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Experiments and calculations are used to determine the optimum parameters of the peroxide delignification of larch wood in the presence of MnSO4 catalyst that provides high yields of cellulose (44.3 wt %) with low residual lignin contents at a temperature of 100°C, an H2O2 content of 6 wt %, a CH3COOH content of 25 wt %, a LWR of 15, and a duration of 3 h The cellulose obtained under optimum conditions has a chemical composition of cellulose, 92.7 wt %; lignin, 0.6 wt %; and hemicellulose, 5.7 wt %. IRS and X-ray diffraction are used to determine that cellulose obtained from larch wood has a structure similar to that of industrial microcrystalline cellulose. The proposed catalytic approach allows cellulose to be obtained from larch wood with a minimal lignin content under mild conditions in one step and with a high yield, a degree of crystallinity of 0.8, and a crystallite size of 3.0 nm. [ABSTRACT FROM AUTHOR]

The process of aspen-wood delignification in the medium “hydrogen peroxide–acetic acid–water–sulfuric acid catalysts” at mild conditions (temperature 70–100 °C, atmospheric pressure) is described by the first order equation. Rate constants vary from 0.25 × 10 −4 (70 °C) to 2.5 × 10 −4 s −1 (100 °C). The activation energy of aspen-wood delignification is near 91 kJ mol −1. The rather high value of activation energy points to the insignificant role of diffusion limitations at used conditions of aspen-wood delignification. The optimal process conditions for obtaining of the pure cellulose (residual lignin content less 1 wt%) with a yield near 45 wt% were selected. Obtained cellulose has the structure similar to the commercial microcrystalline cellulose. [ABSTRACT FROM AUTHOR]