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Dehydrogenations of two hydrogen storage tanks filled with ∼1.6 kg MWCNT-doped LaNi 5 at different setting temperatures (T set = 25–50 °C) and setting hydrogen flow rates (H 2 -FR set = 1.0 and 2.0 SLM) are carried out. By increasing T set to 50 °C under high H 2 -FR set = 2.0 SLM, dehydrogenation rate significantly enhances up to 1.5 time, and the obtained hydrogen release rate of 0.40–0.55 SLM prolongs for 4 h 35 min. The increase of hydrogen release rate favors the utilization with PEMFC stack owning greater rated power. For dehydrogenation under lower H 2 -FR set = 1.0 SLM, although initial dehydrogenation rate is hindered due to the restricted H 2 -FR set , overall performance based on dehydrogenation time, hydrogen capacity, and the obtained hydrogen release rate are preserved. The integrated PEMFC stack (200 W) with LaNi 5 -based tanks (T set = 50 °C and H 2 -FR set = 2.0 SLM) produces total electrical power of 321.2 Wh. This corresponds to the utilized hydrogen capacity of 0.85 wt % H 2 (∼75% of reversible capacity of 1.14 wt % H 2). Some limitations of the current and the power withdrawn from PEMFC stack are observed since the obtained hydrogen release rate from LaNi 5 -based tanks is deficient. The possibility to improve the performance of PEMFC stack coupled with LaNi 5 -based hydrogen storage tank is proposed. • Two H 2 storage tanks filled with 1.6 kg of MWCNT-doped LaNi 5. • Effects of setting temperatures (T set) and H 2 flow rates (H 2 -FR set) on hydrogen sorptions. • Enhanced dehydrogenation rate at high T set and under high H 2 -FR set. • Poor initial desorption rate under low H 2 -FR set despite at high T set. • Performance of PEMFC stack coupled with LaNi 5 -based H 2 storage tanks. [ABSTRACT FROM AUTHOR]

C–H bond activation is a crucial synthetic strategy widely utilized in both academic and industrial settings. Due to the strong and kinetically inert nature of the C–H bond, its functionalization typically requires metal-based catalysts. This review highlights the most significant advancements in homogeneously catalyzed reactions using pincer complexes with metals from groups 8–10, capable of promoting challenging C–H activation, published since 2010. In particular, it focuses on C–H bond activation for borylation, isomerization, and dehydrogenation, among other processes, discussing their scope and mechanistic insights. [ABSTRACT FROM AUTHOR]

Colloidal solutions of gallia‐alumina (Ga,Al)2O3(x:y) solid‐solution nanoparticles with nominal atomic Ga : Al (x:y) ratios of 1 : 6, 1 : 3, 3 : 1, and 1:0 were used to prepare silica‐supported catalysts for propane dehydrogenation (PDH). A comparison of the unsupported and silica‐supported catalysts reveals that the dispersion on silica increases the Ga‐normalized PDH rates for all catalysts, albeit with a notably lower propene selectivity for (Ga,Al)2O3(1:6)/SiO2. Fourier transform infrared (FTIR) spectroscopy allows contrasting the H2 dissociation sites in the calcined and H2‐treated (Ga,Al)2O3(x:y)/SiO2, indicating a transformation of Ga3+ surface sites with Al (mainly) and Ga atoms in the second coordination sphere (Ga(Al/Ga) sites) in the calcined (Ga,Al)2O3(1:6)/SiO2 to predominantly Ga(Ga/Si) surface sites in the H2‐treated material. The resulting sites are similarly unselective as in amorphous gallia on silica. H2 produced during the PDH reaction can cause a similar transformation as H2 pretreatment in (Ga,Al)2O3(1:6)/SiO2, rapidly resulting in a notably lowered selectivity. The stable and selective Ga(Al/Ga) surface sites in (Ga,Al)2O3(1:3)/SiO2 yield a Ga−H band at ca. 1990 cm−1 under H2 dissociation conditions while the less selective surface sites, observed for the other Ga : Al ratios, give Ga−H bands at ca. 2040 and 2060 cm−1. [ABSTRACT FROM AUTHOR]

The non-oxidative dehydrogenation of ethanol into acetaldehyde is one of the efficient solutions for biomass upgrading. In this work, a series of copper catalysts supported on MgO with different Cu loadings ranging from 2.5% to 20% were prepared by an impregnation method. The as-synthesized Cu/MgO catalysts were characterized by N2 adsorption, XRD, TEM, CO2-TPD, XPS and TPR. These catalysts were found to be effective for ethanol dehydrogenation into acetaldehyde. As the Cu loading was increased, the ethanol conversion first increased and then leveled off. At a WHSV of 1.5 h−1 and 250 °C, the 20%Cu/MgO catalyst gave an initial conversion of 81.5%, with 97.7% selectivity toward acetaldehyde. Compared to 20%Cu/SiO2, the 20%Cu/MgO catalyst displayed an equivalent initial acetaldehyde yield, higher acetaldehyde selectivity and longer stability. [ABSTRACT FROM AUTHOR]

