(72b) Potential Woody Biomass Preprocessing Strategies to Mitigate Sticky Biochar Formation in Dilute Acid Conversion Processes

The conversion of lignocellulosic feedstock to value-added products (e.g., organic acids) under dilute acid (5 wt%) conditions results in the production of sticky biochar as a by-product. This sticky biochar tends to accumulate over time in biomass conversion reactors, posing practical challenges when operating continuous conversion processes at an industrial scale. In this study, our aim is to characterize the chemical composition, viscoelastic properties (such as storage modulus and loss modulus), and polymer properties (including glass transition temperature) of the sticky biochars derived from woody biomass under dilute acid conditions. Our hypothesis is that preprocessing woody biomass under mild conditions (0 to 0.5 wt% sulfuric acid, residence time of 15 to 30 minutes, and temperatures ranging from 175°C to 200°C) prior to biomass conversion into organic acids can mitigate the formation of sticky char. To test this hypothesis, we conducted bench-scale acid hydrolysis and dehydration processes to produce biochar as a by-product using various preprocessed woody feedstocks. By comparing the chemical composition, viscoelastic properties, and polymer characteristics of the biochars derived from preprocessed woody feedstocks with those from clean woody biomass, we aim to identify optimal biomass preprocessing conditions to prevent the formation of sticky biochars during downstream conversion processes. Such comparisons will also provide insights into the underlying mechanisms involved in the formation of sticky biochars.