.Flash pyrolysis is a thermochemical process where lignocellulosic biomass (wood, agricultural residues, etc.) is converted into bio-oils. These liquid biofuels offer opportunities for joint production of bio-sourced molecules and alternative fuels.
The main drawback of conventional flash pyrolysis processes concerns the quality of bio-oils, more particularly their content of highly oxygenated molecules that induce significant processing costs. The overall objective of the project was to improve the efficiency of the pyrolysis by integrating within the process a catalyst that allows (i) to produce partially <br />deoxygenated bio-oils in order to allow their co-processing with petroleum feedstocks ; (ii) a more selective production of molecules which may be of interest for chemicals. <br />The strategy adopted was to develop an innovative catalytic post-treatment module that can be integrated within a conventional process for in-situ treatment of pyrolytic vapors. The main issues were: (i) scientifically, to better understand the reaction mechanisms and the effect of the catalysts; (ii) at the technological level, to develop a prototype integrated with a pilot representative of real conditions; (iii) at the industrial level, to define potentially interesting molecules for the green chemistry market, and to evaluate the technical, economic and environmental relevance of such a bio-oil chemistry / energy co-valorization process.
A first, predominantly fundamental line of work consisted in laboratory screening of different types of catalysts on model molecules or real vapors in order to select the most effective active phases, to test improvements and to better understand the reaction mechanisms involved. Besides, a prototype consisting of a particulate filter and a catalytic reactor was developed and integrated into an existing pyrolysis pilot. The tests carried out at two scales allowed, on the one hand to validate its efficiency in erms of particle separation and deoxygenation of bio-oils, and on the other hand to test its stability in real conditions. In support of these various test campaigns, important analytical means have been deployed to
better characterize bio-oils produced with or without a catalyst. Co-processing tests were carried out on the organic fraction, while processing of chemical extraction were modeled on the aqueous phase. All these results finally made it possible to describe technically a potential catalytic pyrolysis process allowing a co-valorization of fuels / chemicals, and to
evaluate their environmental impact by life cycle analysis.
The catalytic material selected for the main part of the work was zeolite HMFI-90, whose activity has been demonstrated at laboratory scale, but also within real conditions on a catalytic filtration prototype that was validated at pilot scale. The catalytic activity is reflected in particular by a significant deoxygenation of the organic fraction, which has been separated and successfully tested as FCC co-processing for the production of fuel. The aqueous fraction contains residual organic molecules potentially recoverable in chemistry, via extraction processing that have been modeled.
The interest of catalysis was demonstrated since catalytic bio-oils can technically be added directly to a petroleum feed in an FCC process for the production of fuels, and thus contribute to the production of fuels of renewable origin. Beyond the work done on the HMFI-90, more exploratory tests have been carried out on second-generation catalysts which deserve to be examined in the light of the preliminary results. The evaluation of the value chain shows that the chemical recovery of substances extracted from bio-oils has an interesting potential, both economic and environmental, but given the inherent uncertainties,
it is recommended to continue this work and to deepen the economic component.
Two PhD theses were completed simultaneously, on complementary topics.
- The first one, mainly fundamental, has improved the understanding of the role of catalysts in the chemical conversion mechanisms of model molecules, and actual pyrolysis vapors
The aim of the project CATAPULT is to assess the technical, economical and environmental relevance of flash pyrolysis as a route for producing bio-oils dedicated to the joint production of chemicals and energy, combining the two following applications:
- chemical upgrading of an appropriate fraction of bio-oil by extracting molecules dedicated to green chemistry (platform or high-value molecules) ;
- co-refining (or co-processing) of the bio-oil residual fractions with petroleum distillates for producing hybrid biofuels.
The major technical barrier remains the quality of bio-oils produced in conventional pyrolysis processes. The overall goal of the project is to explore a way of improving the efficiency of flash pyrolysis, by the joint use of a suitable catalyst which may allow
- to direct the selectivity of pyrolysis reactions in order to optimize the production of molecules identified as interesting and to make easier the downstream separation/extraction operations;
- to upgrade bio-oils in order to improve their compatibility regarding towards further co-processing specifications, by promoting de-oxygenation of organic vapors produced during pyrolysis.
The main scientific issue is to better understand the effect of catalysts on the formation or destruction of these molecules (or families of molecules) which will be previously identified as potentially interesting for extraction/recovery chemical, or conversely undesirable for downstream processing operations. The main technical issue is the development of an innovative module for catalytic post-treatment of pyrolysis vapors which will be implemented and tested on an existing flash pyrolysis pilot.
As a first step, a first generation of catalytic module will be designed on the basis of a supported commercial catalyst, and implemented on the pilot in order to produce two batches of bio-oils reference (with and without catalytic treatment). These tests will also allow evaluating the operating mode of the reference catalyst, especially its stability and ability to be regenerated, those data being hardly available in the literature. Batches of bio-oils will serve as reference products for the standardization of analytical methods and quality tests as a source of molecules or as co-processing feedstock. As a second step, laboratory scale developments will aim at improving the performance of the catalytic module regarding the yield and selectivity of target molecules. Tests conducted on different catalyst formulations and via different methods of support impregnation, will result in selecting a second generation of catalytic module, through a multi-criteria analysis of performance. This second generation of catalytic module will be validated on the pilot, with new analyzes and tests of bio-oil quality. These technical data will ultimately provide economic and environmental indicators to decide on the viability of the route considered.
Though these highly complementary approaches and continuous exchange between laboratory and pilot scales, the project responds to both scientific and industrial issues covering many areas of expertise such as the optimization of catalysts, process development and integrated analysis / testing quality. It will further lead to theoretical schemes of bio-oil fractionation, which might lead to further specific developments.
Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Divers privé)
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.
Céramiques Techniques et Industrielles S.A.S.
Institut de Recherches sur la Catalyse et l'Environnement
SOCIETE INTEROLEAGINEUSE D'ASSISTANCE ET DE DEVELOPPEMENT
Centre de Coopération Internationale en Recherche Agronomique pour le Développement
Help of the ANR 767,943 euros
Beginning and duration of the scientific project: January 2014 - 42 Months