Methane Decomposition Process Research Articles

Influence of MgO promoution to Ni-based composites in hydrogen production methane decomposition process

Catalytic decomposition of methane is a promising process that allows the simultaneous production of hydrogen and carbon nanomaterials with no COx emissions. In this work, for the first time, the possibility of promoting Ni-containing composite materials based on an organic matrix of polyvinyl alcohol (PVA) with MgO was demonstrated. The amount of MgO promoter varied from 1 to 10% by weight of Ni. The synthesized catalysts were characterized by the following methods: elemental analysis, TPR-H2, XRD, FTIR spectroscopy, Raman spectroscopy, SEM, TEM, SSA, and Raman fluorescence enhancement spectroscopy. The catalytic activity of the materials was tested in the pure CH4 decomposition reaction. Promotion with MgO contributes to an increase in the H2 yield per unit mass of Ni from 1.23 to 2.55 mol/gNi. The optimal content of the promoting component was 0.3% wt., which corresponded to 1% wt. from Ni. Carbon formed during CH4 decomposition in the form of nanotubes. The obtained carbon nanotubes (CNTs) were characterized by the following methods: XRD, Raman spectroscopy, SEM, and TEM. The length of the CNTs varies from 1 to 6 μm, the outer diameter ranges from 40 to 60 nm, and the inner diameter ranges from 10 to 20 nm.

Mechanism of activated carbon-catalyzed methane decomposition process for the production of hydrogen and high-value carbon

Mechanism of activated carbon-catalyzed methane decomposition process for the production of hydrogen and high-value carbon

Understanding catalytic methane decomposition: a swift and cost-effective energy decarbonization pathway

Understanding catalytic methane decomposition: a swift and cost-effective energy decarbonization pathway Professor Adélio Mendes from the University of Porto – Faculty of Engineering coordinates the Horizon-funded project “112CO2 – Low temperature catalytic methane decomposition for COx-free hydrogen production” A game-changer low temperature catalytic methane decomposition process proved already >2500 h of continuous operation at 550°C with a constant catalyst productivity of 0.64 gH2/gCat/h. But the experiment is going on, aiming at reaching over 6000 h of fully stable operation, by September 2023; at that moment the technology will reach the stability milestone for becoming a commercial solution. The methane decomposition membrane reactor operates between 550°C and 700°C producing pure hydrogen, according to the reaction equation:

A thermodynamic methodology toward an optimized methane decomposition process for enhanced hydrogen production and low carbon accumulation: Effect of non-hydrocarbon co-feeds

Methane decomposition (MD) is emerging as a proficient technology to pure hydrogen production from a variety of methane-based feedstocks (renewables and non-renewables). Besides pure H2(g), accumulated carbonaceous materials can be extracted and used in electronic devices and catalysis. MD is far from industrialization owing to heavy carbon accumulation leading to immediate deactivation of catalysts. In this work, thermodynamic equilibrium analysis was performed using Gibbs free energy minimization. Temperature (range: 200–1000 °C), (ii) pressure (range: 1–20 bar) and, (iii) feed composition (CH4(g) along with H2O(g), CO2(g) and/or O2(g)) were tuned with an aim to identify theoretical conditions insuring maximized H2(g) generation, low C(s) accumulation and, lesser extent of by-products(g). Operating MD at 800 °C and 1 bar are requirements to achieve maximum methane conversion into H2(g) along with considerable C(s) amounts. Co-feeding of methane with any O2-baring species minimizes carbon accumulation especially in presence of O2(g), (O2+H2O)(g), (CO2+O2)(g) or (CO2+O2+H2O)(g) streams. Not all types of co-feeds are capable of yielding H2(g) in amounts exceeding those expected from pure CH4(g) decomposition. Nonetheless, co-feeding methane with H2O(g) or H2O(g)-containing feed(s) insures maximized H2(g) production. Moreover, depending on the chemistry and content of such species, thermodynamic abundance of by-products can be minimized.

