Synergy in co-liquefaction of oil shale and willow in supercritical water

• A synergy occurs in the yields of oil shale and willow co-liquefaction products.
• The synergies are proportional with product of the shares of the components (xAxB) in the blends.
• The coefficient of proportionality, synergy factor, is the highest for the benzene soluble products.
• The synergy in the yield of benzene solubles is caused mainly by an increase in the yield of high polar heterocompounds.

Co-liquefaction of oil shale kukersite and willow Salix viminalis blends by hydrous pyrolysis in supercritical water was studied under the conditions of 380 °C, 4 h, 38 MPa, and water/blend ratio 3/1 g/g. The actual yields of the consecutive products of extraction with various solvents did not agree with the additive values calculated by proportional contributions of the blend components. At any share of the components (xA, xB), the synergy (Δ) in the yields of the pyrolysis products estimated was proportional with the product of the shares of the components in the blend according to the equimolecular synergy model, Δ = δxAxB. The values of the synergy factors, δ, decreased in the row of the products as follows [%(g/g)−2]: the oil soluble in benzene 62, acetone 11, water 9, and diethyl ether 5.6, solid residue −9.6 and the sum of gas and pyrogenetic water −79. The main increase in the yield of benzene solubles was result of the positive synergy in the yield of high polar heterocompounds, revealing the synergy factor 69%(g/g)−2.