Catalytic Dehydrogenation Of Propane Research Articles

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.

Photothermal catalytic CO2 oxidative dehydrogenation of propane over a dual functional Pt-GaN/SrTiO3 catalyst

Photothermal CO2 oxidative dehydrogenation of propane (CO2-ODHP) is an environmentally friendly and sustainable route for propylene production and CO2 utilization. In the present work, we developed a Pt-GaN/SrTiO3 dual-functional catalyst to facilitate the reaction. The catalyst achieved propylene and CO yields of 1 mmol·gcat-1·h-1 and 1.2 mmol·gcat-1·h-1 under photothermal conditions at 320 °C, surpassing the performance of previously reported catalysts. Additionally, control experiments and in situ DRIFTS analyses corroborated that GaN and Pt were primarily responsible for the activation of C-H and CO bonds, respectively, and the photothermal route worked via a distinguished intermediate for CO2 activation in contrast to the thermal route. DFT calculations supported the reaction route involving the coupling direct dehydrogenation of propane and reverse water-gas shift reaction. The present work shines a light on the design of photothermal catalysts with dual functions, particularly for the activation of CO2 and light hydrocarbons. Additionally, it proposes a strategy to initiate high-temperature reactions at relatively lower temperatures.

Low temperature catalytic activity of molybdenum promoted two-dimensional boron nitride in propane oxidative dehydrogenation reaction

The catalytic oxidation dehydrogenation of propane to propylene, achieved at low temperatures and with high selectivity on catalysts supported by non-noble metals, exhibits significant potential for a wide range of applications. The performance of boron-based catalysts in ODHP is remarkable; however, there is a dearth of research on their low-temperature range performance. The present study employed a straightforward impregnation method to synthesize a range of Mo/h-BN-γ-Al2O3 catalysts with varying molybdenum loadings, focusing on the comparison between commercial h-BN and h-BN-γ-Al2O3 mixed support. The Mo/h-BN-γ-Al2O3 catalyst demonstrates remarkable low-temperature ODHP activity, with an initial conversion rate of 2.36 % and a propylene selectivity of 96 % at a reaction temperature of 260 ℃, exhibiting good stability over 50 h, the catalytic performance of Mo/h-BN-γ-Al2O3 in the low-temperature range surpasses that of commercial h-BN by a significant margin. Comparative experiments, along with physical and chemical characterization techniques, demonstrate that the incorporation of an appropriate quantity of Mo enhances the catalyst's acidity and redox capability. Furthermore, the synergistic effect between MoOx and BOx promotes low-temperature ODHP. The mechanism underlying the catalyst's low-temperature reaction was investigated using in-situ infrared spectroscopy technology.

One-dimensional Ga2O3-Al2O3 nanofibers with unsaturated coordination Ga: Catalytic dehydrogenation of propane under CO2 atmosphere with excellent stability

The pressing demand for propylene has spurred intensive research on the catalytic dehydrogenation of propane to produce propylene. Gallium-based catalysts are regarded as highly promising due to their exceptional dehydrogenation activity in the presence of CO2. However, the inherent coking issue associated with high temperature reactions poses a constraint on the stability development of this process. In this study, we employed the electrospinning method to prepare a range of Ga2O3-Al2O3 mixed oxide one-dimensional nanofiber catalysts with varying molar ratios for CO2 oxidative dehydrogenation of propane (CO2-OPDH). The propane conversion was up to 48.4 % and the propylene selectivity was high as 96.8 % at 500 °C, the ratio of propane to carbon dioxide is 1:2. After 100 h of reaction, the catalyst still maintains approximately 10 % conversion and exhibits a propylene selectivity of around 98 %. The electrospinning method produces one-dimensional nanostructures with a larger specific surface area, unique multi-stage pore structure and low-coordinated Ga3+, which enhances mass transfer and accelerates reaction intermediates. This results in less coking and improved catalyst stability. The high activity of the catalyst is attributed to an abundance of low-coordinated Ga3+ ions associated with weak/medium-strong Lewis acid centers. In situ infrared analysis reveals that the reaction mechanism involves a two-step dehydrogenation via propane isocleavage, with the second dehydrogenation of Ga-OR at the metal–oxygen bond being the decisive speed step.

