Abstract In this research, different catalysts such as sulfonated silica, sulfonated carbon, and sulfonated magnetic carbon were used as solid acid catalysts in the hydrolysis of cellulosic materials. All three types of catalysts were synthesized from rice straw as a cheap, abundant, and available lignocellulosic biomass. Various characteristics of the synthesized catalysts such as specific surface area, surface morphology, functional groups, structure and acidic sites were eva‎luated by BET, SEM/EDS, TEM, FTIR, XRD, CHNS and NH3-TPD analyses. Based on the results of these analyses, the sulfonated silica catalyst has an amorphous structure with a high specific surface area (467 m2/g), which has various functional groups such as hydroxyl and sulfonic on its surface. The total acid density on the surface of this catalyst is 1.31 mmol/g, of which 0.13 mmol/g belongs to sulfonic functional groups. Also, sulfonated carbon catalyst has an amorphous structure with a high surface area (754 m2/g) and has various functional groups such as hydroxyl, sulfonic, and carboxylic. The total acid density on the surface of this catalyst is 3.01 mmol/g, of which 0.20 mmol/g belongs to sulfonic functional groups. Immobilization of magnetic nickel ferrite nano particles on the surface of carbon strongly reduced its specific surface so that its value decreases to 168 m2/g. However, the presence of these particles increases the acidic sites on the surface of the catalyst (3.97 mmol/g), of which 0.24 mmol/g belongs to sulfonic functional groups. In the first and second stages of the research, the catalytic effect of sulfonated silica and magnetic sulfonated carbon in the hydrolysis of pretreated microcrystalline cellulose was investigated, and various operational parameters such as hydrolysis temperature (130-170 ℃), reaction time (1-4 h) and the ratio of catalyst to the substrate (0-1 g/g) were investigated on the production efficiency of reducing sugars and glucose. The maximum TRS yields obtained from hydrolysis of pretreated microcrystalline cellulose with sulfonated silica and sulfonated magnetic carbon were 51.9% in 3 h at 150 ℃ and 68.5% in 3 h at 130 ℃, respectively. In the third stage of the research, the catalytic performance of sulfonated carbon on the hydrolysis of different substrates such as cellobiose, starch, carboxymethyl cellulose, microcrystalline cellulose, and pretreated microcrystalline cellulose was investigated to investigate its effect on the biological hydrogen production during the dark fermentation process. In all the substrates hydrolyzed in the presence of the catalyst, the sugars, biohydrogen, and bioethanol production increased in comparison with the hydrolyzed substrates in the same operational conditions without the presence of the catalyst. This result shows the effectiveness of catalytic hydrolysis in the enhancement of the dark fermentation process efficiency. In the final stage of this research, straw samples pre-processed with different alkalis were subjected to enzymatic hydrolysis and dark fermentation and compared with non-pre-processed rice straw samples. According to the results, all alkaline pretreatment methods significantly increased the efficiency of biological hydrogen production from rice straw, so that the efficiency of hydrogen production from each of the samples pretreated with sodium hydroxide, potassium hydroxide, sodium carbonate, and unprocessed rice straw was 64.1, 136.3, 129.3 and 35.9 mL/g of straw, respectively.

حميد زيلوئي , مهدي بازرگاني پور

فاطمه داور , عليرضا علافچيان , محمد هادي جزيني , مهرداد فرهاديان