• Active high-loaded Ni catalysts modified by Mg for LOHC technology were developed. • Their activity is insured due to Ni highly dispersed state via modification by Mg. • Their utilization allowed for reaching 97% of H 2 yield in 10HQ dehydrogenation. • For the first time complete continuous quinoline hydrogenation was reached. An effect of Mg introduction on efficiency of high-loaded nickel catalysts in dehydrogenation of decahydroquinoline (10HQ) was investigated. 10HQ dehydrogenation is key process for the liquid organic hydrogen carrier (LOHC) storage technology using the quinoline/10HQ pair as H 2 -lean/H 2 -rich substrates. An influence of synthesis technique of Ni/Mg/Al catalysts on their properties has been demonstrated. The catalysts were synthesized through coprecipitation of Ni, Mg, Al precursors to obtain layered double hydroxides (LDH) or via synthesis of (∼72 wt%) Ni-Al 2 O 3 system – also through coprecipitation, followed by modifying with a magnesium-containing precursor. For the catalysts of the first series, the inclusion of magnesium into LDH lattice led to a significant increase in catalytic activity in hydrogen extraction (10HQ dehydrogenation reaction). Despite the decrease in the content of catalytically active nickel, a significant increase in the yield of the dehydrogenation product was observed. This regularity is presumably associated with appearance of basic sites, that accelerates the dehydrogenation reaction. In the case of the second series, activity of pre-reduced (600 °C, H 2) catalysts in dehydrogenation of 10HQ also significantly depends on a MgO content and is maximal at Mg:Ni weight ratio 0.056. Using an in-depth study of structure of the original and reduced catalyst samples (Ni-Al 2 O 3 and Ni-MgNiO x -Al 2 O 3), it was shown that this regularity is associated with the increased resistance of catalytically active Ni particles to agglomeration during the reductive activation. Also, using the Ni-MgNiO x -Al 2 O 3 catalyst for hydrogen storage process (hydrogenation reaction), the possibility of deep quinoline hydrogenation (up to 10HQ) in a flow-type reactor was demonstrated for the first time. [Display omitted] [ABSTRACT FROM AUTHOR]

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Magnesium hydride (MgH2) is considered as an ideal hydrogen storage material with excellent hydrogen capacity, but the slow kinetics impedes its application. Herein, an efficient additive of V2C MXene-anchored PrF3 nanoparticles (PrF3/V2C) was synthesized, which presents excellent catalytic effect in improving the reversibility and stability of hydrogen storage in MgH2. The initial dehydrogenation temperature of the 5 wt.% PrF3/V2C-containing MgH2 (182 °C) is 105 °C lower than that of pure MgH2, and 6.5 wt.% hydrogen is rapidly released from 5 wt.% PrF3/V2C-added MgH2 sample in 6 min at 240 °C. In addition, 5 wt.% PrF3/V2C-containing MgH2 sample possesses outstanding reversible hydrogen storage capability of 6.5 wt.% after 10 cycles of dehydrogenation and hydrogenation. Microstructure analysis shows that the introduction of Pr improves the stability of V-species (V0 and V2+) and O-species (lattice oxygen (OL) and vacancy oxygen (OV)) formed during ball milling, promotes the interaction between V-species and O-species, and enhances their reversibility, which contributes to the significant improvement in re/dehydrogenation reversibility and cycling stability of MgH2. This study provides effective ideas and strategies for the purpose of designing and fabricating high-efficient catalysts for solid-state hydrogen storage materials. [ABSTRACT FROM AUTHOR]

The production of industrial chemicals with renewable biomass feedstock holds potential to aid the world in pursuing a carbon-neutral society. Trimellitic and trimesic acids are important commodity chemicals in industry that are prepared by the oxidation of petroleum-derived trimethylbenzene. To reduce the dependence on the limited oil source, we develop a potential sustainable alternative towards trimellitic and trimesic acids using biomass-based 2-methyl-2,4-pentandiol (MPD), acrylate and crotonaldehyde as starting materials. The process for trimellitic acid includes dehydration/D-A reaction of MPD and acrylate, flow aromatization over Pd/C catalyst, hydrolysis and catalytic aerobic oxidation (60% overall yield). The challenging regioselectivity issue of D-A reaction is tackled by a matched combination of temperature and deep eutectic solvent ChCl/HCO2H. Crotonaldehyde can also participate in the reaction, followed by Pd/C-catalyzed decarbonylation/dehydrogenation and oxidation to provide trimesic acid in 54% overall yield. Life cycle assessment implies that compared to conventional fossil process, our biomass-based routes present a potential in reducing carbon emissions. [ABSTRACT FROM AUTHOR]

Copyright of China Synthetic Fiber Industry is the property of Sinopec Baling Petrochemical Company and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A direct C−H alkylation of naphthoquinones with acetone and 1,3‐dicarbonyl compounds was developed to construct C−C bonds of alkyl‐substituted naphthoquinone derivatives. It proceeded through an oxidative radical cross dehydrogenation coupling process under simple and mild conditions. This method provides a facile and efficient route for synthesis of functionalized naphthoquinones from readily available feedstocks. [ABSTRACT FROM AUTHOR]

To reduce the side reactions and increase olefin selectivity in the dehydrogenation process, a series of low-loaded Pt-based catalysts supported on -Al2O3 (with or without potassium (K) modification) were prepared. The K modification effect on the n-hexane dehydrogenation performances of Pt/Al2O3 catalysts was investigated using various techniques. The added K species selectively occupied the strong acid sites on the Pt/Al2O3 surface, leading to not only the regulated surface acid properties but also the modified metallic function. Specifically, adding an appropriate amount of K reduced the number of acid sites and increased the electron cloud density of Pt sites, leading to enhanced selectivity and stability. Furthermore, the moderate amount of acid sites kept Pt highly dispersed and provided a suitable geometric structure, resulting in good activity. Herein, the Pt–0.8K/Al2O3 catalyst with suitable metal–acid site balance shows an n-hexane conversion of 25% with over 70% C6 olefin selectivity. More importantly, a significantly low deactivation rate at 500 °C for 30 h is superior to most previously reported ones. [ABSTRACT FROM AUTHOR]

