Development of high-performance nickel-based catalysts for production of hydrogen and carbon nanotubes from biogas

Abstract

Selecting a suitable catalyst for implementing the simultaneous production of hydrogen-rich syngas and multi-walled carbon nanotubes through the integration of dry reforming and methane decomposition reactions has recently gained great interests. In this study, a series of bimetallic (NiMo/MgO) and trimetallic (CoNiMo/MgO, FeNiMo/MgO, CoFeMo/MgO) catalysts was prepared and evaluated for a catalytic activity of CH4 and CO2 conversions of biogas in a fixed bed reactor at 800 °C and atmospheric pressure. Among the investigated catalysts, the bimetallic NiMo/MgO catalyst showed the outstanding catalytic performance with 86.4% CH4 conversion and 95.6% CO2 conversion as well as producing the highest syngas purity of 90.0% with H2/CO ratio = 1.1. Moreover, the characterization of the synthesized solid products proved that the well-aligned structured morphology, high purity, and excellent textural properties of CNTs were obtained by using NiMo/MgO catalyst. On the other hand, using trimetallic catalysts which have the composition of Co and Fe leads to the severe deactivation. This could be attributed the catalyst oxidation with CO2 in biogas, resulting in the transformation of metals into large metal oxides. The integrative process with NiMo/MgO catalyst is regarded as a promising pathway, which has a high potential for directly converting biogas into the high value-added products and providing a green approach for managing the enormous amounts of wastes.

Development of Ni–Mo carbide catalyst for production of syngas and CNTs by dry reforming of biogas

“…Whereas the G-band is related to the tangential stretching vibration of C=C bonded atoms in the aromatic layers of graphene crystalline 64 , 65 . The relative integral areas of the G and D bands demonstrated in terms of Ig/Id ratio have been widely applied for quantifying the graphitization degree of MWCNTs 20 , 37 , 59 . As can be seen from the spectra, the respective Ig/Id ratios of the synthesized CNTs were found to be in the range of 0.86–1.29, while the poorest value of 0.73 was given by the commercial CNTs.…”

“…The Ni–Mo catalyst supported on magnesium oxide (MgO) was synthesized by impregnating 7 g of dried MgO nano-powder (Merck, 98%) with a proper matching amount of Ni(NO 3 ) 2 ·6H 2 O and (NH 4 ) 6 Mo 7 ·4H 2 O blended aqueous solution (Sigma-Aldrich, 99.99% trace metals basis) using wetness impregnation method. This procedure gives the nominal Ni and Mo metal loadings of 30wt% (Ni/Mo ratio = 1/1 w/w) 20 . Then, the impregnated solvent was evaporated by a hotplate at 80 °C, attempting to remove excess de-ionized water (DI) from the sample.…”

“…1 ). A detailed description of the reactor has been previously stated in several works in the literatures 20 , 37 . For the subsequent proceeding, the oxide precursor (NiMoO x ) was treated under a variant of activating agents (O 2 , H 2 , and CH 4 ) at a feed flow rate of 100 ml/min to achieve the target catalysts.…”

“…In this regard, most studies have been conducted with a focus on the way to prevent these unwanted carbonaceous deposits on the catalyst surface 16 – 19 . In our previous work 20 , we successfully proposed an effective approach to overcome this momentous concern by transforming the deposited carbon into valuable nanomaterials such as carbon nanotubes (CNTs), which can be simultaneously promoted alongside the catalytic decomposition of methane (CDM) reaction, as shown in Eq. ( 2 ).…”

Mechanism of carbon nanotube growth in expanded graphite via catalytic pyrolysis reaction using carbores P as a carbon source

“…It could be obtained from the local magnification figure that there was a trace phase of the cobalt metal according with 44.2° in sample 3. It is reasonable that the phase differences of those samples should be related to the change of the Co element in the catalyst Co(NO 3 ) 3 •6H 2 O during the catalytic process ( Ince Yardimci et al, 2020 ; Saconsint et al et al, 2022 ).…”