Hydrothermal transformation of cellulosic substrates assisted by photocatalysis – PHOTHER
New concept and materials to develop molecules of interest and H2 at low cost.
The objective is to replace petroleum resources with biomass to generate energy and/or manufacture platform molecules to synthesize drugs, plastics, etc. by developing a less energy-consuming concept, and new, more efficient and less expensive materials.
Make the transformation of hydrolysable fractions of biomass into energy and platform molecules less energy-intensive and more selective
Fossil resources are not inexhaustible and a source of pollution. The objective is then to replace them with one of the most important renewable sources of carbon, the cellulosic part of lignocellulosic biomass, which is inedible. However, nowadays high pressure and temperature and expensive materials based on noble metals are used. This hydrothermal catalytic treatment remains energy-intensive and not very selective. On the other hand, photocatalysis working at room temperature, atmospheric pressure with inexpensive catalysts activated under light has shown its interest. However, this process is slow. Our solutions were then to assist the hydrothermal process by photocatalysis in order to reduce the temperature and improve the efficiency of the photocatalyst by associating it with acidic properties favoring the breaking of the bonds present in the cellulosic substrates. The prospect is then to have a less energy-intensive, more selective process and new photocatalysts which, at the societal level, would make it possible to preserve the competitiveness of the chemical industry and could be extended to other transformations at the origin of new jobs.
A device working under pressure, temperature and irradiation has been developed. It allows working up to temperatures of 200°C and pressures of 40 bars under different irradiations thanks to a sapphire window. The validation of the device was carried out by working with glucose, as a model of cellulosic biomass and commercial TiO2 after developing the analysis of the photocatalytic and hydrothermal degradation products of glucose. The acidity of the materials, an important parameter for the transformation of cellulosic substrates, was evaluated by adsorption of pyridine and IR, adsorption of ammonia and carbon dioxide followed by calorimetry as well as by the study of the transformation of DHA (DiHydroxyAcetone) in order to verify the persistence of acidities and basicities in the aqueous phase. New TiO2/graphene sheet and TiO2/Tantalum composite materials combining photocatalytic properties and acidity and favoring the separation of photogenerated charges have been developed and tested for the production of H2 and the valorization of glucose under T, P, irradiation. Relationships between acid-base properties, surface of materials and glucose conversion have been studied and mechanisms established.
A new device for transforming hydrolysable fraction of biomass under T, P and irradiation has been designed. Platform molecules (levulinic acid, gluconic acid, and ethylene) and H2 has been formed in the presence of glucose and TiO2 at moderate P and T, 120° C and 5 bars and irradiation, thanks to the generation of acidity. This new process also opens new ways for the treatment of aqueous effluent by promoting mineralization and limiting the generation of by-products. The new TiO2/graphene sheets and TiO2/Ta composite materials promote the formation of H2 by photocatalysis by improving the separation of charges and the generation of levulinic acid under P, T and UV. The acid properties of the different materials are described in terms of nature, number of sites and strength, which allowed us to correlate with the photocatalytic properties.
Thanks to this new device and these new materials, the energy consumption to produce platform molecules and/or energy will be reduced and the development of new bio-sourced products will be able to emerge at a lower cost. New perspectives by working with other working atmospheres such as a reducing atmosphere to form sorbitol, or directly with cellulose could be investigated. It would also be interesting to develop this process to respond to an other problem of water pollution.
1-Comparison of hydrothermal and photocatalytic conversion of glucose with commercial TiO2: Superficial properties-activities relationships, I.Abdouli, M. Eternot, F. Dappozze, C. Guillard, N. Essayem, Catalysis Today, 2021, 367, 268-277. (doi.org/10.1016/j.cattod.2020.03.040)
2-Hydrothermal process assisted by photocatalysis: Towards a novel hybrid mechanism driven glucose valorization to levulinic acid, ethylene and hydrogen, I.Abdouli, F. Dappozze , M. Eternot , N. Essayem , C. Guillard , Applied Catalysis B: Environmental 2022, 305, 121051
3- Few Layer Graphene/TiO2 Composites for Enhanced Solar-Driven H2 Production from Methanol, H. El Marouazi, P. Jiménez-Calvo, E. Breniaux, C. Colbeau-Justin, I. Janowska, V. Keller, CS Sustainable Chem. Eng. 2021, 9, 10, 3633–3646
The PHOTHER project aims to develop novel methods for the transformation of cellulosic sources into valuable chemical precursors. The principle is to assist the hydrothermal process with new catalytic materials possessing excellent acid-base and photocatalytic properties. The objective is to decrease the reaction temperature and related energy expenditure limiting the unfavorable side products. This study will be performed thanks to the combined expertise of a team of dedicated researchers internationally recognized for their work in the fields of photocatalysis, catalytic biomass valorization and [photo]catalytic materials. The exploration of all resulting products formed in the gas and liquid phase - along with their selectivity according to the physicochemical, optical and acid-base properties of the involved materials - will allow to gain a detailed knowledge that is central to fully understanding the parameters and mechanisms in this new concept of biomass treatment
Project coordination
Chantal Guillard (Institut de Recherches sur la Catalyse et l'Environnement de Lyon)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
Partner
IES-CNRS Institut de Chimie et Procédés pour l'Energie, l'Environnement et la Santé
CNRS Institut de Recherches sur la Catalyse et l'Environnement de Lyon
Help of the ANR 410,140 euros
Beginning and duration of the scientific project:
March 2018
- 42 Months
