Catalytic Cracking Of Methane Research Articles

Plasma-induced methane catalytic cracking: Effects of experimental conditions

Low-carbon conversion of hydrocarbon fuels and feedstocks, as well as the macroscopic production of H2, are central focus in the advancement of high-value and efficient conversion of CH4. The effects of Ar addition ratio, discharge power and temperature on the results of plasma methane cracking were investigated on a dielectric barrier discharge (DBD) plasma experimental system. The results show that the addition of Ar can improve the methane conversion, and the optimal ratio of CH4 conversion to H2 production after the effect is CH4: Ar = 1:1, at which the methane conversion reaches 49.62% and the H2 selectivity reaches 52.66%. The plasma at 25 °C can make the methane conversion close to the effect of catalytic cracking at 600 °C, while the H2 selectivity is lower, the H2 generation is 32.59% lower than the latter, and the products have more C2–C4 hydrocarbon impurities. The solid byproduct resulting from the DBD plasma cracking of methane primarily consisted of carbon black, possessing an average particle size of 62.21 nm. The incorporation of Ar and the amplification of power augment the CH* radical intensities, which suggests both conditions contribute positively to the dissociation of the CH4 molecule.

Deciphering the Pivotal Reaction Conditions for Hydrogen Production from Tar Catalytic Cracking by Perovskite

The catalytic cracking of pyrolysis gasification tar into H2 has garnered significant attention due to its exceptional conversion efficiency. In this study, the effects of pollutant concentration, residence time, weight hourly space velocity (WHSV), and reaction temperature on the hydrogen performance of LaFe0.5Ni0.5O3 perovskite were comprehensively investigated. Results revealed that moderate pollutant concentration (0.3 g/L), low-medium residence time (250 SCCM), and low WHSV (0.24 gtoluene/(gcat·h)) facilitated efficient interaction between LaFe0.5Ni0.5O3 and toluene, thus achieving high hydrogen production. An increase in reaction temperature had minimal effect on the hourly hydrogen production above 700 °C but caused a significant increase in methane production. Additionally, the effects of oxygen evolution reactions, methane reactions, and methane catalytic cracking reactions of perovskite induced by different reaction conditions on tar cracking products were discussed in detail. Compared to previous reports, the biggest advantages of this system were that the hydrogen production per gram of tar was as high as 1.002 L/g, and the highest hydrogen content in gas-phase products reached 93.5%, which can maintain for approximately 6 h. Finally, LaFe0.5Ni0.5O3 showed good thermal stability, long-term stability, and catalyst reactivation potential.

Methane catalytic cracking by solid materials and molten media for hydrogen production: A review

Excessive emission of carbon dioxide is the leading cause of global warming. Hydrogen has the advantages of high calorific value and zero carbon emissions. It is considered an ideal energy to solve the problem of global warming, so the demand for hydrogen is increasing yearly. Due to economic considerations, methane is the main raw material for hydrogen production. Currently, 48% of the world's hydrogen comes from steam methane reforming. However, this process needs to burn some methane for heating, generating carbon dioxide emissions simultaneously. In order to avoid carbon emissions from hydrogen production, there is an urgent need to develop new methods to produce hydrogen from methane. Because the carbon generated from direct methane cracking exists in solid form while not as carbon dioxide, the direct methane cracking process for hydrogen production has become a hot research topic in recent years. In this paper, a comprehensive review of the research related to catalytic methane cracking for hydrogen production is presented, especially the research on catalytic cracking of methane using solid materials or molten metal media as catalytic media is summarized in detail. Next, a brief overview of the mechanism of catalytic methane cracking for hydrogen production and the characteristics of the generated carbon as a by-product are presented. Finally, the catalytic cracking of methane in molten media or solid materials and the research trend were prospected.

