NiO-Doped Fe_(2)O_(3)/MgO Properties for the Chemical Looping Oxidative Dehydrogenation of Ethane

Ethane chemical looping oxidative dehydrogenation(CL-ODH)to ethylene is a new technology for ethylene preparation.Fe_(2)O_(3)/MgO oxygen carrier was prepared using the co-precipitation method.The influence of added NiO and its different loadings on Fe_(2)O_(3)/MgO were investigated.Then,a series of oxygen carriers were applied in the CL-ODH of the ethane cycle system.Brunauer-Emmett-Teller(BET),X-ray diffractometry(XRD),X-ray photoelection spectroscopy(XPS),and H2-temperature programmed reduction(TPR)were used to characterize the physicochemical properties of these oxygen carriers.It was confirmed that an interaction between NiO and Fe_(2)O_(3) occurred based on the XPS and H2-TPR results.Based on the CL-ODH activity performance tests conducted in a fixed-bed reactor,it was revealed that ethylene selectivity was significantly improved after NiO addition.Fe_(2)O_(3)-10%NiO/MgO showed the best activity performance with 93%ethane conversion and 50%ethylene selectivity at a reaction temperature of 650℃,atmospheric pressure,and space velocity of 7500 mL/(g·h).

Finned Zn-MFI zeolite encapsulated noble metal nanoparticle catalysts for the oxidative dehydrogenation of propane with carbon dioxide

Oxidative dehydrogenation of propane with carbon dioxide(CO_(2)-ODP)characterizes the tandem dehydrogenation of propane to propylene with the reduction of the greenhouse gas of CO_(2)to valuable CO.However,the existing catalyst is limited due to the poor activity and stability,which hinders its industrialization.Herein,we design the finned Zn-MFI zeolite encapsulated noble metal nanoparticles(NPs)as bifunctional catalysts(NPs@Zn-MFI)for CO_(2)-ODP.Characterization results reveal that the Zn2+species are coordinated with the MFI zeolite matrix as isolated cations and the NPs of Pt,Rh,or Rh Pt are highly dispersed in the zeolite crystals.The isolated Zn2+cations are very effective for activating the propane and the small NPs are favorable for activating the CO_(2),which synergistically promote the selective transformation of propane and CO_(2)to propylene and CO.As a result,the optimal 0.25%Rh0.50%Pt@Zn-MFI catalyst shows the best propylene yield,satisfactory CO_(2)conversion,and long-term stability.Moreover,considering the tunable synergetic effects between the isolated cations and NPs,the developed approach offers a general guideline to design more efficient CO_(2)-ODP catalysts,which is validated by the improved performance of the bifunctional catalysts via simply substituting Sn4+cations for Zn2+cations in the MFI zeolite matrix.

A mini review on oxidative dehydrogenation of propane over boron nitride catalysts

Oxidative dehydrogenation of propane is an attractive route for the synthesis of propylene due to its favorable thermodynamic and kinetic characteristics, however, it is challenging to realize high selectivity towards propylene. Recently, it has been discovered that boron nitride (BN) is a promising catalyst that affords superior selectivity towards propylene in oxidative dehydrogenation of propane. Summarizing the progress and unravelling the reaction mechanism of BN in oxidative dehydrogenation of propane are of great significance for the rational design of efficient catalysts in the future. Herein, in this review, the underlying reaction mechanisms of oxidative dehydrogenation of propane over BN are extracted;the developed BN catalysts are classified into pristine BN, functionalized BN, supported BN and others, and the applications of each category of BN catalysts in oxidative dehydrogenation of propane are summarized;the challenges and opportunities on oxidative dehydrogenation of propane over BN are pointed out, aiming to inspire more studies and advance this research field.

Effect of boron species on carbon surface on oxidative dehydrogenation of propane

Carbon catalysts for propane oxidative dehydrogenation(PODH)can potentially replace metal oxide catalysts due to their environmental friendliness(greenness)and excellent catalytic performance.Biomass carbon materials have the advantages of being abundant in variety,inexpensive,and easily available,but their catalytic selectivity is relatively poor in PODH.Therefore,we report here on a boron-doped sisal fiber carbon catalyst,which showed excellent selectivity of propylene in PODH,excluding the effect of surface-covered B2O3 on the catalytic performance by hot water washing.The carbon material exhibited the best catalytic performance with a load of 2%(mass)and a calcination temperature of 1100℃.At a reaction temperature of 400℃,the conversion rate of propane was 2.0%,and the selectivity toward propylene reached 88.6%.The new chemical bonds formed by boron on the surface of the carbon materials had an important effect on the catalytic performance,as determined by XPS characterization.The BAO groups affected the catalytic activity by inhibiting the generation of electrophilic oxygen species,while the BAC content improved the selectivity toward propylene by changing the electron cloud density.

