Dehydrogenation Performance Research Articles

Boron-containing MFI zeolite: Microstructure control and its performance of propane oxidative dehydrogenation

Boron-containing zeolites can catalyze the oxidative dehydrogenation of propane (ODHP) to produce propylene. Enhancing the quantity of active boron-oxygen species and regulating the positioning of these species within the zeolite are the main challenges in developing efficient boron-based catalysts. In this study, a boron-containing zeolite catalyst with exposed (010) crystal facets, referred to as the MFI-type boron-containing zeolite (BMFI), was synthesized using a urea-assisted hydrothermal method. The research indicates that the addition of an appropriate amount of urea can regulate the morphology of the zeolite, with its short-axis flake-like structure enhancing the accessibility of active boron sites and anchoring a higher content of active boron-oxygen species through hydrogen bonding, which significantly improves the ODHP activity and olefin selectivity of the catalyst. The propane conversion rate reached 20 ​%, with a propylene selectivity of 62.3 ​% and a total olefin selectivity of 81.3 ​% at 520 ​°C. Compared to the ellipsoidal boron-containing catalyst formed without urea, the flake-like BMFI catalyst exhibited nearly a 20-fold increase in the reaction rate of propane. The flake-like BMFI possesses a greater number of framework tetrahedrally coordinated boron (B[4]) and defective boron species (B[3]a and B[3]b), and active boron structural evolution occurred during the reaction process, with B[3]a and B[3]b being the active sites for the catalytic reaction. This study provides a reference for the structural design and regulation of boron-based catalysts for the oxidative dehydrogenation of light alkanes.

Decoding the acidity effect of Pt‐based dehydrogenation catalysts on their dehydrogenation performance

AbstractPropane dehydrogenation (PDH) has become a significant method for propylene production. However, the systematic effects of catalyst acidity on dehydrogenation performance remain unclear. In this study, Pt‐based dehydrogenation catalysts with different acidities were prepared using n‐nonane modification, and their dehydrogenation performance was evaluated and compared. The synergistic interactions between the catalyst's acidity and its metallic functionality were thoroughly investigated. The results demonstrate that the relationship between the acidity of the PDH catalyst, the selectivity for propylene, and catalyst coke deposition follows a volcano‐shaped curve. An optimal acidity exists that allows Pt‐based dehydrogenation catalysts to achieve efficient performance. Specifically, the desorption of the target product, propylene, necessitates the combined action of acidic and metallic sites. Excessive acidic sites affect the desorption of propylene on acidic sites, while insufficient acidic sites affect the desorption of propylene on metallic sites. This study provides theoretical guidance for the design of PDH catalyst systems.

Effect of Co-B on the hydrogen storage properties of LiAlH4

In this work, the effect of Co-B on the dehydrogenation properties of LiAlH4 was investigated. The results show that, the amount of hydrogen released from LiAlH4 doped with 5 wt% Co-B was 7.7 wt% at 200 °C, which increased by 6.9 % compared to pure LiAlH4, and the initial dehydrogenation temperature was reduced by 30 °C. In addition, it can release 5.0 wt% H2 at 120 °C, which is 5 times the original dehydrogenation. Meanwhile, the scanning electron microscope and X-ray diffractometer showed that the addition of Co-B formed a new active substance AlCo, which could improve the dehydrogenation performance of LiAlH4.

Effect of La–Ni@3DG catalyst concentration on the hydrogen storage properties of MgH2

