A complete overview of the chemical and biotechnological synthesis of muconic acid, its isomerization, and valorization into chemicals and polymers is presented.

Solid-state incorporation of Sn into beta (β) zeolites is a fast and efficient method to obtain Lewis acidic Snβ catalysts with high activity. The present work emphasizes the fundamental role of the heat-treatment atmosphere in the solidstate incorporation of active Sn in zeolites. Via an array of characterization tools including N 2 -physisorption, X-ray diffraction, diffuse reflectance UV−vis spectrocopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and 119 Sn Mossbauer spectroscopy, it is shown that preheating under an inert atmosphere (pre-pyrolysis) prior to air-calcination affords Snβ catalysts with the highest Sn dispersion and significantly less extra-framework SnO 2 compared to the classic calcination. In situ characterization during pre-pyrolysis by temperature-programed decomposition−mass spectrometry, thermogravimetric analysis, and 119 Sn Mossbauer spectroscopy reveals the in situ generation of Sn(II)O species that are more mobile than Sn(IV)O 2 species generated during calcination. This mobility property essentially enables the high Sn dispersion in Snβ. Based on this knowledge, active sites per catalyst weight are maximized while retaining high turn-over frequencies for the Baeyer−Villiger oxidation reaction (300 h −1 at 80 °C). For Lewis acid densities above 200 μmol•g −1 , the catalytic activity unexpectedly leveled off to 93 mM•h −1 , even under kinetic control. We tentatively ascribe the activity plateau to the incorporation of Sn in less favorable T-sites at high Sn-loadings.

The performance of zeolite catalysts depends not only on the strength and number of Brønsted acid (or exchange) sites but also on synergistic effects derived from their proximity, in particular, and their distribution, in general. Little is known on the genesis of acid sites and site distributions in hydrothermal zeolite synthesis. By an extensive study of five crystallization systems yielding ZSM-5 (MFI) and SSZ-13 (CHA), with a focus on interzeolite conversion (IZC) methods, several synthesis factors and mechanisms that are key in determining the output acid site distribution have been identified. Key in this study were temporal synthesis profiles while probing the distribution and evolution of proximal acid sites with divalent cation capacity measurements. Over the course of different crystallizations, changing local charge distributions are detected, notably within crystalline materials upon prolonged exposure (maturation). Aluminum is clearly the key driver in IZC syntheses, from charge, dissolution, concentration, and mobility points of view. Quasigeneric principles for IZC syntheses are proposed, distinguishing between Al-loving and Al-averse systems, enabling a new degree of control over the acidity and ion-exchange properties of zeolites, of use to tailoring catalytic activity.

The purification of biofuels becomes a challenging issue because of the harmfulness of remaining phenolic molecules for human health and engines. To this end, protonic Y zeolites with different Si/Al ratios were explored as effective adsorbent materials to remove phenol from isooctane solution by using a dual experimental/computational strategy. Phenol was selectively removed from isooctane over HY and USY zeolites with a maximal adsorption capacity of 2.2 mmol.g -1 , that corresponds to 3-4 phenol molecules per zeolitic supercage. The adsorption equilibrium was reached faster over dealuminated zeolites, due to the presence of large pores at the expense of microporosity as well as a low density of acidic sites. We further evidence that the presence of acid sites limits the regeneration capacity since phenol strongly adsorbed on both Brønsted and Lewis acid sites. USY zeolite with the highest Si/Al ratio presents the best regeneration capacity since it has the lower aluminum loading. A fundamental understanding of these performances was obtained by coupling characterization (Infrared Spectroscopy, breakthrough curves and desorption experiments) and modeling tools (Grand Canonical Monte Carlo and Density Functional Theory).