Plasma treated M1 MoVNbTeO_(x)-CeO_(2) composite catalyst for improved performance of oxidative dehydrogenation of ethane

High activity and productivity of MoVNbTeO_(x) catalyst are challenging tasks in oxidative dehydrogenation of ethane(ODHE)for industrial application.In this work,phase-pure M1 with 30 wt%CeO_(2) composite catalyst was treated by oxygen plasma to further enhance catalyst performance.The results show that the oxygen vacancies generated by the solid-state redox reaction between M1 and CeO_(2) capture active oxygen species in gas and transform V^(4+)to V^(5+)without damage to M1 structure.The space-time yield of ethylene of the plasma-treated catalyst was significantly increased,in which the catalyst shows an enhancement near~100% than that of phase-pure M1 at 400℃ for ODHE process.Plasma treatment for catalysts demonstrates an effective way to convert electrical energy into chemical energy in catalyst materials.Energy conversion is achieved by using the catalyst as a medium.

A high propylene productivity over B2O3/SiO2@honeycomb cordierite catalyst for oxidative dehydrogenation of propane

Boron-based metal-free catalysts for oxidative dehydrogenation of propane(ODHP)have drawn great attention in both academia and industry due to their impressive activity and olefin selectivity.Herein,the SiO2 and B2O3 sequentially coated honeycomb cordierite catalyst is designed by a two-step wash-coat method with different B2O3 loadings(0.1%–10%)and calcination temperatures(600,700,800℃).SiO2 obtained by TEOS hydrolysis acts as a media layer to bridge the cordierite substrate and boron oxide via abundant Si\\OH groups.The welldeveloped straight channels of honeycomb cordierite make it possible to carry out the reactor under high gas hourly space velocity(GHSV)and the thin wash-coated B2O3 layer can effectively facilitate the pore diffusion on the catalyst.The prepared B2O3/SiO2@HC monolithic catalyst exhibits good catalytic performance at low boron oxide loading and achieves excellent propylene selectivity(86.0%),olefin selectivity(97.6%,propylene and ethylene)and negligible CO2(0.1%)at 16.9%propane conversion under high GHSV of 345,600 ml·(g B2O3)^-1·h^-1,leading to a high propylene space time yield of 15.7 g C3H6·(g B2O3)^-1·h^-1 by suppressing the overoxidation.The obtained results strongly indicate that the boron-based monolithic catalyst can be properly fabricated to warrant the high activity and high throughput with its high gas/surface ratio and straight channels.

Phosphate modified carbon nanotubes for oxidative dehydrogenation of n-butane

Catalytic performance of phosphate-modified carbon nanotube(PoCNT) catalysts for oxidative dehydrogenation(ODH) of n-butane has been systematically investigated. The Po CNT catalysts are characterized by SEM, TEM, XPS and TG techniques. We set the products selectivity as a function of butane conversion over various phosphate loading, and it is found that the PoCNT catalyst with the 0.8% phosphate weight loading(0.8PoCNT) exhibits the best catalytic performance. When the phosphate loading is higher than 0.8 wt%, the difference of catalytic activity among the PoCNT catalysts is neglectable. Consequently, the ODH of n-butane over the 0.8PoCNT catalyst is particularly discussed via changing the reaction conditions including reaction temperatures, residence time and n-butane/O_2 ratios. The interacting mechanism of phosphate with the oxygen functional groups on the CNT surface is also proposed.

