This MSCA project, named as “CatGTP-Interdisciplinary concepts for one-step CATalytic hydrodeoxygenation of crude Glycerol-To-bioPropylene”, was implemented at “Unité de catalyse et Chimie du solide - UCCS” of the University of Lille (ULille; France). The CatGTP project was looking at developing efficient conversion routes for crude bioglycerol, which a by-product of world-scale biodiesel industry. Herein, major advances both in terms of fundamental catalysis and process optimization of one-step hydrodeoxygenation (HDO) of bioglycerol-to-propylene (GTP) were achieved to: i) provide new mechanistic and kinetic insights on GTP catalysis, and ii) improve the efficiency of GTP route by determining the conditions affecting the process operability and catalysts performance, which are challenging in hydrothermal media.
The data collected in the first part of CatGTP project concerns two model reactions: glycerol-to-propylene (GTP) and ethanol-to-ethylene (ET-to-ETY). The idea was to provide new insights on how occurs the elimination of hydroxyl -OH group from two similar oxygenated molecules. Doing so, HDO biomass-derived molecules, which can involve concomitant dehydration, deoxygenation, hydrogenation over redox, metals and acid systems, could actually be better understood. The main findings concern how to successfully: i) get high loadings of highly reactive sub-2 nm Mo particles onto silicas for single-step HDO of glycerol at; H2-pressure ≤50 bars and temperature ≤ 400ºC, and ii) re-modulate the population of acid-sites and their strength on Al-rich MFI zeolites with high density of H+ for selective dehydration of ethanol at temperature ≤ 225ºC. Thus, highly efficient catalysts (Mo@SBA-15 and acidic ZSM-5 zeolites), were developed to provide high yields in GTP (up to 81%) and ET-to-ETY (up to 92%), respectively. The adopted actions allowed to identify the main deactivations causes for HDO catalysts working in H2O-rich medium.
The second part of CatGTP gave new insights about the most efficient GTP strategies (i.e. high-temperature routes, multi-steps/tandem reactions or single-step HDO) for converting bioglycerol in propylene. These data were collected using various criteria such as process configuration, severity of conditions, sustainability, and propylene/CO2 production. They are discussed as a function of the thermodynamic and operating conditions. Further, high-speed tests were combined with design of experiments to high propylene (> 70%) yield, which were not reported so far for such process, at optimal conditions (T ~ 367°C, velocity ~9,5 h-1 and H2/glycerol ratio ~59).
All the collected data in this MSCA project, which focus on the upgrading of crude bioglycerol by-product and bioethanol excess, to value-added biopropylene and bioethylene, respectively, are highly important for The EU’s society, because they are serving as bases for: i) building a connecting bridge between the biorefinery and polyolefin industries, and ii) complying with global targets for future carbon neutrality set by 2050.
