Optimizing Single-Stage Processes of Microcrystalline Cellulose Production via the Peroxide Delignification of Wood in the Presence of a Titania Catalyst

Abstract

The conventional way of producing microcrystalline cellulose (MCC) from wood raw materials is multistage; it is based on integrating the environmentally hazardous processes of pulping and bleaching of cellulose and the acid hydrolysis of the amorphous phase of cellulose. This work describes an improved single-stage catalytic method for the production of MCC from softwood and hardwood that is based on the peroxide delignification of wood in an acetic acid–water medium under mild conditions (100°C, atmospheric pressure) in the presence of an environmentally safe TiO₂ solid catalyst. The processes of MCC production via the peroxide catalytic delignification of various wood species are optimized experimentally and mathematically. The following optimum modes for the production of MCC with a yield of 36.3–42.0 wt % of absolutely dry wood, a residual lignin content of ≤1.0 wt %, and a hemicellulose content of ≤ 6.0 wt % are determined: For aspen: 5 wt % H₂O₂, 25 wt % CH₃COOH, and a liquid/wood ratio of 10. For birch: 5 wt % H₂O₂, 25 wt % CH₃COOH, and a liquid/wood ratio of 15. For silver fir: 6 wt % H₂O₂, 30 wt % CH₃COOH, and a liquid/wood ratio of 15. For larch: 6 wt % H₂O₂, 30 wt % CH₃COOH, and a liquid/wood ratio of 15.