This research paper explores the influence of varying the quantity of La–Ni@3DG catalyst on the hydrogen storage capabilities of MgH2. La–Ni@3DG catalyst was prepared using lanthanum chloride heptahydrate and nickel chloride hexahydrate as raw materials combined with three-dimensional graphene, then mixed with MgH2 via ball milling to prepare MgH2 + x wt.% La–Ni@3DG (x = 0, 3, 5, 7) composite alloy. X-ray diffraction analysis showed that the composite alloy was mainly composed of the MgH2 phase, with the presence of Mg and (La, Ni) phases detected. With increased La–Ni@3DG addition, the broadening of the MgH2 diffraction peak significantly improved, indicating the catalyst promoted alloy phase structure uniformity and crystallinity. The composite alloy forms new phases such as LaH3, LaNi3H6, and Mg2NiH4 during hydrogen absorption. These phases cooperate with in-situ formed LaH3 and Mg2Ni to significantly improve the reversible hydrogen absorption and desorption properties of MgH2. Adding La–Ni@3DG catalyst has a significant positive effect on the hydrogen absorption and desorption of MgH2, leading to a considerable improvement. At 553 K, the composite alloy reaches hydrogen absorption equilibrium faster than pure MgH2, and the temperature for hydrogen absorption is significantly reduced to 373 K. The dehydrogenation performance is also improved, with 5 wt.% La–Ni@3DG is showing the best dehydrogenation performance at 553 K. The initial dehydrogenation temperature commences at approximately 505 K, while the dehydrogenation activation energy attains its minimum value: a remarkably low 109.91 kJ/mol H2. Additionally, the addition of catalyst reduces the pressure of the hydrogen absorption and desorption platform, effectively reducing the hysteresis effect during hydrogen absorption and desorption when the catalyst content is 5 wt.%, the enthalpy change and entropy change of the composite alloy reach a minimum, −70.45 kJ/mol H2 and 74.38 kJ/mol H2 (hydrogen absorption), −101.93 J/K/mol H2 and 103.68 J/K/mol H2 (hydrogen desorption), respectively.

Effect of different Ga species in Ga-ZSM-5 on dehydrogenation performance of cyclohexane to benzene

Ga-containing ZSM-5 can effectively promote the dehydrogenation process in the methanol-to-aromatics (MTA) process. However, the forms of gallium species are diversity. It remains elusive which active gallium species has the best dehydrogenation activity. The catalytic activity of dehydrogenation of eight different Ga species (GaH2+, GaO+, Ga2O22+, GaH2+, Ga(OH)2+, Ga(OH)2+, GaH(OH)+, Ga+) in Ga-ZSM-5 was investigated by using DFT calculations in the dehydrogenation of cyclohexane to produce benzene as a model reaction. The DFT results combined with microkinetic calculation results suggested that GaH2+, Ga(OH)2+ and Ga2O22+, especially Ga2O22+, are the most likely species responsible for dehydrogenation. Interaction forces between metal ions and reactants and reactant activation energies show an inverted volcano type relationship. Enthalpy and entropy effects analysis indicate that the dehydrogenation of cyclohexane to benzene on Ga species is dominated by the enthalpy barrier. This opens up the prospect of better understanding the effect of dehydrogenating active species in Ga-doped ZSM-5 on the catalytic reaction.

Modulating electronic density of active metal site via MXene intercalated by alkali ions for superior hydrogen production

As the core of a catalyst, the active site plays a crucial role in determining the activity and selectivity in hydrogen production reactions. Herein, the size and surface electron density of bimetallic alloy nanoparticles (NPs) were engineered by (alkali ions)-intercalated-Ti3C2Tx MXene, in which alkali ions were removed by water after the intercalation of Ti3C2Tx. The intercalation of alkali ions can effectively increase the interlayer spacing of Ti3C2Tx, enhance the surface accessibility, and improve the interaction between active metal species and Ti3C2Tx, resulting in monodisperse, ultrafine, and surface electron-rich active metal NPs. Resultantly, the obtained NiPt/(Li+)-Ti3C2Tx exhibits an exceptional catalytic performance with a turnover frequency (TOF) value of 3200 h−1 toward complete dehydrogenation of N2H4·H2O at 323 K, which is about 43 and 4-times higher than that of pristine NiPt NPs (75 h−1) and them on Ti3C2Tx without alkali ions intercalation (787 h−1), respectively, and surpassing all the reported catalysts for this dehydrogenation reaction. Additionally, this catalyst also shows an ultrahigh catalytic performance (7317 h−1) for complete dehydrogenation of N2H4BH3 under the same reaction conditions. This work for the first time found that the more electrons on the surface of the active center, the better the activity for hydrazine decomposition, providing inspiration for regulating catalytic active sites and designing efficient heterogeneous catalysts to achieve nitrogen-based hydride activation.