Catalytic cracking of methane to hydrogen and carbon: Scale-up perspective

Decarbonizing natural gas for the production of H2 and value-added nanostructured graphitic carbons via catalytic decomposition of methane (CDM) presents an attractive alternative to conventional steam-methane reforming. This work is an attempt to establish the practical viability of the CDM process considering the reciprocity of methane conversion, the type and quantity of carbon formation, and the effective lifetime of the catalyst. Effects of the reaction parameters and reactor configurations on the catalyst performance, type of carbon-formation, and the catalyst degradation have been analyzed critically, providing state-of-the-art on laying a foundation for the development of new catalysts with better selectivity and longevity. Finally, a continuous regeneration-recycling system has been modeled by simulating a fluidized-bed reactor for Fe-based catalyst. The energy-exchange efficiency of regeneration/recirculation of catalyst via partial combustion has been established to lay out the guidelines for future development of the CDM process on a commercial-scale.

Influence of Zn and Ni dopants on the physicochemical and activity patterns of CoFe2O4 derived catalysts for hydrogen production by catalytic cracking of methane

Zinc and nickel incorporated CoFe2O4 materials have been synthesized via a wet chemical method. Characterization of these cobalt ferrite based catalysts was undertaken using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and thermal gravimetric analysis (TGA). The catalytic activity of these materials was evaluated by monitoring the direct cracking of methane for the production of hydrogen and carbon. The XRD and SEM results indicated that Ni incorporation preserves the inverse spinel structure of CoFe2O4, whilst Zn incorporation changes its microstructure. The Co 2p, Fe 2p and O 1 s XP spectra confirm the expected oxidation states of the elements in the near surface region of the catalysts. Raman spectra indicate cation redistribution between tetrahedral and octahedral sites upon Ni and Zn incorporation into CoFe2O4. BET surface area analysis revealed Ni incorporation is more effective in increasing the surface area of CoFe2O4 compared to Zn incorporation. Indeed, catalytic activity evaluation showed that Ni incorporation into CoFe2O4 improved methane conversion and correspondingly the hydrogen formation rate. In contrast, Zn incorporation led to very low catalytic activity. The spent catalysts were further characterized and the results are strongly correlated with catalytic activity.

Co-production of syngas and H2 from chemical looping steam reforming of methane over anti-coking CeO2/La0.9Sr0.1Fe1−xNixO3 composite oxides

Chemical looping steam reforming of methane (CL-SRM) is a novel process for the co-production of syngas and hydrogen without an additional purification process. However, the high activity of oxygen carriers is always accompanied by severecarbondeposition via the catalytic cracking of methane, which can result in the rapid deactivation of oxygen carriers and the production of low purity hydrogen. Herein, a series of novel composite oxide carriers of CeO2/La0.9Sr0.1Fe1−xNixO3 with varying doping ratios of Ni are developed to achieve selective and stable production of syngas and H2. The redox performance of CeO2/La0.9Sr0.1Fe1−xNixO3 was evaluated in a fixed bed reactor coupling with various analytical methods. It is found that the Ni doping ratio of 0.2 can significantly enhance the performance and stability of CeO2/La0.9Sr0.1Fe1−xNixO3. It is speculated that the proper doping ratio of Ni can simultaneously improve the surface lattice oxygen vacancies and the lattice oxygen migration rate. The CH4 reforming over CeO2/La0.9Sr0.1Fe0.8Ni0.2O3 displays a very stable performance while avoiding obvious carbon deposition within 20 min, in which, the CH4 conversion, H2 selectivity, and CO selectivity achieve 85%, 96%, and 88%, respectively. The yield of H2 (>95% purity) reaches 23 mL/min in the subsequent steam oxidation of reduced CeO2/La0.9Sr0.1Fe0.8Ni0.2O3. Its lattice oxygen can be completely recovered by the final air oxygenation. The CeO2/La0.9Sr0.1Fe0.8Ni0.2O3 exhibits high reactivity and stability in 10 redox cycles at 850 °C. These results demonstrate that the doping of Ni affords an efficient manner to regulate the lattice oxygen migration rate of perovskite oxides to match the surface reaction rate, thereby avoiding the deep reduction of surface metal ions within perovskite oxides and resulting carbon depositions during CL-SRM.

