Decomposition Of Natural Gas Research Articles

Catalytic methane decomposition process on carbon-based catalyst under contactless induction heating

Hydrogen obtained from decomposition of natural gas with direct sequestration of carbon in solid form could be an attractive and cost-effective alternative for large-scale hydrogen production. We report here the use of a carbon-based catalyst to achieve the catalytic decomposition of methane (CMD) at medium temperature, 800 °C, under induction heating (IH). Analyses of the catalytic results and characterizations of the spent catalyst have shown that the carbon deposited during the reaction acts as the active phase for the reaction and can, therefore, be recycled infinitely. This autocatalytic effect can only be observed when the carbon catalyst operates under IH because the same catalyst operating under Joule heating (JH) deactivates rapidly in the same way as that already reported in the literature and no autocatalytic effect has been observed. The carbon formed is in the form of a graphene layer with a high degree of graphitization and is completely different from the carbon black powder obtained in other processes. These promising results could lay the groundwork for the development of an industrially and economically viable way to convert natural gas into turquoise hydrogen, using renewable energy and low-cost catalysts, with better resistance to poisoning by impurities present in the processing load. The combination of a carbon-based catalyst and non-contact IH could also lead to combined catalytic processes for many challenging reactions.

High-efficiency graphene-coated macroscopic composite for catalytic methane decomposition operated with induction heating

The large-scale production of hydrogen and the direct sequestration of carbon, in solid form, from the decomposition of natural gas could constitute an attractive economic alternative for the production of hydrogen if deactivation by coke or sintering could be mitigated. Here, we report on the use of a 2D graphene-based catalyst with controlled macroscopic shape for the catalytic decomposition of methane (CMD) at medium temperature, ranged from 500 °C to 900 °C, under contactless inductive heating. The presence of a magnetic field seems to have a strong influence on the catalytic performance and allows the maintain of the catalyst stability. Characterizations of the spent catalyst showed that the carbon deposited under inductive heating is in the form of carbon filaments which grow away from the edges or defects of the graphene. This particular growth mode allows one to maintain the catalytic activity of such carbon-based catalyst over longer periods compared to those reported in the literature. These promising results could set a base ground for the develop an industrially and economically viable way to convert natural gas into turquoise hydrogen, using renewable energy and low-cost catalysts, with improved resistance to poisoning by impurities present in the processing charge. The carbon formed could also be effectively use in other downstream applications. The combination of carbon-based catalyst and contactless induction heating could also lead to combined catalytic processes for numerous challenging reactions.

Transient analysis of solar pyrolysis and hydrogen yield via interband cascade laser absorption spectroscopy of methane, acetylene, ethylene, and ethane

A mid-infrared laser absorption sensing method has been developed to measure species concentrations of four hydrocarbons and gas temperature over a range of temperatures in mixture compositions relevant to the pyrolytic decomposition of natural gas. The four measured species (methane, acetylene, ethylene, and ethane) are the most abundant hydrocarbons during the pyrolysis of natural gas, and provide a means to monitor decomposition progress and hydrogen yield through molar balance. In this work, time-division multiplexed signals of three distributed-feedback interband cascade lasers are used to make simultaneous measurements of select C-H stretch rovibrational transitions of the target hydrocarbons in the 3.00–3.34 μm range. The sensor was validated over a range of temperatures and pressures (300–1000 K, 0.03–1 atm) at relevant mixture compositions, with correction methods developed to mitigate cross-species interference. The sensor was demonstrated on a solar-thermal pyrolysis reactor, where time-resolved measurements of species mole fractions were performed across a range of insolation conditions to capture the transient response of the reactor.

Synthesis of COx-free hydrogen via natural gas decomposition over titanium dioxide-supported bimetallic catalysts

Nickel and cobalt-based titania-supported bimetallic catalysts were synthesized using the co-precipitation technique. The total metal loading varied between 20 and 60 wt% while keeping nickel to cobalt ratio of unity. In comparison with low-loading catalysts i.e., 10 and 15 wt% each of nickel and cobalt supported over titania (10NCT and 15NCT), high-loading catalysts (20NCT, 25NCT, and 30NCT) have shown higher activity and stability performances. Among the high-loading catalysts, 25NCT catalyst outperformed the rest of the catalysts with the highest methane conversion and carbon yield. The higher specific surface area (115.1 m2/g), evaluated from physisorption, facilitates better metal particle dispersion; suitable metal-support interaction, and number of reducible species determined by temperature-programmed reduction, have played a vital role in enhanced activity of 25NCT. The morphological analysis revealed the formation of carbon nanotubes via following both tip-growth and base-growth mechanisms.

