Catalytic transformation of the marine polysaccharide ulvan into rare sugars, tartaric and succinic acids

Abstract

[EN] The green macroalga Ulva rigida represents a promising feedstock for biorefinary due to its fast growth and cosmopolitan distribution. The main component of the cell walls of U. rigida is a sulfated glucuronorhamnan polysaccharide known as ulvan. Herein it was found that due to the high (hydrogen)sulfate group content of ulvan, hydrothermal autohydrolysis at 130 degrees C renders a high percentage of rhamnose (78-79 % recovery from the initial content in the raw material), a rare sugar of high added value. In addition, acid catalysis by a triflate-based graphene oxide under oxygen-free conditions at 180 degrees C affords moderate amounts of tartaric acid (24-26 %). The same triflate-based graphene oxide catalyst under oxygen pressure yields remarkably high percentages of succinic acid (65 %). The catalyst preserves its activity for at least five consecutive reuses.