Production of levulinic acid and other chemicals from sugarcane fibre
Energy needs as well as the vast majority of products and chemicals are currently sourced from fossil resources due to historically low feedstock costs and abundant supply. However, the availability of fossil resources have started to decline and the impacts of rising oil prices and negative environmental aspects (CO2 and toxic emissions) have led to a push to source energy and chemicals from other materials. Biomass and non-food crop residues are seen as relatively low cost and abundant renewable sources capable of making a large contribution to the future world's energy and chemicals supply. Levulinic acid and furfural are considered to be versatile platform chemicals that can be utilised to produce fuels, solvents, polymers, pharmaceutical and agrichemical products. At the present time, there is no commercial process available for economic manufacture of levulinic acid from lignocellulosic feedstocks. This is as a consequence of low product concentration, inefficient product separation and recovery, processing issues associated with the presence of lignin, waste disposal caused by typical acid processes and equipment corrosion. Most research approaches on levulinic acid production have used mineral acids on a small variety of feedstocks under small processing condition windows. Also, despite advancement in the use of heterogeneous catalysts and development of alternative reaction pathways for levulinic acid production, at the present time, the use of low corrosivity homogeneous catalysts offer the best processing option if product selectivity can be maintained and the catalyst readily recovered. On this basis, the project examined the production of levulinic acid (and other chemicals) from sugarcane fibre (i.e., bagasse) using an environmentally friendly biodegradable organic acid. After initial screening trials with various sulfonic acids, methanesulfonic acid (MSA) was evaluated in this research for the acid-catalysed conversion of glucose, xylose, glucose/xylose mixtures, treated and untreated bagasse to levulinic acid and furfural. This was to examine the different reaction pathways and interactions of feed components. As sulfuric acid is the main homogeneous catalyst used in the production of levulinic acid and furfural, it was used as a control. Response surface modelling methodology was used in the study to reduce the number of experiments but still obtain information on the relationship between the operating variables and product yield. The effect of polyols as co-solvent on product yield was also evaluated, although only ethylene glycol (EG) was selected for detailed study.