Dehydrogenation Of Propane Research Articles

Regulating Peripheral Nitrogen Dopants in Single-Atom Catalysts to Enhance Propane Dehydrogenation.

For single-atom catalysts (SACs), the dopants situated near the metal site have demonstrated a significant impact on the catalytic properties. However, the effect of dopants situated further away from the metal centers and their working mechanisms remain to be elucidated. Herein, we conduct density functional theory-driven studies on regulating the peripheral nitrogen dopants in graphene-based SACs, with a particular focus on Ir1 SAC, for propane dehydrogenation (PDH). It is found that increasing the distance between the N dopant and the Ir1 site results in a different energy change for the reaction process compared to the dense doping model with only first and second-shell N species. The proposed stochastic doping models demonstrate statistically that increasing the N dopant in farther shells not only enhances the activity of Ir1 but also maintains a high selectivity for propene, which is verified by experimental tests. The modulation of the d-band center of Ir1 by stochastic N dopants effectively modifies the binding strength of reaction intermediates, thereby enabling the optimization of the potential energy surface of PDH. These results deepen the understanding of dopant states around metal sites and provide an important implication for the doping engineering in heterogeneous catalysis.

Boosting Propane Dehydrogenation to Propylene via Electron Hole-Hydrogen Coupling on Cobalt Metal Surface.

Nonoxidative dehydrogenation of propane is useful for the high selectivity to propylene but is suffering from the heavy coke deposition on the catalyst surface. Herein, we present a proof-of-concept application of a hole-hydrogen (H) couple on a metallic cobalt surface to decrease the deactivation rate. The coupled H atoms on the Co surface, partially resulting from propane dehydrogenation, enabled the desorption of propylene to avoid deep hydrogenolysis and coke deposition and realize selective and durable propylene production, while conventional Co metal-based catalysts do not generate propylene. The optimized hole-H coupled Co catalyst provided a low deactivation rate (0.0036 h-1) and a high turnover frequency (55.6 h-1) for propylene production with a high propane flux (48 vol.% C3H8 in gas feeds) at 550 °C.

Facile and Environmentally Friendly Synthesis of Ga2O3/MFI Catalysts for Propane Dehydrogenation.

A GaOx-based catalyst is recognized as a promising catalyst for dehydrogenation of light alkanes. Conventionally, impregnation and calcination are necessary processes for the loading of GaOx. However, the incomplete impregnation of gallium salt solution would generate wastewater, and the calcination for the dissociation of gallium salt would release harmful gases, such as SOx, NOx, and HCl. Meanwhile, the high temperature results in an excessive energy cost and undesired GaOx particle aggregation. Here, we report a facile and environmentally friendly method for the synthesis of GaOx-based catalysts. The gallium salt solution was replaced directly with liquid gallium (LG). Through a simple physical mixing method at room temperature, uniform GaOx nanoparticles with diameters of around 3.5 nm were loaded onto the surface of silicalite-1 (S-1). With the optimal GaOx/MFI catalyst, the propane conversion and propylene selectivity reached 22.9 and 90.1%, respectively, in the propane dehydrogenation reaction. The work offers a clean and economical strategy utilizing liquid metal (LM) as an impregnation solution for the preparation of GaOx-based catalysts.

Regulating Peripheral Nitrogen Dopants in Single‐Atom Catalysts to Enhance Propane Dehydrogenation

Regulating Peripheral Nitrogen Dopants in Single‐Atom Catalysts to Enhance Propane Dehydrogenation

Data-Driven Development of Heterogeneous Catalysts for Propane Dehydrogenation with Machine Learning and Metaheuristic Optimization

Data-Driven Development of Heterogeneous Catalysts for Propane Dehydrogenation with Machine Learning and Metaheuristic Optimization

Constructing matched sub-nanometric cobalt clusters with multiple oxidation and metallic states for efficient propane dehydrogenation

Modulating unique microenvironment including both oxidation and metallic states on sub-nanocluster metal catalysts remains challenging, since designing heterogeneous catalysis within controllable oxidation state is necessary for achieving optimum performance. Here we construct stable sub-nano-Co clusters, which shows different microenvironment with the reported sub-nanocluster catalysts and reported Co-based catalysts. The coexistence of both ionic bonds of Co-O and metallic bonds of Co-Co shows features of multiple oxidation and metallic states, which changes the electronic orbital configuration of the individual Co atom in clusters. The specific microenvironment within low oxidation state and high electron density promotes combination of empty and filled host orbitals to yield high electron transfer between metal and propane, which exhibits higher reactivity than the reported Co-based and other non-noble metals catalysts. The desired reactivity offers the possibility for the exploitation of highly efficient non-noble metal catalysts for propane dehydrogenation in industrial applications.

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.

Controllable Growing Defects in Cambered Boron Nitride Utilizing a Plane Bending Strategy for Efficient Oxidative Dehydrogenation of Propane

Controllable Growing Defects in Cambered Boron Nitride Utilizing a Plane Bending Strategy for Efficient Oxidative Dehydrogenation of Propane

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.

