Alginic acid, a major constituent of macroalgae, was hydrogenated into sugar alcohols over carbon-supported noble metals for the first time. Mannitol and sorbitol were mainly produced via the catalytic hydrogenation of alginic acid, which consists of two epimeric uronic acids. The main reaction pathway is the consecutive hydrogenation of aldehyde- and carboxyl-end of alginic acid dimers followed by the cleavage of C-O-C linkage into monomeric units via hydrolysis. The highest yield of C6 sugar alcohols is 61% (sorbitol: 29%, mannitol: 28%, and galactitol: 4%). The low value of sorbitol to mannitol ratio differs to the case of cellulose hydrogenation due to the composition of alginic acid and isomerization between sugar alcohols under the catalytic system. Such a new and green route to produce sugar alcohols from alginic acid would provide opportunities to diversify biomass resources.

中文翻译：

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大型藻类海藻酸的催化加氢成糖醇

大型藻类的主要成分海藻酸首次在碳负载的贵金属上氢化为糖醇。甘露糖醇和山梨糖醇主要是通过藻酸的催化加氢而产生的，藻酸由两种差向异构的糖醛酸组成。主要反应途径是海藻酸二聚体的醛基和羧基端连续氢化，然后通过水解将COC连接裂解为单体单元。C6糖醇的最高产率为61％（山梨糖醇：29％，甘露糖醇：28％，半乳糖醇：4％）。由于藻酸的组成和在催化体系下糖醇之间的异构化，山梨糖醇与甘露醇之比的低值与纤维素氢化的情况不同。