| 5-hydroxymethy furfural (5-HMF) which with the furfuran, mellowness and aromatic aldehyde conformation can be not only used to sythesize different chemical derivative and new polymer materials, but also was the intermediate product to produce the levulinic acid. The derivative of 5-HMF is widely used to produce fungel, antiseptic and spice, also can be used to replace the Benzene compounds which ususlly is produced from the petroleum to synthesize the polymer materials. Though the low molecular weigh sugars are very rich in the nature and widely available, it is not taken full advantage in the industrial chemical synthesis. As a consequence, it has attracted lots of attention to study the synthesis of 5-HMF using biomass-based low molecular weigh carbohydrates as the raw materials. Based on this we discussed the effect of factors such as different reaction patterns, catalyst, raw material and so on for synthetizing 5-HMF. The results are showed as follows:1. Using the fructose as carbon sources to prepare 5-HMF under Homogenous acid catalysts with microwave assisted heatingWe used the high pressure microwave as the heating mode, the 10%(Sanchez-Rodas et al) fructose as carbon sources and HCl as acid catalyst to research the conversion. The results showed that the optimal condition was HCl with a concentration 0.2 mol/L, the temperature was140℃, the reaction time was 6 min and with the NaCl 33.3%. Under the optimal condition, the yields can up to 75%-80%.2. Conversing the fructose to 5-HMF with the carbon--based solid acid catalyst and microwave assisted heatingWe used the fructose as raw material to produce 5-HMF in the biphasic reaction system and homogeneous reactions system respectively. And we studied the catalytic performance of carbon-based solid acid with different AC-SO3H. The results showed that the optimal condition and the highest yields with different carbon-based solid acid catalyst in biphasic reaction system was as follows:180℃/12 min (67.66%); 130℃ 180℃/6 min (80%-85%); 180℃/12 min (50.3%); 150℃/6 min (75.67%); 150℃/6 min (45.87%); 180℃/12 min (12.4%); 180℃/6 min (14.96%); 150℃/6 min (59.78%)O Because single organic phase catalysis system has the advantages of simple, fast, cheap, and has better application prospect, we focused on the performance of the eight kinds of carbon-based solid acid catalyst under this system. The results showed that two types of AC-SO3H,0 template/sulfonation with 15 h and 1:1 template/sulfonation with 8 h, had high conversion rate, which can be reached 72.69% and 66.33% respectively.3. Preparation of 5-HMF from glucose, xylose, sucrose and straw under microwave assisted heatingWe used the 10% glucose as substrate and HCl as catalyst to research the conversion process. The results showed that the optimal condition was that:HCl with a concentration 0.8 mol/L, the temperature was 160℃, the reaction time was 12 min, the concentration of NaCl was 33.3% and with a AlCl3 5.33%, under the optimal condition, the yields can up to almost 50%. As the main topic of the research was how to transfer the pentose to 5-HMF, the conversion of xylose to 5-HMF with a yield 67.83% was very significant to research the conversion of other pentose. The yield of the conversion of sucrose showed that the conversion of glucose and fructose to 5-HMF should be conducted separatly or to search a equilibriouscondition for the conversion. The yields of the 5-HMF used the staw as raw material indicated that it is almost impossible or very complex and costly to use some raw biomass material such as straw to produce 5-HMF directly. |
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