Improving the yield of levoglucosan platform chemical from the pyrolysis of date pits waste biomass through pre-treatments

Lignocellulosic biomass, as the primary carbon source, serves as the foundation for the entire biorefinery concept. In this regard, date pits constitute an important category of biomass waste in many parts of the world. Levoglucosan, also known as 1,6-anhydro-β-D-glucopyranose (LG), is a significant sugar derivative and a platform chemical produced as a primary product in the cellulose pyrolysis process. Aiming to further improve the yield of levoglucosan from pyrolysis of date pits, pre-treatment methods were carried out via washing crushed date pits with different concentrations of selected acids (sulfuric acid: 1 M/3 M, nitric acid:1 M/3 M), and with hot water. The chemical and elemental compositions of the five considered samples were thoroughly analyzed and characterized by a wide array of ultimate and proximate techniques such as Neutral Detergent Fiber (NDF %), ASH content and organic Matter (%), and Mineral Nutrients Profile (ppm). By utilizing Py-GC/MS system, the product distribution from pyrolysis of raw and treated date pits was obtained at a range of temperatures between 300 and 500 °C. Compared to the raw date pits, pyrolysis of treated date pits pre-treated by 1 M H₂SO₄ acid exhibited a dramatic increase in the concentration of levoglucosan due to the profound removal of the various categories of minerals in date pits and an increase in the NDF %. A positive correlation prevails between the removal efficiency of alkali/alkaline earth metals (AAEMs) and the yield of LG. The former catalyzes ring-opening reaction that results in the destruction of sugar derivatives. On the other hand, pre-treatment with water also increases the yield of LG compared to raw date pits, but to a lesser extent. Outcomes demonstrated herein convey a practical method to enhance the production of commodity chemicals from waste biomass.