“…[34] It was observed that the methane conversions improved drastically from 25 % to 75 % and the Cu promoted catalyst has remained active on stream for approximately 6 h. In this study, the addition of Cu on Mat-1 catalyst improved both methane conversions and catalyst deactivation time. [34] Moreover, the Cu promoter has a larger capacity to diffuse carbon and thus preventing the encapsulation of inactive coke on active Ni phase. Hence, the formation of inactive nickel aluminates was also hindered due to successful impregnation of 15 % Cu on Mat-1 catalysts.…”
“…[34,49] For illustration, the effect of impregnating 15 % Cu to Mat-1 catalyst on the catalytic activity has been explored previously by our research group. [34] It was observed that the methane conversions improved drastically from 25 % to 75 % and the Cu promoted catalyst has remained active on stream for approximately 6 h. In this study, the addition of Cu on Mat-1 catalyst improved both methane conversions and catalyst deactivation time. [34] Moreover, the Cu promoter has a larger capacity to diffuse carbon and thus preventing the encapsulation of inactive coke on active Ni phase.…”
“…Up today, the addition of Cu and Pd onto Al 2 O 3 supported nickel catalyst has not been explored yet. In our previous research work, [34] the activity and stability of 50 %NiÀ 15 %Cu/Al 2 O 3 in catalytic decomposition of methanol/methane mixture were investigated. The activity and stability of the Al 2 O 3 supported copper catalyst were compared to the unpromoted Ni-based catalyst.…”
Thermocatalyatic decomposition (TCD) of methane to CO X free hydrogen and carbon nanofibre (CNF) was investigated over a series of self-designed monometallic Ni catalyst and bimetallic NiÀ Cu and NiÀ Pd catalysts. The catalysts were synthesised from the wet impregnation method and characterised using a series of complementary techniques include TGA, XRD, BET, TPR, FESEM, TEM, and Raman Spectroscopy. Despite a substantial reduction of surface area in the promoted catalysts, the catalytic activity of the promoted catalyst was enhanced due to the nature of the process which is a metal-catalysed reaction. As a whole, bimetallic PdÀ Ni catalyst with a surface area of 2.76 m 2 g À 1 possesed the highest conversion of 77 % after 6 h reaction. The overall TCD reaction was found to be first-order with the calculated activation energy, E a of 38 kJ mol À 1. The methane consumption rates at 1023 K and 1073 K were 0.5 mol s À 1 g cat À 1 and 0.58 × 10 4 mol s À 1 g cat À 1 respectively. Meanwhile, the methane consumption rates improved considerably from 0.58 mol s À 1 g cat À 1 to 0.67 × 10 4 mol s À 1 g cat À 1 under the methane partial pressure of 41 kPa. The XRD profile of the fresh catalysts revealed that mixed oxides were formed over the surface of the support upon the addition of Cu and Pd to 50 % Ni/Al 2 O 3. Moreover, the formation of carbon nanofibers followed both tip and base growth mechanisms as evident from the TEM images. Larger and wider carbon fibres were found in the Pd promoted catalyst.
