| In order to utilize Mulberry tree comprehensively,the two main parts of Mulberry branch(Mulberry bark and Mulberry twig)were analyzed for main chemical composition,trace element content.Cellulose was seperated and characted by Infrared Spectroscopy(FTIR),X-ray diffraction(XRD)is used to study the structure and the change of crystallinity of cellulose before and after treatment.Hemicellulose and lignin were separated and characted by FTIR and Nuclear Magnetic Resonance Spectroscopy(1H NMR,13C NMR,HSQC).The hemicellulose and lignin pyrolysis characteristics were studied by thermo-gravimetric analyzer(TGA),Coats-Redfern integral method was used to calculate the apparent kinetic parameters of lignin mainly thermal cracking stage.The Mulberry branch bio-oil were prepared in a batch-type autoclave with pure water,and Ethanol aqueous solution as liquefaction medium.The main chemical compositions of the bio-oil were characted by FTIR and GC-MS.The primary results are described as follows:(1)The main chemical compositions content of Mulberry branch were:Mulberry twig(Mulberry bark):406.3±0.3 mg-g-,(490.5±0.1 mg·g-1)cellulose,196.4±0.1 mg·g-1(162.6±0.2 mg·g-1)lignin,287.2±0.1 mg·g-1(242.3±0.2 mg·g-1)pentosan.The benefical trace elements Ca,K,Na,Mg,Fe,Zn,Cu were both existed in Mulberry twig and Mulberry bark.The content of Ca and K were highest,respectively Ca 1.0646 ×104(7.41 ×103),K 2.806×103(3.207 ×103).The relative degree of crystallinity of Mulberry twig(mulberry bark)cellulose were 46.0%(57.5%),the cellulose crystallinity reached to 68.4%(69.9%)by 1%NaOH extraction.(2)Hemicellulose fractions were continuous extracted with pure water,dimethyl sulfoxide,saturated Ba(OH)2,1 M KOH and 3 M KOH,the yield were respectively 10.3%,9.5%,19.4%,27.2%,16.1%.Studies have shown that the molecular weight of hemicellulose which extracted with pure water,dimethyl sulfoxide,saturated Ba(OH)2 were relatively low,respectively 56647,60126,55006 g·mol-1,the molecular weight of hemicellulose which extracted with 1 M KOH and 3 M KOH were 67605 g·mol-1 and 63417 g·mol-1.It was confirmed that the hemicelluloses from Mulberry twig were(1?4)linked?-D-xylans as the main chain,4-O-methyl-D-glucuronic acid to form a branched chain attached to the main xylose.The results from thermal analysis showed that the thermal stability of hemicellulose was poor and the thermo-gravimetric scope mainly between 250?330?.(3)The yields of MWL,CEL and AL were 21.3%,12.4%,17.9%.The structure of Mulberry twig lignin mainy on the guajacyl structure(G)and syringyl structural unit(S),it also contained a small mount of hydroxy-phenyl structural unit(H).The results from thermal analysis showed that the thermal stability of lignin was relatively high and the thermo-gravimetric scope mainly between 200?600 0C.The pyrolysis mechanism of AL,MWL and CEL is first-order reaction control mechanism,the numerical value respectively were 42?50 kJ·mol-1,30?34 kJ·mol-1 and 28?32 kJ·mol-1 under different heating rates.(4)The bio-oil conversion rate of Mulberry twig(Mulberry bark)which with pure water,and Ethanol aqueous solution as liquefaction medium were respectively 91.1%(95.72%)?83.5%(87.5%),the yield of heavy oil were 27.46%(30.83%)?26.16%(26.25%),and the yield of light oil were 4.87%(7.91%)and 2.56%(4.16%).The components of Bio-oil was complex,mainly contained aromatic,alkanes,ketone,aldehyde,olefin compounds,etc.No matter what light oil and heavy oil also contained more phenolics mainly included 2-methoxy Phenol,2-methoxy-4-methyl Phenol,Phenol,2-methoxy-4-methyl etc.,the content was about 20%.At the same time The bio-oil which with Ethanol aqueous solution as liquefaction medium contained more ester compounds included Octadecanoic acid ethyl ester,Hexadecanoic acidethyl ester,9,12-Octadecadienoic acid,ethyl ester etc.,the content was about 15%. |
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