Recent Research Achievements

Novel technology improves process performance and economics

A CEBC research team of chemical engineers and chemists has demonstrated a novel process for olefin hydroformylation, a key industrial step in the manufacture of products such as detergents and plasticizers. When dense CO₂ is used to partially replace the excess substrate (1-octene) to create a CO₂-expanded liquid (CXL) phase, both the 1-octene hydroformylation rate and the selectivity towards the desired product (a linear aldehyde) are significantly enhanced.   Further, these enhancements occur at significantly milder pressures and temperatures relative to conventional processes.  These results correlate with experimental measurements of enhanced syngas (a mixture of CO and H₂) solubility in the CXL phase where the reaction occurs.  The new process thus offers both reaction and environmental benefits.  To provide the best process economics, CEBC researchers are currently designing Rh-based catalysts for near-complete recovery and recyclability.

(For more information, see Jin et al., AIChE Journal 52:7 (2006) 2575-2581.)

CEBC team invents new "green" chemo-enzymatic synthesis of the drug (+)-modafinil

Modafinil is a novel psychostimulant that is, unlike well-known psycho-stimulants, not addictive. Modafinil is currently approved for the treatment of narcolepsy, and has potential for treating attention-deficit hyperactivity disorder and chemical dependence. A major challenge in pharmaceutical syntheses is to design a simple, yet environmentally friendly synthesis strategy.

CEBC researchers at the University of Iowa have demonstrated a two-step modafinil synthesis, an efficient chemical step followed by a microbial step. They found that the bacterium Amycolaptosis orientalis can not only oxidize a sulfanyl group but also amidate a carboxylic acid to deliver rac-modafinil. They also found that the fungus Beauveria bassiana can oxidize with exquisite stereoselectivity the sulfanyl group of the b-sulfanyl carboxylic acid intermediate, and that B. subtilis could amidate it to dextro-modafinil.  This chemo-microbial synthesis of rac-modafinil requires half the number of steps than its conventional counterpart, and thus reduces its environmental footprint.  The chemo-microbial synthesis of dextro-modafinil is the first of its kind.

(For more information see Olivio et al., Tetrahedron: Asymmetry, 16 (2005) 3507-3511.)

Researchers produce unique molecule-based nanoparticles

CEBC researchers have demonstrated that the molecular structure of the precursor compounds could lead to new and possibly enabling methods for manipulating the structures of molecule-based nanoparticles.   This discovery opens up new avenues to tailor nano-sized particles whose structures can be varied to enhance applications in absorption and catalysis.  A provisional patent has been filed and the first results are published in the Journal of the American Chemical Society.

(For more information see Johnson et al., Journal of the American Chemical Society, 127 (2005) 9698-9699.)

Molecular models provide insights on novel class of reaction media

CEBC researchers are using state-of-the-art molecular simulation tools to accurately predict the thermodynamic phase behavior of liquids that are expanded with compressed gases such as CO₂. Their findings are leading to new fundamental insights on these unique mixed solvents.  These first results are published in the Journal of Molecular Physics and in the Journal of Physical Chemistry, and are providing valuable guidance in CEBC’s quest to exploit CO₂-based solvents for developing novel manufacturing processes with reduced environmental burden.

(For more information, see Houndonougbo et al., Journal of Physical Chemistry B, 110 (2006) 13195-13202.)

New optical probe developed to monitor CO₂-expanded liquids in-situ

CEBC researchers are leading the way in the rational exploitation of CO₂-expanded liquids (CXLs) as the ideal solvents for a broad class of catalytic reaction systems including selective oxidations, hydroformylations and solid acid catalyzed reactions. By replacing a significant fraction of conventional organic solvents with carbon dioxide (from non-sequestered sources), the CXL mixtures enhance mass transfer and reaction rates, reduce waste, and make reactors inherently safer.   Until now, determining the volumetric expansion of the liquid solvent by CO₂ required specially designed high-pressure cells fitted with viewing windows. 
CEBC researchers have developed a fiber-optic probe as a tool to accurately measure the expansion of CXLs in situ without the need for specially designed view cells.  This tool may thus be applied in laboratory and commercial scale reactors to accurately measure liquid holdup.  The probe is also a useful tool for determining mixture critical points and for characterizing mixing and bubble dynamics in reactors.

(Invention disclosures have been filed.)

Applying green engineering and chemistry principles to synthesize solid acid catalysts

The use of environmentally benign solid acid catalysts as replacements for highly corrosive mineral acids (such as sulfuric acid and hydrofluoric acid) in chemical processes has been an elusive grand challenge of the chemical industry for decades. The major barrier to commercialization of solid acid catalyzed processes is either rapid catalyst deactivation and/or unacceptable product quality. A key to solving this problem is designing a catalyst that is active enough to rapidly convert the starting materials to desired products while avoiding side-reactions that lead to the fouling and catalyst deactivation. CEBC researchers have successfully synthesized C-H type solid acids whose acid strength is greater than sulfuric acid and which show remarkably high catalytic activity. Traditional methods to synthesize these types of materials generate large amounts of solid and liquid wastes. CEBC researchers have developed a greener and more economical route that employs a solventless catalyst purification step and produces the solid acid in high (90+%) yields. Novel processes based on the use of such solid acid catalysts are being developed at CEBC.

CEBC researchers and P&G scientists elucidate selective oxidation mechanisms

A new bleach enhancer catalyst for fabric care was designed at CEBC for an industrial partner. To be used in a laundry detergent, the oxidation catalysts must be selective in its reactions, removing stains while doing no harm to either fabric or dyes. The CEBC industrial partner found that the catalysts do indeed exhibit the necessary efficacy and selectivity to be candidates for implementation. Recent CEBC mechanistic studies explain the somewhat unusual source of the selectivity by showing the moderate reactivity of the activated catalyst for the two main reactions. This unusual detailed characterization was facilitated by the fact that the activated form of the complex could be isolated and characterized.

(For more information, see Yin, et al., Journal of the American Chemical Society, 127:49 17170-17171 (2005); Yin, et al., Inorganic Chemistry, 45:8 3467-3476 (2006).)