Oxidative Dehydrogenation Of Propane Research Articles

Acid-leaching treated ZnO-based materials as highly efficient microwave catalysts for oxidative dehydrogenation of propane by CO2

The oxidative dehydrogenation of propane by CO2 (CO2-ODHP) reaction has received much attention for its potential to produce high-value propylene from two underutilized reactants and to eliminate CO2. However, it is a great challenge to maintain high propylene selectivity with high propane conversion for CO2-ODHP reaction, especially for non-expensive and environmentally friendly catalysts. Herein, a new and effective ZnO/S-1(1.0)-based microwave catalyst for CO2-ODHP was developed by a simple impregnation method and acid leaching treatment. Interestingly, the acid leaching treatment significantly enhanced the catalytic activity and stability. Importantly, both the conversion of propane and the selectivity of propylene were significantly enhanced in the microwave catalytic reaction mode (MCRM). An amazingly high conversion of ∼60 % and selectivity of ∼92 % is achieved. This method of significantly improving the catalytic activity and stability after a simple acid leaching treatment can provide some inspiration for light alkane dehydrogenation reactions.

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 h-BN 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.

Model-Based Design of Experiments for Temporal Analysis of Products (TAP): A Simulated Case Study in Oxidative Propane Dehydrogenation.

Temporal analysis of products (TAP) reactors enable experiments that probe numerous kinetic processes within a single set of experimental data through variations in pulse intensity, delay, or temperature. Selecting additional TAP experiments often involves an arbitrary selection of reaction conditions or the use of chemical intuition. To make experiment selection in TAP more robust, we explore the efficacy of model-based design of experiments (MBDoE) for precision in TAP reactor kinetic modeling. We successfully applied this approach to a case study of synthetic oxidative propane dehydrogenation (OPDH) that involves pulses of propane and oxygen. We found that experiments identified as optimal through the MBDoE for precision generally reduce parameter uncertainties to a higher degree than alternative experiments. The performance of MBDoE for model divergence was also explored for OPDH, with the relevant active sites (catalyst structure) being unknown. An experiment that maximized the divergence between the three proposed mechanisms was identified and provided evidence that improved the mechanism discrimination. However, reoptimization of kinetic parameters eliminated the ability to discriminate between models. The findings yield insight into the prospects and limitations of MBDoE for TAP and transient kinetic experiments.

Advancements of MOFs in the Field of Propane Oxidative Dehydrogenation for Propylene Production.

Compared to the currently widely used propane dehydrogenation process for propylene production, propane oxidative dehydrogenation (ODHP) offers the advantage of no thermodynamic limitations and lower energy consumption. However, a major challenge in ODHP is the occurrence of undesired over-oxidation reactions of propylene, which reduce selectivity and hinder industrialization. MOFs possess a large number of metal sites that can serve as catalytic centers, which facilitates the easier access of reactants to the catalytic centers for reaction. Additionally, their flexible framework structure allows for easier adjustment of their pores compared to metal oxides and molecular sieves, which is advantageous for the diffusion of products within the framework. This property reduces the likelihood of prolonged contact between the generated propylene and the catalytic centers, thus minimizing the possibility of over-oxidation. The research on MOF catalyzed oxidative dehydrogenation of propane (ODHP) mainly focuses on the catalytic properties of MOFs with cobalt oxygen sites and boron oxygen sites. The advantages of cobalt oxygen site MOFs include significantly reduced energy consumption, enabling catalytic reactions at temperatures of 230 °C and below, while boron oxygen site MOFs exhibit high conversion rates and selectivity, albeit requiring higher temperatures. The explicit structure of MOFs facilitates the mechanistic study of these sites, enabling further optimization of catalysts. This paper provides an overview of the recent progress in utilizing MOFs as catalysts for ODHP and explores how they promote progress in ODHP catalysis. Finally, the challenges and future prospects of MOFs in the field of ODHP reactions are discussed.