The industrial catalysts utilized for propane dehydrogenation (PDH) to propylene, an important alternative to petroleum-based cracking processes, either use expensive metals or metal oxides that are environmentally unbenign. We report that a typically less-active oxide, titanium oxide (TiO2), can be combined with earth-abundant metallic nickel (Ni) to form an unconventional Ni@TiOx catalyst for efficient PDH. The catalyst demonstrates a 94% propylene selectivity at 40% propane conversion and superior stability under industrially relevant conditions. Complete encapsulation of Ni nanoparticles was allowed at elevated temperatures (>550°C). A mechanistic study suggested that the defective TiOx overlayer consisting of tetracoordinated Ti sites with oxygen vacancies is catalytically active. Subsurface metallic Ni acts as an electronic promoter to accelerate carbon-hydrogen bond activation and hydrogen (H2) desorption on the TiOx overlayer. [ABSTRACT FROM AUTHOR]

Mesoporous alumina (MA) materials with outstanding textural properties have been synthesized by a facile approach, and were evaluated as supports of Pt-based catalyst for methylcyclohexane dehydrogenation. At 300 °C, the resultant catalyst demonstrates a much higher activity with a maximum hydrogen evolution rate of 2081 mmol/g Pt /min in comparison with the state-of-the-art alumina supported Pt catalysts. Interestingly, even after a long-time reaction of 100 h or regeneration, more than 80% of original activity was still maintained. The superior catalytic performance of the obtained catalyst is associated with the high specific surface area and large mesoporous size of support MA, thus benefiting the increase in the number of Pt active sites and efficiently inhibiting the formation of coke deposition during the reaction. Our contribution has provided a rational design strategy for highly efficient and stable dehydrogenation catalysts, which is a key for the utilization of methylcyclohexane-toluene system in hydrogen storage technology. [Display omitted] • A confined hydrolysis-condensation approach. • Mesoporous alumina with excellent textural properties. • Pt-based catalyst with highly homogenous dispersion of Pt. • Improved catalytic performance for dehydrogenation of methylcyclohexane at low temperature. [ABSTRACT FROM AUTHOR]

Developing solid‐state hydrogen storage materials is as pressing as ever, which requires a comprehensive understanding of the dehydrogenation chemistry of a solid‐state hydride. Transition state search and kinetics calculations are essential to understanding and designing high‐performance solid‐state hydrogen storage materials by filling in the knowledge gap that current experimental techniques cannot measure. However, the ab initio analysis of these processes is computationally expensive and time‐consuming. Searching for descriptors to accurately predict the energy barrier is urgently needed, to accelerate the prediction of hydrogen storage material properties and identify the opportunities and challenges in this field. Herein, we develop a data‐driven model to describe and predict the dehydrogenation barriers of a typical solid‐state hydrogen storage material, magnesium hydride (MgH2), based on the combination of the crystal Hamilton population orbital of Mg−H bond and the distance between atomic hydrogen. By deriving the distance energy ratio, this model elucidates the key chemistry of the reaction kinetics. All the parameters in this model can be directly calculated with significantly less computational cost than conventional transition state search, so that the dehydrogenation performance of hydrogen storage materials can be predicted efficiently. Finally, we found that this model leads to excellent agreement with typical experimental measurements reported to date and provides clear design guidelines on how to propel the performance of MgH2 closer to the target set by the United States Department of Energy (US‐DOE). [ABSTRACT FROM AUTHOR]

The reaction of [Ru(dmso)4Cl2] with a potassium salt of four xanthate (RO–C(＝S)S−; R = Me, Et, iPr and tBu) ligands (depicted as Ln; n = 1–4) in hot methanol afforded a group of mixed-ligand complexes of type [Ru(Ln)2(dmso)2]. The crystal structures of all the four complexes have been determined, which show that the xanthate ligands are bound to the metal center forming four-membered chelates and dmso is coordinated through sulfur and they are mutually cis. The relative thermodynamic stability of this cis and the other possible trans-isomers of these complexes has been assessed with the help of DFT calculations, which have revealed that the cis-isomer is the more stable isomer. The coordinated dmso in the [Ru(Ln)2(dmso)2] complexes could be easily displaced by chelating bidentate ligands (depicted as L′) to furnish complexes of type [Ru(Ln)2(L′)], as demonstrated through isolation of two such complexes, viz. [Ru(L3)2(bpy)] and [Ru(L2)2(phen)] (bpy = 2,2′-bipyridine and phen = 1,10-phenanthroline). The crystal structure of [Ru(L3)2(bpy)] has been determined and the structure of [Ru(L2)2(phen)] has been optimized by the DFT method. The electronic spectra of the four [Ru(Ln)2(dmso)2] complexes and the two derivatives ([Ru(Ln)2(L′)]; n = 3, L′ = bpy; n = 2, L′ = phen), recorded in dichloromethane solutions, show intense absorptions spanning the visible and ultraviolet regions, which have been analyzed by the TDDFT method. The [Ru(Ln)2(dmso)2] complexes are found to serve as efficient catalyst precursors for the acceptorless dehydrogenation of 2-propanol followed by crossed-aldol condensation with substituted benzaldehydes (and related aldehydes), using tert-butoxide as the co-catalyst, producing dibenzylideneacetone derivatives in good yields. [ABSTRACT FROM AUTHOR]