“…[34] It was observed that the methane conversions improved drastically from 25 % to 75 % and the Cu promoted catalyst has remained active on stream for approximately 6 h. In this study, the addition of Cu on Mat-1 catalyst improved both methane conversions and catalyst deactivation time. [34] Moreover, the Cu promoter has a larger capacity to diffuse carbon and thus preventing the encapsulation of inactive coke on active Ni phase. Hence, the formation of inactive nickel aluminates was also hindered due to successful impregnation of 15 % Cu on Mat-1 catalysts.…”
“…[34,49] For illustration, the effect of impregnating 15 % Cu to Mat-1 catalyst on the catalytic activity has been explored previously by our research group. [34] It was observed that the methane conversions improved drastically from 25 % to 75 % and the Cu promoted catalyst has remained active on stream for approximately 6 h. In this study, the addition of Cu on Mat-1 catalyst improved both methane conversions and catalyst deactivation time. [34] Moreover, the Cu promoter has a larger capacity to diffuse carbon and thus preventing the encapsulation of inactive coke on active Ni phase.…”
“…Up today, the addition of Cu and Pd onto Al 2 O 3 supported nickel catalyst has not been explored yet. In our previous research work, [34] the activity and stability of 50 %NiÀ 15 %Cu/Al 2 O 3 in catalytic decomposition of methanol/methane mixture were investigated. The activity and stability of the Al 2 O 3 supported copper catalyst were compared to the unpromoted Ni-based catalyst.…”
Thermocatalyatic decomposition (TCD) of methane to CO X free hydrogen and carbon nanofibre (CNF) was investigated over a series of self-designed monometallic Ni catalyst and bimetallic NiÀ Cu and NiÀ Pd catalysts. The catalysts were synthesised from the wet impregnation method and characterised using a series of complementary techniques include TGA, XRD, BET, TPR, FESEM, TEM, and Raman Spectroscopy. Despite a substantial reduction of surface area in the promoted catalysts, the catalytic activity of the promoted catalyst was enhanced due to the nature of the process which is a metal-catalysed reaction. As a whole, bimetallic PdÀ Ni catalyst with a surface area of 2.76 m 2 g À 1 possesed the highest conversion of 77 % after 6 h reaction. The overall TCD reaction was found to be first-order with the calculated activation energy, E a of 38 kJ mol À 1. The methane consumption rates at 1023 K and 1073 K were 0.5 mol s À 1 g cat À 1 and 0.58 × 10 4 mol s À 1 g cat À 1 respectively. Meanwhile, the methane consumption rates improved considerably from 0.58 mol s À 1 g cat À 1 to 0.67 × 10 4 mol s À 1 g cat À 1 under the methane partial pressure of 41 kPa. The XRD profile of the fresh catalysts revealed that mixed oxides were formed over the surface of the support upon the addition of Cu and Pd to 50 % Ni/Al 2 O 3. Moreover, the formation of carbon nanofibers followed both tip and base growth mechanisms as evident from the TEM images. Larger and wider carbon fibres were found in the Pd promoted catalyst.
“…Schematic diagram for co‐feeding methanol with methane in the reactor. Reproduced with permission . Copyright 2018, Elsevier.…”
Section: Thermodynamics Of Reaction Processmentioning
confidence: 99%
“…A recent promising technique of introducing admixtures as feedstock for CMD was accomplished by using CH 3 OH as an additive thoroughly mixed in methane. The advantages of using CH 3 OH as an additive include safe handling, easy availability, and high energy density.…”
Section: Thermodynamics Of Reaction Processmentioning
Catalytic decomposition of methane is a viable method of producing hydrogen and carbon nanomaterials. Hydrogen gas is mainly used as a reactant in the chemical industry, i.e., petrochemicals, glass, and pharmaceutical industries, whereas carbon may be used in direct carbon fuel cells or marketed as a filamentous carbon. Demand for carbon monoxide (CO)–free hydrogen continues to rise due to the increase in the number of its applications. Currently, a significant amount of hydrogen comes from gasification of natural gas, oxidation, and steam reforming of hydrocarbons. In all these technologies, CO is formed as a by‐product that requires tedious and costly processes to separate hydrogen from syngas. Herein, the recent literature on methane decomposition, methane reaction kinetics, catalyst performance, hydrogen yield, and formation of carbon nanomaterial are reviewed. The scope of this work is limited to direct conversion of methane into carbon and hydrogen; therefore, processes involving synthesis gas as intermediate products are not covered. Finally, catalysts that are often used in methane decomposition, their deactivation, and regeneration are discussed with the aim of documenting the foundation upon which an entirely new class of catalysts can be built to enhance their activity, selectivity, and yield.
A new type of cigarette butts/coal-based composite porous carbon was prepared by potassium hydroxide chemical activation method and used for methane decomposition to hydrogen. The effects of mass mixing ratio of the used cigarette butts/coal and carbonization temperature on the surface properties and structure of carbon materials were studied. The results show that the optimal mass mixing ratio of cigarette butts/coal is 1:3, and the increase in temperature can promote the specific surface area of carbon materials from 1850 to 2785 m 2 /g, the distribution of pore size is also changed from a large number of micropores to mesopores, and the structure became more disordered. DT/YT-3-1023 has the highest initial activity, DT/YT-3-1123 has the highest stability, and a certain amount of carbon fibers are deposited on the surface of carbon materials after the reaction.
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