The energy production from a biomass representative lignin is an attractive option given that the higher bio-oil yields and decreased char formation are provided. In this proposal a novel process will be developed to convert lignin into the more high-quality bio-oil and chemicals with virtually no secondary char effect based on a method known as Infrared Laser Powered Homogeneous Pyrolysis or IR-LPHP. The PI is an expert in diversification of this method, which allows performing the pyrolysis experiments strongly in homogeneous, "wall-less" conditions under irradiation of IR CO2 laser. The principal advantage of this method is that all chemical processes occur only in a small "hot zone" practically at cold conditions of the reactor walls.
The CO2 laser flash pyrolyses the lignin dispersed particles generated by a spray technique in gas phase, followed by a rapid quenching of many products which will diffuse out of the "hot zone" avoiding further secondary processes (degradation, cleavage, or condensation with other molecules). Such an approach is strongly believed to upgrade the liquid product (bio-oil) yields. Markedly different products are expected to be produced under the IR-LPHP of lignin due to the diverse heating rates, temperature, and residence times in the specific "wall-less" condition at the same power of laser irradiation.
On the way to obtain higher yields bio-oil and decrease the char formation, the detrimental heterogeneous influence of the char and reactor walls on the total process has never been elucidated. The novelty of this project is to obtain more high-quality bio-oil in a "wall-less" reactor using the advantages of the flash IR LPHP technique at minimized char - gas phase interaction. This special reactor design allows employing a perspective exploratory research expecting break up lignin?s macromolecular structure, but maintaining the aromatic nature of the building block molecules. For the first time the intermediate radicals formed in the gas-phase lignin pyrolysis in the "wall-less" reactor conditions, will be identified directly using Low Temperature Matrix Isolation (LTMI) Electron Paramagnetic Resonance (EPR) technique. Collaboration with the University at Buffalo team to evaluate kinetic parameters of the key gas-phase reactions will lead to a global, pseudo-first order lumped kinetic model for lignin pyrolysis based on the CHEMKIN - 4 Pro Combustion kinetic package to predict the optimal pathways for formation of aromatic desired compounds. Therefore, this project represents potentially transformative research because it will offer a unique, non-standard approach for producing more high-quality (upgraded) bio-oil at its high yield with the perspective of transformation of bio-oil into alternative transportation fuel and the important chemicals.
The hypothesis put forward by the PI lies on the idea that utilizing the advantages of laser pyrolysis in "wall-less" reactor would have a great potential for application to various biomass pyrolysis processes. Bringing high-volume aromatics efficiently from a material as structurally complex and diverse as lignin becomes a challenging but beneficial for society due to the several environmental advantages of the bio-oil (note that the bio-oil can be upgraded to the bio-fuel in a number of ways - physically, chemically and catalytically) over fossil fuels as a clean fuel as well: CO2/GHG (greenhouse gas) neutral, no SOx emissions (because the plant biomass contains insignificant amounts of sulfur), more than 50% lower NOx emissions than diesel oil in a gas turbine. This project will advance understanding of the new pathways for formation of bio-oil in "wall-less" reactor conditions; therefore, will have broad applications across biomass conversion, biofuels and bioenergy. Developed reaction-kinetic global model will help to understand the efficiency of thermal conversion of lignin into high-quality bio-oil product used both as an energy source and a feedstock for chemical production and can be included in similar models for cellulose, hemicellulose pyrolysis as well in coal industry. Virtually any form of the biomass can be considered for IR-LPHP application. Therefore, the new methodologies satisfying requirements for producing high-quality bio-oils may be economically competitive in using bio-oils as substitute for fuel oil, diesel in many applications, including boilers, furnaces, engines, and turbines for electricity generation.
