst made from just zinc oxide converted the ethanol mostly to acetone, an ingredient in nail polish remover. If the catalyst only contained zirconium oxide, it converted ethanol mostly to ethylene, a chemical made by plants that ripens fruit.

But the isobutene? That only arose in useful amounts when the catalyst contained both zinc and zirconium. And "useful amounts" means "a lot." With a 1:10 ratio of zinc to zirconium, the mixed oxide catalyst could turn more than 83 percent of the ethanol into isobutene.

"We consistently got 83 percent yield with improved catalyst life," said Wang. "We were happy to see that very high yield."

Reactionary Insight

The researchers analyzed the chemistry to figure out what was happening. In the single metal oxides experiments, the zinc oxide created acetone while the zirconium oxide created ethylene. The easiest way to get to isobutene from there, theoretically speaking, is to convert acetone into isobutene, which zirconium oxide is normally capable of. And the road from ethanol to isobutene could only be as productive as Sun found if zirconium oxide didn't get side-tracked turning ethanol into ethylene along the way.

Something about the mixed oxide, then, prevented zirconium oxide from turning ethanol into the undesired ethylene. The team reasoned the isobutene probably arose from zinc oxide turning ethanol into acetone, then zirconium oxide -- influenced by the nearby zinc oxide -- turning acetone into isobutene. At the same time, the zinc oxide's influence prevented the ethanol-to-ethylene conversion by zirconium oxide. Although that's two reaction steps for the catalyst, it's only one for the chemists, since they only had to put the catalyst in with ethanol and water once.

To get an idea of how close the reactions had to happen to each other for isobutene to show up, the team combined powdered zinc oxide and powdered zirconium oxide. This differed from the mixed oxide in that the zinc and zirconium atoms were not incorporated into the same catalyst particles. These mixed powders turned ethanol primarily into acetone and ethylene, with some amounts of other molecules and less than 3 percent isobutene, indicating the magic of the catalyst came from the microstructure of the mixed oxide material.

Balancing Act

So, the researchers explored the microstructure using instruments and expertise at EMSL, DOE's Environmental Molecular Sciences Laboratory on the PNNL campus. Using high-powered tools called transmission electron microscopes, the team saw that the mixed oxide catalyst was made up of nanometer-sized crystalline particles.

A closer look at the best-performing catalysts revealed zinc oxide distributed evenly over regions of zirconium oxide. The worst performing catalyst -- with a 1:1 zinc to zirconium ratio -- revealed regions of zinc oxide and regions of zirconium oxide. This suggested to the team that the two metals had to be close to each other to quickly flip the acetone into isobutene.

Experimental results from other analytical methods indicated that the team could optimize the type of chemical reactions that lead to isobutene and also prevent the catalyst from deactivating at the same time. The elegant balance of acidic and basic sites on the mixed oxides significantly reduced carbon from building up and gunking up the catalysts, which cuts their lifespan.

Future work will look into optimizations to further improve the yield and catalyst life. Wang and colleagues would also like to see if they can combine this isobutene catalyst with other catalysts to produce different chemicals in one-pot reactions.

Reference: Junming Sun, Kake Zhu, Feng Gao, Chongmin Wang, Jun Liu, Charles H.F. Peden, Yong Wang, Direct Conversion of Bio-ethanol to Isobutene on Nanosized ZnxZryOz Mixed Oxides with Balanced Acid-Base Sites, J. Am. Chem. Soc., July 21, 2011, DOI 10.1021/ja204235v.

http://pubs.acs.org/doi/abs/10.1021/ja204235v

This work was supported by the U.S. Department of Energy Offices of Science and of Energy Efficiency and Renewable Energy.

EMSL, the Environmental Molecular Sciences Laboratory, is a national scientific user facility sponsored by the Department of Energy's Office of Science at Pacific Northwest National Laboratory in Richland, Wash. EMSL offers an open, collaborative environment for scientific discovery to researchers around the world. Its integrated computational and experimental resources enable researchers to realize important scientific insights and create new technologies. Follow EMSL on Facebook, LinkedIn and Twitter.

IIC, the Institute for Integrated Catalysis located at Pacific Northwest National Laboratory, is the largest non-industrial catalysis R&D organization in the United States. The IIC conducts catalysis science and engineering research aimed at the control of chemical transformations for a secure energy future.

Pacific Northwest National Laboratory is a Department of Energy Office of Science national laboratory where interdisciplinary teams advance science and technology and deliver solutions to America's most intractable problems in energy, national security and the environment. PNNL employs 4,900 staff, has an annual budget of nearly $1.1 billion, and has been managed by Ohio-based Battelle since the lab's inception in 1965. Follow PNNL on Facebook, LinkedIn and Twitter.

Mary Beckman | Newswise Science News
Further information:
http://www.pnnl.gov

More articles from Life Sciences:

nachricht Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory

nachricht How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>