Production of liquid fuel from long-term storage wood waste by hydrothermal liquidation

The pulp and paper industry leads to the formation of a significant amount of bark and wood waste (BWW), which is not processed in Russia, but is placed in bark dumps, which leads to a negative impact on environmental objects, incl. on the planet’s climate. This article presents an assessment of the resource potential of long-term storage bark and wood waste based on the results of physicochemical and thermal analysis. It was found that during long-term storage BWW undergoes degradation rather weakly, while the proportion of carbon in the composition of BWW remains practically unchanged (at the level of 48.4%). It has been proven that the initial BWW are characterized by high humidity (60.8% to 74.9%), low calorific value (14.56 MJ/kg per d.m.) and moderate ash content (9.8% d.m.a.). For wet biomass, hydrothermal liquefaction can be considered the most suitable conversion method, which makes it possible to obtain liquid fuels without pre-drying, since. Water in this process acts as a solvent and a source of radicals. The average yield of biofuel during hydrothermal conversion of BWW is 10%, while the use of Iron ammonium alum as catalysts provided an increase in oil yield by more than 2 times to 28.4%, the use of copper sulfate led to an increase in yield up to 16.1%. The obtained bio-oil was characterized by a high degree of saturation (atomic ratio H/C was 1.3), but the oxygen content was also high (at the level of 22% wt.). The content of sulfur and nitrogen was minimal (0.6 and 0.2%, respectively). The composition of fuels was dominated by oxygen-containing aromatic compounds of the phenol group (62%), cyclic esters (19.8%), as well as fatty acids, which account for 12.9%.