Facile synthesis of Co-Rh bimetallic catalysts for methane decomposition: Effect of support morphology

In this study, the performance of 10 wt.% Co -1 wt. % Rh/TiO2 catalysts with varying textural properties have been investigated to produce the hydrogen and carbon nanotubes via the methane decomposition process. An improved evaporation-induced self-assembly approach synthesized the mesoporous TiO2 supports, and Co-Rh nanoparticles over the as-synthesized TiO2 supports were created by the co-impregnation method. XRD, BET, TGA, SEM, and TEM studies characterized the fresh and used catalysts. The findings revealed that the texture of TiO2 support has an important influence on catalytic performance. With the increase in calcination temperature, the specific surface area of the catalysts decreases while the anatase content of TiO2 species increases. The catalyst prepared with TiO2 calcined at 600 °C displayed superior catalytic activity and stability due to the better metal dispersion and higher anatase phase content in support. The initial activity depended on the specific surface area, whereas the stability or the hydrogen productivity for the equal deactivation level was related to the anatase composition of the catalyst. The nature of deposited carbon varies due to the phase composition of TiO2. The SEM and TEM images revealed that anatase TiO2 generated smaller multi-walled carbon nanotubes (MWCNTs) with a more consistent diameter distribution than the other catalysts. Catalysts with an amorphous composition increase the formation of CHx carbon species. The apparent activation energies for various Co-Rh catalysts varied between 65 and 85 kJ mol−1. The Co-Rh bimetallic combination had more significant activity than the Ni metal.

Utilization of palm oil fuel ash (POFA) as catalyst support for methane decomposition

An agricultural waste, palm oil fuel ash (POFA) has been evaluated as a Ni catalyst support for the methane decomposition process. The effects of solvent and pre-treatment technique during the POFA pre-treatment have been investigated towards the catalytic performance of Ni supported on POFA (Ni-POFA) catalyst prepared at 10 wt% Ni loading. Methane decomposition of Ni-POFA catalyst was carried out at 550 °C for 6 hrs. The POFA and Ni-POFA were characterized using X-ray fluorescence (XRF), X-ray diffractometer (XRD), N2 adsorption–desorption isotherms and field emission scanning electron spectroscopy (FESEM). The results showed that citric acid solution was the best solvent for POFA pre-treatment. The SiO2 content in the POFA pre-treatment improved from 42.4 to 72 wt%. Good CH4 conversion achieved by Ni-POFA catalyst in the methane decomposition was attributed to high SiO2 in the POFA treated with citric acid. Compared to conventional stirring, pre-treatment of POFA with ultra-sonication technique has produced POFA support with smaller particles size, and Ni-POFA catalyst with better BET surface area and better Ni dispersion. These catalyst properties have contributed to an exceptional catalytic performance of 71% of initial CH4 conversion and 4.2% of initial H2 yield of Ni-POFA catalyst in the methane decomposition. The work suggests that POFA has the potential to be utilized as catalyst support, and pre-treatment is crucial for a reasonable catalytic performance in methane decomposition.

Synthesis and optimization of hydrotalcite derived Ni-Fe-Cu based catalysts for catalytic methane decomposition process using the design of experiment approach

The optimization of hydrotalcite-derived Ni-Fe-Cu-based tri-metallic catalyst for methane catalytic decomposition has been studied using the Taguchi method. Taguchi L9 orthogonal array consisting of four design factors and one response was considered in the optimization study. The catalysts were thoroughly characterized using various techniques like XRD, BET, H2-TPR, FE-SEM, TGA/DTG, and Raman spectroscopy. The optimization study results revealed that the methane decomposition catalyst's performance and the nature of deposited carbon depend on the catalyst's composition. Both graphitic and carbon nanotubes have been deposited in spent catalysts. The diameter of carbon nanotubes formed over the catalyst depends mainly on the Ni loading. The optimal reaction conditions were found to be 14 wt.% Ni loading, 2 wt.% Fe loading, 2 wt.% Cu loading and 700 °C of calcination temperature. The catalyst performance quality was increased by around 30% at optimal conditions after implementing the Taguchi experiment.

Thermocatalytic decomposition of methane on carbon materials and its application in hydrogen production technologies

It is topical now to find the ways of hydrogen production that would eliminate emission of carbon oxides into the atmosphere and provide implementation of the so-called low-carbon economy. The production of hydrogen via thermocatalytic methane decomposition (CMD) on carbon catalysts makes it possible to obtain not only a valuable environmentally friendly fuel represented by hydrogen but also various carbon materials that could be applied in different industries. The use of carbon catalysts is essential for economic efficiency of the methane decomposition process. This work is a review of CMD fundamentals and a brief report on the catalytic activity of carbon materials (activated carbon, carbon black, nanotubes and nanofibers) differing in their structure, physical and chemical properties, which were studied in the indicated process. The main problems and prospects for application of this technology were revealed.