Optimization of nickel catalyst loading in Ni/γAl2O3 for producing carbon nanotubes through natural gas decomposition

Carbon nanotubes can be produced at high quality through hydrocarbon catalytic decomposition. In addition, hydrogen can be produced as a valuable byproduct at a competitive price. In this article, the loading of the active phase in the decomposition catalyst is optimized using natural gas as a widely available hydrocarbon. Natural gas decomposition was investigated using different nickel loadings. Natural gas decomposition, as a widely available hydrocarbon, is investigated by manipulating nickel loading to optimize the loading of the active phase in the decomposition catalyst.Optimizing the catalyst loading can achieve higher quality and yield of carbon nanotube. In addition, a higher carbon nanotube yield will maximize hydrogen production. Increasing the quality of produced carbon and the amount of hydrogen will improve the overall process economics. Nickel is a highly active catalyst for natural gas decomposition and has a higher carbon affinity compared to other metallic catalysts. Different nickel loadings were tested for natural gas decomposition. Optimization was used to calculate the optimum nickel loading based on the experimental results. The optimum nickel loading over alumina was 12.5%. The economic analysis of the process indicated that the optimum nickel loading is 30%.

PROMISING TECHNOLOGIES AND EXISTING EXPERIENCE OF CARBON DIOXIDE EXTRACTION FROM PROCESS AND WASTE GASES

The main technologies for carbon dioxide capturing are analyzed. Promising technologies include “before burning” CO2 capture and CO2 injection into depleted oil fields to enhance oil recovery, which make it possible not only to reduce residual oil saturation, but also to reduce carbon dioxide emissions into the atmosphere effectively. The energy costs of amine processes for extracting carbon dioxide from biogas are analyzed with the use of computer simulation. To extract carbon dioxide from process gases a traditional single-flow absorption scheme can be used in which MDEAmod absorbents the optimal in terms of energy performance minimizing. The MDEAmod absorbent is universal and can be used in CO2 extraction processes, including those under high pressure, from various process gases, in which the CO2 content can vary over a wide range of concentrations and reach 45 % (vol.). The use of this absorbent reduces the heat consumption for the regeneration of the saturated sorbent by 1.4–2.5 times compared to 18 % MEA and reduces the absorbent consumption by 30 %. A laboratory unit for extracting target fractions of biomethane and carbon dioxide from biogas has been created. The model calculation results of the amine CO2 extracting from biogas and those obtained on a laboratory unit are quite close and the deviation of the calculated from the experimentally obtained CH4 concentration in biomethane at a pressure in the absorber Pabs = 0.11–0.2 MPa does not exceed 3 %. The results of extracting carbon dioxide from biogas modeling can be used to optimize the technological absorption schemes for the production of biomethane - an analogue of natural gas. Experimental technology has been developed and equipment for the production and decomposition of natural gas and carbon dioxide hydrates has been created. The thermodynamic parameters of hydrate formation by bubbling have been determined, and hydrate samples have been obtained. Thermodynamic trend of pressure difference of 1.5–2 MPa to methane replace with carbon dioxide in hydrates was experimentally established and thus the possibility of replacing methane gas hydrates with carbon dioxide and using this technology for the conditions of developing gas hydrate deposits in the Black Sea was confirmed. Bibl. 30, Fig. 10, Tab. 3.

Comparative assessment of blue hydrogen from steam methane reforming, autothermal reforming, and natural gas decomposition technologies for natural gas-producing regions

