| The green and efficient utilization of cellulose-based renewable resources is of great significance to the sustainable development of today's society.Biomass carbon sulfonic acid(BCSA)is one of the most important catalysts for cellulose hydrolysis to sugar due to its advantages of wide source of preparation materials,simple preparation process and abundant functional groups on the surface.However,in the process of catalytic cellulose hydrolysis and conversion,the porous BCSA with such layered compact packing structure still has some defects,such as poor stability of acid sites,limited accessibility of active sites and low mass transfer efficiency.In this paper,a new kind of structural recombinant biochar based solid sulfonic acid was prepared from agricultural and forestry waste bamboo powder and cheap water glass as the main raw materials,and the basic structural unit of BCSA,biomass carbon nanosheet,was supported by silica gel.Its structure and physical and chemical properties were studied by means of nitrogen adsorption and desorption(BET)FT-IR transmission electron microscopy(TEM)and thermogravimetric analysis(TGA),as well as the catalytic activity factors and laws in the hydrolysis of cellulose.The main content of the paper is as follows:1?Biomass charcoal(BC)and sodium silicate were the main raw materials,Structural recombination catalysts(IL-SLBCSA)for silica gel supported sulfonated biomass carbon nanosheets were prepared by hydrothermal stripping,acidification,addition of ionic liquid(IL),dehydration and sulfonation,etc.The catalyst IL-SLBCSA has more developed Mesoporous channel structure,The accessibility and mass transfer efficiency of BCSA materials were improved.Researches show that;When the incorporation of IL was 7.5%and the dehydration temperature was 250 ?,the materials prepared had the best catalytic performance in the cellulose hydrolysis reaction(cellulose 0.2 g,catalyst0.1 g),Under the optimized conditions(pure aqueous medium,microwave radiation power 350 W,reaction time 20 min),the reduced sugar yield(RSs)was 72.25%,and the conversion number(TON)was14.52,It is 7.1 times higher than that of BCSA.The catalyst can be reused 4 times and still keep good activity.2?In order to further improve the catalytic activity of BCSA,the preparation of 3-chloropropyl trimethoxysilane doped silica gel supported sulfonated biomass carbon nanosheets(Cl-SLBCSA)and the catalytic hydrolysis of cellulose were studied.The effect of the dehydration temperature of 3-chloropropyl trimethoxysilane on the structural recombination of silica gel supported sulfonated biomass carbon nanosheets was investigated The results showed that under the optimized material preparation conditions(the incorporation amount of3-chloropropanyl trimethoxysilane was 20%and the dehydration temperature was 300 ?),under the optimized hydrolysis conditions(pure water phase,cellulose 0.2 g,catalyst 0.1 g,microwave power 350 W time20 min),the hydrolysis of cellulose was catalyzed.The yield of reducing sugar was 90.15%,and the conversion number was as high as 18.44,which was 9.0 times higher than that of the TON of common BCSA.The catalyst can be reused 4 times and still keep good activity.3?The direct conversion of cellulose to 5-HMF is one of the important conversion technologies for cellulose biomass in the future.On the basis of the above studies,Lewis acid-supported materials(Cl-SLBC-IL-M,M=Cr?Zn?Sn?Fe)were prepared by grafting N-methyl imidazole complex metal chloride onto Cl-SLBCSA.The results showed that the catalytic performance of the catalyst Cl-SLBC-IL-Cr was the best.Under the optimized preparation conditions(the incorporation amount of3-chloropropyl trimethoxysilane was 30%),the optimized hydrolysis conditions(pure water phase,cellulose 0.2 g,catalyst 0.1 g,microwave power 350 W time 20 min)catalyzed the hydrolysis of cellulose.The yield of reducing sugar was 56.27%,and the HMF yield was 19.04%,The catalyst can be reused 4 times and still keep good activity. |
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