The catalytic conversion of glycerol to aromatics (GTA, e.g., benzene, toluene, and xylenes, BTX) over a shaped H-ZSM-5/Al2O3 (60/40 wt%) catalyst was investigated in a continuous fixed-bed reactor to study the addition of the Al2O3 binder in the catalyst formulation on catalyst performance. The experiments were performed under N2 at 550 °C, a WHSV of glycerol (pure) of 1 h−1, and atmospheric pressure. The spent H-ZSM-5/Al2O3 catalysts were reused after an oxidative regeneration at 680 °C and in total 5 reaction-regeneration cycles were performed. Catalyst characterization studies show that the addition of the Al2O3 binder does not affect the surface area and crystallinity of the formulation, but increases the total pore volume (mesopores in particular) and total acidity (Lewis acidity in particular). The H-ZSM-5/Al2O3 (60/40 wt%) catalyst shows a considerably prolonged catalyst life-time (8.5 vs. 6.5 h for H-ZSM-5), resulting in a significant increase in the total BTX productivity (710 vs. 556 mg g−1 H-ZSM-5). Besides, the addition of the Al2O3 binder retards irreversible deactivation. For instance, after 3 regenerations, catalyst performance is comparable to the fresh one. However, after 4 regenerations, some irreversible catalyst deactivation occurs, associated with a reduction in total pore volume, crystallinity, and acidity (Brønsted acidity in particular), and meso-porosity of the Al2O3 binder. This study shows that both the stability and reusability of H-ZSM-5-based catalysts for GTA are remarkably enhanced when using a suitable binder.
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The use of H-ZSM-5 with various binders (Al2O3, SiO2, and kaolinite, 10 wt% on catalyst formulation) for the catalytic conversion of glycerol to bio-based aromatics (GTA) was investigated in a continuous bench-scale unit at a pyrolysis temperature of 450 °C, catalytic upgrading temperature of 500 °C, WHSV of pure glycerol of 1 h−1, and atmospheric pressure, and their performance was compared to H-ZSM-5 (SiO2/Al2O3 molar ratio of 28). The latter gave a peak BTX carbon yield of ca. 31.1C.%, a life-time of ca. 220 min, and a total BTX productivity of ca. 312 mg BTX g−1H-ZSM-5. The introduction of binders affects catalyst performance, which is the most profound and promising for the H-ZSM-5/Al2O3 catalyst. It shows a prolonged catalyst life-time of ca. 320 min and a higher total BTX productivity of ca. 518 mg BTX g−1H-ZSM-5, compared to the H-ZSM-5 without a binder. Catalyst characterization studies show that the addition of the binder does not have a major effect on the specific surface area, total pore volume, and total acidity. Other relevant properties were affected, though, such as micropore volume (SiO2), a reduced Brønsted acidity (Al2O3, and SiO2), and reduced crystallinity (SiO2). Coke formation causes severe catalyst deactivation, ultimately leading to an inactive catalyst for BTX formation. Catalyst characterization studies after an oxidative regeneration showed that the textural properties of the regenerated catalysts were close to those of the original catalysts. However, some dealumination of H-ZSM-5 occurs, resulting in decreased crystallinity and acidity, causing irreversible deactivation, which needs attention in future catalyst development studies.
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The aeronautical industry is expanding after a period of economic turmoil. For this reason, a growing number of airports are facing capacity problems that can sometimes only be resolved by expanding infrastructure, with the inherent risks that such decisions create. In order to deal with uncertainty at different levels, it is necessary to have relevant tools during an expansion project or during the planning phases of new infrastructure. This article presents a methodology that combines simulation approaches with different description levels that complement each other when applied to the development of a new airport. The methodology is illustrated with an example that uses two models for an expansion project of an airport in The Netherlands. One model focuses on the operation of the airport from a high-level position, while the second focuses on other technical aspects of the operation that challenge the feasibility of the proposed configuration of the apron. The results show that by applying the methodology, analytical power is enhanced and the risk of making the wrong decisions is reduced. We identified the limitations that the future facility will have and the impact of the physical characteristics of the traffic that will operate in the airport. The methodology can be used for tackling different problems and studying particular performance indicators to help decision-makers take more informed decisions.
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Reading and writing is modelled in CSP using actions containing the sym- bols ? and !. These reading and writing actions are synchronous and there is a one- to-one relationship between occurrences of pairs of these actions. It is cumbersome to ease the restriction of synchronous execution of the read and write actions. For this reason we introduce the half-asynchronous parallel operator that acts on actions con- taining the symbols ¿ and ¡ and study the impact on a Vertex Removing Synchronised Product.
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Reading and writing is modelled in CSP using actions containing the symbols ? and !. These reading actions and writing actions are synchronous, and there is a one-to-one relationship between occurrences of pairs of these actions. In the CPA conference 2017, we introduced the extended half-synchronous al- phabetised parallel operator X ⇕ Y , which disconnects the writing to and reading from a channel in time; the reading processes are divided into sets which are set-wise asynchronous, but intra-set-wise synchronous, giving full flexibility to the reads. In this paper, we allow multiple writers to write to the same channel set-wise asynchronously, but intra-set-wise synchronously and we study the impact on our (Extended) Vertex Removing Synchronised Product. The advantages we accomplish are that the extension of X ⇕ Y gives more flexibility by indexing the writing actions and the reading actions, leading to a straightforward majority vote design. Furthermore, the extension of X ⇕ Y preserves the advantages of the X ⇕ Y operator.
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