(197a) Conversion of Cellulose and Amino Acids to High-Value-Added Chemicals Using Saturated Steam

Conversion of biomass to high-value-added chemicals, e.g. fuels, polymers, medicines and the other fine-chemical precursors, is one of the most challenging task to achieve sustainable development. Currently, our group has focused on biomass conversion using high-pressure, high-temperature water such as subcritical and supercritical water. In this work, we report that conversion of various biomass derived chemicals to high-value-added chemicals using saturated steam which has milder reactivities compared with subcritical and supercritical water. Especially, we report conversion of cellulose and amino acids to high-value-added chemicals.

<Conversion of cellulose to HMF>

Cellulose is one of the most important poly-saccharides which can be converted to various fine chemicals. In this study, we focused on hydroxymethylfurfural (HMF) as a target compound which can be synthesized from cellulose. HMF has been attracted because it has a potential to be used as various chemical products including fuels and polymers. Normally, to achieve one-pot conversion of cellulose to HMF, hydrolysis reaction (depolymerization of cellulose to glucose) followed by dehydration (dehydration of glucose to HMF) must be conducted in the same reaction vessel. It is well known subcritical and supercritical water can promote chemical reactions including hydrolysis and dehydration of saccharides. However, because these water have high reactivities, not only HMF but also undesirable products are formed from cellulose. To overcome this problem, we used saturated steam which has milder reactivity compared with subcritical and supercritical water. Because of mild hydrolyzability, cellulose was effectively converted to HMF up to 21 %. In addition, we found that pretreatment of cellulose and amount of added water (W/G, molar ratio of water and glucose unit in cellulose) strongly affect to HMF yield. The obtained results indicate that possibility to produce HMF from cellulose using only water, without using special solvents and catalysts.

<Conversion of amino acids to DKPs>

Amino acids are also important chemicals which can be extracted from various biomass including agricultural and marine resources. Amino acids can be converted to various high-value-added chemicals including peptides, surfactants and precursor chemicals. In this study, we focused on diketopiperazines (DKPs) which are cyclic dipeptides having various bioactivities. DKPs are normally synthesized from protected-amino acids using condensation agents because of low reactivity of amino acids. Here we report that the synthesis of DKPs from free amino acids by dehydration under saturated steam. Glycine and alanine were used as model amino acids in this study. Glycine and alanine were respectively converted to DKPs corresponded to each amine acids under saturated steam. In addition, as with the case of the cellulose, amounts of added water was strongly affected to DKP yield. These results also indicated that saturated steam has a high potential to obtain various fine chemicals induced by dehydration.