Photothermal catalytic CO2 oxidative dehydrogenation of propane over Co-Mn bimetallic oxides supported on MCM-41 molecular sieve

Compared with conventional thermal catalysis reaction, the photothermal CO2-assisted oxidative dehydrogenation of propane (CO2-ODHP) to produce propylene and CO is an environmentally friendly and sustainable method that operates at lower temperatures. In the present work, we have developed a series of Co-Mn/MCM-41 catalysts and utilized them in the photothermal CO2-ODHP reaction. Among these catalysts, the sample with Co and Mn loadings of 3 % resulted in activities of 225.7 μmol gcat−1 h−1 of propylene and 272.0 μmol gcat−1 h−1 of CO at 250 °C. Characterization results revealed that the electron transfer and interplay between Co and Mn oxides enhance the photoelectronic response and reduce impedance, facilitating the electron transfer process. Besides, the Co and Mn bimetallic species could enhance photothermal conversion efficiency and further enhance the local temperature during the reaction. The present work introduces a novel strategy for building supported bimetallic oxides in achieving CO2-ODHP via the photothermal route and is also expected to provide an optional catalyst required satisfactions including efficient electron transfer and photothermal conversion for other photothermal reactions.

Catalytic propane dehydrogenation by anatase supported Ni single-atom catalysts

With the increasing production of propane from shale gas and the growing demand for propylene, propane dehydrogenation (PDH) has gained significant attention as a promising route for the on-purpose production of propylene. As a cheap yet efficient catalyst, Ni-based catalysts have attracted interest because of its ability to activate alkane. Single-atom catalysts (SACs) can maximize the metal atom utilization. Here, we demonstrate that anatase TiO2 supported Ni SAC (Ni1/A-TiO2) exhibits not only superior intrinsic activity and propylene selectivity but also much better stability than the corresponding Ni nanoparticle (NP) catalyst (NiNP/A-TiO2) in PDH reaction at 580 °C. The rate of propylene production on Ni1/A-TiO2 is about 1.96 molC3H6 gNi−1 h−1, about 65 times higher than that of NiNP/A-TiO2 sample (0.03 molC3H6 gNi−1 h−1). In combination of high-angle annular dark-field scanning transmission electron microscopy, in-situ diffuse reflectance infrared Fourier transform spectra, in-situ X-ray photoelectron spectroscopy and X-ray absorption spectroscopy characterizations, we confirm that the Ni SAC mainly contains individual Ni atom singly dispersed on the support in positive Ni (II) valence state. In addition, as a result of strong metal-support interaction (SMSI) between Ni NP and TiO2 carrier under reduced conditions, the Ni NPs sites are encapsulated by TiOx overlayer (~2 nm thick) thus display poor reaction performance.

Theoretical research on Pd cluster catalysts for the direct dehydrogenation of propane to propylene

AbstractIn this article, the feasibility of catalytic dehydrogenation of propane by Pd clusters (Pd7, Pd6C, Pd6Si, Pd6Ge, and Pd6Sn) was investigated by using density functional theory (DFT). It was found that Pd6Sn has the strongest electron mobility and the ability to activate CH bonds, and the highest adsorption barrier (−75.16 kcal/mol) with propylene. The first pathway of the Pd6Sn‐catalyzed primary reaction has the lowest decisive step barrier (16.65 kcal/mol), and the second pathway of the secondary reaction has the highest decisive step barrier (62.25 kcal/mol). It was demonstrated that both the catalyst's electron‐leaping ability and the ability to activate CH bonds were the key factors affecting the activity, and the adsorption strength of the catalyst to the product was the main factor affecting the selectivity. It was shown that Pd cluster‐catalyzed PDH is theoretically feasible and Pd6Sn is likely to be a potential cluster catalyst for propane dehydrogenation.

