Society’s growing demands on everyday products and materials are increasingly difficult to meet in an environment that seeks to avoid petroleum-based processes. Instead of abandoning fossil materials altogether, more research should be done on their efficient and clean conversion. One option for this is the oxidative dissolution of kerogen in water under conditions that satisfy the subcritical range (T = 150–200 °C, pO2 = 0.5–4 MPa). The resulting mixture contains a substantial amount of various aliphatic carboxylic and dicarboxylic acids. Both batch and semi-continuous processes were set up to find the main factors and optimal conditions for the kerogen dissolution process. The rate of transformation of organic carbon to dissolved organic compounds was mainly influenced by elevated temperature and oxygen partial pressure. To obtain high yields of organic carbon dissolution and to avoid the formation of excess CO2, the oxidation of kerogen should be carried out fast (< 1 h) and under high oxygen pressure. By employing a temperature of 175 °C and O2 pressure of 2 MPa, over 65% of the initial organic carbon dissolves in about one hour. Prolonged reaction times or harsher oxidation conditions resulted in a rapid degradation of dissolved matter and also of the valuable products formed. The organic matter content of the initial oil shale had a direct effect on the further degradation of dicarboxylic acid and consequently on the overall yield. The suitability of using a trickle-bed reactor for kerogen dissolution is discussed in detail on the basis of experimental results.
1. Derenne, S., Largeau, C., Casadevall, E., Sinninghe Damsté, J. S., Tegelaar, E. W., de Leeuw, J. W. Characterization of Estonian Kukersite by spectroscopy and pyrolysis: Evidence for abundant alkyl phenolic moieties in an Ordovician, marine, type II/I kerogen. Org. Geochem., 1990, 16(4–6), 873–888.
https://doi.org/10.1016/0146-6380(90)90124-I
2. Blokker, P., Van Bergen, P., Pancost, R., Collinson, M. E., De Leeuw, J. W., Sinninghe Damste, J. S. The chemical structure of Gloeocapsomorpha prisca microfossils: implications for their origin. Geochim. Cosmochim. Acta, 2001, 65(6), 885–900.
https://doi.org/10.1016/S0016-7037(00)00582-2
3. Lille, Ü., Heinmaa, I., Pehk, T. Molecular model of Estonian kukersite kerogen evaluated by 13C MAS NMR spectra. Fuel, 2003, 82(7), 799–804.
https://doi.org/10.1016/S0016-2361(02)00358-7
4. Lille, Ü. Current knowledge on the origin and structure of Estonian kukersite kerogen. Oil Shale, 2003, 20(3), 253–263.
5. Behling, R., Valange, S., Chatel, G. Heterogeneous catalytic oxidation for lignin valorization into valuable chemicals: What results? What limitations? What trends? Green Chem., 2016, 18(7), 1839–1854.
https://doi.org/10.1039/C5GC03061G
6. Demesa, A. G., Laari, A., Turunen, I., Sillanpa, M. Alkaline partial wet oxidation of lignin for the production of carboxylic acids. Chem. Eng. Technol., 2015, 38(12), 2270–2278.
https://doi.org/10.1002/ceat.201400660
7. Kindsigo, M., Kallas, J. Degradation of lignins by wet oxidation: model water solutions. Proc. Est. Acad. Sci. Chem., 2006, 55(3), 132–144.
8. Cherubini, F., Stromman, A. H. Chemicals from lignocellulosic biomass: opportunities, perspectives, and potential of biorefinery systems. Biofuel. Bioprod. Bior., 2011, 5(5), 548–561.
https://doi.org/10.1002/bbb.297
9. Wang, Z., Yan, J., Wang, T., Zai, Y., Qiu, L., Wang, Q. Fabrication and properties of a bio-based biodegradable thermoplastic polyurethane elastomer. Polymers, 2019, 11(7), 1–13.
10. Cornils, B., Lappe, P. Dicarboxylic acids, aliphatic. In: Ullmann’s Encyclopedia of Industrial Chemistry, Wiley-VCH Verlag GmbH & Co. KGaA, 2000.
11. Yuan, W.-G., Liu, G.-L., Huang, C., Li, Y.-D., Zeng, J.-B. Highly stretchable, recyclable, and fast room temperature self-healable biobased elastomers using polycondensation. Macromolecules, 2020, 53(22), 9847–9858.
https://doi.org/10.1021/acs.macromol.0c01665
12. Kallemets, K. Economic sustainability of Estonian shale oil industry until 2030. Oil Shale, 2016, 33(3), 272–289.
https://doi.org/10.3176/oil.2016.3.06
13. Veski, R., Veski, S. Aliphatic dicarboxylic acids from oil shale organic matter – historic review. Oil Shale, 2019, 36(1), 76–95.
https://doi.org/10.3176/oil.2019.1.06
14. Durand, B. Sedimentary Organic Matter and Kerogen: Definition and Quantitative Importance of Kerogen. Editions Technip., Paris, 1980.
