(560s) Hydrothermal Catalytic Conversion of Biomass into Chemicals: Strategy and Mechanism

Hydrothermal catalysis is an important thermochemical conversion process that is used to valorize biofeedstocks into valuable platform chemicals over various heterogeneous/homogeneous catalysts [1]. Hydrothermal processing has significant potential for any type of fresh biofeedstocks with high moisture content and usually performed in water at 150-300 degrees C under pressures of 4-8 MPa. In SARI, one-pot hydrothermal catalytic conversion of sugar-rich microalgae as fresh biofeedstocks to important and valuable platform chemicals, such as glycols (1,2-propanediol and ethylene glycol) 5-hydroxymethylfurfural (5-HMF) and lactic acid (LA) with yields of 53.6%, 48.0% and 83.0% respectively were developed under mild reaction conditions over heterogeneous catalysts [2-4]. Based on the HPLC, GCMS and ¹³C NMR analysis, complete reaction networks for hydrogenation, dehydration and hydrolysis reaction were systematically investigated to gain insights into the activation of the C-O and C-C bonds in the absence of molecular hydrogen or oxygen [5]. The roles of the active components, promoter and support of catalysts in the formation of chemicals were examined to reveal the structure-activity relationship [6]. The formation mechanism of glycols, 5-HMF and LA were further investigated by density functional theory (DFT) calculations to corroborate with our experiment. In addition, to understand the key roles of water for the hydrogenation, dehydration and hydrolysis reaction, the physicochemical properties of water and the interactions of water with biofeedstocks especially for the hydrogen transfer reaction were also discussed by trace method. To develop this novel technology at demonstration scale, it is necessary to establish a baseline to develop key process models and to perform a techno-economic assessment to get a better sense of the viability of the technology in future.

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