تهيه كاتاليست اسيدي هتروژن بر پايه مشتقات كاراگينان براي تبديل قندها به 5-هيدروكسي متيل فورفورال و اتيل لوولينات

Conversion of such hexoses as fructose and glucose, the most abundant derivatives of biomass, to 5-hydroxymethylfurfural (HMF), as a major platform for the production of chemicals and fuels, has attracted a wide audience. Yet, due to the high costs of its production, commercialization of HMF may prove uneconomical. For this reason, a path for the conversion of a heterogeneous catalyst may make the production possible. For this dissertation, first, using MBA, pure carrageenan and acidic groups were improved and stabilized, and then, used in the dehydration of sugars for production 5-hydroxymethylfurfural (HMF) and ethyl levulinate (EL). In the first study, fructose was converted to 5-hydroxymethylfurfural (HMF) using κC-g-MBA, a catalyst with acidic and high thermostable sulfonic groups. The study was intended to compare fructose with glucose. The catalyst was recognized and eva‎luated using XRD, BET, FESEM, SEM, FT-IR, and TGA, and to convert fructose to HMF, DMSO was used as solvent. In this process, various parameters, including the effect of temperature on the reaction, time of reaction, amount of the catalyst, and the effect of solvent on obtaining the best yield were analyzed. In view of the results obtained, for fructose, a yield 89.1% of HMF, in 60 min, and 160 °C, for glucose, a yield of 16.9% of HMF, in 120 min and 160 °C were obtained. The catalyst proved efficient with Bronsted acidic groups. The catalyst recovery was also analyzed; however, the yield decreased slightly after several recoveries. In the second study, the heterogeneous acidic catalyst ιC-g-MBA was used to convert fructose to 5-hydroxymethylfufural (HMF). The catalyst was recognized using XRD, BET, FESEM, FT-IR, and TGA techniques. The reaction temperature, amount of catalyst, and effect of the solvent on obtaining the optimal yield were analyzed. For fructose, a yield of 88.2% of HMF, in 60 min, and 160 °C, for glucose, a yield of was 25.2% of HMF, in 120 min and 160 °C were obtained. The catalyst possesses such unique properties as proper yield and easy extractability. Further, using the recovered catalyst, a model reaction was achieved such that the yield was still high after four recoveries. In the third study, fructose was dehydrated and converted to ethyl levulinate using two solid heterogeneous catalysts: κC-g-MBA and ιC-g-MBA. To improve on the yield of ethyl levulinic, the parameters effective on the reaction were analyzed. With κC-g-MBA, a yield of 79.9% of ethyl levulinate, in 5 hours, and a temperature of 180 °C in ethanol was obtained. A yield of 82.9% of ethyl levulinate with the acidic catalyst ιC-g-MBA was obtained in 5 hours and 180 °C in ethanol.

محمد ديناري، عليرضا نجفي

شادپور ملك پور

عبدالرضا حاجي پور، حسين توكل، عباس رحمتي