Hydrogen (H2) is recognized as a clean energy carrier with great potential for the future energy systems. Given the existing challenges in direct H2 storage and delivery, the current option for utilizing hydrogen energy is to produce hydrogen from its storage carriers on‐site, and the development of a highly active, highly selective, and highly stable catalyst for H2 production is an important part of this. Herein, PdAg alloy was deposited on mesoporous carbon nitride (mpg‐C3N4) as a catalyst for the dehydrogenation of the formic acid (FA). The synergistic effect of Pd and Ag metals for catalysis was explored. The role of the supports on the catalytic performance was also demonstrated by depositing PdAg alloy on several carriers of Silica@Resorcinol‐Formaldehyde Spheres, Carbon Flower Particles and SBA‐15. Pd1Ag1/2/mpg‐C3N4 showed a considerable activity during FA dehydrogenation with a turnover frequency (TOF) value of 887 h−1 at 333 K, demonstrating that carbon nitride as a carrier has a significant enhancement on the catalytic hydrogen production from formic acid. [ABSTRACT FROM AUTHOR]

In the quest for the more rapid and eco‐compatible preparation of complex molecules from widely available ones, borrowing hydrogen is one of the most elegant manners to directly functionalize alcohols. Such catalytic cycles reduce the synthetic cost, and avoid waste and additional steps associated with adjusting the redox state for the functionalization of carbon chains. In this field, the last ten years have seen the development of general strategies to control the absolute stereochemistry of the created molecules. This enantiocontrol can arise from the three distinct steps of the catalytic cycle, namely the initial dehydrogenation, carbonyl functionalization or final hydrogen back‐transfer. This review presents the different enantioselective approaches developed according to these principles and highlights the great potential of these transformations, the current limitations and future challenges. [ABSTRACT FROM AUTHOR]

This research focused on the catalytic role of TiSiO 4 on the sodium aluminium hydride (NaAlH 4) desorption properties. The results revealed that 10 wt% TiSiO 4 -doped NaAlH 4 had a 55 °C lower desorption onset temperature than post-milled pure NaAlH 4. After 120 min, the TiSiO 4 -doped NaAlH 4 composite's analysis of desorption kinetics at 150 °C liberated approximately 4.4 wt% more hydrogen than the undoped NaAlH 4 sample (0.5 wt%). The calculated decomposition activation energies for the two-step desorption of 10 wt% TiSiO 4 -doped NaAlH 4 were 81 kJ/mol and 95 kJ/mol, respectively, which were 31 kJ/mol and 24 kJ/mol, slightly less than the post-milled NaAlH 4. The particle size reduction enhances the NaAlH 4 hydrogen storage with TiSiO 4 addition. The X-ray diffraction results demonstrated that TiSiO 4 significantly improved the NaAlH 4 's ability to desorb hydrogen by forming AlTi and Si or Si-containing as active species during heating. The results of this study open new possibilities for the improvement of NaAlH 4 -catalyst systems, which are advantageous for solid-state hydrogen storage research. • TiSiO 4 additive reduce the onset desorption temperature of NaAlH 4. • The addition of TiSiO 4 also improved the desorption kinetics of NaAlH 4. • The E A for the two-dehydrogenation stages of TiSiO 4 -doped NaAlH 4 was decreased. • The in-situ formation of AlTi and Si or Si-containing species play a catalytic role. [ABSTRACT FROM AUTHOR]

Chromium and molybdenum incorporated MgO and MgO–C catalysts were synthesized for hydrogen production from a non-oxidative ethane dehydration reaction. Hydrogen production studies were carried out using a microwave-heated reactor system. The study investigated the effects of reaction temperature, type of active metal, and catalyst preparation method (physical mixture or core–shell structure) on hydrogen selectivity and ethane conversion during dehydrogenation reactions. The results showed that the optimal reaction temperature for the non-oxidative ethane dehydration reaction was 450 °C. Above this temperature, the selectivity of undesired byproducts increased. Catalysts containing molybdenum exhibited higher ethane conversion. Moreover, a comparison of MgO–C-supported catalysts with MgO-supported catalysts revealed that the core–shell catalysts exhibited superior ethane conversion. Notably, the 5Mo@MgO–C catalyst demonstrated exceptional catalytic activity, achieving a high ethane conversion rate of 72% along with excellent stability. [ABSTRACT FROM AUTHOR]

The complex structure of Ti/HA (HA: hydroxyapatite) implants prepared by additive manufacturing technology plays an essential role in its application in bone repair. Digital light processing (DLP) is widely used to prepare bioceramics with complex structures. However, it is a challenge to prepare Ti/HA biomaterials by DLP due to the high ultraviolet (UV) absorption of Ti powder. In the present work, TiH2 powder coated with a TiO2 layer is selected to reduce the UV absorption and improve the curing depth for DLP printed green bodies of TiO2@TiH2/HA, because the TiO2@TiH2 powder can be reduced by 12.7% compared to the TiH2 powder without any oxidation. Then, the shell layer of TiO2 undergoes dehydrogenation and reduction reaction with the core phase of TiH2 during the sintering process to transfer TiO2@TiH2/HA into TixOy@Ti/HA. In addition, the effects of HA content on compressive strength and biocompatibility are investigated in the TixOy@Ti/HA biomaterials. The results show that when adding 60 vol%HA, the maximum monolayer curing depth of the slurry reaches 90.1 ± 3.5 µm. 40%TixOy@Ti/60%HA shows the maximum effect in promoting the pre‐osteoblast differentiation and a relatively high compressive strength of 48.7 ± 3.5 MPa. This work provides an experimental basis for the preparation of ceramic–metal composites with high UV absorptivity using DLP. [ABSTRACT FROM AUTHOR]