Interest in blue hydrogen production technologies is growing. Some researchers have evaluated the environmental and/or economic feasibility of producing blue hydrogen, but a holistic assessment is still needed. Many aspects of hydrogen production have not been investigated. There is very limited information in the literature on the impact of plant size on production and the extent of carbon capture on the cost and life cycle greenhouse gas (GHG) emissions of blue hydrogen production through various production pathways. Detailed uncertainty and sensitivity analyses have not been included in most of the earlier studies. This study conducts a holistic comparative cost and life cycle GHG emissions’ footprint assessment of three natural gas-based blue hydrogen production technologies – steam methane reforming (SMR), autothermal reforming (ATR), and natural gas decomposition (NGD) to address these research gaps. A hydrogen production plant capacity of 607 tonnes per day was considered. For SMR, based on the percentage of carbon capture and capture points, we considered two scenarios, SMR-52% (indicates 52% carbon capture) and SMR-85% (indicates 85% carbon capture). A scale factor was developed for each technology to understand the hydrogen production cost with a change in production plant size. Hydrogen cost is 1.22, 1.23, 2.12, 1.69, 2.36, 1.66, and 2.55 $/kg H2 for SMR, ATR, NGD, SMR-52%, SMR-85%, ATR with carbon capture and sequestration (ATR-CCS), and NGD with carbon capture and sequestration (NGD-CCS), respectively. The results indicate that when uncertainty is considered, SMR-52% and ATR are economically preferable to NGD and SMR-85%. SMR-52% could outperform ATR-CCS when the natural gas price decreases and the rate of return increases. SMR-85% is the least attractive pathway; however, it could outperform NGD economically when CO2 transportation cost and natural gas price decrease. Hydrogen storage cost significantly impacts the hydrogen production cost. SMR-52%, SMR-85%, ATR-CCS, and NGD-CCS have scale factors of 0.67, 0.68, 0.54, and 0.65, respectively. The hydrogen cost variation with capacity shows that operating SMR-52% and ATR-CCS above hydrogen capacity of 200 tonnes/day is economically attractive. Blue hydrogen from autothermal reforming has the lowest life cycle GHG emissions of 3.91 kgCO2eq/kg H2, followed by blue hydrogen from NGD (4.54 kgCO2eq/kg H2), SMR-85% (6.66 kgCO2eq/kg H2), and SMR-52% (8.20 kgCO2eq/kg H2). The findings of this study are useful for decision-making at various levels.

Ni-\u03b3-AL2O3 catalysts for obtaining nanocarbon by decomposition of natural gas

γ-Al2O3 was synthesized by the Sol–gel method, Ni (NO3)2 was placed in the pores by the impregnation method, and Ni-γ-Al2O3 was obtained by pyrolysis in a hydrogen stream in a CVD device. By the method of chemical vapors phase deposition (CVD) on Ni-Al2O3 catalytic converter with decomposition of methane in the natural gas produced carbon nanotubes (CNT) (Chunduri et al. in Mater Express 4(3):235–241, 2014; Zhou et al. in Appl Catal B 208:44–59, 2017). The catalytic activity of the catalysts in methane decomposition was examined from 650 °C to 900 °C by the method of chemical vapors phase deposition (CVD), the yield of CNTs tends to increase with the growth at the ratio of natural gas supply to hydrogen. The specific surface increases with an increase of nickel content and can reach 265.5 m2/g for a sample of 2% Ni-A12O3 at 850 °C. Growth at the temperature of methane decomposition leads to reduction in its specific surface. It has been established that the use of the Ni-Cu/γ-Al2O3 catalytic system, in which copper acts as a stabilizing additive, makes it possible to double the maximum yield of the carbon product during the decomposition of natural gas.

ПРИМЕНЕНИЕ ПРОЦЕССА КАРНОЛА ДЛЯ ПРОИЗВОДСТВА МЕТАНОЛА И СНИЖЕНИЯ ВЫБРОСОВ УГЛЕКИСЛОГО ГАЗА

The Carnol system is the production of methanol from carbon dioxide (obtained from coal-fired power plants) and natural gas, and the use of the resulting methanol as an alternative fuel. The Carnol process produces hydrogen by thermal decomposition of natural gas, which then interacts with the CO2 extracted from the flue emissions of power plants. The resulting carbon can be stored or used as a raw material. The paper provides an estimated characteristic of the reduction of CO2 emissions of the Carnol process and system, and compares it with other traditional methanol production processes, including the use of biomass of industrial raw materials and vehicles powered by methanol fuel cells. CO2 emissions from a Carnol system that uses methanol as an alternative fuel can be reduced by 56 % compared to a conventional coal-fired power plant system. In the case of the use of methanol as fuel for motor vehicles, carbon dioxide emissions.