Single-step propane transformation on vanadium-supported catalyst revealed by operando DRS UV–vis study

The present study investigated the influence of silica support texture on the catalytic performance of VOx/silica catalysts in the selective oxidation of propane. Two- and three-dimensional mesoporous materials, SBA-15 and MCF, were synthesized using hydrothermal methods to create different pore structures. Vanadium (approximately 5 wt%) was incorporated into the silica matrices (MCF, SBA-15) and SiO2 (used as a reference system) through impregnation. The surface composition, valence state, and reducibility of the VOx species accommodated in VOx/silica catalysts were characterized using X-ray diffraction (XRD), diffuse reflectance ultraviolet–visible spectroscopy (UV–vis DRS), temperature-programmed reduction with hydrogen (H2-TPR), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR) techniques. The catalytic properties of the catalysts were evaluated in the propane selective oxidation conducted at 470 °C, utilizing a mixture of oxidants (N2O and O2). Propane oxidation resulted in propane conversion of 34 %, propene selectivity of 49 %, and propene oxide selectivity of 20 %, corresponding to space–time yield of propene reaching 37 gC3H6 kgcat−1·h−1and propene oxide equal to 20 gPO kgcat−1h−1. The textural properties of the support materials noticeably influenced the stability of the catalysts. The vanadium catalysts supported on three-dimensional mesocellular silica foams (MCF) demonstrated superior activity, achieving turnover frequency (TOF) values of 9.0 × 10−4 s−1 for propene and 6.67 × 10−4 s−1 for propene oxide (PO). The unique three-dimensional ultra-large pores of the MCF material facilitated the generation of significant amounts of propene oxide, along with propene, while minimizing the formation of CO, CO2, and other oxygen-bearing by-products. Operando UV–vis studies supported by two-dimensional correlation analysis (2D COS) were employed to explain the diversity in the catalytic performance of VOx/silica catalysts. It has been found that the oligomeric vanadium species are the active sites in propane oxidative dehydrogenation, whereas the monomeric forms participate in propene oxide formation. Moreover, the reduction of V5+ to V4+ and even V3+ was identified as a crucial step in the reaction.A reaction scheme has been proposed based on catalytic experiments and spectroscopic insights.

O2 and CO2 assisted oxidative dehydrogenation of propane using ZrO2 supported vanadium and chromium oxide catalysts

Zirconia supported vanadium oxide (vanadia) and chromium oxide (chromia) catalysts of 1–3 wt% of V or Cr were prepared, characterized, and tested for the oxidative dehydrogenation (ODH) of propane (C3H8) with O2 and CO2. Characterization results reveal that 2.5% metal loading is in slight excess of monolayer loadings for this ZrO2, which has a surface area of 48 m2.g−1. The reaction results reveal that supported vanadia catalysts are better for O2-ODH and supported chromia catalyst are better for CO2-ODH at a reaction temperature of 550 °C. Furthermore, the C3H8 conversion and propene (C3H6) yield increases with loading and the highest conversion and yield are also achieved at 2.5% metal loading. With higher loadings the conversion and yield decreases, clearly indicating that the surface metal oxide species are more active than their crystalline counterparts. As the contact time increases, for inlet stoichiometric ratios of the reactants for the two reactions, C3H8/CO2 = 1 and C3H8/O2 = 2, C3H8 conversion and C3H6 yield both monotonically increase and appear to approach a constant value; however, the difference between C3H8 conversion and C3H6 yield also increases. The C3H6 selectivity during O2-ODH (∼30%) is much lower than C3H6 selectivity during CO2-ODH (86–94%). Furthermore, during CO2-ODH of propane the conversions of C3H8 and CO2 are similar, and it appears that under the operating conditions used, the dry reforming of propane does not occur. Overall, the CO2-ODH of propane reaction at 550 °C using stoichiometric ratios of C3H8/CO2 over ZrO2 supported chromia catalyst provides a better C3H6 yield and selectivity, with an additional advantage of converting CO2.