Reactions

OPINION Reactions ShareShare onFacebookTwitterWechatLinked InRedditEmail C&EN, 2021, 99 (29), p 5August 9, 2021Cite this:C&EN 99, 29, 5(Credit: Shutterstock/C&EN)Figure1of1▸ Letters to the editorGreen steelC&EN and writer Mark Peplow are to be commended for the article “The Race for Green Steel,” focusing, as the title might suggest, on the deleterious consequences for the atmosphere of conventional steelmaking processes and methods for remediation (June 14, 2021, page 22). The graphics on pages 24 and 29 were particularly instructive.I was particularly interested in Sweden’s use of hydrogen generated electrolytically using wind power as well as hydrogen produced by other means to produce steel in an arc furnace, as these methods had the lowest carbon dioxide footprint (see chart page 29).The other methods of producing hydrogen were not discussed in detail, but some did seem to involve shale gas (chiefly methane). In this context, the catalytic cracking of methane could be mentioned (see Chem. Eng. Sci. 2001, DOI: 10.1016/S0009-2509(00)00270-0). It should have the benefits of not being restricted to a small number of sites and not being dependent on the wind.Thomas F. SpandeBethesda, MarylandI was intrigued by the discussion of the direct electrolysis of iron ore without using any reducing agents such as hydrogen or carbon.It got me thinking, What if dry NaCl were added to the iron ore? Its melting point of 801 °C is lower than that of iron, about 1,500 °C, so it would melt and form a separate layer. Could the reaction then be forced toFe2O3 + 6NaCl J 2Fe + 3Na2O + 3Cl2(1 kg of Fe2O3 to 2.2 kg of NaCl)with gaseous chlorine captured? Then if the Na2O could be separated and reacted with water and CO2:Na2O + CO2(aq) J Na2CO3So the result is to produce commercial chlorine and sodium carbonate and to absorb atmospheric carbon dioxide. Three commercial products and one environmental benefit. Also a sink for the oxygen reported to be excessively generated. Not too bad for an industrial reaction. Of course I don’t know the thermodynamics or the kinetics or the phase mixing, so I’m only daydreaming. But what if it could be made to work?Paul PalmerVacaville, CaliforniaThe cover story in the June 14 edition caught my attention. The author did an admirable job in several respects:The fundamental chemistry of steelmaking was very useful.The brief history of steelmaking was quite interesting.The description of multiple alternative approaches was very well done and required very few pages.I do question some aspects of the article, however:All the alternative technologies under consideration rely on “eye-watering” quantities of electric power. The quest to eliminate carbon from life will require huge quantities of electric power in this and countless other applications in daily life. I wonder what source will generate this quantity of power. Wind and solar have well-documented and fundamental limitations.I would have been interested in a spreadsheet showing the total cost of traditional versus green steelmaking methods. I suggest that the current economic analysis depends heavily on taxes and government force. Human history tells a story. In the long run, in science, entropy always wins; in like manner, in the long run, true economics will always trump government-mandated selections of winners and losers.Mike KernerLisle, IllinoisThe article on page 26 emphasizes the efficiency of electrolytic processes that require a stable supply of copious electric power. This seems like an ideal situation for one of the small, modular nuclear electric-power-generation plants that currently are on the horizon. Coupled with a small nuclear plant, these iron-smelting plants could operate independently with their own power supply.Martha DibbleePortland, Oregon CorrectionAug. 2, 2021, page 16: The feature story about bacteriophage use in agriculture incorrectly locates an October 2020 focus group. The workshop took place in the eastern region of Ghana, not in Accra.

Hydrogen Production via Methane Cracking on Dry-Coated Fe/ZrO2 with Support Recycle in a Fluidized Bed Process

Hydrogen can be produced by catalytic cracking of methane in a fluidized bed to yield solid carbon as a byproduct. We report the use of a catalyst consisting of Fe2O3 dry coated on dense ZrO2 beads...

