Hydrogen and CNT Production by Methane Cracking Using Ni–Cu and Co–Cu Catalysts Supported on Argan-Derived Carbon

Abstract

The 21st century arrived with global growth of energy demand caused by population and standard of living increases. In this context, a suitable alternative to produce COx-free H2 is the catalytic decomposition of methane (CDM), which also allows for obtaining high-value-added carbonaceous nanomaterials (CNMs), such as carbon nanotubes (CNTs). This work presents the results obtained in the co-production of COx-free hydrogen and CNTs by CDM using Ni–Cu and Co–Cu catalysts supported on carbon derived from Argan (Argania spinosa) shell (ArDC). The results show that the operation at 900 °C and a feed-ratio CH4:H2 = 2 with the Ni–Cu/ArDC catalyst is the most active, producing 3.7 gC/gmetal after 2 h of reaction (equivalent to average hydrogen productivity of 0.61 g H2/gmetal∙h). The lower productivity of the Co–Cu/ArDC catalyst (1.4 gC/gmetal) could be caused by the higher proportion of small metallic NPs (<5 nm) that remain confined inside the micropores of the carbonaceous support, hindering the formation and growth of the CNTs. The TEM and Raman results indicate that the Co–Cu catalyst is able to selectively produce CNTs of high quality at temperatures below 850 °C, attaining the best results at 800 °C. The results obtained in this work also show the elevated potential of Argan residues, as a representative of other lignocellulosic raw materials, in the development of carbonaceous materials and nanomaterials of high added-value.

Combined Methane Cracking for H2 Production with CO2 Utilization for Catalyst Regeneration Using Dual Functional Nanostructured Particles

“…Knowing that uncatalyzed methane decomposition exhibits very slow kinetics at temperatures below 1000 °C, utilization of a solid catalyst is essential, allowing this reaction to be initiated efficiently at a relatively lower temperature. , Among the transition metal-based catalysts, nickel is recognized as one of the most efficient in hydrocarbon cracking. ,,− Considering that unsupported nickel is prone to sintering at high temperatures, the use of a support material is necessary. , Significant efforts have been dedicated to developing straightforward and effective synthesis methods for producing suitable Ni-based supported catalysts to facilitate methane decomposition. The maximum H 2 yield (in terms of CH 4 conversion; TOF CH 4 ) ranging from 6.02 to 38.15 h –1 was achievable in a temperature range of 550–900 °C by using Ni-based catalysts. − …”

Synthesis of Ni-Cu-CNF Composite Materials via Carbon Erosion of Ni-Cu Bulk Alloys Prepared by Mechanochemical Alloying

“…In this regard, various catalytic compositions which were efficient in the process were developed and abundantly studied. Among such catalysts, Ni-Cu systems are of particular interest due to their low cost and high activity in the decomposition of methane and other hydrocarbons [42][43][44][45][46][47]. However, due to the high temperatures required for the decomposition of hydrocarbons, the process is complicated by the sintering of metal particles and coking (deposition of non-structured carbon).…”

A Themed Issue in Honor of Prof. Dr. Vicente Rives

“…This Special Issue has received eighteen contributions, six review papers [1][2][3][4][5][6], and twelve research papers [7][8][9][10][11][12][13][14][15][16][17][18]. Most of the papers originated from groups who have previously worked with Prof. Rives, but five of the contributions came from authors who had not previously worked with him [6,7,13,17,18].…”

“…Therefore, it was not surprising that these materials were the basis of eight of the papers published in this Special Issue [2][3][4]10,11,[15][16][17]. Other materials included Ni-based catalysts [1], g-C 3 N 4 [5], mesoporous silica [6], MOFs [7], carbons [8,9], AlPO 4 [12], acid-modified clays [13], and porous aluminosilicates [17]. Finally, one of the papers was devoted to the study of cultural heritage conservation [14].…”

“…The research papers also reported on very interesting applications of the different materials studied. Rodríguez-Castellón et al reported on the esterification of levulinic acid to methyl levulinate, catalyzed by Zr-MOFs [7]; Monzón et al studied the production of H 2 and CNT from methane using bimetallic catalysts based on carbon [8], whilst Carriazo et al used carbon composites for the preparation of advanced supercapacitors [9]. Labajos et al explored new routes for the preparation of LDHs using various amines in the synthesis process [10], while Nebot-Díaz et al used LDH as precursors of nanoparticle black pigments for the ceramic industry [11].…”