Active lattice oxygen trigger for propane total oxidation: [MnO6] tunnel-restrained Cu2+ chain in α-MnO2

The elimination of propane is particularly important in volatile organic compounds (VOCs) emissions control. We designed a special Cu-type α-MnO2 with tunnel-restrained Cu2+ chain for propane total oxidation. It can effectively elevate the reaction rate and reduce the apparent activation energy. Cu2+ mainly stabilizes as tunnel [CuO4] configurations, changing the charge distribution and ligand field inside the tunnel, compared to the original ionic [KO8] and [KO12] in α-MnO2. The covalency between Cu−O as well as exacerbated Jahn-Teller distortion of [MnO6] occur. The resulting charge transfer of Cu−O−Mn units via bridging O atoms further affects the outside-tunnel properties, specifically, facilitating oxygen vacancy formation and lattice oxygen activation. Moreover, abundant oxygen vacancies can promote the dehydrogenation of propane to generate alcohol at low temperatures. The above intermediates undergo successively oxidation with activated lattice oxygen to produce C3~C1 carboxylates as temperature elevates.

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.

CrMn‐based catalysts for oxidative dehydrogenation of propane to propylene with CO2

AbstractThe paper investigates the catalytic oxidative dehydrogenation of propane with carbon dioxide (ODH‐CO2) as a promising route for propylene production, an avenue yet to be commercially developed. Utilizing the incipient wetness catalyst preparation method, CrMn catalysts were synthesized on three supports (γ‐Al2O3, ZSM‐5, and SBA‐15). Comprehensive characterization through Brunauer–Emmett–Teller (BET) analysis, X‐ray diffraction (XRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM)/scanning transmission electron microscopy (STEM)‐energy‐dispersive X‐ray spectroscopy (EDS), and hydrogen temperature programmed reduction (H2‐TPR) was conducted to comprehend catalyst behaviour. Among the six catalysts tested, Cr/SBA‐15 was exhibited as the best performer, achieving propane and CO2 conversions of 36.2% and 14.1%, respectively, with a propylene selectivity of 33.4%. Over a 50‐h time on stream (TOS), it demonstrated gradual declines in conversions while retaining 75% of initial values. The incorporation of manganese as a promoter effectively mitigated coke formation, albeit with slight reductions in propane conversion and propylene selectivity.

Data-driven catalyst design for oxidative dehydrogenation of propane with CO2 using decision tree regression

Interpretable machine learning (ML) techniques have made significant progress in the design of high-performance materials. Here we employ decision tree (DT) models to discover and optimize multicomponent catalysts for the oxidative dehydrogenation of propane with CO2 (ODPC). While DT models have been used to improve a single target variable, this study leverages interpretable models by simultaneously considering the criteria for improving all the multiple target variables of ODPC, namely C3H8 conversion, CO2 conversion, and C3H6 yield. Instead of using literature data, we establish a consistent laboratory-scale database, and DT models are trained on multiple target variables representing catalytic performance. The trained DT models identify key input variables, including active metals, compositions, and support materials and provide criteria in the form of inequalities for the design of new ODPC catalysts. Despite using a database of binary and ternary metal oxides only, the fulfilment of all criteria suggests quaternary metal oxides with Cr, Ni, Mo, and ZrOx. The DT-proposed multicomponent catalysts show superior ODPC performance to the database catalysts, with a synergistic effect between the active elements. This exploitation of the relationship information between catalyst components and performance highlights the benefit of interpretable ML techniques in the design of high-performance multicomponent catalysts.

Stable and homogeneous intermetallic alloys by atomic gas-migration for propane dehydrogenation

Intermetallic nanoparticles (NPs) possess significant potentials for catalytic applications, yet their production presents challenges as achieving the disorder-to-order transition during the atom ordering process involves overcoming a kinetic energy barrier. Here, we demonstrate a robust approach utilizing atomic gas-migration for the in-situ synthesis of stable and homogeneous intermetallic alloys for propane dehydrogenation (PDH). This approach relies on the physical mixture of two separately supported metal species in one reactor. The synthesized platinum-zinc intermetallic catalysts demonstrate exceptional stability for 1300 h in continuous propane dehydrogenation under industrially relevant industrial conditions, with extending 95% propylene selectivity and propane conversions approaching thermodynamic equilibrium values at 550–600 oC. In situ characterizations and density functional theory/molecular dynamics simulation reveal Zn atoms adsorb on the particle surface and then diffuse inward, aiding in the formation of ultrasmall and highly ordered intermetallic alloys. This in-situ gas-migration strategy is applicable to a wide range of intermetallic systems.

Propane Dehydrogenation on PtxZny Active Sites in Silicalite-1.