Process Intensification through Directly Coupled Autothermal Operation of Chemical Reactors

Summary Autothermal operation of a chemical reactor involves coupling exothermic and endothermic chemical reactions for the purpose of thermal management without resorting to external energy sinks or sources. Often this is accomplished through regenerative or recuperative heat exchange between spatially or temporally separated exothermic and endothermic reactions. However, it is also possible to directly couple these reactions simultaneously within the same reactor volume, eliminating the heat-transfer bottleneck that characterizes much of chemical manufacture. It is not widely recognized that directly coupled autothermal operation allows dramatic process intensification. This perspective defines autothermal operation and contrasts it with conventional heat transfer for thermal management of chemical processes. The intensification and cost savings that can be achieved are quantified, and the implications to modular chemical process intensification are presented. Guidelines are proposed for designing directly coupled autothermal processes. Diverse examples are presented. Several challenges to expanding the field are critically discussed.

Hydrogen production from microwave catalytic pyrolysis of spruce sawdust

The production of energy from wood biomass is as old as humanity itself. In the last 20 years there has been enormous progress in research of torrefaction, pyrolysis and mainly gasification of biomass. Products from conventional pyrolysis of biomass are gas known as pyrolysis gas, a liquid condensate known as bio-oil and char named bio-char. Most of the articles dealing with convectional pyrolysis of biomass are focused on the production of bio-oil. Only some works deal with the possibility of producing high-quality syngas (H2+CO) or hydrogen itself. For this purpose, the technology of microwave pyrolysis could be suitable. Microwaves can generate microplasma and hot spots, which promote heterogeneous catalytic reactions and produce a greater concentration of hydrogen in the resulting gas than convectional pyrolysis. In this work, an experimental study of spruce sawdust microwave pyrolysis was performed in the presence of catalysts to maximize the yield of hydrogen or syngas. Experiments were carried out in a microwave reactor with a power of 400W. As catalysts char from sawdust, or sawdust char-doped with metal ions (Ni, Co, Fe) were used. Ions of metals were used to increase the yield of hydrogen (e.g. Nickel is widely used in the catalytic cracking of methane). The influence of the catalyst on the quantity of products (gas, liquid and solid) was studied, as well as the amount of hydrogen generated in the pyrolysis gas, or the amount of waste water in the liquid condensate.

Theoretical investigation of the mechanism of tritiated methane dehydrogenation reaction using nickel-based catalysts

The mechanism of tritiated methane dehydrogenation reaction catalyzed by nickel-based catalyst was investigated in detail by density functional theory (DFT) at the B3LYP/[6-311++G(d, p), SDD] level. The computational results indicated that the dehydrogenation of tritiated methane is endothermic. The decomposition of tritiated methane catalyzed by Ni to form Ni-based carbon (Ni–C) after a four-step dehydrogenation companied with releasing tritium. After the first and second dehydrogenation steps, Ni+CT4 formed NiCT2. After the third and fourth dehydrogenation steps, NiCT2 formed NiC. The first and second steps of dehydrogenation occurred on both the singlet and triplet states, and the lowest energy route is Ni+CT4→1COM→1TS1→3IM1→3TS2→3IM2. The third and fourth steps of dehydrogenation occurred on both the singlet and quintet states, and the minimum energy reaction pathway appeared to be IM3→1TS4→5IM4→5TS5→5IM5→5pro+T2. The fourth step of dehydrogenation TNiCT→T2NiC was the rate-determining step of the entire reaction with the rate constant of k2=2.8×1013exp(−313,136/RT) (in cm3mol−1s−1), and its activation energy barrier was calculated to be 51.8kcal/mol. The Ni-catalyzed CH4 and CD4 cracking dehydrogenation processes are also investigated and the hydrogen isotope effect is evaluated. The hydrogen isotope effect value of kH/kT is computed to be 2.94, and the value of kD/kT is computed to be 1.39. The catalytic dehydrogenation reactions of methane and deuterated methane are likely to occur, accompanied by the tritiated methane catalytic cracking reaction in the fusion process.

