Clean Technology

Most Recent Inventions

Rechargeable Desalination Battery

UW–Madison researchers have designed a rechargeable desalination cell that can operate on seawater and is capable of performing a desalination/salination cycle with a net potential input as low as 0.2 volts. The cell comprises a sodium-storage electrode coupled to a chloride-storage electrode made of nanocrystalline bismuth foam.

The bismuth-based electrodes are able to store chloride ions in their bulk by oxidizing Bi to BiOCl in the presence of an oxygen source, such as water. Advantageously, BiOCl is insoluble in water over a wide pH range and inert against water oxidation. It also is stable over a wide range of anodic potentials. As a result, the new electrodes can be used for chloride removal in a variety of aqueous sources.

The BiOCl electrode can be converted back to a bismuth electrode by a reduction reaction, where the chloride ions are released into the electrolyte. This reverse reaction allows for the repeated use of the electrode for chloride storage/release via multiple chlorination/dechlorination cycles.

Modified Cyanobacteria for Competitive Sugar Production

UW–Madison researchers have developed strains of Synechococcus sp. Strain PCC 7002 with the highest reported glycogen or starch production rate of any cyanobacteria or algae. The strains are genetically modified to overexpress a glucose-1-phosphate adenylyltransferase.

Boron- and Nitride-Containing Catalysts for Oxidative Dehydrogenation of Small Alkanes and Oxidative Coupling of Methane

UW–Madison researchers have developed improved ODH catalysts for converting short chain alkanes to desired olefins (e.g., propane to propene and ethene) with unprecedented selectivity (>90 percent).

The new catalysts contain boron and/or nitride and minimize unwanted byproducts including CO and CO2. They contain no precious metals, reduce the required temperature of the reaction and remain active for extended periods of time with no need for costly regenerative treatment.

In addition to driving ODH reactions, the new catalysts can be used to produce ethane or ethene via oxidative coupling of methane (OCM).

“Green” Catalytic Systems for Solvent-Free Alcohol Oxidations

Research from the University of Wisconsin-La Crosse has led to the discovery and development of a novel suite of catalytic systems for industrially-relevant green oxidations including the oxidative conversion of primary and secondary alcohols to value-added aldehydes and ketones. Similar systems have been developed for the oxidation of olefins to produce important epoxides, and for the oxidation of alkanes to produce alcohols. Specifically the team has developed a series of iron-based catalysts known as ‘helmet’ phthalocyaninaoto complexes of iron(III). Preliminary studies have focused on the use of what is commonly referred to as the ‘diiPc’ iron(III) system. Notably, the team has shown that this system is capable of catalytically oxidizing a diverse array of substrates including five non-benzylic alcohols (1-pentanol, 2-pentanol and cyclohexanol as well as 2,4-dimethyl-3-pentanol and 5-hydroxymethylfurfural) in the absence of added organic solvent. The presence of water as the monodentate axial ligand in the diiPc complex allows for markedly increased solubility in non-aromatic alcohols, making it an ideal catalyst for use with a much wider and more diverse range of substrates under solvent free conditions. It is envisaged that modification of the diiPc and related ligands will be undertaken to impart further enhancements to catalyst solubility in substrates or water, and/or superior stability in substrate alcohols. In addition to the diiPc system, the team have also developed a means of forming derivatized catalysts utilizing what is commonly referred to as a “helmet naphthalocyaninato” iron(III) complex. Specifically, a sulfonated version has been produced that possesses excellent solubility in water due to the added hydrophilic groups. To date, the sulfonated helmet naphthalocyaninato complex has been shown to provide for efficient formation of acetone from isopropanol as well as conversion of 2-pentanol to 2-pentanone using hydrogen peroxide as the primary oxidant. As such we anticipate that the same system would also be effective in the oxidation of 2-butanol to produce methyl ethyl ketone (MEK), an important commodity scale industrial chemical, and in many other commercially important transformations. Furthermore, preliminary studies have shown this molecule can be immobilized on various solid supports including anion-exchange resins, thereby resulting in a heterogeneous catalyst that can be utilized in the development of catalytic transformations that occur under flow conditions. Additionally, we now know that the sulfonated catalyst efficiently catalyzes the oxidation of phenol with hydrogen peroxide to produce para-benzoquinone. This transformation, along with other related reactions, is very important in the treatment of wastewater.

Slippery Antifouling Surfaces with Health, Environmental and Consumer Applications

UW–Madison researchers have developed a new approach for fabricating and functionalizing SLIPS on objects of arbitrary shape, size and topology (e.g., inside a hollow tube, etc.). The new SLIPS have greater control over how fluids behave when they come in contact. For example, they can be designed with oil-free regions to immobilize fluid droplets and/or control how they slide across the surface.

The new SLIPS are antifouling to bacteria, fungi and mammalian cells, and may be used for the controlled release of antibiotics and to prevent thick liquids or dirt from building up on a surface. They are fabricated via the infusion of oils into reactive polymer multilayers.

Most Recent Patents

Visible-Range Sunlight Drives CO2 Reduction Process for Cheaper Syngas

UW–Madison researchers have developed a new method of reducing CO2 to CO via a reverse water gas shift reaction using visible solar light. The reaction produces a syngas mixture which can be further converted to liquid fuels.

In this process, CO2 (which can be obtained from many industrial processes) is contacted with a plasmonic catalyst in the presence of hydrogen. The catalyst is exposed to visible-range sunlight so that it undergoes an optical phenomenon called surface plasmon resonance, which causes metal electrons to oscillate in a certain way and accelerates the rate of CO2 reduction.

The process results in CO2 being reduced to water and CO that can be collected for downstream products.

Microbes Produce High Yields of Fatty Alcohols from Glucose

UW–Madison researchers have developed a method to produce fatty alcohols such as 1-dodecanol and 1-tetradecanol from glucose using genetically engineered microorganisms. The organism, e.g., a modified E. coli strain, overexpresses several genes (including FadD and a recombinant thioesterase gene, acyl-CoA synthetase gene and acyl-CoA reductase gene). Other gene products are functionally deleted to maximize performance.

The strain is cultured in a bioreactor in the presence of glucose.

Platinum-Free Catalysts for Fuel Cells

UW–Madison researchers have developed a new scheme to improve the efficiency of oxygen reduction reactions in electrochemical cells. Their method combines a redox catalyst with a charge transfer mediator capable of transferring electrons and protons. Careful redox mediator/redox catalyst pairings avoid the need for expensive metal cathodes (or anodes). Favorable pairings include quinones with cobalt or iron-containing redox catalysts, and nitroxyl-type materials paired with nitric oxide-type redox catalysts.