Advances in Catalyst Design and Reaction Strategies for Carbon-Neutral
Conversion of Bioglycerol to Propylene, 1,2-Propanediol, and Hydrogen
Abstract
The inevitable depletion of fossil resources and the anthropogenic
climate change arising from their excessive utilization make necessary
the search for renewable feedstocks and developing eco-friendly
technologies for producing greener energy, fuels and chemicals. Through
the present mini-review, we intend to share with the research community
our relevant contributions to advance the production of carbon-neutral
propylene, 1,2-propanediol and biohydrogen through thermo-chemical
conversion of biomass-derived glycerol, aided by diverse heterogeneous
catalysts. The reported achievements, which have been recently
recognized by the “ACI/NBB Glycerine Innovation Award”, are organized
and discussed in four marked sections. Thus, after having highlighted
the possible economic and environmental benefits of producing such
value-added commodities from bioglycerol excess, we present different
re-designing actions to improve the properties of transition
metals-based (e.g. Pt, Pd, Ni, Cu or Mo) supported on γ-Al2O3 or SiO2
for boosting glycerol transformation via: i) steam reforming, ii)
aqueous-phase reforming, iii) hydrogenolysis and iv) hydrodeoxygenation
reactions. Then, the catalytic role of metallic, acid and/or redox sites
in these reactions is discussed together with the identification of the
main factors affecting their stability under H2O-rich conditions. The
effect of reaction configurations and operating conditions in the
conversion of glycerol to the target product are also assessed. The
gained knowledge on re-modulating catalyst properties and optimizing
reaction strategies, including mechanisms and process operability, is
expected to provide a comprehensive guideline for continuously improving
the efficiency of bioglycerol upgrading routes.