(726b) Optimizing Alkaline-Oxidative Pretreamtent of Hybrid Poplar to Maximize Lignin Co-Product Value

Diversification of the product portfolio of lignocellulose-to-biofuels processes to include renewable, bio-based chemicals is widely recognized as an opportunity both to improve the economics of these processes and to buffer against market fluctuations. Thus, there is an obvious and compelling need to develop integrated processing approaches that enable multi-product biorefineries. In particular, there is an opportunity for technologies that can be integrated with conversion processes employing a biomass pretreatment/fractionation strategy, whereby it may be possible to utilize all or a fraction of the process-modified lignins for purposes other than as a solid fuel. Although the high heterogeneity of lignin and its low susceptibility to depolymerization creates a number of well-documented challenges complicating its conversion to higher-value products, process-derived lignin nevertheless represents an immense opportunity if they can be generated in a way that optimally couples with conversion strategies. We recently identified that a two-stage alkaline-oxidative pretreatment/delignification process is capable of yielding lignins from hardwoods that are highly susceptible to acidic depolymerization to monomers. In this work, we build on these compelling findings to develop an integrated processing approach through the optimization of this two-stage pretreatment to yield multiple products (lignocellulose-derived polysaccharides and lignin streams that are highly susceptible to depolymerization) with properties that are suited for applications across a diverse range of target markets and product values. Specifically, we will present results from the initial screening of alkaline pre-extraction conditions for 3 hybrid poplar lines over a range of times, temperatures (95-155°C), alkali loadings (50 to 150 mg NaOH/g biomass) to assess the impact of pre-extraction conditions on the yields and properties of the extracted lignins, as well as the impact of these processing conditions on integration with the second stage of the pretreatment and ultimate product yields, product value, and processing costs.