Co-based catalysts have shown great promise for propane dehydrogenation (PDH) reactions due to their merits of environmental friendliness and low cost. In this study, ordered mesoporous molecular sieve-supported CoOx species (CoOx/Al-SBA-15 catalyst) were prepared by one-step organometallic complexation. The catalysts show worm-like morphology with regular straight-through mesoporous pores and high external specific surface area. These typical features can substantially enhance the dispersion of CoOx species and mass transfer of reactants and products. Compared with the conventional impregnation method, the 10CSOC (10 wt.% Co/Al-SBA-15 prepared by the organometallic complexation method) sample presents a smaller CoOx size and higher Co2+/Co3+ ratio. When applied to PDH reaction, the 10CSOC delivers higher propane conversion and propylene selectivity. Under the optimal conditions (625 °C and 4500 h−1), 10CSOC achieves high propane conversion (43%) and propylene selectivity (83%). This is attributed to the smaller and better dispersion of CoOx nanoparticles, more suitable acid properties, and higher content of Co2+ species. This work paves the way for the rational design of high-performance catalysts for industrially important reactions. [ABSTRACT FROM AUTHOR]

PtSn/Al2O3 and PtSnSr/Al2O3 were prepared by the incipient wetness impregnation method. The added Sn and Sr are uniformly distributed on the surface without damaging the original crystal structure and surface texture properties. The addition of Sn not only changes the dispersion of Pt, reduces the reduction temperature of Pt, but also provides electrons to Pt, increases the electron cloud density on the surface of Pt, and reduces the deep propylene adsorption. The addition of Sr reduces the number of total acid sites and strong acid sites, reduces the generation of adverse effects and carbon deposition, slows down the deactivation of the catalyst, and improves the selectivity of propylene. Pt1.5Sn1.5Sr/Al2O3 showed the best catalytic reaction performance and remained stable after five cycles of regeneration. [ABSTRACT FROM AUTHOR]

The characteristics and catalytic properties of Pd/SiO2, Pd/MCM-48, and Pd/SBA-15 catalysts during the dehydrogenation of decalin were investigated. This study has prepared a series of supported Pd catalysts and tested them in a flow reactor. Synthesized catalysts were studied by low-temperature nitrogen adsorption, temperature programmed reduction, high-resolution transmission electron microscopy and thermogravimetric analysis. Catalysts supported on mesoporous silicas MCM-48 and SBA-15 exhibit higher activity than catalysts on amorphous SiO2. The catalyst activities seemed to be primarily related to the particle size and dispersion of palladium. MCM-48 and SBA-15 make it possible to obtain smaller palladium particles that exhibit higher activity in the dehydrogenation reaction of decalin. Kinetic parameters for the dehydrogenation of decalin over the various Pd catalysts were obtained to determine the release of the hydrogen. The studied palladium catalysts supported on MCM-48 and SBA-15 can be recommended as potential catalysts for hydrogenation/dehydrogenation of aromatic compounds considered as liquid organic hydrogen carriers. [ABSTRACT FROM AUTHOR]

Cu/SiO2 catalysts were prepared by co-precipitation (CP), hydrothermal (HT), ammonia evaporation (AE), and sol–gel (SG) methods and tested for their performance in the dehydrogenation reaction of secondary butyl alcohol to methyl ethyl ketone. The results showed that the Cu/SiO2 catalyst prepared by the sol–gel method has the best performance. By BET and H2–TPR characterization, it can be found that the catalysts prepared by sol–gel method has the largest specific surface areas and lowest reduction temperatures. Based on the characterization results of XRD, XPS and XAES, it shows that the catalyst prepared by sol–gel method has a better dispersion of copper components and a higher content of Cu0 species after reduction, which leads to its higher catalytic activity. At a copper loading of 22.96% (w%), the conversion of secondary butyl alcohol was up to 99.0% and the selectivity of methyl ethyl ketone was up to 99.8% by using the Cu/SiO2 catalysts prepared by sol–gel (SG) methods. [ABSTRACT FROM AUTHOR]

In this work, the precursors and intermediates of catalytic dehydrogenation of toluene, ethylbenzene, and styrene (TES) stream were detected, quantified, and classified at 750–800 °C. The classification approach for tracing the structural changes of the produced precursors was designed based on different residence times of intermediates, leading to the presentation of a morphology prediction model for precipitated coke according to the restriction of stream pass. The results revealed that the coke structure of encapsulating is formed by heavier precursors produced at a restricted direction of flow. On the other hand, the filamentous coke made from lighter precursors is formed at smooth streams with no restricted areas. [ABSTRACT FROM AUTHOR]

Owing to the massive expansion and intermittent nature of renewable power, green hydrogen production, storage, and transportation technologies with improved economic returns need to be developed. Moreover, the slowness of the dehydrogenation reaction is a primary barrier to the commercialization of liquid organic hydrogen carrier (LOHC) technology. The present study focused on increasing the speed of dehydrogenation, resulting in the proposal of a triple-loop dehydrogenation system comprising reaction, heating, and chilling loops. The reactor has a rotating cage containing a packed bed of catalyst pellets, which is designed to enhance both heat and mass transfer by helping to detach precipitated hydrogen bubbles from the catalyst surface. In addition, the centrifugal force aids in isolating the gas phase from the LOHC liquid. A dehydrogenation experiment was conducted using the reaction and chilling loops, which revealed that the average hydrogen production rate during the first hour was 52.6 LPM (liter per minute) from 26.3 L of perhydro-dibenzyl-toluene with 1.5 kg of 0.5 wt% Pt/Al2O3 catalyst. This was approximately 48% more than the value predicted with the reaction kinetics measured with a small-scale plug flow dehydrogenation reactor with less than 1.0 g of 5.0 wt% Pt/Al2O3 catalyst. The concept, construction methods, and results of the preliminary gas infiltration, flow visualization, and reactor pumping experiments are also described in this paper. [ABSTRACT FROM AUTHOR]