Hydrogen production by methane decomposition: Analysis of thermodynamic carbon properties and process evaluation

Methane decomposition is a promising approach to reduce the carbon footprint of hydrogen production. Solid carbon is one of the products and can improve the economics as a valuable byproduct or it is to be stored. The morphology of the produced carbon affects not only its economic value, but thermodynamic properties as well. Thermodynamic properties of graphite are usually used for modelling and simulation tasks for methane decomposition. In this study, the impact of the produced carbon type on the decomposition of methane is analyzed. Based on experimental data from literature for e.g. amorphous carbon, carbides, carbon filaments and nanotubes, the equilibrium of the methane decomposition reaction in dependence of temperature and carbon type is evaluated. The highest equilibrium methane conversion is observed for multiwall carbon nanotubes and the lowest for coke as carbon product. If another carbon morphology than graphite occurs, the reaction enthalpy is, in average, increased by 17.6%. To evaluate the potential influence on a production process, a methane decomposition process based on an electrically heated moving bed reactor is simulated. The specific electrical energy input and the methane consumption is calculated in dependence of the main process parameters and the produced carbon type. In a base case simulation the specific electrical energy input is 1.13kWh/NmH23. About 60% of the electrical power is required for heating the reactor. The energy input is highly affected by the amount of recycled bed material, the effectiveness of heat transfer, the methane conversion and by the carbon type. In the simulated temperature range of between 800 and 1300 K, the specific electrical energy input for a produced carbon type that differs from graphite is in average increased by 14.2% and by 58% in maximum. Further research on thermodynamic properties of different carbon types and their relevance for different methane pyrolysis processes is required.

Deposition of vertical carbon nanosheets by MPECVD at atmospheric pressure

The deposition process is studied of vertical carbon nanosheets by microwave (MW) plasma-enhanced chemical vapor deposition (PECVD) at atmospheric pressure. A coaxial MW plasma source with a surface-wave discharge at 2.45 GHz produces plasma in a gas mixture (Ar/H2/CH4) in the processing chamber. The emissive spectra of the plasma column in pulsed regime of the source are registered by an iHR550 spectrometer. The light from the plasma column is collected by a lens system connected to the spectrometer by an optical fiber. The dependence of the gas temperature in the plasma column on the absorbed MW power is obtained from the recorded OH-band and CN-band spectra by using the LIFBASE program. The plasma density is estimated from the Stark broadening of the Hβ-line, while the electron temperature is estimated by the line-ratio method using argon lines. The composition of the outlet gases from the chamber is measured and analyzed by an Agilent Micro gas chromatograph. The results obtained demonstrate the high efficiency of the methane decomposition process in the hot region of the plasma column (T g ~ 3000 K). The deposition of vertical carbon nanosheets is carried out at fixed plasma parameters and controlled substrate temperature. Cu plate and Ni-foam are used as substrates. The carbon nanostructures formed on the metallic substrates are studied by SEM; the dependence is thus obtained of their morphology on the plasma parameters, gas temperature and substrate temperature. The structures are confirmed as graphene sheets via Raman spectroscopy. The results demonstrate the viability of our system for deposition of vertical carbon sheets at atmospheric pressure.

Joint-use of activated carbon and carbon black to enhance catalytic stability during chemical looping methane decomposition process

Chemical-looping methane decomposition using activated carbon as a catalyst has been considered a potentially promising approach for high-purity H2 production with low cost and low CO2 emission. However, activated carbon is known to deactivate fast despite its high initial catalytic activity. Oppositely, carbon black has shown stable catalytic methane decomposition that even increases slowly with time of reaction. Considering these two different activity trends, activated carbon and carbon black are jointly used to prepare catalysts and then test for the decomposition of the methane via chemical looping in this study that aimed to examine catalyst and reaction properties which may combine the high initial activity of activated carbon with the steady-and-increasing activity of carbon black. These mixed catalysts are examined using X-ray diffraction analysis (XRD), scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS), Brunauer-Emmett-Teller (BET) and high-resolution transmission electron microscopy (HRTEM) before and after reaction testing to reveal chemical and physical constituents which contributed to their reactivities, and the mechanism of long catalytic activity has been discussed. The results point to insights and potential directions for modifying carbonaceous catalysts for chemical looping thermo-catalytic decomposition of methane.

