Showing papers on "Partial oxidation published in 2017"
TL;DR: A direct stepwise method for converting methane into methanol with high selectivity over a copper-containing zeolite, based on partial oxidation with water, involving methane oxidation at CuII oxide active centers, followed by CuI reoxidation by water with concurrent formation of hydrogen.
Abstract: Direct functionalization of methane in natural gas remains a key challenge. We present a direct stepwise method for converting methane into methanol with high selectivity (~97%) over a copper-containing zeolite, based on partial oxidation with water. The activation in helium at 673 kelvin (K), followed by consecutive catalyst exposures to 7 bars of methane and then water at 473 K, consistently produced 0.204 mole of CH3OH per mole of copper in zeolite. Isotopic labeling confirmed water as the source of oxygen to regenerate the zeolite active centers and renders methanol desorption energetically favorable. On the basis of in situ x-ray absorption spectroscopy, infrared spectroscopy, and density functional theory calculations, we propose a mechanism involving methane oxidation at CuII oxide active centers, followed by CuI reoxidation by water with concurrent formation of hydrogen.
495 citations
TL;DR: It is found that the CuII moieties responsible for the conversion are formed in the presence of O2 and that high temperature together with prolonged activation time increases the population of such active sites, and there is a linear correlation between the reducibility of the materials and their methanol productivity.
Abstract: Cu-exchanged zeolites possess active sites that are able to cleave the C–H bond of methane at temperatures ≤200 °C, enabling its selective partial oxidation to methanol. Herein we explore this process over Cu-SSZ-13 materials. We combine activity tests and X-ray absorption spectroscopy (XAS) to thoroughly investigate the influence of reaction parameters and material elemental composition on the productivity and Cu speciation during the key process steps. We find that the CuII moieties responsible for the conversion are formed in the presence of O2 and that high temperature together with prolonged activation time increases the population of such active sites. We evidence a linear correlation between the reducibility of the materials and their methanol productivity. By optimizing the process conditions and material composition, we are able to reach a methanol productivity as high as 0.2 mol CH3OH/mol Cu (125 μmol/g), the highest value reported to date for Cu-SSZ-13. Our results clearly demonstrate that high...
250 citations
TL;DR: In this article, a nickel-based catalyst with high activity at low temperature for partial oxidation of methane (POM) was synthesized by two-step preparation method, where Ni-nanoparticles supported on CeO2 nanoparticles were synthesized and a new procedure was developed where cetyltrimethylammonium bromide (CTAB) acted as morphology controlling agent and polyvinylpyrrolidone (PVP) as size controlling agent for nickel nanoparticles.
Abstract: The objective of the current study was to synthesize a nickel based catalyst with high activity at low temperature for partial oxidation of methane (POM). Ni-nanoparticles supported on CeO2 nanoparticles were synthesized by two step preparation method. First, 30–50 nm CeO2 was synthesized by solvo-thermal method and then Ni- nanoparticles were deposited over it following a newly developed procedure, where cetyltrimethylammonium bromide (CTAB) acted as morphology controlling agent and polyvinylpyrrolidone (PVP) as size controlling agent for nickel nanoparticles. The characterizations of synthesized catalysts were done by BET-Surface area, XRD, SEM, TEM, TPR, H2-chemisorpton, TGA and XPS analysis. The catalysts showed excellent coke resisting ability during POM and produces synthesis gas with H2/CO ratio almost 2. The catalyst activated methane at 400 °C with 10% methane conversion and converts methane almost completely at 800 °C. The catalyst showed above 98% methane conversion at 800 °C during 90 h of time on stream (TOS) reaction with H2/CO ratio 1.98. Average 5.5 nm Ni particles, use of CeO2 as a support played a very crucial role for methane activation at such lower temperature. The synergistic effect between small Ni-nanoparticles and CeO2 nanoparticles of Ni-CeO2 catalyst is the main reason for such activity. Detailed study of other reaction parameters like temperature, Ni loading, weight hourly space velocity (WHSV) was also carried out and reported.
163 citations
TL;DR: In this paper, the design of WO3-based oxygen carriers was described as the primary source of lattice oxygen with high melting points and attractive syngas selectivity. But the authors did not consider the effect of surface-grafted nickel species on the lattice availability and methane conversion capacity, and the NiO nanoclusters were introduced, considering the doping effect on chemical bonding disruption.