Bimetallic PtSn catalysts with notable activity and selectivity are widely used in propane dehydrogenation to propylene. However, at high temperature, catalysts are prone to carbon deposition, leading to a decrease in stability. CO2-oxidative propane dehydrogenation (CO2-PDH) has become a new research hotspot due to its potential to eliminate carbon deposition and promote the forward movement of dehydrogenation reaction while converting propane. The reverse water-gas shift catalyst β-Mo2C with propane dehydrogenation catalyst PtSn@S-1 were mixed in CO2-PDH, aiming to develop highly active, selective and stable catalysts. The catalysts were characterized by XRD, CO2-TPD, C3H6-TPD, and thermogravimetric analysis. The research results indicate that in CO2-PDH, the stability of the powder-mixed tandem catalyst PtSn@S-1& β-Mo2C significantly improves by adding β-Mo2C in series to PtSn@S-1, and the catalyst remains active without deactivation during continuous operation for 1440 min, and the high stability of the catalyst is attributed to the removal of partial carbon deposition by CO2 during the reaction process. After optimizing the reaction conditions, it is found that when n(CO2): n(C3H8) is 1.0 and m(PtSn@S-1):m(β-Mo2C) is 1.0: 0.4, the powder-mixed tandem catalyst PtSn@S-1& β-Mo2C exhibites the best performance in CO2-PDH. The propane conversion rate remains stable at above 43.0% after 500 min and propylene selectivity exceeds 99%. [ABSTRACT FROM AUTHOR]

Pt single atoms catalysts with precise coordination environment and high stability are expected to achieve high performance of propane dehydrogenation (PDH). In this work, an innovative synthetic strategy is proposed to construct the S-1@0.1Pt9Zn@DPS-1 nanocomposite as a highly efficient PDH catalyst. Defect engineering is applied to induce the formation of defective porous silicalite-1 (DPS-1), which is favorable for achieving the uniformly distributed ZnO nanoclusters. The ZnO nanoclusters were further served as anchoring sites to stabilize the isolated Pt atoms. The structural characterization revealed that penta-O coordinated Pt single atom coupled with ZnO nanoclusters decorated on the DPS-1. Moreover, the atomically dispersed Pt atoms with the ideal coordination environment could act as the predominant active sites for PDH process. As expected, the optimal S-1@0.1Pt9Zn@DPS-1 catalyst delivered an excellent PDH performance (propane conversion of 40.7%, propylene selectivity of 97.5%) and good cycling regeneration stability. This work provides a new way for improving the activity and stability of catalysts in the field of industrial catalysts. [ABSTRACT FROM AUTHOR]

Structured catalysts coatings exhibit excellent performance on non‐adiabatic gas–solid process, deriving from their enhanced heat and mass transfer properties. However, the coating catalysts prepared by traditional hydrothermal method of zeolite encapsulating noble metal are prone to spalling, especially under conditions of large flow rate and high temperature. Herein, we prepared PtZn clusters encapsulated in silicalite‐1 zeolite coating on stainless steel with high bonding strength by an improved in situ growth method. The optimized catalyst exhibited ultra‐thin, uniform, continuous, and high degree of crosslinking, thereby enhancing mass transfer and thermal stability. In propane dehydrogenation reaction, the optimized PtZn@S‐1‐R showed a high specific activity of 14.7 molC3H6 molPt−1 s−1 and a propylene selectivity above 99% at 600°C with a high weight hourly space velocity of 120 h−1. The metal‐encapsulated zeolite coating catalysts broaden the application avenue for heterogeneous catalysis with great application prospects. [ABSTRACT FROM AUTHOR]

Pd nanocatalyst supported on amine-functionalized mesoporous graphitic carbon nitride (Pd/NH2-mpg-C3N4) was investigated for dehydrogenation of formic acid. The catalyst was analyzed and tested to investigate the effect of amine functionalization on hydrogen generation from formic acid. Pd nanocatalyst was dispersed uniformly on NH2-mpg-C3N4 without agglomeration. The turnover frequency value of Pd/NH2-mpg-C3N4 was 1870 h−1, which was higher than that of Pd/mpg-C3N4 because of the amine functionalization. The Pd/NH2-mpg-C3N4 was also tested to investigate the effect of various reaction conditions (formic acid concentration, sodium formate concentration, and reaction temperature) on hydrogen generation from formic acid. Formic acid concentration negatively affected the catalytic activity, whereas sodium formate concentration positively affected it. Reaction temperature significantly affected the catalytic activity. The apparent activation energy of the Pd/NH2-mpg-C3N4 catalyst was 60.7 kJ mol−1, and a hydrogen generator with the catalyst exhibited high conversion efficiency at an elevated temperature. Consequently, a hydrogen generator with Pd/NH2-mpg-C3N4 is suitable for polymer electrolyte membrane fuel cell systems.

In this study, the variations in hydrogen content and oxide content in alloys under 0 W, 500 W, 1000 W, 1500 W, 2000 W, 2500 W, 3000 W, and at 20 kHz, 30 kHz, 40 kHz were investigated. Hydrogen content was assessed using porosity and computed tomography, while oxygen content in the alloy was measured using element analyzer and elemental scanning. Compared to other conditions, the melt had the lowest hydrogen and oxide contents at a frequency of 20 kHz and an ultrasonic power of 2500 W, with values of 0.099 cm3/100 g and 0.0015 %, respectively. Experimental observations also indicate that the variations in hydrogen content and oxide content in the alloy during ultrasonic treatment are almost similar. In most cases, lower hydrogen content corresponds to lower oxide content in the same alloy. This is because hydrogen bubbles and oxides become a single entity. At the same time, ultrasonic purification increases the tensile strength of the alloy to 200.1 MPa and the elongation rate to 0.72 %. This study primarily investigates the relationship between hydrogen bubbles and oxides in aluminum melt under different ultrasonic frequencies and power levels, providing significant reference for the purification of various fluids under ultrasonic fields.