An Overview of Economic Analysis and Environmental Impacts of Natural Gas Conversion Technologies

This study presents an overview of the economic analysis and environmental impact of natural gas conversion technologies. Published articles related to economic analysis and environmental impact of natural gas conversion technologies were reviewed and discussed. The economic analysis revealed that the capital and the operating expenditure of each of the conversion process is strongly dependent on the sophistication of the technical designs. The emerging technologies are yet to be economically viable compared to the well-established steam reforming process. However, appropriate design modifications could significantly reduce the operating expenditure and enhance the economic feasibility of the process. The environmental analysis revealed that emerging technologies such as carbon dioxide (CO2) reforming and the thermal decomposition of natural gas offer advantages of lower CO2 emissions and total environmental impact compared to the well-established steam reforming process. Appropriate design modifications such as steam reforming with carbon capture, storage and utilization, the use of an optimized catalyst in thermal decomposition, and the use of solar concentrators for heating instead of fossil fuel were found to significantly reduced the CO2 emissions of the processes. There was a dearth of literature on the economic analysis and environmental impact of photocatalytic and biochemical conversion processes, which calls for increased research attention that could facilitate a comparative analysis with the thermochemical processes.

Hydrogen and hydrogen-derived fuels through methane decomposition of natural gas – GHG emissions and costs

Abstract Hydrogen can be produced from the decomposition of methane (also called pyrolysis). Many studies assume that this process emits few greenhouse gas (GHG) because the reaction from methane to hydrogen yields only solid carbon and no CO2. This paper assesses the life-cycle GHG emissions and the levelized costs for hydrogen provision from methane decomposition in three configurations (plasma, molten metal, and thermal gas). The results of these configurations are then compared to electrolysis and steam methane reforming (SMR) with and without CO2 capture and storage (CCS). Under the global natural gas supply chain conditions, hydrogen from methane decomposition still causes significant GHG emissions between 43 and 97 g CO2-eq./MJ. The bandwidth is predominately determined by the energy source providing the process heat, i.e. the lowest emissions are caused by the plasma system using renewable electricity. This configuration shows lower GHG emissions compared to the “classical” SMR (99 g CO2-eq./MJ) but similar emissions to the SMR with CCS (46 g CO2-eq./MJ). However, only electrolysis powered with renewable electricity leads to very low GHG emissions (3 g CO2-eq./MJ). Overall, the natural gas supply is a decisive factor in determining GHG emissions. A natural gas supply with below-global average GHG emissions can lead to lower GHG emissions of all methane decomposition configurations compared to SMR. Methane decomposition systems (1.6 to 2.2 €/kg H2) produce hydrogen at costs substantially higher compared to SMR (1.0 to 1.2 €/kg) but lower than electrolyser (2.5 to 3.0 €/kg). SMR with CCS has the lowest CO2 abatement costs (24 €/t CO2-eq., other > 141 €/t CO2-eq.). Finally, fuels derived from different hydrogen supply options are assessed. Substantially lower GHG emissions, compared to the fossil reference (natural gas and diesel/gasoline), are only possible if hydrogen from electrolysis powered by renewable energy is used (>90% less). The other hydrogen pathways cause only slightly lower or even higher GHG emissions.

Use of Thermal Black as Eco-Filler in Thermoplastic Composites and Hybrids for Injection Molding and 3D Printing Applications.

Thermal black (TB) is one of the purest and cleanest forms of carbon black (CB) commercially available. TB is manufactured by the decomposition of natural gas in the absence of oxygen while the common furnace CB is derived from the burning of organic oil. TB has a larger particle size, a lower surface area, and lower level of particle aggregation, while being the most eco-friendly grade among the CB family. This study is the first-time evaluation of TB as filler in composites and hybrids based on thermoplastics such as polypropylene (PP), polyamide 6 (PA6), polyphenylene sulfide (PPS), and acrylonitrile butadiene styrene (ABS). TB loadings in composites were varied from 1 up to 40 wt. % and, in hybrids, the TB was used in combination with carbon fibers (CFs) at total contents up to 20 wt. %. TB-containing composites and hybrids based on PA6 and ABS were also extruded in filaments, used in 3D printing, and the obtained 3D printed parts were characterized. TB provided a very high loadability in thermoplastics while preserving their viscosity and performance. TB can replace a fraction of expensive CFs in composites without important changes in the composites’ performance. The composites and hybrids exhibited electrical resistivity and good mechanical and thermal properties when compared to commercial compounds, while enabling significant cost savings. TB also showed to be an excellent coloring agent. TB proved to be an outstanding eco-filler for compounds to be used in injection molding and 3D printing technologies.

