Public defence in Bioproduct technology, M. Sc. (Tech.) A. Topias Kilpinen

Title of the thesis: Hydrolysis of biomass into sugars and other commodities with gaseous hydrogen chloride

Doctoral researcher: M. Sc. (Tech.) A. Topias Kilpinen
Opponent: Professor Mark Mascal, University of California, Davis, USA
Custos: Professor Eero Kontturi, Aalto University School of Chemical Engineering

Conversion of biomass into sugars with hydrogen chloride gas

From the macropolymers present in lignocellulosic biomass, cellulose and hemicellulose can be converted via hydrolysis into monomeric sugars, which are highly versatile platform chemicals. Conventional hydrolysis systems for biomass typically utilize liquid-solid systems, which use liquid acid to hydrolyze solid biomass. But it is also possible to conduct hydrolysis in gas-solid system by substituting the liquid acid with gaseous hydrogen chloride (HCl). 

In a gas-solid system, HCl reacts with the trace amounts of water within the solid biomass under ambient conditions, forming hydrochloric acid, and catalyzing hydrolysis inside the cell wall structure. Employing anhydrous HCl gas for biomass hydrolysis presents distinct advantages over traditional liquid–solid acid systems, such as the ability to use nearly dry biomass (<10% moisture content) for hydrolysis, high sugar yields (>90%), and easy acid separation through evaporation. 

This thesis investigates the hydrolysis of biomass into sugars and other commodity chemicals with anhydrous HCl gas under relatively low overpressure of 0.1 MPa. Aspen wood flour was utilized as a raw material for HCl gas catalyzed hydrolysis and methanolysis. The thesis is comprised of three studies: Comparison of concentrated hydrochloric acid hydrolysis with gaseous HCl hydrolysis under relatively low pressure, selective removal of C5 sugars from biomass via HCl gas hydrolysis, and the production of furfural from methyl xylosides acquired via acid-catalyzed methanolysis of aspen wood flour.

Overall, the outcomes of the thesis provide an extensive study of the utilization of HCl gas for the hydrolysis of biomass with relatively low overpressures. In addition, novel applications for HCl gas hydrolysis in the form of biomass pre-treatment are introduced.

 

→Thesis available for public display 10 days prior to the defence

Contact information:
A. Topias Kilpinen
[email protected]

→Doctoral thesis in the School of Chemical Engineering

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