Bio-oil Upgrading via Ether Extraction, Looped-Oxide Catalytic Deoxygenation, and Mild Electrocatalytic Hydrogenation Techniques

Abstract

To overcome the disadvantages of primary bio-oil, two technical routes, namely, bio-oil ether extraction coupled with ether-soluble fraction microwave-assisted catalytic esterification (ES-MACE) and looped-oxide catalytic deoxygenation/mild electrocatalytic hydrogenation (MECH)/catalytic cracking to produce hydrocarbons, were conducted for bio-oil upgrading. With the first route, it was found that the highest ether extraction efficiency was achieved when the volume ratio of bio-oil/ether was 1:2 and the ES quality was effectively improved in comparison to primary bio-oil; after the ES-MACE, the relative content of acids in the ES decreased dramatically, while that of esters increased. With the second route, the oxygen content in the bio-oil deoxidized by a Zn powder decreased by 23.92%. Moreover, the relative contents of acids, alcohols, and sugars diminished, while those of esters, carbonyls, and phenols rose. Then, the MECH step further refined the deoxidized bio-oil; the relative contents of acids, esters, carbonyls, phenols, sugars, and furans decreased, and that of alcohols increased substantially. At the same time, the hydrogen/carbon effective ratio greatly improved after the refining process. Finally, catalytic cracking by proton-exchanged zeolite Socony Mobil-5 of the obtained bio-oil was carried out to produce hydrocarbons; the carbon yield of aromatics, olefins, and total chemicals increased along with the hydrogen/carbon effective ratio.