Vibrational Spectroscopic Characterization of Glycerol Reaction Pathways over Metal‐Modified Molybdenum Carbide Surfaces

Abstract

As the production of biodiesel increases, it is economically preferable to upgrade the excess by‐product, glycerol, into value‐added products. Metal‐modified molybdenum carbide (Mo2C) is a class of promising catalysts for this application due to their promising hydrodeoxygenation (HDO) activity. In this work, Pt, Fe and Cu were used to modify the Mo2C surface and tune the product selectivity of glycerol. Pt/Mo2C showed reforming activity to produce syngas, Fe/Mo2C cleaved all the C−O bonds of glycerol to produce propylene, while Cu/Mo2C broke only one C−O bond of glycerol to form acetol. Consecutive temperature‐programmed desorption (TPD) experiments demonstrated an enhanced stability of all surfaces when compared to Mo2C. High‐resolution electron energy loss spectroscopy (HREELS) characterization indicated that the Fe/Mo2C surface weakened the C−O bonds of glycerol, while the Pt/Mo2C surface showed no activity towards C−O bond cleavage. This study demonstrated that the Pt/Mo2C, Fe/Mo2C and Cu/Mo2C surfaces were active, selective and stable for converting glycerol into syngas, propylene, and acetol, respectively. The combination of TPD and HREELS also served as an example of utilizing surface spectroscopy to identify the reaction pathways and intermediates on model catalyst surfaces. This should, in turn, provide insights to guide the design of metal‐modified carbide catalysts for the upgrading of biomass‐derived oxygenates.

Bioglycerol-to-Propylene Routes: From Fundamental Catalysis to Process Design and Marketing

“…There is still no commercialized GTP catalyst that can convert crude bioglycerol under hydrothermal conditions to produce a high propylene yield without excessive H 2 consumption. Thus, cutting-edge preparation and functionalization strategies are being explored to improve the catalyst properties for the GTP reaction in both a homo- and heterogeneous catalysis medium. ,,− ,− These efforts are focusing on controlling the nature and population of active sites for efficiently eliminating C–O and controlling C–C hydrogenation.…”

“…In a homogeneous medium, the catalyst is used as a liquid or gas in full contact with the reactant, ,, whereas in a heterogeneous catalysis, the approach involves dispersing an actives species over a solid support to improve its functional characteristics. ,,,,,, Impregnation is the most widely used method for developing a GTP catalyst because of its ease of use; however, it may lead to low metal dispersion and easy leaching in an aqueous medium, particularly when with a high loading of metals . Other synthesis strategies, such as pH-assisted, slurry or sequential impregnation, ,,, modified impregnations, ,,,,,, coprecipitation, ,,,, homogeneous dissolution, and/or post­recrystallization, ,, melt-infiltration, physical vapor deposition (PVD), , physical mixtures, , or include combined methods. ,,− ,− ,, The preactivation treatment of the catalyst, which depends on the active sites required for the target GTP reaction, involves manly in situ or ex situ thermo-treatments under a controlled atmosphere, such as calcination, ,,,, reduction, ,,,,,,, carburization, , sulfidation, , or include the cofeed of acids or reductive agents or hydrogen donor molecules ,,,,, With these strategies, the type and population of target ac...…”

“…Indeed, GTP routes is undergoing advances in research in terms of both fundamental catalysis and process design ,,− by exploring different transformation strategies from both heterogeneous and homogeneous catalysis. GTP routes are being investigated through high-temperature processes, ,,,,,, multisteps reactions, including triple-stage reactors, , separate double reactors, ,, tandem or dual-bed catalysts, ,,, and single-step conversion strategies. ,,,− ,,,,− These studies conclude that in the future GTP catalysis may become a sustainable bridging route between the biorefinery and polyolefin industries.…”

“…Indeed, GTP routes is undergoing advances in research in terms of both fundamental catalysis and process design ,,− by exploring different transformation strategies from both heterogeneous and homogeneous catalysis. GTP routes are being investigated through high-temperature processes, ,,,,,, multisteps reactions, including triple-stage reactors, , separate double reactors, ,, tandem or dual-bed catalysts, ,,, and single-step conversion strategies. ,,,− ,,,,− These studies conclude that in the future GTP catalysis may become a sustainable bridging route between the biorefinery and polyolefin industries. Nonetheless, integrating GTP routes in a unified network, from biomass to sustainable propylene, raises intrinsic challenges, such as the nature of the most efficient GTP configurations, control of the interoperability of multisteps and/or combined bed reactors, influenced by contact states between catalyst beds, operating conditions, reaction mechanisms, and so forth.…”

A bio-based click reaction leading to the dihydropyridazinone platform for nitrogen-containing scaffolds

“…Since then, great achievements have been witnessed centered around the production and transformation of platform molecules such as levulinic acid (LA), [7][8][9] lactic acid, 10 and glycerol. 11 The molecular families have become gradually enriched as more newly-developed biomass-derived chemicals have reached the evaluation criteria for platform molecules proposed by scientific communities, 5 which has dramatically boosted the development of biorefinary technologies.…”