Liquefaction Of Bamboo Biomass And Foundation Study On The Product Refining Process

Numerous attempts have been focused on the conversion of lignocellulosic biomass into liquid fuels and other chemicals.Lignocellulosic biomass is the most abundant renewable resources on earth,which is regarded as a feedstock for the liquid biofuels and green chemicals of the future.Directional liquefaction is an effective thermochemical process which can convert the biomass into liquid fuels or platform chemicals.It is known that lignocellulose is an intrinsic complex structure that consists of three major components:cellulose,hemicellulose and lignin.Current works on the thermochemical conversion of biomass generate liquefied products with complex and undesirable composition,due to the secondary decomposition of polysaccharides and re-condensation of liquefied products,which makes the subsequent separation and biorefinery process economically impractical.The major challenge is the effective utilization of each biomass fraction into its components,reducing the complexity of the following separation and conversion process.Here,in this study is to demonstrate a simple and directional liquefaction process which involves a selective conversion of holocellulose into a handful of useful chemicals.The aim of the present study was also to understand the reaction pathways to improve the quality of liquefied products.The main research content and results are as follows:?1?The effect of temperature,reaction time and catalyst dosage on the liquefaction of bamboo powder was investigated.And the effect of temperature on the bamboo powder in ethanol and blended solvents?ethanol-phenol?was also investigated.The results showed that the optimum conditions of bamboo powder in ethanol are:the reaction temperature,200?;the reaction time,60min;the catalyst dosage,3%;the ratio of ethanol to bamboo,15:1,the conversion of bamboo powder is 78%.The optimum conditions of bamboo powder in ethanol-phenol are:the reaction temperature,190?;the reaction time,70min;the catalyst dosage,3%;the ratio of phenol to bamboo,1:1;the ratio of ethanol to bamboo,13:1;under this condition,the conversion of bamboo powder is 98.5%.Temperature has the most significant effect on the liquefaction.As the temperature increasing,the relative content of glycosides and furans decreased in ethanol medium,while the glycosides were not detected.Compared with liquefaction products of ethanol medium,there are more phenolic compounds in mixed solvent.?2?Glucose and xylose,the simple carbohydrates,as well as starch and cellulose,were used as the model compounds of C₆ and C₅ carbohydrates for the liquefaction under ethanol-rich reaction medium in this part.The influence of reaction temperature,reaction time and acid dosage were investigated on the material conversion and yield of ethyl glycosides.It was found that xylose,as the simplest structure,was decomposed at the beginning of the reaction.The maximum ethyl xylosides yield was 86.35%at 150?for 10min,ethyl-a-D-xylopyranoside and ethyl-?-D-xylopyranoside was 51.66 and 34.69%,respectively.?3?Based on the study of model compounds,directional liquefaction coupled with efficient stepwise fractionation of bamboo biomass into ethyl glycosides and aromatic products with acid in ethanol medium was investigated by controlling the liquefaction process.We investigated the experimental parameters,like type of catalyst,acid dosage and reaction temperature on the bamboo conversion and platform chemicals.It was found that H₂SO₄ was the best catalyst on the liquefaction of bamboo biomass.Under a shorter reaction time of30min at temperature 180?,the maximum yield of ethyl glycoside and its derivatives was40.86%based on raw materials,with 16.07%ethyl glucosides and 10.11%ethyl xylosides,respectively.While the lignin component was converted into aromatic platform molecules with a yield of 26.74%with reaction time of 30min at temperature 200?.As evidenced by the result of GC-MS,five carbon sugars and six carbon sugars were the predominant products,which occupied 90%of the identified monosaccharides.The majority?about 80%?of the chemical compounds identified in the aromatic products were phenolic compounds:vanillin,2-?4-hydroxy-3-ethoxyphenyl?acetic acid,ethyl 4-hydroxy-3-methoxybenzoate and p-Hydroxycinnamic acid ethyl ester.?4?An emulsion liquid membrane?ELM?extractor?W/O/W?was constructed for the separation of monosaccharides and aromatic products.Several parameters including the concentration of surfactant Span80,the concentration of NaOH in internal phase and the ratio of organic membrane phase to internal phase on the phenolics extraction.The changes of the phenolics content were tracked by UV-visual spectrophoter.The result showed that,under the optimum conditions?kerosene,liquid paraffin concentration:5%;NaOH concentration:0.4mol/L;the treatment ratio:1:1;emulsification speed:2 000 r/min;emulsification time:20min;the volume ratio of membrane phase to internal phase:1:4?,the observed phenolics extraction efficiency is 97%.