The improvement of Pt-based catalysts for propane dehydrogenation (PDH) has progressed by recent investigations that have identified Zn as a promising promoter for Pt subnanometer catalysts. It is desirable to gain insights into the structure, stability, and activity of such active sites and the factors that influence them, such as Zn:Pt ratio, Pt coordination and nuclearity. Here, we employ density functional theory and microkinetic simulations to investigate the stability of PtxZny (x=1-3, y=0-3) active sites grafted on silanols of Silicalite-1 and the PDH activity of Pt. We find that the coordination of a Pt atom to a nest of grafted Zn(II) atoms increases the stability of the Pt1Zny sites, whose activity is similar for y=0-2 and drops dramatically for y>2. We further demonstrate, via linear scaling relations and microkinetic simulations, that the turnover frequency obeys a volcano law as a function of propylene binding strength. The Pt2Zn1 and Pt3Zn1 sites are stable and exhibit activity similar to Pt1Zn2, but only Pt1Zn2 manifests reaction kinetics consistent with experimental data, strongly suggesting the active site composition in the synthesized catalyst samples. The methodology presented here suggests a general strategy for deducing active site information such as composition through simple kinetic experiments.

Modification of Zeolites with Tin to Synthesize Pt–Sn/MFI Catalysts for Propane Dehydrogenation

Modification of Zeolites with Tin to Synthesize Pt–Sn/MFI Catalysts for Propane Dehydrogenation

Sustainable propane dehydrogenation reaction triggered by strong metal-support interaction

Sustainable propane dehydrogenation reaction triggered by strong metal-support interaction

High stable PtZnLa/Beta catalyst with low Pt loading for propane dehydrogenation

A high stable and active Pt-Zn-La/Beta catalyst with 0.1 wt% Pt loading was studied for catalyzing propane dehydrogenation (PDH) in this work, which is constructed by anchoring La and Zn species onto silanol nests of Beta zeolite at first and then loading Pt on the resultant material after calcination. It is found that the Beta zeolite with the Si/Al ratio of 9.75 is more appropriate than the one with higher Si/Al ratio to be used as the support after the dealumination. And that anchoring La and Zn species prior to Pt onto the silanol nests are quite important. In Pt0.1Zn0.4La0.4/Beta catalyst, La significantly dispersed and stabilized Pt1Zn1 ensembles on the zeolite surface while Zn isolated the Pt atoms and therefore the catalyst is much active, highly selective and catalytic stable. With this catalytic structure, the catalyst provided a high initial propylene formation rate of 113.8 molC3H6·gPt−1·h−1 with extremely low deactivation constant of 0.0149 h−1 and a high propylene selectivity of 98 % at 600 °C.

An Active and Regenerable Nanometric High‐Entropy Catalyst for Efficient Propane Dehydrogenation

AbstractPropane dehydrogenation (PDH) is crucial for propylene production, but commercially employed Pt‐based catalysts face susceptibility to deactivation due to the Pt sintering during reaction and regeneration steps. Here, we report a SiO2 supported nanometric (MnCoCuZnPt) high‐entropy PDH catalyst with high activity and stability. The catalyst exhibited a super high propane conversion of 56.6 % with 94 % selectivity of propylene at 600 °C. The propylene productivity reached 68.5 molC3H6 ⋅ gPt−1 ⋅ h−1, nearly three times that of Pt/SiO2 (23.5 molC3H6 ⋅ gPt−1 ⋅ h−1) under a weight hourly space velocity of 60 h−1. In a high‐entropy nanoparticle, Pt atoms were atomically dispersed through coordination with other metals and exhibited a positive charge, thereby showcasing remarkable catalytic activity. The high‐entropy effect contributes to the catalyst a superior stability with a low deactivation constant of 0.0004 h−1 during 200 hours of reaction under the industrial gas composition at 550 °C. Such high‐entropy PDH catalyst is easy regenerated through simple air combustion of deposited coke. After the fourth consecutive regeneration cycle, satisfactory catalytic stability was observed, and the element distribution of spent catalysts almost returned to their initial state, with no detectable Pt sintering. This work provides new insights into designing active, stable, and regenerable novel PDH catalysts.

Support Screening to Shape Propane Dehydrogenation SnPt-Based Catalysts.

Propane dehydrogenation reaction (PDH) is an extremely attractive way to produce propylene; however, the catalysts often lead to byproduct formation and suffer from deactivation. This research focuses on the development of efficient Pt/Sn-based shaped catalysts by utilizing Mg-modified mesoporous silica, sepiolite (natural SiMgO x mesoporous clay), and sepiolite/bentonite/alumina as supports with the aim of achieving superior stability and selectivity for industrial propylene production by PDH. The catalysts were prepared by sequential impregnation of the supports with the corresponding solutions of tin chloride and platinum chloride, by obtaining a nominal loading of 0.7 wt % of Sn and 0.5 wt % of Pt. A range of analytical techniques were used to characterize the catalysts, including X-ray diffraction, nitrogen physisorption isotherms, Hg intrusion porosimetry, thermogravimetric analyses, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The basicity of the catalysts was assessed using carbon dioxide temperature-programmed desorption (CO2-TPD). The results confirm that the support material plays a critical role in catalyst performance; in particular, the presence of weak basic sites, due to magnesium addition, improved selectivity to propylene and reduced coke formation. Catalytic pellets of Sn-Pt supported on macroporous sepiolite or sepiolite and bentonite-modified mesoporous alumina performed comparably with propane conversion very close to thermodynamic equilibrium and selectivity to propylene above 95%. The latter support led to improved stability and was regenerated at milder temperatures, making it suitable for industrial applications.