Promoted catalytic performances of highly dispersed V-doped SBA-16 catalysts for oxidative dehydrogenation of ethane to ethylene

V-doped SBA-16 catalysts(V-SBA-16) with 3D nanocage mesopores have been successfully synthesized by a modified one-pot method under weak acid condition.The obtained materials were characterized by means of small angle XRD,N_2 adsorption–desorption,TEM,UV–Vis and UV-Raman spectroscopy.These characterization results indicated that well-order mesoporous structures were maintained even at higher vanadium loadings and high concentration of VOx species were incorporated into the framework of SBA-16 support.The catalytic performances of V-SBA-16,V/SBA-16 and V/Si O_2 catalysts were comparatively investigated for the oxidative dehydrogenation of ethane to ethylene.The highest selectivity to ethylene of 63.3% and ethylene yield of 25.6% were obtained over 1.0V-SBA-16 catalyst.The superior catalytic performance of V-SBA-16 catalysts could be attributed to the presence of isolated framework VO x species,the unique structure of SBA-16 support and weak acidity.Moreover,V/Si O_2 catalyst exhibited relatively poor catalytic activity duo to the formation of V_2O_5 nanoparticles on the surface of Si O_2 support and the low dispersion of VO x species.These results indicated that the catalytic performances of the studied catalysts were strongly dependent on the vanadium loading,the nature and neighboring environment of VO x species and the structure of support.

Numerical investigation of complex chemistry performing in Ptcatalyzed oxidative dehydrogenation of ethane fixed-bed reactors

Ethylene is one of the most important basic chemicals in the modern chemical industry.Thermal or catalytic cracking of hydrocarbons is the main industrial technologies nowadays,which suffer from equilibriumlimitation and rapid coke formation.The oxidative dehydrogenation of ethane(ODHE)is considered to be a promising alternative process since it overcomes equilibrium-limitations,avoids catalyst deactivation by coke formation,and decreases the number of side reactions.In this study,particle-resolved 2 D CFD simulations of fixed-beds filled with eggshell catalysts coupled with micro-kinetics of Pt-catalyzed ODHE were performed to understand the effect of operation conditions and catalyst properties on ethylene selectivity.The catalyst bed was created by discrete element method(DEM)and the central longitudinal section of the reactor tube was defined as the 2 D simulation region.Both of the homogeneous and catalytic heterogeneous chemical reactions were described by detailed micro-kinetics within the particle-resolved CFD simulation.At first,the established model of monolith reactors was verified by comparing the simulated results with experimental results reported in literature.Then,the effects of operation conditions and catalyst concentration on the ethylene selectivity in randomly packed beds were explored.The specific variation of certain operation conditions including inlet flow rate,inlet temperature,pressure,inlet C2 H6/O2 ratio and N2 dilution ratio can effectively increase ethylene selectivity.And the reduction of ratio of catalytic active area to geometric area Fcat/georepresenting catalyst properties from 140 to 30 increases the selectivity from 42.2%to 59.3%.This research can provide reference for the industrialization of ODHE process in the future.

Balancing the Activity and Selectivity of Propane Oxidative Dehydrogenation on NiOOH(001)and(010)

Propane oxidative dehydrogenation(ODH)is an energy-efficient approach to produce propylene.However,ODH suff ers from low propylene selectivity due to a relatively higher activation barrier for propylene formation compared with that for further oxidation.In this work,calculations based on density functional theory were performed to map out the reaction pathways of propane ODH on the surfaces(001)and(010)of nickel oxide hydroxide(NiOOH).Results show that propane is physisorbed on both surfaces and produces propylene through a two-step radical dehydrogenation process.The relatively low activation barriers of propane dehydrogenation on the NiOOH surfaces make the NiOOH-based catalysts promising for propane ODH.By contrast,the weak interaction between the allylic radical and the surface leads to a high activation barrier for further propylene oxidation.These results suggest that the catalysts based on NiOOH can be active and selective for the ODH of propane toward propylene.

Flour-derived borocarbonitride enriched with boron-oxygen species for the oxidative dehydrogenation of propane to olefins

The preparation of porous materials by the simple and low-cost methods is one of the hot topics in materials science.Here,the porous carbon-incorporated BN(P-CBN)was synthesized from the low-cost flour by a fermentation combined with freezedrying technology and ammonolysis.P-CBN-x samples not only maintain the pores of the fermented dough,but also produce abundant oxygen-containing boron species(B-OH,O-O and B-O).Due to the unique structural advantages,P-CBN-x catalysts exhibit remarkably better catalytic performance than bulk BN for the oxidative dehydrogenation of propane(ODHP)to produce olefins.Attractively,P-CBN-23 obtains high C_(3)H_(8 )conversion of 62.1%and olefin yield of 42.7%.In-situ DRIFTS experiments and DFT calculations demonstrate the B-OO-B species in P-CBN-x framework is the most active species for the C3H8activation and the B-O…O-B species can be readily regenerated by O_(2),thus promoting the conversion of propane to olefin.