Optimized Dehydrogenation of Magnesium Hydride with Fe and Cu Additives

Solid state hydrogen storage with the use of MgH2 has gained widespread attention because of its good reversible storage capacity. This metal hydride however slowly releases hydrogen at high temperatures ranging between 325 – 375 oC. An important feature required of MgH2 is its ability to commence hydrogen release at a fast rate and reduced temperature. Transition metal-containing alloys/compounds having either Fe or Cu as the principal element have been used to improve the dissociation of hydrogen from MgH2. Studies involving the use of each metal in its elemental form as an additive are minimal. This study investigated the catalytic effects of elemental Fe and Cu on the hydrogen release performance of MgH2 for potential applications in transportation and power generation. It was observed that MgH2/Fe had a better dehydrogenation performance; the temperature of onset of MgH2/Fe and MgH2/Cu dehydrogenation were 205, and 215 oC which were 98 and 88 oC lower than that for as-received MgH2. The highest amount, 1.9 wt. % H2 was released by MgH2/Fe while 1.44 wt. % H2 was released by MgH2/Cu. The activation energy for dehydrogenation was reduced from 150.5 kJ/mol for as-received MgH2 to 89.8 and 79.8 kJ/mol in MgH2/Cu and MgH2/Fe respectively. It took 18.8 min for as-received MgH2 to commence dehydrogenation while that for MgH2/Fe and MgH2/Cu composites started from 12.2 and 13.4 min respectively. The in-situ formed Fe and Cu in MgH2 after milling acted as active catalytic sites for its improved dehydrogenation with MgH2/Fe behaving better.

Comparative Study of PtM (M=Cu, Zn, Ga, Mn, Fe, In, Ce) Bimetals on Zincosilicate for Propane Dehydrogenation Reaction.

Silicoaluminate zeolites have relatively strong Brönsted (B) acid properties that can easily lead to deep cracking reactions, making them less favourable as carriers for propane dehydrogenation. Here, we utilise zincosilicate zeolite with less B-acid produced by the introduction of the heteroatom Zn into the framework as a carrier, followed by simultaneous ion exchange (IE) of M monometallic or PtM bimetallic (M=Cu, Zn and Ga, etc.). The optimized PtZn/Zn-4 exhibits a superior propane dehydrogenation performance over PtCu/Zn-4 and PtGa/Zn-4, which can achieve a propane conversion of about 30 % in a pure propane atmosphere at 550 °C and can be operated for at least 168 h without significant deactivation. Characterization techniques such as spherical aberration corrected transmission electron microscopy, in situ X-ray photoelectron spectroscopy, and in situ diffuse reflectance infrared fourier transform spectroscopy with different gas adsorptions are used to investigate these PtM@zeolite catalysts in order to deepen the understanding of acid site identification, promoter effect and catalysis.

Non-Classical Deactivation Mechanism in a Supported Intermetallic Catalyst for Propane Dehydrogenation.

Platinum-based supported intermetallic alloys (IMAs) demonstrate exceptional performance in catalytic propane dehydrogenation (PDH) primarily because of their remarkable resistance to coke formation. However, these IMAs still encounter a significant hurdle in the form of catalyst deactivation. Understanding the complex deactivation mechanism of supported IMAs, which goes beyond conventional coke deposition, requires meticulous microscopic structural elucidation. In this study, we unravel a nonclassical deactivation mechanism over a PtZn/γ-Al2O3 PDH catalyst, dictated by the PtZn to Pt3Zn nanophase transformation accompanied with dezincification. The physical origin lies in the metal support interaction (MSI) that enables strong chemical bonding between hydroxyl groups on the support and Zn sites on the PtZn phase to selectively remove Zn species followed by the reconstruction towards Pt3Zn phase. Building on these insights, we have devised a solution to circumvent the deactivation by passivating the MSI through surface modification of γ-Al2O3 support. By exchanging protons of hydroxyl groups with potassium ions (K) on the γ-Al2O3 support, such a strategy significantly minimizes the dezincification of PtZn IMA via diminished metal-support bonding, which dramatically reduces the deactivation rate from 0.2044 to 0.0587 h-1. These findings decode the nonclassical PDH deactivation mechanism over supported IMA catalysts and elaborate a new logic for the design of high-performance IMA based PDH catalysts with long-term stability.