Optimization of a fluidized bed reactor for methane decomposition over Fe/Al2O3 catalysts: Activity and regeneration studies

Catalytic methane decomposition was investigated over 40 wt% Fe/Al2O3 catalyst in fluidized bed reactor (FLBR). After optimization of FLBR conditions in terms of catalyst bulk density, particle size, minimum fluidization velocity, and the catalyst bed height, the catalyst activity and stability tests were conducted by comparison with a fixed bed reactor (FBR). Although a similar stable methane conversion was obtained over both reactors, the pressure drop during 35 min operation of FBR was 9 times higher than that of FLBR, which indicated the possibility of continuous operation of methane decomposition process over FLBR. Further, the influence of the space velocity, feed dilution and regeneration on catalysts reactivity was studied in FLBR to conclude that a reaction condition of 12 L/gcat∙h, feed of 20%H2–80%CH4 and CO2-regeneration of deactivated catalysts may be favourable for operating methane decomposition in FLBR continually and effectively to provide stable hydrogen.

Optimization of nickel loading of mixed oxide catalyst ex-hydrotalcite for H2 production by methane decomposition

Hydrogen production free of CO and CO2 was carried out by methane decomposition process using Ni-mixed oxides from hydrotalcite like-materials (ex-HTs) as catalysts. The chemical composition was changed in order to evaluate the influence of the Ni-loading on the main physicochemical (ICP-AES, XRD, XPS, TPR, adsorption/desorption of N2 at 77K and CO2-TPD) properties and on the catalytic performance. For all Ni-loadings (from 7.5 to 58 atomic%), the hydrotalcite structure was the only precursor. After calcination at 850°C, different mixed oxides were formed as a function of Ni-loading, although Ni-Mg-Al mixed oxide matrix or non-stoichiometric spinel phase was the main phase for all catalysts, with the exception of the 58 Ni atomic% sample, in which the NiO segregated from the Mg-Al matrix was the main phase.Methane conversion close to 55% was achieved, hydrogen was the only gaseous product. The most active catalyst was that containing 46% Ni at. Transmission Electron Microscopy (TEM) images of the spent catalysts showed the appearance of multiwall carbon nanotubes (MWCNTs) although under severe reaction conditions, e.g. high temperatures for thermo-programmed temperature experiments, and the long reaction times for isothermal experiments produced low quality MWCNTs.

Rotating gliding arc assisted methane decomposition in nitrogen for hydrogen production

Hydrogen production from methane decomposition via an atmospheric pressure rotating gliding arc (RGA) discharge reactor co-driven by a magnetic field and tangential flow is investigated. The motion and V–I characteristics of the RGA are studied with a high-speed camera and oscilloscope. Optical emission spectroscopy (OES) is used to characterize RGA plasmas in N2 and CH4 + N2, and the RGA plasma is shown to occur as a warm plasma. For the CH4 + N2 plasma, CN, C2, and CH spectral lines are observed. The vibrational and rotational temperatures are 0.56–0.86 eV and 1325–1986 K, respectively. The effects of load resistance, the CH4/N2 ratio, and the feed flow rate on the performance of methane decomposition are investigated. The maximum CH4 conversion rate and H2 selectivity are 91.8% and 80.7% when the CH4/N2 ratio is 0.1 and 0.05, respectively, at a flow rate of 6 L/min. The possible reaction mechanisms of the methane decomposition process are discussed. This study is expected to establish a basis for the further industrial applications of H2 production.

Hydrogen production via decomposition of methane over activated carbons as catalysts: Full factorial design

The thermo-catalytic decomposition of methane is proposed as an alternative for producing hydrogen without CO2 emissions. The present study was divided into three parts. First, a screening study of the rate of methane decomposition (RCH4) was performed using two types of activated carbons as catalysts with progressive time of methane decomposition at four different temperatures. The catalysts differed in textural properties. A full factorial design consisting of 20 experimental points for each catalyst was applied in the second part. Quadratic RCH4 models as functions of the relative time of catalyst deactivation and decomposition temperature were developed by regression analysis of variance. The results of the RCH4 models showed that the relative time had twice as much influence as temperature. Finally, a general RCH4 model was then developed representing both catalysts regardless of their textural properties. All the empirical models were consistent with experimental results and were adequate for designing the methane decomposition process.