The ethylene dehydrogenation catalyst in a certain styrene unit was caked after long-term use. In order to analyze the caking cause of ethylbenzene dehydrogenation catalyst, solubility experiment, baking experiment and X-ray fluorescence spectrum test were carried out. The experimental results showed that the white solid on the surface of the caking catalyst could be dissolved in the water. After the caking catalyst was roasted at 800 °C for 4 h, the white substance was existed. The small granular particles were not crushed easily and were hard. The X-ray fluorescence spectrometer test showed that the white solid was a potassium-containing substance on the catalyst surface. The block formation of the ethylbenzene dehydrogenation catalyst in this unit is caused by the migration and aggregation of potassium during long-term use of the catalyst. The research provided some technical reference for reducing the caking of ethylbenzene dehydrogenation catalyst in the production. [ABSTRACT FROM AUTHOR]

Herein, using azo-amine (H2L) and azo-imine (L1–3) ligands, singlet diradical Ni(II) complexes [1] and [2] were synthesized from Ni(0)(COD)2 in THF. In separate reactions, homoleptic NiII complexes, [3a]2+–[3c]2+, were synthesized from [NiII(H2O)6](ClO4)2 and L1–3, respectively. All these complexes were characterized thoroughly. The X-ray structures of [1] and [2] showed that the amine side arm in [1] and the imine side arm in [2] are de-coordinated. The dN–N lengths in these two complexes were found to be ∼1.32 Å, which corresponds to the one-electron reduced azo-bond length. These complexes, [1] and [2], showed 1H NMR signals characteristic of diamagnetic compounds. These studies, along with DFT calculations, indicated that the unpaired spins on ligands coupled antiferromagnetically with the two unpaired spins on NiII to result in s = 0 ground states. Complex [1] showed ligand-based redox-induced dehydrogenation of the distal amine side arm to result in L1. Complexes [3a]2+–[3c]2+ have dN–N lengths of ∼1.27 Å and dC–N lengths of ∼1.28 Å. In cyclic voltammetry, complex [3a]2+ showed four well-resolved reversible reductive waves at 0.5 V to −1.6 V in dichloromethane. The first two waves became irreversible when they were measured in acetonitrile solution. The electron transfer series of [3a]2+ was further characterized by spectro-electrochemistry, EPR, and DFT calculations. These showed that all the reductions were associated with the ligand. It was further probed by redox events in complexes [3b]2+ and [3c]2+. While the electron donor –OMe group on the phenyl ring of the azo moiety in [3b]2+ showed a prominent cathodic shift of the potentials, the –F substitution on the phenyl group on the imine side arm of [3c]2+ has almost no effect. It has to be noted here that the oxidation of [2] by two electrons returns it back to complex [3a]2+. Reduction of [3a]2+ by two electrons also resulted in complex [2], indicating reversible ligand redox-induced hemilability of the imine moiety between [3a]2+ and [2]. Moreover, characterization of the electron transfer series of [3a]2+ and [2] has shown superior redox non-innocent behaviour and coordination ability of the azo-pyridine moiety in nickel(II) complexes over the imino-pyridine moiety of the ligand. [ABSTRACT FROM AUTHOR]

Developing a suitable catalyst for ammonia borane (AB, NH 3 BH 3) hydrolysis and clarifying the catalytic mechanism are essential and challenging at present. In this work, RuNi nanoalloys are supported on an N/O co-coped glucose-derived carbon (g-C) with the adsorption-NaBH 4 reduction method. Attributed to the particular geometric and anchoring effects, as well as the improved hydrophilicity of the multi-level porous support, the RuNi alloys are highly and firmly confined in the framework of g-C. Specifically, the optimal Ru 0.25 Ni 0.75 @g-C with an average alloy particle size of 1.4 nm exhibits pleasurable specific hydrogen evolution rate (437,990 mL min−1 g Ru −1) and turnover frequency (1612.37 min−1) in NaOH aqueous solution (1.5 M) at 303 K, superior to the corresponding monometallic counterparts (i.e., Ni@g-C and Ru@g-C) and many previous results. In addition, apart from satisfactory durability, the optimal alloy catalyst delivers an encouraging apparent activation energy (28.1 kJ mol−1). Our work not only explains the geometric and electronic effects on the catalytic performance but also offers a promising catalyst for hydrogen release from liquid-phase AB. [Display omitted] • Coupling geometric and electronic engineering over RuNi nanoalloy catalysts • RuNi ultrafine alloys are highly and firmly decorated in the framework of g-C • Ru 0.25 Ni 0.75 @g-C shows exceptional catalytic performance in AB hydrolysis • Further verifying the dominant role of an O–H cleavage in H 2 O [ABSTRACT FROM AUTHOR]