Enhanced microwave-catalytic performance for CO2 oxidative propane dehydrogenation by acidified and Bi-doped ZnO-based microwave catalysts

The oxidative dehydrogenation of propane by carbon dioxide (CO2-ODHP) has great potential in producing propylene. Resource utilization of CO2 will be the dominant trend in the future to mitigate environmental problems and cope with the growth in energy demand. However, simultaneously achieving high propane conversion, high propylene selectivity, and high CO2 conversion at low temperatures remains challenging. Herein, we report a novel efficient microwave catalyst (1.0-Zn4Bi1/Silicalite-1+SiC) by doping Bi on ZnO/Silicalite-1 and then acid treatment. The (1.0)-Zn4Bi1/Silicalite-1+SiC microwave catalyst exhibited 92 % C3H8 conversion, 84 % C3H6 selectivity, and 45 % CO2 conversion under microwave mode, significantly better than under the thermocatalysis (without microwave: 27 % C3H8 conversion, 92 % C3H6 selectivity, and 14 % CO2 conversion). The CO2 capture capacity was improved by adding Bi to ZnO/Silicalite-1. In addition, acid modification increased the propane and CO2 conversion by 1.9 and 1.3 times, respectively. Notably, acid treatment enriched the pore structure of the catalysts, altered surface acidity and alkalinity, and promoted C3H8 and CO2 activation and C3H6 desorption. In particular, the acid treatment enriches the state of the presence of Zn species in the catalyst. Microwave irradiation reduces the apparent activation energy of the catalytic system and accelerates the removal of coke from the catalyst surface. Microwave catalysis can activate CO2 and propane at lower temperatures than thermocatalysis.

Cr-MIL-101 derived nano Cr2O3 for highly efficient dehydrogenation of n-hexane

Nano Cr2O3 (n-Cr2O3) was prepared by the thermolysis of the mesoporous Cr-MIL-101, and its catalytic performance for n-hexane dehydrogenation was investigated and compared with Cr2O3 obtained by traditional method. It is found that dehydrogenation of n-hexane on n-Cr2O3 catalyst can produce n-hexenes and benzene efficiently, and the catalytic performance is related to the calcination temperature. The optimal n-hexane conversion can be obtained on n-Cr2O3 calcinated under 600 °C, is 40.6%, and the selectivities to n-hexenes and benzene are 20.1% and 69.3%, respectively. The conversion of n-hexane for n-Cr2O3 catalyst is decreased with calcination temperature increase, while the catalyst stability in dehydrogenation reaction is enhanced. n-Hexane conversion of p-Cr2O3-1 (obtained by precipitation method) and p-Cr2O3-2 (calcinating Cr(NO3)·9H2O directly) catalysts are very low (<7.5%), and their specific activity for n-hexane dehydrogenation are 1.5 and 1.7 g/(m2·h) respectively, lower than that of n-Cr2O3-600 (2.0 g/(m2·h)). The results of BET, XRD, TEM and FT-IR reveal that n-Cr2O3 is the nanoparticles with large specific surface area that more dehydrogenation active sites are exposed, while p-Cr2O3 is the large particles with extremely low surface area that few dehydrogenation active sites are presented. By contrast, industrial Cr2O3/Al2O3 catalyst possesses the highest specific activity of 2.4 g/(m2·h) due to the dispersion effect of Al2O3. Therefore, highly catalytic activity of n-Cr2O3 for n-hexane dehydrogenation is attributed to the unique properties of small particle, large specific surface area and more exposed active sites. This work not only explains the high dehydrogenation activity of nano-Cr2O3 derived by Cr-MIL-101, but also provides guidance for the precise design and synthesis of high-performance CrOx-based catalyst for the dehydrogenation of alkanes.