Unraveling the influence of CO2 and Ce loading over ZSM-5 for oxidative dehydrogenation of propane

Utilization of CO2 as a soft oxidant for oxidative dehydrogenation of propane to propene (ODHP) is of great importance to attain net-zero carbon emissions and to reduce greenhouse gases contributing to global warming. Here, Ce was impregnated into ZSM-5 (denoted as CZ-5 catalyst) to enhance the C3H8 conversion and C3H6 selectivity due to the redox properties of Ce to activate CO2 into CO and O* and induce propane bond cleavage (C-H). After characterization of the catalyst’s physicochemical properties, NH3-TPD and pyridine IR analysis revealed that introducing Ce regulates the acidic properties of ZSM-5 catalysts by increasing the number of Lewis acid sites while simultaneously decreasing the amount of Brönsted acid sites. The increment in Lewis’s acid sites considerably improved the C3H6 selectivity. The oxygen transfer from Ce4+ to Ce3+ during the reaction also contributed to the outstanding performance of the 12 %CZ-5 catalyst. Regarding optimum conditions, 2 % CO2 concentration and 12 % Ce loading were the optimum amount of oxidant and Ce content that produce the highest C3H6 yield of 34.08 %. The catalytic effectiveness and stability were preserved despite several hours of propane conversions at 550 °C. Therefore, modifying ZSM-5 with Ce could be a feasible way for improving propene selectivity and catalyst stability for ODHP.

Deep Potential Molecular Dynamics Study of Propane Oxidative Dehydrogenation.

Oxidative dehydrogenation (ODH) of light alkanes is a key process in the oxidative conversion of alkanes to alkenes, oxygenated hydrocarbons, and COx (x = 1,2). Understanding the underlying mechanisms extensively is crucial to keep the ODH under control for target products, e.g., alkenes rather than COx, with minimal energy consumption, e.g., during the alkene production or maximal energy release, e.g., during combustion. In this work, deep potential (DP), a neural network atomic potential developed in recent years, was employed to conduct large-scale accurate reactive dynamic simulations. The model was trained on a sufficient data set obtained at the density functional theory level. The intricate reaction network was elucidated and organized in the form of a hierarchical network to demonstrate the key features of the ODH mechanisms, including the activation of propane and oxygen, the influence of propyl reaction pathways on the propene selectivity, and the role of rapid H2O2 decomposition for sustainable and efficient ODH reactions. The results indicate the more complex reaction mechanism of propane ODH than that of ethane ODH and are expected to provide insights in the ODH catalyst optimization. In addition, this work represents the first application of deep potential in the ODH mechanistic study and demonstrates the ample advantages of DP in the study of mechanism and dynamics of complex systems.

Investigation of AFeO3 (A=Ba, Sr) Perovskites for the Oxidative Dehydrogenation of Light Alkanes under Chemical Looping Conditions.

Oxidative dehydrogenation (ODH) of light alkanes to produce C2 -C3 olefins is a promising alternative to conventional steam cracking. Perovskite oxides are emerging as efficient catalysts for this process due to their unique properties such as high oxygen storage capacity (OSC), reversible redox behavior, and tunability. Here, we explore AFeO3 (A=Ba, Sr) bulk perovskites for the ODH of ethane and propane under chemical looping conditions (CL-ODH). The higher OSC and oxygen mobility of SrFeO3 perovskite contributed to its higher activity but lower olefin selectivity than its Ba counterpart. However, SrFeO3 perovskite is superior in terms of cyclic stability over multiple redox cycles. Transformations of the perovskite to reduced phases including brownmillerite A2 Fe2 O5 were identified by X-ray diffraction (XRD) as a cause of performance degradation, which was fully reversible upon air regeneration. A pre-desorption step was utilized to selectively tune the amount of lattice oxygen as a function of temperature and dwell time to enhance olefin selectivity while suppressing CO2 formation from the deep oxidation of propane. Overall, SrFeO3 exhibits promising potential for the CL-ODH of light alkanes, and optimization through surface and structural modifications may further engineer well-regulated lattice oxygen for maximizing olefin yield.

