Applications of near-/supercritical fluids to conversion of lignocellulosic biomass and product upgrading

Activity: Talks and presentationsTalks and presentations in private or public companies

Description

Research Seminar held by Dr. Marco Maschietti.

AbstractThis presentation focuses on my research experiences on the application of: i) lignin conversion to biocrude and chemicals using near-critical water medium; ii) supercritical carbon dioxide as a solvent for upgrading lignocellulosic biocrude.Lignin is the most abundant aromatic biopolymer on earth and could potentially be a source of aromatic chemicals on a scale compatible to current petrochemical productions. Excess lignin can be recovered from Kraft pulp mills or from lignin-rich residues of lignocellulosic to ethanol processes. My activities at Chalmers University of Technology (Sweden, 2011-2013) and currently at Aalborg University (Denmark, since 2014) were focused on studying the feasibility of the conversion of Kraft lignin into bio-crude and 1-ring aromatics. The technical feasibility of the process was proved operating a continuous-flow small pilot unit (1 kg/h feed), with the reactor at 25 MPa, temperatures from 290 to 370 °C, using K2CO3 (0.4 % to 2.2 %) and phenol as char-suppressing agent. Lignin slurry was converted into bio-crude (up to 86 %), water soluble organics (up to 11 %), with char suppressed down to 16 %. As the main topic of a Marie-Curie grant I was awarded, a small scale (100 cm3) injection batch reactor was realized at Aalborg University with the aim of reacting biomass slurry in near-critical water producing results comparable to those that can be obtained from continuous-flow pilot units. Differently from typical lab-scale batch reactors, this reactor allows: 1) injection of slurry of biomass in a pre-pressurized pre-heated reaction chamber (fast heating of the biomass); 2) pressure control during batch operation; 3) fast ejection and quenching of the products. This new reactor was used to study the effect of the phenol/lignin ratio in the process, as well as an oxidative process variant aimed at production of carboxylic and dicarboxylic acids. Supercritical carbon dioxide (sCO2) is a solvent merging advantageous properties of liquids (high densities) and gas (favorable transport properties). It behaves as a low to intermediate polarity solvent and its properties can be tuned to large extent on the basis of the operating pressure and temperature. My research experience related to sCO2 comprises separation of citrus oils, fish oils, and fractionation of perfluoropolyethers, while the current focus is on exploring the potential of sCO2 as a means for upgrading lignocellulosic biocrudes produced from hydrothermal liquefaction (HTL) or pyrolysis processes. Preliminary results in this area showed the possibility of extracting up to approx. 50 % of a heavy HTL biocrude. The extraction process was investigated for pressures and temperatures in the range 112 to 400 bar and 40 to 120 °C, corresponding to solvent densities in the range 548 to 882 kg/m3. The effect of increasing temperature, while keeping a high solvent density, was proven to dramatically affect the efficiency of the process. The extracts showed reduced density as well as 40 % reduction of TAN compared to the feed. Ketones, 1-ring phenols and low molecular weight fatty acids were concentrated in the extract, with recoveries up to 80 %, with ketones and phenols exhibiting the highest distribution factors. Observed selectivities suggest the feasibility of downstream separation of the key classes of extractives using sCO2 as a solvent.
PresenterMarco Maschietti has been associate professor in the section of chemical engineering at Aalborg University (Denmark) since 2014. He got a PhD in Industrial Chemical Processes at Sapienza University of Rome (Italy) in 2005, with a dissertation on separation of fish oils using supercritical carbon dioxide as a solvent. He did postdoctoral research work at Sapienza University focusing on supercritical carbon dioxide applications but also in a broad domain of chemical engineering. He worked as R&D Project Manager in a food company, where he invented a new type of time-temperature indicators for perishable products. In 2011 he moved to Chalmers University of Technology (Sweden) where his focus was on converting lignin into biocrude and chemicals using near-critical water as reaction medium. At Aalborg University, his current research focuses on two areas: 1) application of near-/supercritical fluids (CO2 and water) in biomass conversion processes and in the chemical industry in general, with the aim of promoting the shift towards the use of “green” chemicals and the development of biorefineries; 2) offshore oil and gas processes, with the aim of reducing the environmental footprint of this industry.
Period12 Mar 2019
Held atDepartment of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, United States