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Hydroconversion feeds are mixtures comprising alkanes and cycloalkanes, for which the binary impact on the respective reaction pathways, is still not completely understood. Methylcyclohexane admixture on n-octane hydroconversion over Pt/HUSY catalysts has been investigated using the pure compounds and their equimolar mixtures in a wide range of operating conditions. The hydroconversion behavior on catalysts with various Pt loading was examined to investigate the role of the active sites. No impact of methylcyclohexane admixture to n-octane was observed over catalysts which ensured ideal hydrocracking (0.5 and 0.1 wt%Pt). In contrast, methylcyclohexane addition decreased the octane isomer yield at iso-conversion over 0.07 wt%Pt/HUSY. A lower metal loading of 0.04 wt%Pt led to a pronounced decrease in n-octane conversion in the mixture. The methylcyclohexane conversion was not affected by n-octane addition regardless of the metal–acid balance. The negative admixture impact on the n-octane conversion and isomers yield, combined with the absence of any impact on the methylcyclohexane behavior, was attributed to preferred cycloalkane adsorption on metal sites, resulting in a reduced metal site availability for alkanes. A cycloalkane admixture to an alkane in hydrocracking can, hence, induce a regime shift from ideal to nonideal hydrocracking. Consequently, bifunctional catalysts developed purely for alkane hydroconversion may prove not to be optimal for realistic feeds, including cycloalkanes.

Resins are interesting catalysts for organic reactions, which are characterized by a remarkable swelling behavior upon exposure to liquids, typically resulting in selective sorption in the case of mixtures. Hence, when constructing kinetic models for reactions catalyzed by such resins, the component partitioning between the bulk liquid and polymer liquid and its effect on their thermodynamic activities have to be properly taken into account. A kinetic model is developed for acidic resin-catalyzed esterification, while comparing two scenarios for capturing the thermodynamics within the resin pores. For the specific case study on a single resin with a specific solvent, compensation effects between the calculated thermodynamic activities in the resin and the estimated rate coefficients render only minor performance differences between the two scenarios. Still, aiming at extending the scope toward other solvents and/or resins, it is deemed crucial to explicitly account for the resin’s selective sorption and swelling behavior.

Natural organic matter (NOM) negatively affects water quality and can cause serious issues during water treatment processes. Anion exchange resins (AER) have already proven their effectiveness to remove a major part of this NOM. However, due to its complexity, understanding and improving NOM removal remains challenging. This study aimed to provide in-depth insights in NOM removal with macroporous styrenic weak (WBA), strong (SBA) and combined weak/strong basic AER. Batch experiments were performed with resins in two industrially relevant counter ion forms: OH-and free base form for SBA and WBA resins respectively, using NaOH conditioning, and Cl-form resins using NaCl and HCl conditioning for SBA and WBA resins respectively. Synthetic water containing model compounds for different NOM fractions was used, focussing on the biopolymer fraction which is typically poorly removed by classical ion exchange processes and is a known disinfection by-product precursor in drinking water. The applied resin conditioning procedure influenced the equilibrium pH and consequently NOM removal efficiency and mechanisms. When ion exchange is the dominant driving force for NOM removal, the Cl-form proved to be most efficient. For uncharged NOM containing hydroxyl groups, SBA resins in the OH-form are preferable due to H-bonding. Adsorption of aromatic NOM through π-π interactions with the polystyrene backbone was not affected by the resin conditioning. This work clearly demonstrates that not only the AER type, but also the conditioning procedure and the corresponding counter ion form play a key role in the design of successful NOM removal processes.

Abstract: Background: The performance of two adsorbents, i.e. a new ultra stable adsorbent SH-ePMO and a commercial ion exchange resin TP-214, for the removal of mercury from aqueous solutions was investigated. The operating variables studied were initial mercury concentration and contact time. Results: The adsorption isotherms showed favourable adsorption. The adsorption isotherms were analysed using Langmuir and Freundlich models. The Langmuir model yielded the best fit for the SH-ePMO, whereas the Freundlich model fitted best the adsorption on TP-214. The maximum adsorption capacities were 66 and 456 mg/g for SH-ePMO and TP-214, respectively. TP-214 is capable of purifying water to parts per trillion levels. The adsorption kinetics showed a fast adsorption for both adsorbents. The kinetics was analysed using Lagergren's pseudo-first-order and pseudo-second-order kinetic models. The pseudo-first-order kinetic model showed a good description of the experimental data of both adsorbents. Conclusions: This study clearly shows the potential of the ultra stable SH-ePMO for removing mercury from aqueous solutions and confirms the performance of the ion exchanger resin TP-214.