The development of hierarchical SAPO-11 catalysts typically relies on expensive synthetic mesoporogens or post-synthetic treatment that compromise structural integrity. Herein, we present a novel, cost-effective mesoporogen-free strategy for synthesizing hierarchical SAPO-11 by exploiting halloysite nanotubes (HNTs) as a dual-function precursor, serving simultaneously as a source of silicon and aluminum and as a template for secondary porosity. Hydrothermal synthesis conditions (180-200 degrees C, 48-72 h) were optimized to leverage HNTs' inherent mesoporosity and chemical composition, yielding SAPO-11 with high crystallinity, moderate acidity and enhanced textural properties. Characterization by XRD, SEM, TEM, nitrogen sorption, Py-IR and NH3-TPD confirmed the hierarchical porosity (mesopore volume up to 54 %) and controlled acidity, attributed to pseudomorphic transformation of HNTs during synthesis. Pt-loaded catalyst supported on hierarchical SAPO-11 demonstrated higher platinum dispersion and catalytic efficiency, achieving a C16-isomers yield of 80 % under optimized conditions (380 degrees C, 3.5 MPa H2, LHSV 4 h-1, H2/feedstock volume ratio 500 nL & times; L-1), outperforming conventional SAPO-11 and other hierarchical counterparts. The hierarchical structure facilitated diffusion of multi-branched isomers, reducing cracking byproducts (cracking/isomerization ratio of 0.29 vs. 0.43 for conventional SAPO-11). Furthermore, stability tests over 500 h on stream confirmed the catalyst's resistance to deactivation, attributed to its hierarchical porosity, mild acidity, and optimal metal-acid balance. This mesoporogen-free approach offers a scalable, eco-friendly route to high-performance catalysts that provide activity, selectivity, and stability while leveraging abundant natural resources.
Liquid organic hydrogen carriers (LOHCs) based on α,ω-alkanediol/lactone systems offer significantly lower dehydrogenation enthalpies than conventional aromatic carriers. This study investigates how the chain length and branching of alkyl substituents on the lactone ring influence the thermodynamic equilibrium of reversible hydrogen storage. Using a hybrid approach combining experimental thermochemistry and high-level quantum-chemical calculations (G3MP2), the reaction enthalpies, entropies, and Gibbs energies for both liquid and gas phases have been determined. Results reveal that extending the chain and increasing the branching of the alkyl group substantially reduce the Gibbs reaction energy. For instance, 2-tert-butyl-γ-butyrolactone exhibits a negative Gibbs reaction energy (−5.3 kJ·mol−1 at 298.15 K), indicating that thermodynamically spontaneous hydrogen release is possible at room temperature, provided suitable catalysts are available. However, while highly branched substituents greatly facilitate hydrogen release, they reduce volumetric hydrogen storage density and make the reverse hydrogenation step more challenging. Ultimately, a structure-property analysis demonstrates that tuning the size and branching of alkyl substituents provides a versatile strategy to balance the competing thermodynamic demands of hydrogen storage and release, enabling the rational design of tailored diol/lactone LOHCs.
The current research aims to evaluate the photocatalytic activity of (TiO2) with various loading ratios (5%-60%) supported on mesoporous aluminosilicate (zeolite type) called Siral, with aluminum content ranging from 20% to 70%, to enhance the performance of degradation of ibuprofen (IBP) as a pharmaceutical pollutant. The batch reactor is furnished with solarium light to simulate sunlight UV for efficient degradation. The supported substance (Siral) exhibits elevated surface area and a regular mesoporous structure; hence, it might be regarded as an efficient photocatalyst support. The characterizations and effectiveness of the prepared catalyst were achieved by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM) and UV-visible spectroscopy. The results exhibit the highest photo-degradation ratio (90%) for (60% TiO2/Siral40) after 4 hours. The highest surface area is 448.3685 m²/g for 15% TiO₂/Siral40. The photodegradation efficiency increases as the weight percentage of TiO2 particles rises from 5 to 60 %. TiO2/Siral NCs photocatalysts demonstrate remarkable photostability and reusability, especially in organic molecule degradation.
To make a hydrogen economy feasible, it is crucial to identify efficient hydrogen storage technologies. While storing hydrogen by hydrogenation of aromatic and dehydrogenation of alicyclic hydrocarbons is technically feasible, it is associated with a high energy demand for hydrogen release that limits the energetic efficiency of the storage cycle if no suitable source of waste heat is available. This study investigates whether the release of hydrogen through the cyclization of diols forming lactones is energetically more favorable. To this end, equilibrium constants for the dehydrogenation reactions at 298.15 K, 400 K, and 500 K were determined using a combination of combustion calorimetry, vapor pressure measurements, and quantum chemical calculations. The results reveal that, compared to aromatic hydrocarbons, the equilibrium position for the dehydrogenation of diols is significantly more favorable for hydrogen release, and the reaction enthalpies are markedly lower. The most advantageous properties were observed for the 1,4-butanediol/gamma-butyrolactone system. The reaction enthalpy per mole of hydrogen for the dehydrogenation at 298.15 K is exceptionally low, at 42.5 kJ & sdot;mol-1. High hydrogen yields can already be expected at temperatures below 400 K at ambient pressure. Under such conditions, hydrogen release from 1,4-butanediol can be carried out with low energy input for heating the hydrogen carrier and for providing the enthalpy of reaction. This reduced thermal demand contributes to a higher prospective energy efficiency of the respective hydrogen storage cycle, which may represent in some application scenarios a significant economic advantage. Thermodynamics of reversible hydrogen storage with LOHC systems: 1,4-butanediol/gamma-butyrolactone, 1,5-pentanediol/delta-valerolactone and 1,6-hexanediol/s-caprolactone was studied in this work.
Functional traits can vary in response to tree species mixing, which in turn might influence biomass production and, consequently, carbon (C) sequestration in diverse forests. However, evidence for consistent broad-scale patterns in tree trait responses, particularly regarding trait identity and their contribution to above-ground biomass outcomes, remains limited. Using data from even-aged forest stands in 11 tree diversity experiments in Europe and Brazil, encompassing 40 tree species, we estimated the influence of species mixing on above-ground biomass components (woody, litterfall and understory biomass), as well as effects of mixing on plasticity-driven changes in species- and community-level functional traits. At the community level, specific leaf area (SLA) and leaf area index (LAI) were higher in mixtures than expected values based on monocultures, while leaf nitrogen per area decreased, and leaf nitrogen per mass remained stable. SLA increases were primarily due to the response of less dominant tree species. Woody and litterfall biomass increased in mixtures, whereas understory biomass remained unchanged. At the species level, diversity-driven plastic changes were observed in multiple traits, but only SLA showed a consistent shift across species. Tree diversity effects on above-ground biomass were influenced by both functional diversity and diversity-driven trait shifts, where increased SLA and LAI enhanced woody biomass accumulation, while higher LAI in diverse stands reduced understory biomass. Together, these results show that tree species mixing alters canopy structure and light-related traits, with shifts in SLA and LAI constituting key pathways through which mixed forests accumulate more woody biomass.Read the free for this article on the Journal blog.