Effect of Ball-Milling Parameter on the Synthesis of MWCNT/Alumina Hybrid Compound

The effects of ball-milling parameter on the structures and properties of the synthesis of multi-walled carbon nanotubes (MWCNT)/alumina hybrid compound via methane decomposition process using Ni-Alumina catalyst were researched. The structural evaluation of particles compound was investigated by particle size analysis, energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), FTIR spectrometer and scanning electron microscopy (SEM). The results indicated that with 300rpm 15h, the microstructure of the hybrid compound is greatly refined, and methane decomposition process distributed uniformly, thus increasing the efficiency of the carbon nanotubes growth process.

Methane as an effective hydrogen source for single-layer graphene synthesis on Cu foil by plasma enhanced chemical vapor deposition

A single-layer graphene is synthesized on Cu foil in the absence of H(2) flow by plasma enhanced chemical vapor deposition (PECVD). In lieu of an explicit H(2) flow, hydrogen species are produced during the methane decomposition process into their active species (CH(x<4)), assisted with the plasma. Notably, the early stage of growth depends strongly on the plasma power. The resulting grain size (the nucleation density) has a maximum (minimum) at 50 W and saturates when the plasma power is higher than 120 W because hydrogen partial pressures are effectively tuned by a simple control of the plasma power. Raman spectroscopy and transport measurements show that decomposed methane alone can provide a sufficient amount of hydrogen species for high-quality graphene synthesis by PECVD.

Synthesis of MWCNT-Alumina Hybrid as Composite Reinforcement Using Nickel Catalyst

This work focuses on synthesis of MWCNT-alumina hybrid compound via methane decomposition process using nickel catalyst. The catalysts prepared through in situ process by using nickel salt and aluminium powder which then calcined at 900oC followed by methane decomposition process to grow MWCNT on alumina surface. The Scanning Electron Microscopy (SEM) and High Resolution Transmission Electron Microscopy (HRTEM) images confirmed the formation of MWCNT with homogenous dispersion on alumina particles.

Effect of catalyst calcination temperature on the synthesis of MWCNT–alumina hybrid compound using methane decomposition method

This work focuses on synthesis of MWCNT–alumina hybrid compound via methane decomposition process using Ni–Al 2O 3 catalyst. The catalysts prepared through in situ process by using nickel salt and aluminium powder which are then calcined at three different calcination temperatures (700 °C, 900 °C and 1100 °C). The catalyst calcined at 900 °C followed by methane decomposition process successfully yielded MWCNT–alumina hybrid compound. No trace of CNT was detected for catalyst calcined at 700 °C and 1100 °C. The scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) micrograph confirmed the formation of MWCNT with homogenous dispersion on alumina particles.

An experimental investigation into the CO 2 gasification of deactivated activated-carbon catalyst used for methane decomposition to produce hydrogen

A series of experiments was conducted to study the CO 2 gasification of a deactivated palm-shell-based activated-carbon (ACPS) catalyst used for the thermocatalytic decomposition of methane to produce hydrogen. This catalyst becomes deactivated due to the accumulation of carbon deposits during the methane-decomposition process. The CO 2 gasification was carried out at 850, 900, 950 or 1000 °C to study the deactivated ACPS, which was used at methane-decomposition temperatures of 850 or 950 °C. A series of six methane-decomposition cycles at 950 °C alternating with five gasification cycles using CO 2 at 900, 950 and 1000 °C was also carried out to evaluate the stability of the catalyst. The experiments were conducted using a thermobalance by monitoring the change in mass of the catalyst with time, i.e., the mass gain during methane decomposition or the mass loss during CO 2 gasification. Gasification of the virgin and deactivated ACPS showed strong temperature dependence, with the half and complete gasification times having an exponential dependence on temperature. The gasification reactivity at different conversions was higher for the virgin ACPS and increased with increases in the decomposition temperatures used for deactivation of the ACPS. The activation energies of virgin ACPS and ACPS deactivated at a decomposition temperature of 850 °C decreased with an increase in conversion, while they increased for the ACPS deactivated at a decomposition temperature of 950 °C; the activation energies varied between 81 and 163 kJ/mol. The gasification reactivity changed with methane conversion, showing maximum values for both the virgin and deactivated ACPS at a decomposition temperature of 950 °C. The initial gasification reactivity of the catalyst decreased after three gasification cycles at 1000 °C, while no significant change was observed with gasification cycles at 950 or 900 °C.