15. Degtereva, Z., Fomina, A. Production of dibasic acids C4-C10 from oil shale kukersite. Acad. Sci. Est. SSR, 1959, 8(2), 122–136 (in Russian).
16. Pobul, L., Fomina, A. Purification and fractionation of mixtures of saturated dicarbonic acids obtained by the oxidation of kukersite kerogen. Acad. Sci. Est. SSR, 1962, 11(3), 203–211 (in Russian).
17. Fomina, A., Pobul, L., Degterjowa, S., Veski, R., Kirret, O., Nikopensius, I., Männik, A., Pärn, A., Poom, A., Murumets, K., Ulanen, J., Tänav, I., Kotov, A. Method for Processing Causticobiolites of the Sapropelite Type with an Oxidizing Agent. German Patent No. 2259502, 1974.
18. Fomina, A. S., Pobul, L. The deriving of dibasic aliphatic acids from a new raw material. Acad. Sci. Est. SSR, 1957, 6(2), 190–198.
19. Kogerman, P. N. Hundred years of the chemical investigation of an oil shale: the chemical constitution of the Estonian oil shale “Kukersite”. In: Oil Shale and Cannel Coal. International Petroleum Conference. The Institute of Petroleum, Glasgow, 1938, 115–123.
20. Bajc, S., Amblès, A., Largeau, C., Derenne, S., Vitorović, D. Precursor biostructures in kerogen matrix revealed by oxidative degradation: oxidation of kerogen from Estonian kukersite. Org. Geochem., 2001, 32(6), 773–784.
https://doi.org/10.1016/S0146-6380(01)00042-0
21. Proskuryakov, V. A., Soloveichik, Z. V. Oxidation of oil shale by atmospheric oxygen. 1. Oxidation of an aqueous alkaline suspension of Gdov shales in an autoclave. Tr. Vsesoj. N. I. Instituta po Pererab. i Issl. Topl., 1961, 10, 64–80 (in Russian).
22. Proskuryakov, V. A., Soloveichik, Z. V. Oxidation of oil shale by atmospheric oxygen. 2. Oxidation of Gdov shales with continuous air supply. Tr. Vsesoj. N. I. Instituta po Pererab. i Issl. Topl., 1961, 10, 81–90 (in Russian).
23. Proskuryakov, V. A., Yakovlev, V. I., Kudrjukov, O. I. Oxidation of oil shale by atmospheric oxygen. 3. Oxidation of common Syrtian shales. Tr. Vsesoj. N. I. Instituta po Pererab. i Issl. Topl., 1962, 11, 20–27 (in Russian).
24. Kaldas, K., Preegel, G., Muldma, K., Lopp, M. Wet air oxidation of oil shales: Kerogen dissolution and dicarboxylic acid formation. ACS Omega, 2020, 5(35), 22021–22030.
https://doi.org/10.1021/acsomega.0c01466
25. Kolaczkowski, S. T., Plucinski, P., Beltran, F. J., Rivas, F. J., McLurgh, D. B. Wet air oxidation: a review of process technologies and aspects in reactor design. Chem. Eng. J., 1999, 73(2), 143–160.
https://doi.org/10.1016/S1385-8947(99)00022-4
26. Luck, F. A review of industrial catalytic wet air oxidation processes. Catal. Today, 1996, 27(1–2), 195–202.
https://doi.org/10.1016/0920-5861(95)00187-5
27. Bhargava, S. K., Tardio, J., Prasad, J., Föger, K., Akolekar, D. B., Grocott, S. C. Wet oxidation and catalytic wet oxidation. Ind. Eng. Chem. Res., 2006, 45(4), 1221–1258.
https://doi.org/10.1021/ie051059n
28. Li, L., Chen, P., Gloyna, E. F. Generalized kinetic model for wet oxidation of organic compounds. AIChE J., 1991, 37(11), 1687–1697.
https://doi.org/10.1002/aic.690371112
29. Lin, S. H., Ho, S. J., Wu, C. L. Kinetic and performance characteristics of wet air oxidation of high-concentration wastewater. Ind. Eng. Chem. Res., 1996, 35(1), 307–314.
https://doi.org/10.1021/ie950251u
30. Sánchez-Oneto, J., Portela, J. R., Nebot, E., Martínez-de-la-Ossa, E. J. Wet air oxidation of long-chain carboxylic acids. Chem. Eng. J., 2004, 100(1–3), 43–50.
31. CRC Handbook of Chemistry and Physics, Internet Version 2005 (Lide, D. R., ed.), 2005.
http://www.hbcpnctbasc.com
32. Kaldas, K., Preegel, G., Muldma, K., Lopp, M. Reactivity of aliphatic dicarboxylic acids in wet air oxidation conditions. Ind. Eng. Chem. Res., 2019, 58(25), 10855–10863.
https://doi.org/10.1021/acs.iecr.9b01643