Hydrogen production via thermocatalytic decomposition of methane over Ni-Cu-Pd/Al2O3 catalysts

Non-oxidative decomposition of natural gas is a handsome technique for clean hydrogen production but high reaction temperature and rapid catalyst deactivation limitizes its applications. In current work, decomposition of methane into COX free hydrogen and carbon nanofiber were studied over the bimetallic catalysts. The materials were prepared by wet impregnation method and analyzed by BET, TGA, XRD, FESEM, and TEM. It was observed that with an increase in the metal loading, the surface area was reduced but the methane conversions and catalyst stability were improved since the catalyst activity depend upon the active nickel sites that compensate the surface deficiencies. The highest conversion was given by Ni–Cu–Pd/Al2O3 (80%) over a period of 6 h despite having a low BET surface area (2.43 m2 g−1). The physiochemical properties reported that the synthesized catalyst possessed nanostructure and CNF were also produced along with hydrogen as products of TCD.

Generalized Redox-Responsive Assembly of Carbon-Sheathed Metallic and Semiconducting Nanowire Heterostructures.

One-dimensional metallic/semiconducting materials have demonstrated as building blocks for various potential applications. Here, we report on a unique synthesis technique for redox-responsive assembled carbon-sheathed metal/semiconducting nanowire heterostructures that does not require a metal catalyst. In our approach, germanium nanowires are grown by the reduction of germanium oxide particles and subsequent self-catalytic growth during the thermal decomposition of natural gas, and simultaneously, carbon sheath layers are uniformly coated on the nanowire surface. This process is a simple, reproducible, size-controllable, and cost-effective process whereby most metal oxides can be transformed into metallic/semiconducting nanowires. Furthermore, the germanium nanowires exhibit stable chemical/thermal stability and outstanding electrochemical performance including a capacity retention of ∼96% after 1200 cycles at the 0.5-1C rate as lithium-ion battery anode.

Effect of structural promoters on the catalytic performance of cobalt-based catalysts during natural gas decomposition to hydrogen and carbon nanotubes

ABSTRACTCatalytic thermal decomposition of natural gas to CO/CO2-free hydrogen production was studied over cobalt catalysts supported on Al2O3, MgO, and SiO2. The physico-chemical properties of the fresh catalysts were investigated by X-ray diffraction (XRD), temperature-programmed reduction (TPR), and surface area. In addition, the morphological structure of as-deposited carbon over the spent catalysts was characterized by transmission electron microscope (TEM), Raman spectroscopy, thermogravimetric analysis, and XRD. The obtained results proved that the catalytic activity and longevity of the cobalt-based catalysts strongly depended on the nature of the applied support. Among the catalysts tested, the Co/Al2O3 catalyst exhibited the highest activity and stability due to the higher dispersion and stabilization of cobalt particles because of formation of CoAl2O3 spinel phase. The lower activity of Co/SiO2 catalyst is mainly attributed to the aggregation of cobalt metal particles because of weak metal–support interaction. It was observed that both type and morphological structure of deposited carbon were strictly depended on the nature of the support. TEM images revealed that multi-walled carbon nanotubes were produced over Al2O3- and MgO-supported catalysts, whereas both carbon nanofibers and amorphous carbon were formed over the Co/SiO2 catalyst.

La2O3 supported bimetallic catalysts for the production of hydrogen and carbon nanomaterials from methane

The production of hydrogen and carbon nanomaterials was investigated via catalytic decomposition of natural gas. Bimetallic catalysts, containing Ni and Co, supported over La2O3 were tested for decomposition reaction. The variation in metal loading, gas hourly space velocity (GHSV) and reaction temperature were studied to assess the influence of these important parameters on the catalytic performance. The catalytic testing and characterization results revealed that among all the tested catalysts, the catalyst containing 12.5 wt% Ni and 12.5 wt% Co supported over La2O3 showed higher methane conversion as well as carbon nanomaterials yield. Different characterization techniques such as Inductively coupling plasma atomic absorption spectroscopy (ICP-AES), Brunauer–Emmett–Teller (BET), temperature-programmed reduction (TPR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM) were employed to study the morphological nature of the catalysts before and after reaction.

Production of hydrogen and carbon nanofibers from methane over Ni–Co–Al catalysts

Catalytic decomposition of natural gas has been opted as an alternative route for hydrogen production. Nickel- and Cobalt-based bimetallic catalysts over alumina support were prepared by the co-precipitation method for the investigation of hydrogen production via catalytic decomposition of methane. The effect of different important parameters such as reaction temperature, gas hourly space velocity (GHSV) and metal loading were studied. The catalytic activity and stability results revealed that the catalyst having 25 wt.% each of Ni and Co (25NCA) exhibited the best performance among all tested catalysts. The textural and morphological nature of the calcined and spent catalysts were examined using different characterization techniques including BET, temperature-programmed reduction (TPR), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HR-TEM).

