The Preparation Of Hierarchical Zeolites And Their Applications In The Hydrolysis Of Cellulose

Nowadays, many countries are trying their best to find the clean substitutive resource because of the pressure of fossil resource exhaustion and climate change problem. In this situation, biomass, as an abundant renewable resource in nature, attracts much attention of researchers. And as the major form of biomass, the studying of the applications of cellulose becomes the hot field.In this paper, we investigated the hydrolysis of cellulose to reducing suger. Firstly, we studied the hydrolysis of cellulose catalyzed by acidic ionic liquid. Then, we made effort to the synthesis of meso- and micro- porous catalytic materials used in hydrolysis of cellulose. And we studied the catalytic properties of these materials preliminary.At first, we employed ionic liquid [Bmim]Cl as solvent and used acidic ionic liquid [Bmim]HS04 as catalysts to study the hydrolysis of cellulose. The results indicated that reaction conditions such as reaction temperature, catalyst amount and water amount have obvious effect on the hydrolysis process. Under the optimized reaction conditions, the yield of reducing sugar is 92%. However, the difficulty of products separation and too much catalysts needed in the catalysis process made us to develop the solid catalytic materials.Zeolite is a kind of solid catalytic materials which have high surface area, high activity and high stability. The catalytic processes that using zeolites as catalysts are clean. And the synthesis methods of zeolites have been developed well. Introducing zeolites to the reaction of hydrolysis of cellulose is common subject for many researchers. However, the conflict between micropore system of zeolites and the huge structure of cellulose limits the use of zeolites in hydrolysis of cellulose. We resolved this limitation by introducing mesopores to zeolites. To increase the acid strength and acid amount of zeolites, we modified the zeolites by grafting sulfe group into zeolites surface.Hierarchical aluminium phosphate molecular sieves (A1PO-nH) were synthesized templated by saccharides. Factors including saccharide kind, adding order of reactant, amount of template and so on, were investigated. Also, we prepared metal atom doped A1PO-5H (MeAPO-5H) under the optimized synthesis conditions. The obtained AIPO-nH samples were characterized by XRD, N2 physisorption, FT-IR, TG, SEM, TEM and XRF. The results proved the presence of lots of mesopores in all the samples. To verify the effective of these MeAPO-5H in resolving the reactant diffusion limitation, some oxidation reactions as probe reactions were carried out. The results indicated that MeAPO-5H was high effective in decrease the reactant diffusion limitation. Furthermore, hydrolysis of cellulose catalyzed by MeAPO-5H was carried out. We found that these samples showed low activity in the process of hydrolysis of cellulose.We further treated ZSM-5 by acid or base to prepare mesoporous ZSM-5. The effect of treatment conditions on physic and chemic properties of ZSM-5 were investigated. After modifying the conditions of alkali treatment, sulfonation processes of mesoporous ZSM-5 were carried out to produce high amount of acid sites on zeolites surface. Finally, we studied the hydrolysis reaction of cellulose catalyzed by modified ZSM-5, and found that these zeolites showed high activity in the hydrolysis of cellulose.