Ultrafast Charge Transfer in a Core-shell CdS@Cu-TCPP-Pt Heterojunction for Photocatalytic Hydrogen Production Coupled with Selective Benzylamine Oxidation.

Photocatalytic selective oxidation of organic substances coupled with hydrogen production is believed to be one of the most favorable pathways to make full use of photogenerated charge carriers. However, this catalytic reaction is often discouraged due to the rapid recombination of photogenerated carriers in practical applications. In this work, a core-shell CdS@Cu-TCPP-Pt nanorod heterojunction was dexterously designed for boosting the photocatalytic dehydrogenation performance of benzylamine. The transient absorption results revealed that the photogenerated electron-holes could be effectively separated by properly matching the energy levels in CdS@Cu-TCPP. Surprisingly, Pt embedded in Cu-TCPP not only provided abundant hydrogen production active sites but also facilitated ultrafast charge transfer, which endowed CdS@Cu-TCPP-Pt with remarkable photocatalytic performances for the coproductions of N-benzylidenebenzylamine (1 mL) with a conversion of 23.48% and H2 (20.75 mmol g-1 h-1) under visible irradiation, far surpassing those of CdS and Cu-TCPP. Obviously, the present work verifies that designing and fabricating a hybrid photocatalyst with high separation efficiency of electron-hole pairs is also a significant avenue for other high-performance cooperative dual-functional photocatalytic reactions.

Ga-doped spinel-typed Co-Al catalysts for CO2-assisted ethane dehydrogenation

A series of Ga-doped spinel-typed Co-Al catalysts were prepared via one-step evaporation-induced self-assembly (EISA) method. These catalysts present promising catalytic performance for CO2-assisted ethane dehydrogenation, which can be ascribed to the conjunction effect of cobalt and gallium species. The incorporation of Ga into the structure of Co-Al spinel has been recognized for enhancing CO2 conversion via reverse water-gas shift reaction, leading to a favorable equilibrium shift towards ethylene, along with an improved catalyst stability as a result of coexisting Boudouard reaction. Through X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure (XAFS), NH3 and CO2 temperature-programmed desorption (TPD) characterizations, coordinatively unsaturated Co2+ and Ga3+ cations were identified as collaborative catalytic active sites, with gallium species taking the prominent role. These sites were closely associated with the formation of acid-base pairs on the catalyst surface, which were crucial for the adsorption and activation of the reactants.

Highly Dispersed Pd‐CeOx Nanoparticles in Zeolite Nanosheets for Efficient CO2‐Mediated Hydrogen Storage and Release

AbstractFormic acid (FA) dehydrogenation and CO2 hydrogenation to FA/formate represent promising methodologies for the efficient and clean storage and release of hydrogen, forming a CO2‐neutral energy cycle. Here, we report the synthesis of highly dispersed and stable bimetallic Pd‐based nanoparticles, immobilized on self‐pillared silicalite‐1 (SP‐S‐1) zeolite nanosheets using an incipient wetness co‐impregnation technique. Owing to the highly accessible active sites, effective mass transfer, exceptional hydrophilicity, and the synergistic effect of the bimetallic species, the optimized PdCe0.2/SP‐S‐1 catalyst demonstrated unparalleled catalytic performance in both FA dehydrogenation and CO2 hydrogenation to formate. Remarkably, it achieved a hydrogen generation rate of 5974 molH2 molPd−1 h−1 and a formate production rate of 536 molformate molPd−1 h−1 at 50 °C, surpassing most previously reported heterogeneous catalysts under similar conditions. Density functional theory calculations reveal that the interfacial effect between Pd and cerium oxide clusters substantially reduces the activation barriers for both reactions, thereby increasing the catalytic performance. Our research not only showcases a compelling application of zeolite nanosheet‐supported bimetallic nanocatalysts in CO2‐mediated hydrogen storage and release but also contributes valuable insights towards the development of safe, efficient, and sustainable hydrogen technologies.