Abstract: Partially oxidizing methane into syngas via a two-step chemical looping scheme is a promising option for methane transformation. Providing the optimum lattice oxygen to selectively produce syngas represents the major challenge for the development of oxygen carrier materials in chemical looping processes. This paper describes the design of WO3-based oxygen carriers as the primary source of lattice oxygen with high melting points and attractive syngas selectivity. To further enhance the lattice oxygen availability and methane conversion capacity, NiO nanoclusters are introduced, considering the doping effect on chemical bonding disruption in both bulk and surface regions. For Ni0.5WOx/Al2O3, the nickel cations incorporated into the bulk of WO3 can strongly weaken the tungsten–oxygen bond strength and increase the availability of lattice oxygen. The surface-grafted nickel species can effectively activate methane molecules and catalyze the partial oxidation reaction. Total methane conversion and syngas yield ...
125 citations
TL;DR: In this paper, a Co-Co3O4@carbon composites were synthesized via pyrolysis of a CoMOFs@glucose polymer, followed by partial oxidation of Co nanoparticles (NPs).
Abstract: Controllable pyrolysis of metal−organic frameworks (MOFs) in confined spaces is a promising strategy for the design and development of advanced functional materials. In this study, Co-Co3O4@carbon composites were synthesized via pyrolysis of a Co-MOFs@glucose polymer (Co-MOFs@GP) followed by partial oxidation of Co nanoparticles (NPs). The pyrolysis of Co-MOFs@GP generated a core–shell structure composed of carbon shells and Co NPs. The controlled partial oxidation of Co NPs formed Co-Co3O4 heterojunctions confined in carbon shells. Compared with Co-MOFs@GP and Co@carbon-n (Co@C-n), Co-Co3O4@carbon-n (Co-Co3O4@C-n) exhibited higher catalytic activity during NaBH4 hydrolysis. Co-Co3O4@C-II provided a maximum specific H2 generation rate of 5,360 mL·min−1·gCo
−1 at room temperature due to synergistic interactions between Co and Co3O4 NPs. The Co NPs also endowed Co-Co3O4@C-n with the ferromagnetism needed to complete the magnetic momentum transfer process. This assembly-pyrolysis-oxidation strategy may be an efficient method of preparing novel nanocomposites.
102 citations
TL;DR: Information is collected on the production of valuable chemicals by thermal hydrolysis and wet oxidation and on their main features, which seem to be more suitable for yielding higher amounts of acid than diluted, undigested and primary ones.
100 citations
TL;DR: In this paper, the authors studied the performance of bimetallic Pt-Pd/γ-Al2O3 catalysts in low-temperature combustion (LTC) diesel engines.
Abstract: Low temperature combustion (LTC) diesel engines are being developed to meet increased fuel economy demands. However, some LTC engines emit higher levels of CO and hydrocarbons and therefore diesel oxidation catalyst (DOC) efficiency will be critical. Here, CO and propylene oxidation were studied, as representative LTC exhaust components, over model bimetallic Pt-Pd/γ-Al2O3 catalysts. During CO oxidation tests, monometallic Pt suffered the most extensive inhibition which was correlated to a greater extent of dicarbonyl species formation. Pd and Pd-rich bimetallics were inhibited by carbonate formation at higher temperatures. The 1:1 and 3:1 Pt:Pd bimetallic catalysts did not form the dicarbonyl species to the same extent as the monometallic Pt sample, and therefore did not suffer from the same level of inhibition. Similarly they also did not form carbonates to as large an extent as the Pd-rich samples and were therefore not as inhibited from this intermediate surface species at higher temperature. The Pd-rich samples were relatively poor propylene oxidation catalysts; and partial oxidation product accumulation deactivated these catalysts. Byproducts observed include acetone, ethylene, acetaldehyde, acetic acid, formaldehyde and CO. For CO and propylene co-oxidation, the onset of propylene oxidation was not observed until complete CO oxidation was achieved, and the bimetallics showed higher activity. This was again related to less extensive poisoning, less dicarbonyl species formation and less overall partial oxidation product accumulation.
100 citations
TL;DR: In this article, solid-state ion-exchanged Cu/mordenites exhibit a significantly higher activity for the partial oxidation of methane to methanol than comparable reference catalysts.
