Place: W1-3, 1st floor Multimedia Lecture Hall
Time: Jan 13th, 3pm
Conversion of Sugars Into Monomers for Bio-based Polymers Via Lewis Acid Molecular Sieves
Mark E. Davis
of Technology, Pasadena, CA 91125
Chemocatalytic routes for the conversion of sugars into monomers that can be used to create known and new polymers have significant potential to enable large-scale production of bio-based polymers. Starting from glucose, reaction pathways that lead to the synthesis of terephthalic acid (PTA) and racemic lactic acid (LA), that can be used to prepare bio-based polyethylene terephthalate (PET) and polylactic acid and/or polyacrylates (dehydration of lactic acid to acrylic acid), respectively, will be discussed. For each of the reaction pathways, molecular sieve catalysts that have isolated Lewis acid sites (via insertion of elements such as Sn, Ti, Zr, into the silica frameworks) have been synthesized and shown to accomplish reactions heretofore unexplored with these types of solid catalysts. For example, a large pore molecular sieve that contains Sn (Sn-Beta) is able to isomerize glucose to fructose in aqueous media with high activity and selectivity. With isotopically labeled glucose, it is demonstrated that the isomerization reaction catalyzed by Sn-Beta proceeds by way of an intramolecular hydride shift, confirming that framework tin centers in Sn-Beta act as Lewis acids. The same large pore molecular sieve containing Zr (Zr-Beta) can selectively catalyze Diels-Alder-dehydration reactions with ethylene and oxidized variants of 5-hydroxymethylfurfural (HMF: prepared from glucose) to give new routes to PTA. Additionally, some of the reaction pathways employ conversions that involve combining the Lewis acid molecular sieves with other catalysts in one-pot systems, e.g., glucose to HMF and fructose to lactates. These examples illustrate the potential of exploiting new chemocatalytic pathways to produce valued chemicals from biomass.
Mark E. Davis is the Warren and Katharine Schlinger Professor of Chemical Engineering at the California Institute of Technology and a member of the Comprehensive Cancer Center at the City of Hope and the Jonsson Comprehensive Cancer Center at UCLA. He has over 425 scientific publications, two textbooks and over 75 US patents. Professor Davis is a founding editor of CaTTech and has been an associate editor of Chemistry of Materials and the AIChE Journal. He is the recipient of numerous awards including the Colburn and Professional Progress Awards from the AIChE and the Somorjai, Ipatieff, Langmuir, Murphree and Gaden Prizes from the ACS. Professor Davis was the first engineer to win the NSF Alan T. Waterman Award. He was elected in the National Academy of Engineering in 1997, the National Academy of Sciences in 2006 and the National Academy of Medicine in 2011. In 2014, he received the Prince of Asturias Award for Technical and Scientific Research from the King of Spain, and in 2015, he was elected into the National Academy of Inventors. Professor Davis’ research efforts involve materials synthesis in two general areas; namely, zeolites and other solids that can be used for molecular recognition and catalysis, and polymers for the delivery of a broad range of therapeutics. He is the founder of Insert Therapeutics Inc., Calando Pharmaceuticals, Inc. a company that created the first RNAi therapeutic to reach the clinic for treating cancer, and Avidity Nanomedicines. He has been a member of the scientific advisory boards of Symyx (Nasdaq: SMMX) and Alnylam (Nasdaq: ALNY). Professor Davis has achieved All American Status for Masters Track and Field in the 400, 200 and 100 Meter Dashes. In 2011, he won the 400 Meter Dash for men of age 55-59 at the Masters World Championship.