Hierarchical boroncarbonitride nanosheets as metal-free catalysts for enhanced oxidative dehydrogenation of propane

Boroncarbonitrides (BCNs) are recently developed new catalytic system for efficient oxidative dehydrogenation (ODH) of alkanes to alkenes. Herein, a series of novel hierarchical BCN materials are synthesized using asymmetric hydrogen bonds self-assembly between methylguanidine and boric acid, along with ammonia deposition. The XRD, S(T)EM, and XPS characterizations confirm the presence of ternary BCN solid solution covered by small serrated-like BCN nanosheets materials in the 2D plates. The unique hierarchical structure and developed mesoporosity of the BCN material contribute to its outstanding catalytic performance. The optimal catalyst delivers robust catalytic performance and long-term stability in the ODH of propane reaction with propylene and total olefin selectivity of 74.7% and 89.7% at a stable 20.4% propane conversion, much better than BCN sheets and h-BN catalyst. Results show that the in-situ formation of suitable amounts of amorphous BOX species within the BCN structure, along with the maintenance of the 2D skeleton at elevated temperatures, is a significant contribution in the enhanced ODH reactivity. Moreover, density functional theory calculation also demonstrates that the presence appropriate carbon content in BCN catalysts can significantly promote the ODH of propane reaction.

Efficient conversion of propane in a microchannel reactor at ambient conditions

The oxidative dehydrogenation of propane, primarily sourced from shale gas, holds promise in meeting the surging global demand for propylene. However, this process necessitates high operating temperatures, which amplifies safety concerns in its application due to the use of mixed propane and oxygen. Moreover, these elevated temperatures may heighten the risk of overoxidation, leading to carbon dioxide formation. Here we introduce a microchannel reaction system designed for the oxidative dehydrogenation of propane within an aqueous environment, enabling highly selective and active propylene production at room temperature and ambient pressure with mitigated safety risks. A propylene selectivity of over 92% and production rate of 19.57 mmol mCu−2 h−1 are simultaneously achieved. This exceptional performance stems from the in situ creation of a highly active, oxygen-containing Cu catalytic surface for propane activation, and the enhanced propane transfer via an enlarged gas-liquid interfacial area and a reduced diffusion path by establishing a gas-liquid Taylor flow using a custom-made T-junction microdevice. This microchannel reaction system offers an appealing approach to accelerate gas-liquid-solid reactions limited by the solubility of gaseous reactant.

Support effects in vanadium incipient wetness impregnation for oxidative and non-oxidative propane dehydrogenation catalysis

Oxidative propane dehydrogenation with carbon dioxide (OPDH) is an attractive technology, co-producing carbon monoxide and propylene with a potentially negative greenhouse gas balance. Vanadium oxide containing materials are a promising class of catalysts for such process. In this study, we introduce vanadium into a range of micro- and mesoporous aluminosilicate materials by incipient wetness impregnation with NH4VO3 and the complexing agent oxalic acid, targeting a surface density of 0.6 V atoms per nm² of pristine support. Aspects of this impregnation procedure and its interaction with the support are discussed in the context of potential sources of variability in the dispersion of VOx species within the catalyst materials. The results indicate no formation of a monolayer of vanadium species, and differences in catalyst dispersion are discernible through comprehensive characterization techniques, including thermogravimetric analysis (TGA), X-ray diffraction, Raman spectroscopy, H2-TPR and UV-Vis spectroscopy. The materials are evaluated for the catalytic CO2-assisted propane dehydrogenation in two pressure regimes while being compared to classic non-oxidative propane dehydrogenation (PDH). Results are analyzed using a multivariable analysis of reactants and products, which provided valuable insights for catalyst design. The larger pore material with few acid sites (MCM-41 with Si/Al = 180) demonstrates the highest activity in terms of PDH and high pressure OPDH, i.e. high propane conversion and quasi-equivalent propylene production with similar CO2 co-conversion and CO co-production). Yet, in terms of responding to the introduction of CO2, the zeolites seem to respond better in terms of producing less H2 for only a small decrease in propylene. These microporous materials, except for the most acidic aluminous BEA, exhibit a significant increase in their production rates when increasing the total pressure in OPDH.

Inside Cover Picture

Oxidative dehydrogenation of propane is attractive because of its exothermic nature but suffers from the over‐oxidation to CO and even CO2 as undesired by‐products. Ni single atoms supported on calcium aluminate are shown to be a potential candidate for propane oxidative dehydrogenation with higher propylene selectivity than that of Ni nanoparticles, which benefits from the positive chemical nature of single atoms. More details are discussed in the article by Qiao et al. on page 370—376.image

From microkinetic model to process: understanding the role of the boron nitride surface and gas phase chemistry in the oxidative dehydrogenation of propane

In the oxidative dehydrogenation of propane over boron nitride, propylene selectivity is lost due to unselective gas-phase chemistry.