Highly Dispersed Pd-CeOx Nanoparticles in Zeolite Nanosheets for Efficient CO2-Mediated Hydrogen Storage and Release.

Formic acid (FA) dehydrogenation and CO2 hydrogenation to FA/formate represent promising methodologies for the efficient and clean storage and release of hydrogen, forming a CO2-neutral energy cycle. Here, we report the synthesis of highly dispersed and stable bimetallic Pd-based nanoparticles, immobilized on self-pillared silicalite-1 (SP-S-1) zeolite nanosheets using an incipient wetness co-impregnation technique. Owing to the highly accessible active sites, effective mass transfer, exceptional hydrophilicity, and the synergistic effect of the bimetallic species, the optimized PdCe0.2/SP-S-1 catalyst demonstrated unparalleled catalytic performance in both FA dehydrogenation and CO2 hydrogenation to formate. Remarkably, it achieved a hydrogen generation rate of 5974 molH2 molPd -1 h-1 and a formate production rate of 536 molformate molPd -1 h-1 at 50 °C, surpassing most previously reported heterogeneous catalysts under similar conditions. Density functional theory calculations reveal that the interfacial effect between Pd and cerium oxide clusters substantially reduces the activation barriers for both reactions, thereby increasing the catalytic performance. Our research not only showcases a compelling application of zeolite nanosheet-supported bimetallic nanocatalysts in CO2-mediated hydrogen storage and release but also contributes valuable insights towards the development of safe, efficient, and sustainable hydrogen technologies.

CO2-mediated oxidative dehydrogenation of propane to propylene and syngas: Reaction and energy performance matrices

The performance of CO2-assisted oxidative dehydrogenation of propane to propylene is investigated. The energy performance matrices are defined as energy efficiency and exergy efficiency at both the reactor level and the overall system level. Oxidants are the main factor that dictates the performance of the dehydrogenation of propane. Oxygen is a strong oxidant which helps in promoting the endothermic dehydrogenation of propane. CO2 is considered a mild oxidant that hinders the over-oxidation of propane. The addition of CO2 promotes propane conversion but sacrifices the other performance matrices including propylene selectivity and the H2/CO ratio of the syngas. Consequently, the energy and exergy efficiencies of the reactor as well as the DHP system decrease with increasing CO2 supply. The addition of O2 has positive impacts on the energy performance matrices at a certain temperature range (from 863 K to 1273 K). However, the addition of O2 leads to an adverse impact on the propylene selectivity and H2/CO ratio of the syngas. Under the absence of O2, the DHP exhibits a propane conversion of 91% with the propylene selectivity and system exergy efficiency of 90% and 86%, respectively when the CO2/C3H8 ratio of 0.25 at 973.15 K. This work provides strong evidence that the reaction performance matrices have a strong relation to the energy performance matrices and offers a baseline for future research and optimization in the presence of O2 and CO2.

Stabilizing ultra-small bimetallic PtSn clusters within S-1 crystals for effective propane dehydrogenation with low Pt loading

It’s a great challenge for enhancing the stability over Pt-based catalysts with low Pt loading during propane dehydrogenation based upon the manipulation of ultra-small PtSn clusters and their compositions. Here, we developed a novel strategy to produce and stabilize sub-nanometer PtSn clusters even atomical dispersion within Silicalite-1 crystals via tailoring calcination atmosphere from air to argon, which could achieve a stable performance of propane dehydrogenation with only 0.15 wt% Pt loading. Argon calcination atmosphere of PtSn@Silicalite-1 significantly decreased the size of PtSn clusters, which further presented a strikingly catalytic performance with the high formation of propylene over 8.0 mol[C3H6]·g[Pt]−1·h−1 even after 3840 min at 600 °C (WHSV=760 g[C3H8]·g[Pt]−1·h−1). Hardly any deactivation was obtained over PtSn8@S-1-Ar-50 after long-term runs for 3840 min with an extremely low deactivation constant of 0.0001 h−1 so far, which was mainly derived from the outstanding stability of PtSn sub-nanometers within S-1 crystals through appropriate flow rate of argon calcination atmosphere.

