Research On New Process Of Upgrading Bio-oil By Catalytic Hydrogenation

Bio-oil is a renewable alternative to the production of liquid fuels and chemicals.However,the negative effects resulted from acids and aldehydes in bio-oil restrict its development.Thus the catalytic upgrading of bio-oil is imperative.In this work,unstable components in bio-oil such as aldehydes,ketones were converted by the oxidation of H₂O₂ or the alkylation of dimethyl furan at relatively low temperature,which can be considered by catalytic hydrogenation refining for relatively high-grade liquid fuel.When H₂O₂ was chosen as the oxidant,the physical and chemical properties of the resulting bio-oil were improved significantly under optimum upgrading conditions of 100 ?,12.5wt% Amberlyst-36 ion exchange resin and alcohol-oil ratio of 1:1.After the oxidative esterification,the acid value of bio-oil was reduced from 40.88 mgNa OH·g-1 to 14.82 mgNa OH·g-1.Besides,the moisture content of bio-oil was reduced from 36.37% to 17.54% and calorific value was enhanced from 14.46 MJ·kg-1 to 25.13 MJ·kg-1.While the viscosity was reduced from 18.49 mm2·s-1 to 7.04 mm2·s-1 and C element content was increased from 38.42% to 51.01% with the oxygen element content reduced from 52.75% to 39.86%.Compared to the bio-oil upgrading by esterification,the unstable acids,aldehydes and ketones in bio-oil were efficiently turned into stable target products with the using of H₂O₂.In addition,the target products containing ester,alcohol and ether of the upgraded bio-oil by oxidation esterification reached 84.2%,which was higher than that of esterification upgraded bio-oil?19.6%?.The relative content of aldehydes and ketones fell to 5.12% and 4.23%,and the content of acids fell to 0.08% and 2.6%,which were all less than those of the esterification upgraded bio-oil.Water and methylene chloride were used for the extraction and separation of oxidation esterification upgraded bio-oil to obtain high value-added sugars and their derivatives.Using the upgraded oil under the optimum conditions,further upgradation by catalytic hydrogenation for bio-oil was performed.However,the result was not that ideal.Thus vacuum distillation was adopted for the extraction of the upgrade bio-oil under 90 ? with a extraction yield of 54.44% and the raffinate were phenols and esters with long carbon chain.The resulting oil phase was treated by catalytic hydrogenation with Pd/C as the catalyst.Results showed that the coke yield was only 1.4%,high calorific value of the bio-oil was further upgraded to 31.38 MJ·kg-1 and the water content was reduced to 13.78%.In order to obtain more valuable products,2-methyl furan was used on the bio-oil pre-alkylation treatment.More C10+ products were produced via the additional reaction of the unstable of aldehydes and ketones.The resultants were further catalytic hydrogenated and the final refined oil possessed a relatively high calorific value of 33.43 MJ·kg-1.Furthermore,the mechanism of the alkylation hydrogenation of the model compounds were explored.