Welcome

Context: Several important industrial reactions involve the use of catalysts with an adequate quantity of acid or basic sites of a proper strength to selectively yield the target products. For these reactions, the presence of sites of opposite nature, i.e. acid and basic sites, on the catalysts’ surface is detrimental to the selectivity. For example, the formation of acetol from glycerol is catalyzed by basic sites, while glycerol dehydration to acrolein is favoured on acid sites and both products are always detected in various proportions when converting glycerol.

In this project, we will examine a reaction which is of a great importance for enhancing the potential of the biomass-derived chemistry: the synthesis of Guerbet alcohols, i.e. the synthesis of higher alcohols from lower alcohols, which involves also basic sites. Nevertheless, irrespective of the chosen catalytic formulation, both types of sites will coexist on the surface and it is thus necessary to control not only the strength and the amount of the desired sites (basic ones) but also to hinder as much as possible the number/strength/action of the undesired ones (strongly acidic ones). In this context, it is still relevant to reliably get a huge amount of data on catalysts having both acid and basic sites in order to properly back-tune their composition and thus to improve the selectivity of catalyzed reactions. The data acquired in this project will be not only applied to the aforementioned Guerbet synthesis, but can also be profitably transferred to all the catalytic reactions based on acid-base functions.

Expected progress: The progress beyond the state of the art will first consist on full and fine characterization of both acid and base surface properties of various families of solids related to their catalytic behavior. Conventionally, for a reaction involving one type of sites (e.g., acid sites), the development efforts are often limited to the specific tuning of these sites, but not on the hindering of the action of their counterparts (e.g., basic sites), which are unavoidably present. The original concept developed in the present work concomitantly considers both types of sites, for a new globally rationalized approach of the catalytic systems’ tuning. Further, yielding propanol and isobutanol from – bioresourced – ethanol and methanol is an original and novel variant of the Guerbet reaction, while being of major interest from an industrial point of view, within the current context of promotion of the sustainable chemistry. Another progress is the development of a parallel testing equipment with up to 8 reactors, which the project aims at commercializing after the demonstration of its capabilities at a cost of about 100 k€, thus well below the market prices, in order to make it available to the scientific community.

Main deliverables: Novel, well characterized catalysts, the properties of which have been tuned/back-optimized for the target reaction, are expected from this work. At the end of this work, these catalysts as well as all the families of developed catalysts with various acid-base properties will be available as reference materials for other acid base catalytic reactions. For doing this, a database gathering the properties of each catalyst will be created with an open internet access. This database will include the acid-base properties of the catalysts and related catalytic properties in the selected reactions, as well as the synthesis recipe.

As aforementioned, the targeted chemical products are propanol and isobutanol through the studied innovative Guerbet chemistry. Further, the reaction of conversion of glycerol used here as a test reaction will also yield products (acrolein and acetol) that receive a lot of interest from the industry since it should lead to commercial application.