Combined carbon capture and catalytic oxidative dehydrogenation of propane to propylene conversion through a plug-flow dual-phase membrane reactor

Combined carbon capture and conversion (3C) technologies play a vital role in our battle against global warming and climate. Using electrochemical cells for 3C is an attractive option due to their intrinsically high efficiency and selectivity. Here we report an electrochemical membrane reactor for CO2/O2 capture from flue gas and instant conversion of propane to propylene over a catalyst bed. The membrane consists of a dual metal-carbonate phase, which allows CO2/O2 (in 2:1 mol ratio) co-transport through the membrane. The reactor is in tubular plug-flow geometry, which enables a continuous and gradual addition of CO2/O2 into a flowing propane stream along the axial length of the membrane, thus achieving an excellent balance between conversion and selectivity, while avoiding overoxidation and suppressing coking. The plug-flow membrane reactor exhibits a C3H6 yield of ∼30 %, C3H8 conversion of ∼35 % and C3H6 selectivity of 85 % at 600 °C for an impressive 173 h of continuous operation with minimal degradation.

Elucidation of Catalytic Propane Dehydrogenation Using Theoretical and Experimental Approaches: Advances and Outlook

Elucidation of Catalytic Propane Dehydrogenation Using Theoretical and Experimental Approaches: Advances and Outlook

Techno-economic analysis of bromine mediated propane oxidative dehydrogenation to produce propylene

The production of propylene from propane is becoming increasingly important. Catalytic propane dehydrogenation (PDH) is the major on-purpose propylene production process today. The conventional PDH process has a relatively high energy consumption (6.1–9.4 kWh/kg C3H6) which results in high direct CO2 emissions and modest propylene yield (0.8–0.9 kg C3H6/kg C3H8). A bromine-mediated propane oxidative dehydrogenation process (Br-ODH) is evaluated in this techno-economic study which can potentially improve both the process energy efficiency and product yield. To investigate the Br-ODH process feasibility, a heat integrated process model was designed using Aspen Plus® V12 for a 450 kta propylene facility using reaction data from the literature. The partial oxidation of propane under bromine limited conditions selectively produces a propylbromide intermediate which can be readily separated from propane. Propylbromide undergoes dehydrobromination under relatively mild conditions to produce the propylene product in a second step. Bromine is regenerated by conversion of the hydrogen bromide byproduct either thermochemically or electrochemically. Due to the current interest in use of renewable electricity in chemical processes, the electrochemical regeneration process was evaluated in this study. Based on the model, the Br-ODH process can achieve approximately 10% higher propylene yield with 37% lower utilities than conventional PDH. However, the use of high-cost electrolyzers resulted in the capital investment increasing by approximately 11%. Capital cost was also increased due to the requirements of high alloy materials of construction for the potentially corrosive halogen containing equipment. The sensitivity analysis showed that the production cost was most sensitive to the propane price. For the electrolyzer-based regeneration process the capital cost was found to be key parameter that might limit competition with conventional PDH; however, the development of a commercial thermochemical HBr oxidation process analogous to the Deacon process for chlorine would likely bring significant cost savings.

Two-dimensional atomically thin Pt layers on MXenes: The role of electronic effects during catalytic dehydrogenation of ethane and propane

Two-dimensional atomically thin Pt layers on MXenes: The role of electronic effects during catalytic dehydrogenation of ethane and propane

Photo-thermal synergistic catalytic oxidative dehydrogenation of propane over a spherical superstructure of boron carbon nitride nanosheets

The oxidative dehydrogenation of propane (ODHP) is an attractive reaction for increasing the production of light olefins due to its favorable thermodynamic and kinetic characteristics. However, the overoxidation of propene to thermodynamically favored COx leads to a trade-off between propane conversion and propene selectivity, limiting the optimization of the overall catalytic performance. Here we show that photo-thermal synergistic catalysis driven by a spherical superstructure of semiconducting boron carbon nitride nanosheets (SS-BCNNSs) breaks the conversion–selectivity trade-off, resulting in a remarkable enhancement of propane conversion, along with a well-maintained selectivity for propene under mild conditions. The mechanism study shows that the introduction of light irradiation during the ODHP process could change the reaction order, activate the reactants, and reduce the activation energy for ODHP. DFT calculations reveal that the photogenerated electrons provided by SS-BCNNSs promote oxygen adsorption and significantly reduce the energy barrier for generating active B-O·species, which in turn produces more active sites and enhances the reactivity.