Methane Catalytic Cracking to Make Hydrogen and Graphitic Nano Carbons (Nanotubes, Microfibers, Microballs, Onions) with Zero Emission

Methane was catalytically decomposed to hydrogen and highly graphitic carbon nanotubes, microfibers, microballs, and nano onions. Over Mo x –Ni(Fe,Co) y –MgO z , single-walled carbon nanotubes (SWNTs) and thin-walled carbon nanotubes (TWNTs) were produced; over Ni/Y, individually separated SWNTs were generated; over La2NiO4, multiwalled carbon nanotubes (MWNTs) were made. Over Ni/MCM-41, with the addition of benzene, the carbon microballs (CMBs) were produced. Over Fe–Cr alloy and LaNi0.9Co0.1O3, the carbon nano onions (CNOs) and carbon microfibers (CMFs) were produced, respectively. The methane conversion efficiency and carbon growth rate followed the order: CNOs > CMBs > CMFs > MWNTs > TWNTs > SWNTs.

Simulation of methane catalytic cracking in a bubbling fluidised bed

AbstractA three‐phase bubbling fluidised bed model has been developed to simulate and predict the performance of a methane catalytic cracking fluidised bed reactor, using Ni/(porous and non‐porous) Al2O3 catalysts, under relevant conditions. The model includes the chemistry and hydrodynamics occurring within the fluidised bed reactor. Methane cracking kinetics, developed in a previous work using a thermo balance, was used in the model. The model predictions were compared to the results from an experimental study carried out in a lab‐scale fluidised bed. Good fit between experimental data and the model was obtained under a wide range of reaction conditions.

Microfluidic size selective growth of palladium nano-particles on carbon nano-onions

Size selective growth of palladium nano-particles 2-7 nm in diameter on the surface of carbon nano-onions (CNOs) (derived from catalytic cracking of methane) in water involves pretreating the CNOs with p-phosphonic acid calix[8]arene then H(2)PdCl(4) followed by dynamic thin film processing under hydrogen in a vortex fluidic device.

Reaction and Deactivation Rates of Methane Catalytic Cracking over Nickel

The kinetics of methane catalytic cracking over nickel supported on porous and nonporous aluminas was modeled using a separable kinetics approach in order to develop initial rate and activity decay equations. The model parameters were estimated using a set of experiments conducted in an electrobalance. The experimental work covered the 500–650 °C temperature range, using pure methane, as well as different partial pressures of CH4/N2 and CH4/H2 mixtures at atmospheric pressure. The model results showed a good match with the experimental data, and the estimated kinetic parameters agreed well with those reported in the literature. The morphology of the support affected the initial reaction rate and catalyst deactivation. The methane cracking activation energy was estimated to be 88 and 75 kJ/mol for the porous and nonporous catalysts, respectively. The activation energy for the encapsulating carbon formation was estimated to be 147 and 149 kJ/mol for the porous and nonporous catalysts, respectively. The deac...

Carbon Nanomaterials Formed by the Catalytic Cracking of Methane

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

Methane Catalytic Cracking to Make CO<sub>x</sub> Free Hydrogen and Carbons (Nanotubes, Microfibers, Microballs)

The catalytic cracking of methane to produce COx free hydrogen and a spectrum of advanced carbon nano materials was studied. Over several genres of catalysts by cracking of undiluted methane we produced hydrogen and highly graphitic carbon nanotubes (single-, thin- and multi-walled), straight microfibers, nano onions over the solid oxides solution, perovskite structured mixed oxides and mesoporous supported catalysts. The influences of reaction temperature on the methane conversion over various catalysts were investigated. The yields of carbon materials were monitored during the cracking running and the results indicated that these series of catalysts are promising for the commercialization of carbon nanotubes, microfibers and microballs.