Fine-tuning Pt nanoparticle and coordination for enhanced catalytic efficiency in microwave-assisted methylcyclohexane dehydrogenation over Pt/Al2O3 catalysts

The advancement of microwave-assisted catalysis technology will play a crucial role in the realms of energy conversion and catalysis. In this study, we developed a series of Pt/Al2O3-H catalysts by varying the reduction temperature and duration to control the Pt particle size, aiming to optimize the catalytic performance for microwave-assisted methylcyclohexane (MCH) dehydrogenation. Among the synthesized catalysts, Pt/Al2O3-H-400–15 emerged as the most effective, characterized by Pt particles of 1.5 nm and a Pt-Pt coordination number of 2.8. This particular catalyst demonstrated a high metal-support interaction, which significantly enhanced its activity and stability during the dehydrogenation process. Notably, it showed superior performance in MCH dehydrogenation under microwave irradiation, maintaining high stability and minimal methane formation over 626 h. The enhanced catalytic behavior under microwave irradiation is attributed to the elimination of low-temperature dead zones, which are commonly observed in traditional thermal catalysis, resulting in higher efficiency, greater activity, and reduced by-product and coke formation. This study underscores the potential of microwave-assisted catalysis as a more effective alternative to conventional thermal methods for the dehydrogenation of MCH.

Impact of various metal promoters on the propane dehydrogenation performance of cobalt-based catalysts

Large-scale exploitation of natural gas and shale gas has spurred the development of the propane dehydrogenation technology. While cobalt-based catalysts, known for their low cost and low toxicity, effectively activate C–H bonds, they are often deactivated because of coke formation. In this study, we prepared SBA-15 molecular sieves using a hydrothermal synthesis method and developed a series of Co-based catalysts supported on SBA-15 with various metal promoters (denoted Co-X/SBA-15, where X = Mn, Fe, Mg, Zn, or La) via an incipient wetness impregnation method. Characterization techniques and activity evaluation results revealed that the Co–O–Mg structure in the Co-Mg/SBA-15 catalyst stabilizes the primary Co2+ active site and hinders the reduction of the CoOx species. The incorporation of Mg enhances the total alkalinity of the catalyst, facilitating propane adsorption and propylene desorption, leading to superior activity and stability. Although the addition of La improved propylene selectivity, it did not significantly enhance propane conversion. Conversely, the introduction of Mn, Fe, and Zn into the catalyst inhibited the reaction.

Morphological regulation of Pt/CeO2 and its catalytic dehydrogenation of methylcyclohexane in fixed bed reactor

A series of Pt/CeO2 compounds with hollow spheres (Pt/CeO2–S), wires (Pt/CeO2–W), and particle (Pt/CeO2–P) morphologies were prepared and further used for catalytic liquid organic hydrogen carrier (LOHC) dehydrogenation. The exposure and distribution of different crystal faces affected the nucleation process of crystals and then formed different microscopic morphologies. Compared with Pt/CeO2–W and Pt/CeO2–P, Pt/CeO2–S showed hollow spherical structures with significantly higher oxygen vacancy concentrations and specific surface areas. These structural differences not only affected platinum (Pt) dispersion, but also affected the activity and stability of the catalyst, thus promoting methylcyclohexane (MCH) conversion. The fixed bed reaction showed that Pt/CeO2–S had excellent catalytic activity, with the MCH conversion rate at 97.7 % and hydrogen release rate of 350.50 mmol/g(Pt)/min, and it still maintained stable activity after 72 h. Under the same conditions, the MCH conversion rates for Pt/CeO2–W and Pt/CeO2–P were only 77.23 % and 32.02 %, respectively. Therefore, through the growth pattern and morphology controls of catalyst supports, this was an effective means for improving the dehydrogenation performance of LOHC.