Introduction
Materials and methods
Materials
Bio-oil blending and upgrading reactions
Product analysis and characterisation
Results and discussions
Product yields
Tab.1 Mass balance (% mass fraction with respect to the original feed amount) of the products of bio-oil reactions with methanol, ethanol and isopropanol, respectively (270°C, 100 bar, 2 h) |
Solvent | Liquid yield /wt-% | Total solid yield /wt-% | Total gas yielda) /wt-% | ||
---|---|---|---|---|---|
Total liquid yield | Water-free liquid yield | Water yieldb) | |||
Methanol | 59.68 | 41.91 | 17.77 | 21.22 | 19.10 |
Ethanol | 82.84 | 63.48 | 19.36 | 7.91 | 9.25 |
Isopropanol | 86.23 | 69.96 | 16.27 | 5.14 | 8.63 |
a) Gas yield was calculated by difference assuming no losses; b) Water yield was calculated using the water content measured in Table 2. |
Tab.2 Physicochemical properties of liquid products of bio-oil reactions with methanol, ethanol and isopropanol |
Properties | Bio-oil alcohol blendsa) | Bio-oil alcohol reaction liquid productsa) | Bio-oil | ||||
---|---|---|---|---|---|---|---|
BM1 | BE1 | BI1 | BM2 | BE2 | BI2 | ||
H2O wt-% | 13.42 (0.9)b) | 12.27 (0.3) | 11.90 (0.7) | 29.78 (0.3) | 23.37 (0.2) | 18.87 (0.4) | 31.69 (0.3) |
pH | 3.67 | 3.54 | 3.06 | 4.04 | 3.84 | 3.80 | 2.39 |
C wt-% c) | 48.13 (0.5) | 55.16 (0.0) | 58.28 (0.0) | 46.05 (1.3) | 58.76 (0.3) | 61.91 (0.3) | 49.26 (0.4) |
H wt-% c) | 9.52 (0.1) | 10.06 (0.1) | 10.35 (0.1) | 9.60 (0.4) | 10.52 (0.1) | 10.36 (0.1) | 7.91 (0.0) |
N wt-% c) | 0.20 (0.0) | 0.18 (0.0) | 0.17 (0.0) | 0.71 (0.0) | 0.18 (0.0) | 0.19 (0.0) | 0.20 (0.0) |
O wt-% c), d) | 42.16 (0.6) | 34.60 (0.1) | 31.20 (0.0) | 43.63 (1.7) | 30.53 (0.4) | 27.54 (0.2) | 42.63 (0.4) |
HHV MJ/kg e) | 21.56 (0.9) | 25.60 (0.2) | 27.55 (0.0) | 23.03 (1.1) | 27.55 (0.2) | 28.85 (0.1) | 17.51 (0.1) |
a) BM1, BE1, BI1 refers to bio-oil-methanol, bio-oil-ethanol and bio-oil-isopropanol blends; BM2, BE2, BI2 refers to bio-oil-methanol, bio-oil-ethanol and bio-oil-isopropanol reaction products; b) Mean±standard deviation; c) CHNO water-free basis for the blends and reaction products; d) Oxygen content calculated by difference; e) HHV dry basis for the blends and reaction products HHV dry basis= HHVwet/ (1-H2O/100); S contents are zero in all samples. |
Physicochemical properties of bio-oil and treated bio-oils
Characterisation of bio-oil and treated bio-oils
GC-MS analysis
Tab.3 Distribution of chemical composition in bio-oil samples. Detailed composition including the compounds in each group is included as a supplementary material |
Compound | Total relative content area /% | ||||||
---|---|---|---|---|---|---|---|
Bio-oil | BM1 | BM2 | BE1 | BE2 | BI1 | BI2 | |
Acids | 4.63 | 4.33 | ‒ | 4.66 | 3.92 | 5.79 | 4.78 |
Phenols | 37.03 | 27.85 | 32.73 | 28.49 | 28.76 | 31.12 | 38.04 |
Esters | 3.74 | 3.41 | 29.89 | 2.76 | 27.68 | 3.66 | 22.35 |
Ketones | 17.40 | 12.99 | 13.12 | 13.22 | 11.42 | 13.64 | 15.33 |