Promotional nature of Sn on Pt/CeO_(2)for the oxidative dehydrogenation of propane with carbon dioxide

The oxidative dehydrogenation of propane with CO_(2)(CO_(2)-ODP)is a promising technology for the efficient production of propene in tandem with CO_(2)reduction to CO.However,the rational design of high-performance catalysts for this green process is still challenged by limited understanding of the nature of active sites and the reaction mechanism.In this work,the effects of SnO_(2) promoter on Pt/CeO_(2)activity and propene selectivity in CO_(2)-ODP are elucidated through varying the Sn/Pt molar ratio.When the ratio increases,propane conversion gradually decreases,while the propene selectivity increases.These dependences are explained by increasing the electron density of Pt through the promoter.The strength of this effect is determined by the Sn/Pt ratio.Owing to the electronic changes of Pt,CO_(2)-ODP becomes more favorable than the undesired CO_(2)reforming of propane.Sn-modified Pt–O–Ce bonds are reasonably revealed as the active sites for CO_(2)-ODP occurring through a redox mechanism involving the activation of CO_(2)over oxygen vacancies at Sn-modified Pt and CeO_(2)boundaries.These atomic-scale understandings are important guidelines for purposeful development of high-performance Pt-based catalysts for CO_(2)-ODP.

Recent progress in Cr-based catalysts for oxidative dehydrogenation of light alkanes by employing CO_(2) as a soft oxidant

CO_(2) can be used as a soft oxidant for oxidative dehydrogenation of light alkanes(CO_(2)-ODH),which is beneficial to realize the reuse of CO_(2) and meet the demand for olefins.The core of this reaction is the catalyst.Cr-based catalysts have attracted much attention for their excellent catalytic performance in CO_(2)-ODH reactions due to their various oxidation states and local electronic structures.In this paper,the synthesis and modification methods of Cr-based catalysts for CO_(2)-ODH are reviewed.The structure-activity relationship and reaction mechanism are also summarized.Moreover,the reasons for the deactivation of Cr-based catalysts are analysed and the main challenges faced by Cr-based catalysts in the CO_(2)-ODH process,as well as the future development trend and prospect,are discussed.

Unravelling the role of boron dopant in borocarbonitirde catalytic dehydrogenation reaction

Borocarbonitride(BCN) materials are newly developed metal-free catalytic materials exhibiting high selectivity in oxidative dehydrogenation(ODH) of alkanes. However, the in-depth understandings on the role of boron(B) dopants and the intrinsic activities of –C=O and –B–OH still remain unknown.Herein, we report a series of BCN materials with regulable B content and surface oxygen functional groups via self-assembly and pyrolysis of guanine and boric acid. We found that the B/C ratio is the key parameter to determine the activity of ODH and product distribution. Among them, the high ethylbenzene conversion(~57%) and styrene selectivity(~83%) are achieved in ODH for B_(1)CN. The styrene selectivity can be improved by increasing of B/C ratio and this value reaches near 100% for B_5CN.Structural characterizations and kinetic measurements indicate that –C=O and –B–OH dual sites on BCN are real active sites of ODH reaction. The intrinsic activity of –C=O(5.556 × 10^(-4)s^(-1)) is found to be 23.7 times higher than –B–OH(0.234 × 10^(-4)s^(-1)) site. More importantly, we reveal that the deep oxidation to undesirable CO_(2) occurs on –C=O rather than –B–OH site, and B dopant in BCN materials can reduce the nucleophilicity of –C=O site to eliminate the CO_(2) emission. Overall, the present work provides a new insight on the structure–function relationship of the BCN catalytic systems.

Electrifying Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ) for focalized heating in oxygen transport membranes