Amorphous silica-alumina as robust support for catalytic dehydrogenation of propane: Effect of Si/Al ratio on nature and dispersion of Cr active sites

The effect of amorphous silica-alumina (ASA) with Si/Al ratios of 0.01, 0.1, 1, and 3 on the catalytic performance of chromium catalysis in the propane dehydrogenation reaction were studied. The characterization results reveal that the Si/Al ratio significantly affects the nature and dispersion of chromium species, reducibility, the surface concentration of Cr3+, and acidity. ASA catalysis with Si/Al ratios of 0.1 and 0.01 showed a remarkable increase in Cr6+ species and the lowest α-Cr2O3, which have the highest propane conversion (with initial propylene yield of 60 and 57, respectively) due to the reduction of surface monochromate Cr6+ species, which are the precursor of coordinatively unsaturated active sites (c.u.s.) to active Cr3+ species. Si/Al increase to the values of 1 and 3 can restrict the access of reactants to active Cr species due to the decrease in chromium reduction and increase in α-Cr2O3.

Surface modification of PtSn/Al2O3 catalyst by organic acid chelation and its effect on propane dehydrogenation performance

A series of Pt-based catalysts has been prepared by a chelating-agent-assisted impregnation method, and characterized by N2 adsorption/desorption, XRD, XPS, H2-TPR, NH3-TPD, pyridine-FTIR, CO-DRIFT-IR, Raman, and TG techniques to investigate the influence of organic acids on physicochemical properties. It was found that, except in the case of tartaric acid, organic acid-assisted preparation not only led to higher dispersion of Pt particles in comparison with organic acid-free catalyst PtSn/Al2O3, but also changed the concentration of Lewis acid sites and modified the interaction between the metallic Pt sites and the support. Experiments on the catalytic dehydrogenation of propane have revealed that the optimal dehydrogenation performance, with a propane conversion of 35% and a propylene selectivity of 93%, was obtained over the citric acid-assisted catalyst (PtSn/Al2O3-CA). Lewis acid sites are mainly responsible for activating C–H bonds during the tandem activation–cleavage process, whereas coke deposition and the aggregation of Pt sites are mainly responsible for deactivation of the catalyst.

Restructured zeolites anchoring singly dispersed bimetallic platinum and zinc catalysts for propane dehydrogenation

Restructuring of a heterogeneous catalyst under reaction conditions is a common phenomenon. Severe restructuring of a catalyst can result in deactivation in many catalytic systems—for example, the catalytic dehydrogenation of propane to propylene. Herein, we report the utilization of catalyst restructuring to improve activity and stability for the propane dehydrogenation reaction. A bimetallic platinum and zinc (Pt1Znm) catalyst protected by an in situ restructured silicalite-1 zeolite is prepared. The catalyst yields outstanding activity (initial conversion of ∼69.2%, initial selectivity of ∼91.1%) with high stability at 580°C, which is better than several commercial catalysts. Characterization shows the singly dispersed bimetallic sites of Pt1Znm serve as the catalytic sites during the reaction. Moreover, the less-stable silicalite-1 zeolite undergoes restructuring during the dehydrogenation reaction, forming a crucial protective layer on the Pt1Znm bimetallic nanocatalysts.

Monolithic foam of oriented boron nitride bowl for selective oxidative dehydrogenation of propane and pollutant removal

Bowl-like structures have great potential in the field of catalysis, environmental remediation, energy storage, etc., because of the large surface area, porous structure, and buffer hollow space. Herein, we developed a unique approach to control the opening direction of bowl-like structures via self-assembly strategy at the gas/liquid interface of liquid B2O3 environment foam. BN@BPO4 self-supporting monolithic foam with oriented bowl-like structure was obtained, which is built by numerous oriented bowl-like blocks and shows a double layer structure with face-to-face opening. The opening size can be adjusted by changing the amount of Cu(NO3)2 additives that is beneficial for the production of hexagonal boron nitride (h-BN). We believe the as-generated h-BN can enhance the gas trapping capacity of liquid B2O3 environment foam to precisely control pressure differential between large and small bubbles and thus favors the oriented opening of bowl-like structure. Further, pure h-BN monolithic foam with oriented bowl-like structure prepared at higher temperature possessed multimodal hierarchically porous structure and excellent performance in the catalytic oxidative dehydrogenation of propane into propene and the removal of organic pollutants. This work provides an extended assembly interface strategy of oriented bowl-like structure materials for different applications.