Alcohols/ethers | 9.62 | 23.60 | 10.75 | 22.54 | 14.31 | 13.57 | 4.75 |
Aldehydes | 8.57 | 6.01 | ‒ | 7.23 | ‒ | 7.12 | ‒ |
Sugar derivatives | 6.83 | 7.19 | ‒ | 7.94 | ‒ | 9.01 | ‒ |
Hydrocarbons | ‒ | ‒ | 0.30 | ‒ | ‒ | ‒ | ‒ |
Others | 12.22 | 14.61 | 13.24 | 13.19 | 13.89 | 16.10 | 14.73 |
FTIR analysis
Tab.4 Classes of compounds identified in the bio-oil and treated bio-oils using FTIR analysis |
Frequency range /cm‒1 | Frequency range /cm‒1 | Group | Class of compound | ||||||
---|---|---|---|---|---|---|---|---|---|
Bio-oil | BM1 | BM2 | BE1 | BE2 | BI1 | BI2 | |||
3500–3200 | 3367 | 3357 | 3346 | 3359 | 3360 | 3359 | 3360 | O–H stretching | Phenols, polymeric O–H, water impurities |
3200–2800 | 2927, 2853 | 2929, 2840 | 2946, 2837 | 2974, 2929 | 2975, 2930 | 2971, 2932 | 2972, 2934 | C–H stretching | Alkanes-methyl group |
1750–1650 | 1709 | 1710 | 1703 | 1710 | 1703 | 1711 | 1707, 1651 | C=O stretching | Ketones, aldehydes |
1650–1590 | 1648 | 1603 | 1610 | 1603 | 1603 | 1605 | C=C stretching alkene | C–C multiple bond stretching | |
~1600–1450 | 1515 | 1515 | 1515 | 1515 | 1515 | 1515 | 1515 | C=C stretching aromatic | |
1470–1350 | 1450, 1363 | 1449, 1361 | 1449, 1377 | 1448, 1378 | 1452, 1378 | 1465, 1380 | 1466, 1380 | C–H deformation | Alkanes-methylene group |
1300–950 | 1268, 1033 | 1268, 1193, 1031 | 1268, 1219, 1114, 1018 | 1270, 1043 | 1271, 1086, 1044 | 1276, 1160, 1126, 1100, 1051 | 1288, 1161, 1127, 1106, 1034 | C–O stretching O–H bending | Primary, secondary, tertiary alcohols, phenols |
975–525 | 861, 811 | 889, 812 | 878, 811 | 878 | 949, 815 | 949, 816 | C–H bending | Mono-, polycyclic, substituted aromatic rings |
13C NMR analysis
TGA analysis
Tab.5 Boiling point distribution of bio-oil and treated bio-oils distillation rangea) |
Distillation range /°C | Weight /% | ||||||
---|---|---|---|---|---|---|---|
BO | BM1 | BM2 | BE1 | BE2 | BI1 | BI2 | |
35‒150 | 41.31 (0.5)b) | 50.17 (0.0) | 62.79 (0.4) | 52.80 (0.1) | 54.62 (0.7) | 52.50 (0.2) | 50.46 (0.2) |
150‒200 | 11.79 (0.1) | 10.17 (0.0) | 7.83 (0.0) | 9.77 (0.0) | 8.38 (0.2) | 9.62 (0.2) | 9.14 (0.1) |
200‒250 | 9.66 (0.1) | 8.33 (0.0) | 6.32 (0.0) | 7.91 (0.0) | 7.22 (0.2) | 7.73 (0.2) | 7.86 (0.1) |
250‒300 | 7.64 (0.1) | 6.66 (0.0) | 5.03 (0.0) | 6.20 (0.1) | 6.09 (0.2) | 6.14 (0.1) | 6.72 (0.1) |
300‒350 | 6.29 (0.1) | 5.66 (0.0) | 4.38 (0.0) | 5.28 (0.0) | 5.35 (0.1) | 5.24 (0.1) | 5.99 (0.1) |
<350 | 76.70 (0.9) | 80.99 (0.0) | 86.36 (0.4) | 81.97 (0.0) | 81.66 (0.0) | 81.24 (0.3) | 80.18 (0.2) |
350‒400 | 5.50 (0.0) | 5.00 (0.0) | 4.07 (0.0) | 4.70 (0.0) | 4.94 (0.2) | 4.64 (0.1) | 5.53 (0.1) |
400‒450 | 4.72 (0.1) | 4.42 (0.1) | 3.63 (0.0) | 4.20 (0.0) | 4.38 (0.1) | 4.13 (0.1) | 4.83 (0.0) |
450‒500 | 4.20 (0.1) | 3.93 (0.1) | 3.17 (0.0) | 3.74 (0.0) | 3.90 (0.0) | 3.67 (0.1) | 4.20 (0.0) |
>500 | 8.88 (1.1) | 5.66 (0.2) | 2.77 (0.4) | 5.39 (0.0) | 5.13 (0.3) | 6.32 (0.6) | 5.25 (0.3) |
a) The distillation range was selected based on [49]; b) Mean±standard deviation. |