Abstract: The selective oxidation of methane to methanol is a highly challenging target, which is of considerable interest to gain value-added chemicals directly from fuel gas. Copper-containing zeolites, such as Cu/mordenite, have been currently reported to be the most efficient catalysts for this reaction. In this work, it is shown that solid-state ion-exchanged Cu/mordenites exhibit a significantly higher activity for the partial oxidation of methane to methanol than comparable reference catalysts, i.e., Cu/mordenites prepared by the conventional liquid-phase ion exchange procedure. The efficiency of these Cu/mordenites remained unchanged over several successive cycles. From temperature-programmed reduction (TPR) measurements, it can be concluded that the solid-state protocol accelerates Cu exchange at the small pores of mordenite: those are positions where the most active Cu species are presumably located. In situ ultraviolet–visible (UV-vis) spectroscopy furthermore indicates that different active clusters inc...
96 citations
TL;DR: In this article, the performance of double perovskite-type oxide La1.6Sr0.4FeCoO6 as an oxygen carrier was investigated for co-production of syngas and hydrogen via chemical looping steam methane reforming (CL-SMR).
Abstract: Co-production of syngas and hydrogen via chemical looping steam methane reforming (CL-SMR) using double perovskite-type oxide La1.6Sr0.4FeCoO6 as an oxygen carrier was studied. The reaction mechanisms, including the synergistic effects, the metal transitions, the oxygen diffusion and the migration of reaction boundary during the two-step reactions, were systematically investigated by the characterizations of the oxygen carriers at different reaction stages using XRD, XPS, H2-TPR and TG technologies. Meanwhile, isothermal reactions were carried out in a fixed-bed reactor to analysis the reaction products. Three reaction stages including the total oxidation of methane with the active adsorbed oxygen, partial oxidation of methane with the lattice oxygen, and the methane decomposition were identified, using the surface of the oxygen carrier particles as reaction boundary. A large number of syngas was generated due to the concordant of methane dissociation with the lattice oxygen diffusion, and the resistant to coke formation was enhanced effectively. In the steam dissociation stage, the deep reduced metals (Fe2+ and Co0) combining with the abundant oxygen vacancies provided enough active sites for the breakage of H O bond of H2O. The oxygen vacancies were neutralized immediately by the O atom, and the two H atoms combined together to form amounts of H2. These results suggested that, the positive roles displayed by the synergistic effects between multi-metals in double perovskite structure could effectively promote the partial oxidation of methane and steam splitting. It provides a potential way to develop more active oxygen carrier for CL-SMR to co-produce syngas and hydrogen by comprehensively considering the methane dissociation and the lattice oxygen diffusion.
93 citations
TL;DR: In this paper, an iron-containing mixed-oxide nanocomposites were used for thermochemical CO2 splitting and methane partial oxidation in a cyclic redox scheme, where methane was introduced as an oxygen "sink" to promote the reduction of the redox materials followed by reoxidation through CO 2 splitting.
Abstract: We report iron-containing mixed-oxide nanocomposites as highly effective redox materials for thermochemical CO2 splitting and methane partial oxidation in a cyclic redox scheme, where methane was introduced as an oxygen "sink" to promote the reduction of the redox materials followed by reoxidation through CO2 splitting. Up to 96% syngas selectivity in the methane partial oxidation step and close to complete conversion of CO2 to CO in the CO2-splitting step were achieved at 900° to 980°C with good redox stability. The productivity and production rate of CO in the CO2-splitting step were about seven times higher than those in state-of-the-art solar-thermal CO2-splitting processes, which are carried out at significantly higher temperatures. The proposed approach can potentially be applied for acetic acid synthesis with up to 84% reduction in CO2 emission when compared to state-of-the-art processes.
91 citations
TL;DR: In this article, the characterization and reactive properties of copper zeolites with twelve framework topologies (MOR, EON, MAZ, MEI, BPH, FAU, LTL, MFI, HEU, FER, SZR, and CHA) are compared in the stepwise partial oxidation of methane into methanol.