Effect of Cu on Ni nanoparticles used for the generation of carbon nanotubes by catalytic cracking of methane

In this study, a simple method for the addition of Cu to unsupported nickel nanoparticles is employed to investigate the promotion effect of copper during the nickel-catalyzed decomposition of methane into carbon nanotubes. Bulk nickel and copper acetates were mixed by grinding the parent salts in a mortar, to obtain samples with selected Ni/Cu atomic ratios (NiCu 0.03, NiCu 0.07 and NiCu 0.16) that were decomposed in situ on methane streams using a thermogravimetric analyzer (TGA). Weight increase was related quantitatively to the production of carbon nanotubes by catalytic cracking of methane, and the materials were complementary characterized ex situ by electron microscopy. The results suggest that copper most likely induces the disaggregation of nickel particles during the course of the catalytic cracking, but copper by itself was not effective to improve quantitatively the production of carbon nanotubes. In spite of very low methane conversions, good quality multiwalled carbon nanotubes are obtained and characterized by HRTEM.

Direct conversion of methane to synthesis gas using lattice oxygen of CeO 2–Fe 2O 3 complex oxides

Three kinds of complex oxides oxygen carriers (CeO 2–Fe 2O 3, CeO 2–ZrO 2 and ZrO 2–Fe 2O 3) were prepared and tested for the gas–solid reaction with methane in the absence of gaseous oxidant. These oxides were prepared by co-precipitation method and characterized by means of XRD, H 2-TPR and Raman. The XRD measurement shows that Fe 2O 3 particles well disperse on ZrO 2 surface and Ce–Zr solid solution forms in CeO 2–ZrO 2 sample. For CeO 2–Fe 2O 3 sample, only a small part of Fe 3+ has been incorporated into the ceria lattice to form solid solutions and the rest left on the surface of the oxides. Low reduction temperature and low lattice oxygen content are observed over ZrO 2–Fe 2O 3 and CeO 2–ZrO 2 samples, respectively by H 2-TPR experiments. On the other hand, CeO 2–Fe 2O 3 shows a rather high reduction peak ascribed to the consuming of H 2 by bulk CeO 2, indicating high lattice oxygen content in CeO 2–Fe 2O 3 complex oxides. The gas–solid reaction between methane and oxygen carriers are strongly affected by the reaction temperature and higher temperature is benefit to the methane oxidation. ZrO 2–Fe 2O 3 sample shows evident methane combustion during the reducing of Fe 2O 3, and then the methane conversion is strongly enhanced by the reduced Fe species through catalytic cracking of methane. CeO 2–ZrO 2 complex oxides present a high activity for methane oxidation due to the formation of Ce–Zr solid solution, however, the low synthesis gas selectivity due to the high density of surface defects on Ce–Zr–O surface could also be observed. The highly selective synthesis gas (with H 2/CO ratio of 2) can be obtained over CeO 2–Fe 2O 3 oxygen carrier through gas–solid reaction at 800 °C. It is proposed that the dispersed Fe 2O 3 and Ce–Fe solid solution interact to contribute to the generation of synthesis gas. The reduced oxygen carrier could be re-oxidized by air and restored its initial state. The CeO 2–Fe 2O 3 complex oxides maintained very high catalytic activity and structural stability in successive redox cycles. After a long period of successive redox cycles, there could be more solid solutions in the CeO 2–Fe 2O 3 oxygen carrier, and that may be responsible for its favorable successive redox cycles performance.

Experimental investigation of the catalytic cracking of methane over a supported Ni catalyst

AbstractTGA experiments on the catalytic cracking of methane and methane diluted with hydrogen over a 5 wt% Ni/γ‐alumina catalyst at 500°C and 1 and 10 bar are described. Carbon deposition on the catalyst, as expressed in specific weight of carbon, varies with time. Eventually, the deposition stops because of deactivation. The specific weight at this point depends on the hydrogen partial pressure and there is also a weak dependence on the degree of contact between catalyst particles. A model based on assuming carbon deposition proceeds through whisker formation and growth, and deactivation occurs through encapsulation adequately describes the experimental observations up to 20 vol% hydrogen in the feed.