Constructing PtCe cluster catalysts by regulating metal-support interaction via Al in zeolite for propane dehydrogenation

Pt-based catalysts as one of the most used industrial catalysts in heterogeneous catalysis, it is essential for the on-purpose catalytic dehydrogenation of propane to propylene (PDH). Here, the highly dispersed PtCe clusters are constructed by high-silica Beta zeolite as support to improve the catalytic stability and propylene selectivity in the PDH reaction. The defect sites derived from silanol nests are responsible for dispersing PtCe clusters inside the channels of the high-silica Beta-557 zeolite, while the trace Al sites play an important role in further stabilizing the active site structure by regulating the metal-support interaction. The closely associated Pt and Ce species are critical to embody the outstanding catalytic activity (propane conversion of ∼42.2%, propylene selectivity of ∼91.9%) with excellent stability (deactivation constant: 0.013 h−1) at 550 °C. This work proposed an efficient strategy for designing stable PtCe bimetallic clusters by utilizing silanol nests and Al sites to regulate the metal-support interaction synergistically.

Recent progress in catalytic dehydrogenation of propane over Pt-based catalysts.

Light alkenes are the key building blocks in the chemical industry. As a propene on-purpose production technology, propane dehydrogenation has drawn particular attention due to the growing demand for propene and the discovery of large reserves of shale gas. The development of highly active and stable propane dehydrogenation catalysts is significant in the world-wide research field. Supported platinum-based catalysts are widely studied for propane dehydrogenation. This article reviews the developments of platinum-based catalysts in propane dehydrogenation, particularly focusing on the influence of the promoter effect and support effect on the structure and catalytic performance and especially on how promoters and supports enable Pt to form highly dispersed and stable active sites. At the end, we propose the prospective research directions of propane dehydrogenation.

Production of low carbon number olefins from natural gas: Methane-involved catalytic non-oxidative propane dehydrogenation

Low carbon number olefins such as ethylene and propylene are important chemical products with large production and extensive usage. Natural gas is a clean and abundant natural resource, which mainly contains methane as the major component and co-existing other light alkanes. It is highly efficient and profitable if natural gas can be directly converted to low carbon number olefins in a one-step process. In this work, non-oxidative dehydrogenation is practiced under mild reaction conditions using a simulated natural gas consisting of methane and propane with their natural abundance. It is found that similar amounts of methane and propane are converted simultaneously over a Pt-based catalyst with an interesting product distribution where low carbon number olefins are dominant. Control experiments demonstrate a synergistic effect between methane and propane, which is responsible for the distinctive reaction behaviors that enable effective natural gas conversion towards desired products. The catalyst optimization is also performed and PtRu/mesoTiO2 is selected as the candidate with both high activity and preferred product selectivity. Completely different product compositions are obtained when thermodynamic equilibrium calculations are compared with experimental results, indicating the reaction process is heavily kinetically controlled. After excluding the possibility of mass transfer limitations, a simplified kinetic model is established and tested to be capable of describing the experimental observations, which also better explains the uniqueness of the process with co-fed methane and propane. The study concerning methane-involved catalytic propane dehydrogenation could help to develop an innovative process for better utilization of natural gas resources.

Investigate of the optimum process conditions for Co/HZSM-5 catalyzed propane dehydrogenation by a response surface method

Co/HZSM-5 catalyst was fabricated for catalytic dehydrogenation of propane to propylene, which was pretreated to allow the reaction to react at low temperatures. A response surface approach was employed to examine the effect of process conditions on the reaction. The morphological and oxidative performance of Co/HZSM-5 was characterized by XRD, XPS, SEM, NH3-TPD, H2-TPR, and nitrogen physical absorption-desorption. Besides, the in-situ catalyst performance was evaluated by a fixed-bed reactor. Combining the actual experimental conditions, the optimal process conditions parameters obtained by the response surface method were as follows: a reaction temperature of 461 °C, a Co loading of 2.4%, and a GHSV of 4300 h–1. At this point, the propylene yield reached 27.7% and the corresponding propylene selectivity was up to 93.8 %.