Abstract: The characterization and reactive properties of copper zeolites with twelve framework topologies (MOR, EON, MAZ, MEI, BPH, FAU, LTL, MFI, HEU, FER, SZR, and CHA) are compared in the stepwise partial oxidation of methane into methanol. Cu2+ ion-exchanged zeolite omega, a MAZ-type material, reveals the highest yield (86 μmol g(cat.)−1) among these materials after high-temperature activation and liquid methanol extraction. The high yield is ascribed to the relatively high density of copper–oxo active species, which form in its three-dimensional 8-membered (MB) ring channels. In situ UV/Vis studies show that diverse copper species form in different zeolites after high-temperature activation, suggesting that there are no universally active species. Nonetheless, there are some dominant factors required for achieving high methanol yields: 1) highly dispersed copper–oxo species; 2) large amount of exchanged copper in small-pore zeolites; 3) moderately high temperature of activation; and 4) use of proton form zeolite precursors. Cu-omega and Cu-mordenite, with the proton form of mordenite as the precursor, yield methanol after activation in oxygen and reaction with methane at only 200 °C, that is, under isothermal conditions.
TL;DR: In this article, a perovskite catalytic particle of Fe2O3−NiO/La 0.8Sr 0.2FeO3 was used as an oxygen carrier and investigated its long-term activity and stability in a novel methane Chemical Looping Reforming Decomposition (CLRD) process.
Abstract: This work introduced a perovskite catalytic particle of Fe2O3–NiO/La0.8Sr0.2FeO3 as an oxygen carrier and investigated its long-term activity and stability in a novel methane Chemical Looping Reforming-Decomposition (CLRD) process. Carbon dioxide (CO2) was injected for the oxidation of the reduced catalytic particle and its carbon deposit, resulting in the accelerated production of syngas. The catalytic particle showed over 97% of CH4 conversion over 60 min and the reduced catalytic particle was partially re-oxidized by both O2 and CO2 with the conversion of CO2 into CO maintaining about 93% over 80 min. The separate phases of Fe2O3/NiO were gradually merged to the single crystal phase of NiFe2O4 during the calcination of the two metal oxides and the continuous redox reaction cycle. The increased crystallinity can lead to the improvement of both activity and stability due to the enhanced oxygen-carrying capacity. The structure of the catalytic particle was well preserved and its activity has been stable in the long-term CLRD cycle with the combination of CO2 utilization.
TL;DR: In this article, a new ethanol electro-oxidation enhancement mechanism was proposed in which Pt3Co with Pt-skin promoted partial oxidation of ethanol over C-C bond cleavage, thereby resulting in higher CH3COOH production than CO2 production.
Abstract: In order to maximize the Pt utilization in catalysts and improve catalytic processes, we report a convenient strategy for preparation of Pt3Co with Pt-skin structured bimetallic nanocatalysts directly supported on porous graphitic carbon. Notably, the thickness of the Pt-skin is only 1–2 atomic layers, about 0.5 nm. Surprisingly, the bimetallic nanocatalysts composed of Pt3Co with Pt-skin are first used as ethanol electro-catalysts, with the mass activity of 0.79 mA μgPt–1, which is a 250% enhancement compared with commercial Pt/C (0.32 mA μgPt–1). On the basis of the results of electrochemical in situ Fourier transform infrared spectroscopy (FTIRS) and density functional theory (DFT), a new ethanol electro-oxidation enhancement mechanism is proposed in which Pt3Co with Pt-skin promotes partial oxidation of ethanol over C–C bond cleavage, thereby resulting in higher CH3COOH production than CO2 production.
TL;DR: In this article, the authors showed that when hybridized with reduced graphene oxide (rGO), the conduction band electrons photoformed on TiO2 are transferred to rGO, promoting efficient charge separation and enhanced photocatalytic cycles.
Abstract: Partial oxidation of cyclohexane (CHA) to cyclohexanone (CHA-one) with molecular oxygen (O2) is one of the most important reactions. Photocatalytic oxidation has been studied extensively with TiO2-based catalysts. Their CHA-one selectivities are, however, insufficient because the formed CHA-one is subsequently decomposed by photocatalysis involving the reaction with superoxide anion (O2●–) produced by one-electron reduction of O2 on TiO2. Here we report that TiO2, when hybridized with reduced graphene oxide (rGO), catalyzes photooxidation of CHA to CHA-one with enhanced activity and selectivity under UV light (λ > 300 nm). The TiO2/rGO hybrids produce CHA-one with twice the amount formed on bare TiO2 with much higher selectivity (>80%) than that on bare TiO2 (ca. 60%). The conduction band electrons photoformed on TiO2 are transferred to rGO, promoting efficient charge separation and enhanced photocatalytic cycles. The trapped electrons on rGO selectively promote two-electron reduction of O2 and suppress o...
