Life-cycle Assessment for the Production of IonoSolv Dissolving Pulp Fiber

Lignocellulosic biomass is a competitive alternative to replace fossil fuels and to be utilized as feedstock for the sustainable and carbon-neutral generation of fuels, chemicals, and high added-value materials. To realize this potential, a cost-effective and low energy-demanded biomass pretreatment technology is highly required. This thesis is mainly focused on the fractionation of lignocellulosic biomass using a protic ionic liquid following by a chlorine-free bleaching process to obtain dissolving pulp fiber (DPF) at industrial scale. The aim of this work is to achieve process improvements leading to an increase in the product’s quality and to identify the environmental burdens in each step of the process. Firstly, the use of N,N-dimethylbutylammonium hydrogen sulfate as a low-cost ionic liquid for the fractionation of spruce softwood followed by alkaline hydrogen peroxide has been shown. Secondly, the concept of Life-cycle Assessment was defined to evaluate the environmental impacts of producing cellulose fiber. The complete pretreatment process, including synthesizing the ionic liquid, lignocellulose fractionation, and the bleaching stage were modeled together in Aspen Plus to obtain the mass and energy flows. The mass and energy flows were implemented to create detailed LCA inventories; the environmental impacts for each stage of the pretreatment were evaluated and compared to one another. Herein, the ReCiPe 2016 methodology was used to categorize LCI entries into 18 midpoints, and further, they were aggregated into 3 endpoints (damage) indicators. The fractionation step with the bleaching stage were shown to have higher environmental impacts than synthesizing the ionic liquid.