Catalytic Decomposition of Natural Gas to CO/CO2-Free Hydrogen Production and Carbon Nanomaterials Using MgO-Supported Monometallic Iron Family Catalysts

Monometallic Fe, Co, and Ni/MgO catalysts with 50 wt.% metal loadings were prepared and examined for natural gas decomposition to nanocarbonaceous materials, particularly multiwalled carbon nanotubes (MWCNTs) and co-valuable hydrogen. The catalytic testing was carried out in a fixed-bed horizontal reactor at 700°C under atmospheric pressure. The fresh and/or used catalysts were characterized using XRD, TPR, HRTEM, SEM, TG/DTA, Raman spectroscopy, and BET surface measurements. The resulting data showed that the 50%Co/MgO catalyst displayed higher catalytic decomposition activity of natural gas to COx-free hydrogen production (∼88%), higher yield of MWCNTs, and excellent stability up to 10 h time-on-stream. On the other hand, the Ni-containing catalyst showed lower catalytic activity toward hydrogen and CNTs production, principally due to the formation of rock-salt MgxNi(1-x)O solid solution as observed from XRD and TPR data. Accordingly, the concentration of Ni particles required for natural gas feed was extremely low. The d orbital of Ni was presumed to be occupied during the formation of the solid solution, which inhibits the solublization or adsorption of hydrocarbons on Ni particles. The MWCNTs obtained over Ni-based catalyst had narrow and homogeneous diameters (∼11–13 nm). However, the Fe/MgO catalyst exhibited intermediate activity between those of Ni and Co˭MgO catalysts toward hydrogen production (∼44%). This catalyst produced mixtures of carbon nanofibers and nanotubes.

Effect of progressive Co loading on commercial Co–Mo/Al2O3 catalyst for natural gas decomposition to COx-free hydrogen production and carbon nanotubes

Successive cobalt increments from 3.1% up to 40.0% in a commercial hydrotreating catalyst containing originally 3.1%Co and 10.5%Mo on γ-Al2O3 was investigated at a reaction temperature of 700°C and atmospheric pressure for the catalytic decomposition of natural gas to CO/CO2 free hydrogen and carbon nanomaterials. The fresh and used catalysts were characterized by XRD, BET, TEM and TG-DTA analysis. The catalytic performance data showed that the increase of cobalt concentration improved the catalytic dissociation activity and longevity toward hydrogen production. All surface properties declined with successive addition of cobalt in the catalysts. XRD results showed that the crystallinity was remarkably enhanced and Co3O4 phases predominate upon addition of the cobalt precursor. The catalytic activity was found to be primarily dependent on the extent and degree of isolation of Co3O4 phases on the catalyst surface which reflects that the current reaction is a metal catalyzed one. The influence of metal content on the total carbon yield and the degree of graphitization of the resulting CNTs was investigated by TGA, XRD, Raman spectroscopy and TEM analysis.

Various nickel doping in commercial Ni–Mo/Al2O3 as catalysts for natural gas decomposition to COx-free hydrogen production

Non-oxidative decomposition of natural gas to COx-free hydrogen production over commercial nickel-molybdate hydrotreating catalysts with different Ni loading from 5 to 40wt% were studied at 700 °C. The catalysts were characterized by XRD, BET, TEM, Raman spectroscopy and TG-DTA analysis. The catalytic decomposition activities showed that a tremendous hydrogen production (∼90%) was obtained over 20–40wt%Ni/Mo–Al2O3 catalysts. Moreover, all catalysts exhibited excellent durability up to 9 h with stable catalytic activity toward H2 production. Although the increase of Ni content reduces the catalyst surface area, the H2 productivity and longevity increases with increased Ni content, i.e., the catalytic decomposition activity primarily depends on the active Ni sites which overcompensates the surface deficiencies. TEM, TGA and XRD data of used catalysts indicated that a higher thermal stability and graphitization degree of multi-walled carbon nanotubes were obtained on all Ni containing catalysts. Higher metal loading produced carbon nanofibers beside CNTs due to increment of particle size and long reaction time.