TL;DR: In this paper, the double perovskite-type oxides La1−xSrxFeCoO6 (x = 0, 0.2, 0., 0.4, 0.8, 1.0) were investigated for the purpose of chemical looping steam methane reforming (CL-SMR).
TL;DR: In this paper, the evolution of the catalyst structure during TPR and CO 2 Temperature Programmed Oxidation (TPO) was investigated using time-resolved in situ X-ray diffraction (XRD).
Abstract: Fe–Ni catalysts present high activity in dry reforming of methane, with high carbon resistance, but suffer from deactivation via sintering and Fe segregation. Enhanced control of the stability and activity of Fe–Ni/MgAl 2 O 4 was achieved by means of Pd addition. The evolution of the catalyst structure during H 2 Temperature Programmed Reduction (TPR) and CO 2 Temperature Programmed Oxidation (TPO) was investigated using time-resolved in situ X-ray diffraction (XRD). During reduction of Fe–Ni–Pd supported on MgAl 2 O 4 , a core shell alloy forms at the surface, where Fe–Ni is in the core and Fe–Ni–Pd in the shell. A 0.2 wt% Pd loading or Ni:Pd molar ratio as high as 75:1 showed the best performance in terms of both activity and stability of the catalyst at 1023 K and total pressure of 101.3 kPa. Experimental results and DFT calculations showed that Pd addition to bimetallic Fe–Ni reduces the tendency of Fe to segregate to the surface of the alloy particles under methane dry reforming (DRM) conditions, due to the formation of a thin Fe–Ni–Pd surface layer. The latter acts as a barrier for Fe segregation from the core. Segregation of Fe from the trimetallic shell still occurs, but to a lesser extent as the Fe concentration is lower. This Ni:Pd molar ratio is capable of controlling the carbon formation and hence ensure high catalyst activity of 24.8 mmol s −1 g metals −1 after 21 h time-on-stream.
TL;DR: In this article, ULSC cobalt monoxide (CoO) nanoparticles were synthesized and subjected to partial oxidation (corrosion) with ceric ammonium nitrate (CAN) to form mixed-valence CoOx (1 < x < 2) water oxidation catalysts.
Abstract: Ultra-small rock salt cobalt monoxide (CoO) nanoparticles were synthesized and subjected to partial oxidation (‘corrosion’) with ceric ammonium nitrate (CAN) to form mixed-valence CoOx (1 < x < 2) water oxidation catalysts. Spectroscopic, microscopic and analytical methods evidenced a structural reformation of cubic CoO to active CoOx with a spinel structure. The superior water oxidation activity of CoOx has been established in electrochemical water oxidation under alkaline conditions. Electrochemical water oxidation with CoOx was recorded at a considerably low overpotential of merely 325 mV at a current density of 10 mA cm−2 in comparison to 370 mV for CoO. Transformation of both octahedral CoII and CoIII sites into amorphous Co(OH)2–CoOOH is the key to high electrochemical activity while the presence of a higher amount of octahedral CoIII sites in CoOx is imperative for an efficient oxygen evolution process.
TL;DR: In this paper, a thermodynamic and kinetic analysis of the combined reforming has been conducted using the software suite MATLAB ®, and the aim of this complicated assessment is to identify optimized combination of the three reformers and also the corresponding operating conditions that would utilize significant amount of CO 2 while ensuring CO 2 fixation, minimum carbon formation and optimum energy requirements.
