INNO INDIGO: Conversion of lignocellulosic wastes into biofuels and bioplastics

Fossil fuels have been and are expected to be the main energy form that driving our society. However, a lot of greenhouse gases, like CO2 was produced in the energy converting process, which has made the environmental issues an arising hot topic. Therefore, it is critical to replace fossil fuels to prevent CO2 emissions and improve climate change. Bioproducts, the chemical products derived from biomass, have become an emerging promising alternative and have the great potential to be the alternative to petrochemical products. Among them, lactic acid is attracting significant focus from both academia and industry due to its wide application in our daily life, in particular as the precursors of biodegradable plastics. In this study, lactic acid is produced from the chemo-catalytic conversion of lignocellulosic biomass-derived glucose on the homogeneous ErCl3 catalyst in an aqueous solution. By the process optimization, a fully selective glucose conversion of glucose to acetic acid, levulinic acid, and lactic acid, with the highest lactic acid yield of 97% is obtained on the homogeneous catalyst at 260 °C. Furthermore, the techno-economic analysis (TEA) was leveraged for the concept design of lactic acid biorefineries. The study shows that the selling price of lactic acid, the price of glucose feedstock, and the catalyst price and recyclability are the most sensitive parameter for the overall process benefit. Therefore, this work highlights the highly feasible and beneficial process of the lactic acid biorefinery industrial process.

The key outcome of the project is an experimental demonstration and a conceptual design of the catalytic process for the conversion of glucose to nearly 100% organic acids with a high lactic acid yield up to 97%. It represents a highly selective process of lignocellulosic biomass to bio-chemicals. The process is highly beneficial at the current market prices and has a high potential for industrial implementation. All the partners and participants in the project have gained the necessary skills on the chemo-catalytic converting glucose to value-added chemical (herein, mainly lactic acid), the batch reactors, and the HPLC for product analysis, etc. One master (Petter Tingelstad) student and two postdocs (Dr. Zhenping Cai, and Dr. Hongfei Ma) have been involved in this project. All of them have been trained and educated the related knowledge and experimental skills in chemical engineering, those skills are important for their future career.

Plastic pollution involves the accumulation of plastic products in the environment partly because of their non¬biodegradability. The existing means for their disposal can be harmful to humans and the environment. It has led to extensive research efforts directed at the discovery of polymeric biodegradable materials in plastics applications. One of the promising polymers used in these applications is an aliphatic polyester derived from lactic acid. The main focus in this project will be to develop a catalytic process to convert lignocellulosic biomass wasters to lactic acid and hydroxyl acetone as the monomer of biodegradable plastics polylactic acid (PLA) and polyhydroxyalkanoates (PHA). Lignocellulosic wastes will be evaluated to be of relevance for all partners in Norway, Spain and India. The efficient catalysts will be developed with an aim of high yield of the targeted products, through a better understanding of the reaction mechanism as a function of catalysts. The outcome of this project has important and far­reaching implications towards ensuring a clean environment.