Industry decarbonization requires the development of highly efficient and flexible technologies relying on renewable energy resources,especially biomass and solar/wind electricity.In the case of pure oxygen production,oxygen transport membranes(OTMs)appear as an alternative technology for the cryogenic distillation of air,the industrially-established process of producing oxygen.Moreover,OTMs could provide oxygen from different sources(air,water,CO_(2),etc.),and they are more flexible in adapting to current processes,producing oxygen at 700^(-1)000℃.Furthermore,OTMs can be integrated into catalytic membrane reactors,providing new pathways for different processes.The first part of this study was focused on electrification on a traditional OTM material(Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ)),imposing different electric currents/voltages along a capillary membrane.Thanks to the emerging Joule effect,the membrane-surface temperature and the associated O_(2) permeation flux could be adjusted.Here,the OTM is electrically and locally heated and reaches 900℃on the surface,whereas the surrounding of the membrane was maintained at 650℃.The O_(2)permeation flux reached for the electrified membranes was~3.7 NmL min^(-1)cm^(-2),corresponding to the flux obtained with an OTM non-electrified at 900℃.The influence of depositing a porous Ce_(0.8)Tb_(0.2)O_(2-δ) catalytic/protective layer on the outer membrane surface revealed that lower surface temperatures(830℃)were detected at the same imposed electric power.Finally,the electrification concept was demonstrated in a catalytic membrane reactor(CMR)where the oxidative dehydrogenation of ethane(ODHE)was carried out.ODHE reaction is very sensitive to temperature,and here,we demonstrate an improvement of the ethylene yield by reaching moderate temperatures in the reaction chamber while the O_(2) injection into the reaction can be easily fine-tuned.

Oxidative Dehydrogenation of Propane over Supported Nickel Single-Atom Catalyst

Oxidative dehydrogenation of propane has been an ever-growing field for propylene production due to its exothermic properties,of which overoxidation is the major drawback,with CO and even CO_(2) as undesired by-products.For the purpose of getting higher propylene selectivity as well as yield,herein,we report Ni single atoms supported on calcium aluminate as an efficient catalyst candidate for propane oxidative dehydrogenation.Beneficial from higher valence states of Ni1 species,it shows 2—3 times as much propylene selectivity as that of Ni nanoparticles.About 14.2%C_(3)H_(6) yield with 47.3%propylene selectivity has been achieved on Ni single atom catalyst and a good stability during 20 h test can be obtained as well.

Heterogeneous catalytic partial oxidation of lower alkanes(C_1–C_6) on mixed metal oxides

This review paper aims at analysing the state of the art for partial oxidation and oxidative dehydrogenation(ODH) reactions of lower alkanes C_1–C_6into olefins and oxygenated products(aldehydes, anhydrides,carboxylic acids) on metal oxide catalysts with cations of variable oxidation state, such as Mo and V in particular. Key parameters to be met by the catalysts, such as their redox properties, their structural aspects, active sites composed of ensembles of atoms isolated one from the others, mechanisms of reactions, are discussed. Main features of the different reactions of C_1–C_6alkanes and catalysts are analysed and their generalisation for determining more active and more selective catalysts is attempted. Prospective views for the future of the domain are proposed.

Heme perbxidases are responsible for the dehydrogenation and oxidation metabolism of harmaline into harmine

Harmaline and harmine areβ-carboline alkaloids with effective pharmacological effects.Harmaline can be transformed into harmine after oral administration.However,enzymes involved in the metabolic pathway remain unclear.In this study,harmaline was incubated with rat liver microsomes(RLM),rat brain microsomes(RBM),blood,plasma,broken blood cells,and heme peroxidases including horseradish peroxidase(HRP),lactoperoxidase(LPO),and myeloperoxidase(MPO).The production of harmine was determined by a validated UPLC-ESI-MS/MS method.Results showed that heme peroxidases catalyzed the oxidative dehydrogenation of harmaline.All the reactions were in accordance with the Hill equation.The reaction was inhibited by ascorbic acid and excess H_(2)0_(2).The transformation of harmaline to harmine was confirmed after incubation with blood,plasma,and broken blood cells,rather than RLM and RBM.Harmaline was incubated with blood,plasma,and broken cells liquid for 3 h,and the formation of harmine became stable.Results indicated an integrated metabolic pathway of harmaline,which will lay foundation for the oxidation reaction of dihydro-P-carboline.Moreover,the metabolic stability of harmaline in blood should not be ignored when the pharmacokinetics study of harmaline is carried out.

Co-promoted Mo-carbide catalytic system for sustainable manufacturing of chemicals via co-processing of CO_(2) with ethane

The study reports progress in developing a molybdenum carbide-based catalyst for co-processing ethane and CO_(2).The cobalt promoting of molybdenum carbide improved the activity and stability of ethane transformation in the presence of CO_(2) substantially without any impact on ethylene selectivity.The Mo-Co supported catalyst also showed interesting performance in catalyzing ethane dry reforming and that application could be a perspective further use for this system.In addition,the comprehensive analysis of mono-and bi-metallic catalysts revealed that Co-promoting prevented rapid Mo-carbide oxidation.Further,tuning operation conditions allowed to control catalyst’s selectivity and maximize CO_(2) utilization or ethylene formation.