Abstract: Dry reforming of methane is one of the few chemical reactions which can effectively convert carbon dioxide (CO 2 ), a major green-house gas, into a valuable chemical precursor, syngas (a mixture of CO and H 2 ), that can be converted into chemicals and fuels via different synthesis routes such as the Fischer Tropsch synthesis. The inherent limitations of dry reforming reaction, for instance, rapid catalyst deactivation by coke deposition and the very high energy requirements, has restricted its use as a commercial technology. This study was performed to evaluate the potential of overcoming the limitations of dry reforming by integrating it with other commercial methane reforming technologies such as steam reforming and partial oxidation reforming in the context of industrial operating conditions. A thermodynamic and kinetic analysis of the combined reforming has been conducted using the software suite MATLAB ® . The aim of this complicated assessment is to identify optimized combination of the three reformers and also the corresponding operating conditions that would utilize significant amount of CO 2 while ensuring CO 2 fixation, minimum carbon formation and optimum energy requirements. The thermodynamic equilibrium product distribution calculations involved the Peng Robinson (PR), Redlich Kwong (RK) and Soave Redlich Kwong (SRK) equations of state (EOS) to identify the best EOS that accounts for the non-ideality associated with the high pressure operation. The study evaluated simultaneous effects of temperature (200 °C–1200 °C), pressure (1–20 bar) and feed mole ratios (of methane, steam, carbon dioxide and oxygen) on the equilibrium product distribution. The addition of oxygen and steam to dry reforming helped in decreasing energy requirements while simultaneously increasing the syngas yield ratio (H 2 :CO ratio). The numerical evaluation revealed an optimized operating condition of ∼750 °C at 1 bar pressure at a feed mole ratio CH 4 :H 2 O:O 2 :CO 2 of 1:0.4:0.3:1. For this optimization, the system boundaries were limited only to a reformer block without considering the upstream and dowstream processes. At this optimized condition, the carbon deposition was eliminated and the CO 2 conversion was observed to be 47.84% with an energy requirement of 180.26 kJ. The study is further extended to include kinetic analysis of combined dry and steam reforming of methane. The preliminary findings of kinetic evaluation indicated an excellent agreement between combined kinetic model with the thermodynamic equilibrium results.
TL;DR: In this article, the selective oxidation of methane to methanol is achieved by means of a photocatalytic process, where the formation of V2O5 on the surface is an effective alternative for modifying the acid base surface properties, thus significantly decreasing the undesired CO2 formation.
Abstract: The selective oxidation of methane to methanol is achieved by means of a photocatalytic process. For this purpose, designed Bi- and V-containing beta zeolites prepared by incipient wetness impregnation have been used under different test conditions. While the zeolite proves to be photoactive under UVC irradiation toward the total oxidation process, the formation of V2O5 on the surface is an effective alternative for modifying the acid–base surface properties, thus significantly decreasing the undesired CO2 formation. At the same time the zeolite framework serves as a scaffold for increasing the surface area and distribution of the metal oxide. Additionally, the addition of low Bi amount favors the formation of a BiVO4/V2O5 heterojunction, which acts as a visible light photocatalyst while at the same leading to total selectivity to methanol at the expense of ethylene formation.
TL;DR: In this article, the authors determined the kinetic model representation and parameters associated with the selective oxidation of coal derived char (Wyodak and Illinois #6) with a metal ferrite (CaFe2O4) of which are needed for advancement of the process concept using thermogravimetric analysis coupled with mass spectrometry.
TL;DR: Nickel supported on η-Al 2 O 3 and ZSM-5(80) catalysts with and without the addition of ceria-zirconia, were prepared by co-precipitation and wet impregnation methods and used for the low temperature catalytic partial oxidation of methane (CPOM) as discussed by the authors.
Abstract: Nickel supported on η-Al 2 O 3 and ZSM-5(80) catalysts with and without the addition of ceria-zirconia, were prepared by co-precipitation and wet impregnation methods and used for the low temperature catalytic partial oxidation of methane (CPOM). The catalysts were tested under reaction temperatures of between 400 and 700 °C with a WHSV of 63,000 mL g −1 h −1 . The activity of the catalyst was found to be dependent on the support and preparation method. The optimum catalyst composition of those tested was 10% Ni on 25%CeO 2 -ZrO 2 /ZSM-5(80), prepared by co-precipitation, where the reaction reached equilibrium conversion at 400 °C (T 50%
TL;DR: In this paper, a comprehensive CFD model, validated against syngas (50/50 H2/CO by mole) metal engine experiments, was used to simulate the engine combustion process.
TL;DR: The potential of solar thermal chemical-looping reforming for efficient and sustainable co-production of synthesis gas and hydrogen is discussed in this article, where the challenges and opportunities for future research and development are discussed.
