322 / 2018-07-27 15:14:25

In-situ Hydrodeoxygenation of Furfural as a Model Component in Bio-oil

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In-situ hydrodeoxygenation (HDO) of furfural as a representative compound of furans in bio-oil was investigated over supported Ni catalysts. It was found that obvious coke was formed when the temperature was higher than 140oC, while the addition of methanol, ethanol, or isopropanol could completely inhibit the coke formation. When methanol was used as the both of solvent and hydrogen donor, the support with mesopore structure, larger pore size, and stronger acidic sites, was more favorable to the conversion of furfural and to the formation of furan and 2-methylfuran. Under higher temperatures, the furfural conversion was improved up to 93%, but the product distribution became more complex. An increased loading amount of Ni favored the conversion of furfural and the formation of deep hydrogenated products like tetrahydrofuran and butanol. Furfural conversion could hardly be changed under different methanol to water ratios, while the product distribution varied remarkably. Based on optimized reaction conditions, in-situ HDO of an eight-component synthetic bio-oil was tested, and the results verified the adaptability of the method for conversion of bio-oil. It was deduced that the carbon atom in aldehyde group mainly adsorbed on Ni sites, while the oxygen atom of aldehyde mainly adsorbed on acid sites of the support. If the carbon atom on the ring structure linked with carbonyl group was attacked by H atom, the decarbonylation product of furan and CO would be obtained. If the adsorbed carbon and oxygen atom in carbonyl group was both attacked by H atom, alcohol would be generated, and would be further converted to 2-methylfuran by hydrogenolysis.