Chemically exfoliated boron nanosheets for efficient oxidative dehydrogenation of propane.

Oxidative dehydrogenation of propane (ODHP) is a promising technique for producing propene due to its low operative temperature and coke-resistant feature. Recently, boron-based catalysts have been widely investigated for ODHP owing to their brilliant performance. Herein, we report that boron in the form of nanosheets can be prepared feasibly by exfoliating layered MgB2 with hydrochloric acid, and can efficiently and stably catalyze ODHP. At 530 °C, the catalyst exhibits propene and ethene selectivities as high as 63.5% and 18.4%, respectively, at a 40% propane conversion. The olefin productivity reaches 2.48 golefin gcat-1 h-1, superior to the commercial h-BN and other reported boron-based catalysts. Even after testing for 100 h at 530 °C, the catalyst still maintains excellent stability. This work expands the effective boron-based catalyst family for ODHP and demonstrates the great potential of the new type of 2D material-boron nanosheet for energy and catalytic applications.

Understanding the impact of small vanadia clusters and their coverage effects on undoped and Ni-doped ceria nanorod supports on propane oxidative dehydrogenation

Vanadia deposition over ceria and Ni-doped ceria enhanced propene selectivity during propane oxidative dehydrogenation.

Explainable machine-learning predictions for catalysts in CO2-assisted propane oxidative dehydrogenation.

Propylene is an important raw material in the chemical industry that needs new routes for its production to meet the demand. The CO2-assisted oxidative dehydrogenation of propane (CO2-ODHP) represents an ideal way to produce propylene and uses the greenhouse gas CO2. The design of catalysts with high efficiency is crucial in CO2-ODHP research. Data-driven machine learning is currently of great interest and gaining popularity in the heterogeneous catalysis field for guiding catalyst development. In this study, the reaction results of CO2-ODHP reported in the literature are combined and analyzed with varied machine learning algorithms such as artificial neural network (ANN), k-nearest neighbors (KNN), support vector regression (SVR) and random forest regression (RF)and were used to predict the propylene space-time yield. Specifically, the RF method serves as a superior performing algorithm for propane conversion and propylene selectivity prediction, and SHapley Additive exPlanations (SHAP) based on the Shapley value performs fine model interpretation. Reaction conditions and chemical components show different impacts on catalytic performance. The work provides a valuable perspective for the machine learning in light alkane conversion, and helps us to design catalyst by catalytic performance hidden in the data of literatures.

Propylene Production via Oxidative Dehydrogenation of Propane with Carbon Dioxide over Composite MxOy-TiO2 Catalysts.

The CO2-assisted oxidative dehydrogenation of propane (ODP) was investigated over titania based composite metal oxides, 10% MxOy-TiO2 (M: Zr, Ce, Ca, Cr, Ga). It was found that the surface basicity of composite metal oxides was significantly higher than that of bare TiO2 and varied in a manner which depended strongly on the nature of the MxOy modifier. The addition of metal oxides on the TiO2 surface resulted in a significant improvement of catalytic performance induced by a synergetic interaction between MxOy and TiO2 support. Propane conversion and propylene yield were strongly influenced by the nature of the metal oxide additive and were found to be superior for the Cr2O3-TiO2 and Ga2O3-TiO2 catalysts characterized by moderate basicity. The reducibility of the latter catalysts was significantly increased, contributing to the improved catalytic performance. This was also the case for the surface acidity of Ga2O3-TiO2 which was found to be higher compared with Cr2O3-TiO2 and TiO2. A general trend was observed whereby catalytic performance increased significantly with decreasing the primary crystallite size of TiO2. DRIFTS studies conducted under reaction conditions showed that the adsorption/activation of CO2 was favored on the surface of composite metal oxides. This may be induced by the improved surface basicity observed with the MxOy addition on the TiO2 surface. The Ga2O3 containing sample exhibited sufficient stability for about 30 h on stream, indicating that it is suitable for the production of propylene through ODP with CO2 reaction.