TL;DR: In this paper, a series of nickel aluminate-based spinel catalysts with varying Ni deficiency (corresponding to a Ni/Al molar ratio in the 0.13-0.50 range) was explored for the partial oxidation of methane under different operation conditions in terms of temperature, volume hourly space velocity, O/C molar ratios and time on stream.
Abstract: The viability of a series of nickel aluminate-based spinel catalysts with varying Ni deficiency (corresponding to a Ni/Al molar ratio in the 0.13–0.50 range) was explored for the partial oxidation of methane under different operation conditions in terms of temperature, volume hourly space velocity, O/C molar ratio and time on stream. Thus spinel-type catalysts with a Ni loading between 11 and 31 wt.% were prepared by coprecipitation. A wide number of techniques including WDXRF, XRD, N2 physisorption, Raman spectroscopy, XPS, UV–vis-NIR DRS, H2-TPR, TEM and TGA-MS were used to characterise the calcined, reduced and post-run samples. With respect to the reference stoichiometric sample (Ni/Al = 0.50) alumina excess in the precursor oxide provoked notable changes in the surface area, structural properties connected with the relative cation distribution between tetrahedral and octahedral coordination and reducibility of the resultant spinel phase. It was found that the catalytic performance of these non-stoichiometric samples could be optimised for a Ni/Al molar ratio of 0.25, which corresponded to a metal loading of 19 wt.%Ni. The oxidation activity was associated with the remarkable intrinsic activity of nickel particles derived from Ni2+ cations with a preferential occupancy of octahedral sites in the lattice of the oxide. The promising catalytic behaviour of this sample was further proven by the notable activity and stability shown under severe reaction conditions with a reduced loss of yield of hydrogen with time on stream.
TL;DR: In this article, a remarkable catalytic membrane reactor for partial oxidation of methane (POM) reaction at low temperature (650-750 °C) was presented. But the performance of the catalytic separation was not analyzed.
TL;DR: In this paper, a simple and easy to use method based on the zone division of Ellingham diagram was offered to distinguish the oxidation ability of various metal oxides, and three zones including complete oxidation, partial oxidation and inert zones were divided.
TL;DR: In this paper, a 5-wt. copper supported on ceria nanopolyhedra, nanorods and nanocubes was used as a catalyst for hydrogen production from partial oxidation of methanol (POM).
Book•
12 Oct 2017TL;DR: In this paper, the authors present a comprehensive guide to the principles and techniques of chemical looping partial oxidation, with authoritative explanations from a pioneer of the chemical LOOPING process, and gain a holistic overview of metal oxide reaction engineering with coverage of ionic diffusion, nanostructure formation, morphological evolution, phase equilibrium, and recyclability properties of metal oxides during redox reactions.
Abstract: This is the first comprehensive guide to the principles and techniques of chemical looping partial oxidation. With authoritative explanations from a pioneer of the chemical looping process, you will:Gain a holistic overview of metal oxide reaction engineering, with coverage of ionic diffusion, nanostructure formation, morphological evolution, phase equilibrium, and recyclability properties of metal oxides during redox reactionsLearn about the gasification of solid fuels, the reforming of natural gas, and the catalytic conversion of methane to olefinsUnderstand the importance of reactor design and process integration in enabling metal oxide oxygen carriers to produce desired productsDiscover other applications of catalytic metal oxides, including the production of maleic anhydride and solar energy conversionsAspen Plus® simulation software and results accompany the book online. This is an invaluable reference for researchers and industry professionals in the fields of chemical, energy and environmental engineering, and students studying process design and optimization.
TL;DR: In this article, the dual phase membranes (Ce 0.9 Gd 0.1 O 2−δ -Ba 0.5 Co 0.8 Fe 0.2 O 3 −δ (CGO-BSCF)) were used for partial oxidation of methane (POM) to syngas.
TL;DR: In this paper, the photocatalytic partial oxidation of 4-methoxybenzyl alcohol (MBA) and 4-nitrobenzoic acid (NBA) to corresponding aldehydes or acids was performed in water under simulated solar light at different pHs by using Pt, Au, Pd and Ag loaded Degussa P25 TiO 2 catalysts, prepared by photoreduction.