Hydrogen has received attention as a next-generation renewable energy source; accordingly, sustainable production and safe transportation are crucial for its effective utilization. In this study, we focused on dihydrolevoglucosenone (Cyrene TM ), which was a biodegradable ketone derived from cellulose, as a renewable organic hydride. Furthermore, hydrogenation using alcoholic fermentation with baker's yeast was proposed for a novel hydrogen storage, wherein water and nicotinamide adenine dinucleotide serve as hydrogen sources. Cyrene TM was hydrogenated with baker's yeast to produce 1,6-anhydro-3,4-dideoxy- β -D- threo -hexopyranose (Cyrene-OH). Cyrene-OH stored hydrogen via chemical bonding, and was dehydrogenated by warming in the presence of an iridium complex catalyst to produce hydrogen gas and reproduce Cyrene TM . Therefore, this study demonstrated a new sustainable and renewable hydrogen gas production and storage cycle. This cycle, which uses readily available Cyrene TM and baker's yeast, enables hydrogen energy production and storage in isolated areas and should contribute to Sustainable Development Goal 7 (Affordable and Clean Energy). • Cyrene TM derived from cellulose was used as a renewable organic hydride. • Hydrogenation and hydrogen storage using alcoholic fermentation was demonstrated. • A new sustainable hydrogen gas production and storage cycle was established. [ABSTRACT FROM AUTHOR]

Alkenes constitute an enabling motif in organic synthesis, as they can be functionalized to form highly substituted molecules. Z‐alkenes are generally challenging to access due to the thermodynamic preference for the formation of E‐alkenes compared to Z‐alkenes. Dehydrogenation methodologies to selectively form Z‐alkenes have not yet been reported. Herein, we report a Z‐selective, propargylic dehydrogenation that provides 1,3‐enynes through the invention of a Co‐catalyzed oxidation system. Observation of a kinetic isotope effect (KIE) revealed that deprotonation of the propargylic position is the rate limiting step. Additionally, isomerization experiments were conducted and confirmed that the observed Z‐selectivity is a kinetic effect. A proposed stereomechanistic model for the Z‐selectivity is included. [ABSTRACT FROM AUTHOR]

Decarbonylative and dehydrogenative cascade annulation of aldehydes with N‐(o‐cyanobiaryl)acrylamides was developed for the synthesis of a broad spectrum of alkyl‐ and carbonyl‐substituted pyrido[4,3,2‐gh]phenanthridines. Secondary and tertiary aldehydes can undergo the decarbonylative cascade under DTBP/malonic acid conditions, while aryl, primary, and secondary aldehydes can undergo dehydrogenative reaction under TBHP system. Such transformations were triggered by alkyl and acyl radicals, and the annulations were accomplished through intramolecular additions of carbon‐centered radical to nitrile group and iminyl radical to aromatic ring. [ABSTRACT FROM AUTHOR]

NaAlH 4 is a reversible hydrogen storage material and has attracted great attention recently. However, the application of NaAlH 4 in hydrogen storage still has great difficulties. In this study, 2D MXene Ti 2 C-doped NaAlH 4 samples were prepared in-situ by reaction ball milling of NaH under moderate condition. TPD measurement results show that all the as-prepared samples exhibit good thermodynamic performance except for the sample doped with 1 wt% Ti 2 C. And DSC analysis results show that at the heating rate of 5 K/min, the first and second dehydrogenation peak temperatures of the sample doped with 7 wt% Ti 2 C were 127.1 °C and 150.6 °C respectively, which are 57.4 °C and 123.6 °C lower than those of pure NaAlH 4 (after ball milling), respectively. Meanwhile, NaH/Al-7 wt.% Ti 2 C sample displays a superior kinetics behavior. Isothermal hydrogen evolution curves show that NaH/Al-7 wt.%Ti 2 C released 5.21 wt% H 2 within 30 min at 150 °C and then absorbs 5.2 wt% H 2 in 90 s at 120 °C. Even at a lower temperature of 80 °C, the sample still absorbed 4.71 wt% H 2 within 60 min. In addition, almost no release capacity attenuation was observed for NaH/Al-7 wt.%Ti 2 C after 10 hydrogen absorption/desorption cycles. The improvement of the hydrogen storage properties can be ascribed to the high reactivity of NaAlH 4 produced in situ and catalysis of lamellar Ti3+/0 species formed by the reduction of high valent Ti in Ti 2 C during ball milling. • Ti 2 C doped NaAlH 4 samples were prepared in-situ under moderate condition. • NaH/Al doped 7 wt% Ti 2 C displays excellent hydrogen storage properties. • Ti3+/0 species exhibit efficient catalysis on de/rehydrogenation of NaH/Al complex hydride. [ABSTRACT FROM AUTHOR]

This study presents a new dehydrogenative synthesis of alkenyl isothiocyanates, providing compounds with bromo and isothiocyanate groups. These reactive functionalities offer versatility for further transformations. Application in an amine sensor utilizing a coumarin-attached product demonstrates practical utility. This streamlined approach facilitates access to alkenyl isothiocyanates, valuable tools for biological studies. [ABSTRACT FROM AUTHOR]

The catalytic production of propylene via propane dehydrogenation (PDH) is a key reaction in the chemical industry. By combining operando transmission electron microscopy with density functional theory analysis, we show that the intercalation and ordering of carbon on Pt interstitials to form Pt−C solid solutions is relevant for increasing propylene production. More specifically, we found that at the point of enhanced propylene formation, the structure of platinum nanoparticles is transformed into a transient caesium chloride‐type Pt−C polymorph. At more elevated temperatures, the zincblende and rock salt polymorphs seemingly coexist. When propylene production was highest, multiple crystal structures consisting of Pt and carbon were occasionally found to coexist in one individual nanoparticle, distorting the Pt lattice. Catalyst coking was detected at all stages of the reaction, but did initially not affect all particles. These findings could lead to the development of novel synthesis strategies towards tailoring highly efficient PDH catalysts. [ABSTRACT FROM AUTHOR]