| With the depletion of petroleum, coal, natural gas and other fossil fuels, the global energy crisis is increasing fairly rapidly. Biomass is one of renewable energy form with zero net carbon emission; the utilization of biomass is in accordance well with the concept of low carbon economy. Studying on the transformation of biomass has been paid great interesting for the exploitation of new energy and renewable resources.In this dissertation, coprecipitation method was adopted for the preparation of a series of mixed metallic oxides MgMOx(M=Cr,Ni,Al,Mn,Zn,Fe) and their catalytic properties were investigated for the liquefaction of microcellulose and bagasse in the thermal compressed water. The liquefied products of biomass feedstock were separated into gas phase, water and THF extraction fractions and solid residues. The main chemical compositions and relative content of water extraction products were characterized by GC-MS and the effects of reaction temperature and time on acid/hydroxide number of aqueous phase were analyzed as well. GPC was used to measure the molecular weight distribution of polymers dissolved in THF and the qualitative analysis of functional groups was carried out by FT-IR. Simultaneously, the chemical element composition and high heat valve of the solid residue were characterized by element analyzer and calculated. The effects of reaction temperature, time, ratio of liquid to solid (L/S), atmosphere and catalysts on liquefaction of microcellulose and bagasse were investigated in detail. Experimental results indicated that 96.2% of microcellulose was converted when the MgMnOx was used as catalyst at 250℃for 30 min with L/S ratio 10, while 90.4% of baggase was converted at an elevated temperature of 270℃for 5 min with L/S ratio 10 and more than of 51.5% products dissolved in water phase.Water dissolving phase were mainly composed of cyclopentyl ketene and its derivatives, 2-hydroxypropanoic acid and a small amount of acid, alcohol and ether with the mass-average molecular weight of THF extraction phase was 659 g·mol-1 while MgMnOx was used as catalyst for the liquefaction of microcellulose. As for the liquefaction of bagasse, the average number of molecular weight in tetrahydrofuran (THF) dissolving fractions decreased from 1021 g·mol-1 to 802 g·mol-1 while the same catalyst was adopted. The results demonstrated that the bagasse liquefaction products distribution and composition were significantly affected by the catalyst. For example, water soluble phase in catalytic liquefaction of bagasse were mainly composed of cyclopentenone, 2, 5-Hexanedione, phenol and its derivatives, 4-oxo-pentanoic acid, p-hydroxy-Benzaldehyde but, the aqueous phase were mainly composed of furfural and its derivatives when no catalyst was used.As an environmental friendly liquefaction catalyst, MgMnOx can effectively promoted liquefied degradation of microcellulose and baggase. So reported result is significant for the reference of biomass liquefaction process. |
