Wood hydrothermal treatment impact on wood components and their further utilization for high-valued products | Koksnes hidrotermiskās apstrādes ietekme uz koksnes komponentiem un to tālāka izmantošana vērtīgu produktu ieguvei

Inglés. Birch and spruce wood were pretreated by HTT and it was found that for both species the yield of lignocellulose decreases with the increase of HTT temperature. Nonvolatiles, acids, aldehydes and sugars were determined in the HTT filtrates, and the most important finding was that the maximum yield of sugars was obtained at 170 and 180 °C from birch and spruce wood, respectively. At higher temperatures the yield of sugars decreased due to acid catalyzed decomposition. Thermogravimetry showed that the higher HTT temperature increased the activation energy of wood decomposition, which can be explained by a higher content of cellulose which requires more energy for thermal decomposition than hemicelluloses. However, at temperature 190 °C and higher the activation energy decreased again because of the decrease of the degree of polymerization of cellulose. Analytical pyrolysis experiments showed that HTT alone is not sufficient to maximize the yield of sugars in the pyrolysis of the lignocellulose residue, but HTT combined with activation with diluted sulfuric acid selectively increases the yield of sugars in the pyrolysis condensates up to 30-40% of cellulose. The main pyrolysis product is levoglucosan, which can be separated from the mixture of other condensable pyrolysis products by preparative chromatography with a Lewatit VPOC 1074 strongly basic anion exchange resin in OH- form giving a fraction with 90% levoglucosan content, which can be easily crystallized to obtain up to 99% pure levoglucosan.

Letón. Darba mērķis bija veikt koksnes hidrotermiskās apstrādes (HTA) pētījumus, lai atdalītu hemiceluložu frakciju, un noskaidrot HTA ietekmi uz koksnes komponentu termisko konversiju un to tālākas izmantošanas iespējas vērtīgu produktu ieguvei. Konstatēts, ka tikai HTA nepietiekami palielina celulozes konversiju cukuros, tādēļ nepieciešama HTA koksnes aktivācija ar sērskābi, kā rezultātā celulozes konversija cukuros sasniedz 30-40%. Veikta pirolīzes kondensātu analīzes metožu izstrāde ar AEŠH, izpētīts pirolīzes produktu sastāvs, kā arī izstrādāta anhidrocukura levoglikozāna izdalīšanas un attīrīšanas metode ar jonu apmaiņas sveķiem.