Hydrogen is an important energetic vector nowadays. The most common industrial method to produce ultrapure hydrogen is by steam methane reforming (SMR), where hydrogen is first produced as a mixture mainly composed of hydrogen, carbon monoxide, methane, and carbon dioxide. A purification step by pressure swing adsorption (PSA) is carried out usually using activated carbon and 5A zeolite as adsorbents. The design of this process requires fundamental information about the adsorption and diffusion of the components of SMR-off gas, which is only available in the literature for a limited number of adsorbents. In this work, adsorption Henry’s law constants and reciprocal diffusion time constants have been measured for hydrogen, carbon monoxide, methane, and carbon dioxide on BPL 4X10 activated carbon and 13X zeolite pellets from pulse experiments. Adsorption isotherms of these gases in both adsorbents at temperatures between 298 and 338 K, up to pressures of 20 bar for hydrogen and 2–5 bar for the other gases, have also been measured volumetrically. A PSA cycle for hydrogen purification using BPL activated carbon and 13X zeolite has been designed introducing the measured adsorption and diffusion data in a simulation tool. The process can yield 99.99+% hydrogen with 90% recovery and 7.2 mol H2 kg–1 h–1. If 13X zeolite is replaced by 5A zeolite with the same operating conditions, the hydrogen purity falls down to 99.81%.

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Volatile fatty acids (VFAs) are produced in the anaerobic digestion of urban or food wastes and sewage sludge. The interest in these compounds has increased because of their use as platform chemicals. In this paper, the application of natural terpenoids and eutectic solvents to sustainably recover VFAs from aqueous solutions by extraction has been evaluated. First, a screening of solvents has been done using COSMO-RS, selecting three terpenoids: geraniol, citral, and eugenol, and two hydrophobic eutectic solvents formed by octanoic acid and menthol or thymol. These solvents have been tested in the extraction of acetic, propionic, butyric, and valeric acids. The highest yields were obtained using geraniol and the (octanoic acid + thymol) eutectic solvent, being comparable or higher than those for organic solvents from the literature. The back-extraction of the VFAs from both solvents has been studied using NaOH and Na 2 CO 3 solutions, concluding that the eutectic solvent is not chemically stable to be reused, whereas the reusability of geraniol was confirmed in consecutive cycles of extraction. The technical viability of the proposal was confirmed in scale-up experiments using geraniol in a packed column, and VFA extraction yields higher than 98% were obtained in the simulation of a countercurrent extractor.

Liquid-phase O methylation of phenol was carried out with dimethyl carbonate (DMC) over as-synthesized KNaX zeolite with impregnated alkaline metal hydroxides. The presence of alkaline hydroxides is associated with hydroxysodalite impurity in the X zeolite. This zeolite exhibited better properties as basic catalyst than those prepared by postsynthesis treatments (ionic exchange). Phenol conversion and selectivity toward anisole were 100% and 85%, respectively, at 438 K with a DMC/phenol molar ratio of 2. The crystallinity and composition of the KNaX zeolite were retained after reaction, making it possible to recover the catalyst without loss of the impregnated alkaline hydroxides during the reaction. The reactivation of the KNaX zeolite was carried out at low temperature (373 K), achieving the same conversion and selectivity to anisole in the phenol methylation as in the first reaction.