Catalytic Methanation of Carbon Dioxide by Active Oxygen Material Ce_xZr_1−xO₂ Supported NiCo Bimetallic Nanocatalysts

Abstract

A series of active oxygen material Ce x Zr 12x O 2 -supported NiACo bimetallic nanosized catalysts were prepared by coprecipitation method, which is simple and fit for industrial use with lower cost than other methods. The effect of CeO 2 / ZrO 2 mole ratio, Co metal addition, and PEG-6000 addition were investigated. The catalysts were characterized through X-ray diffraction, H 2 thermal-programmed reduction, N 2 adsorption, Raman spectroscopy, CO pulse chemisorption, X-ray photoelectron spectroscopy, oxygen storage capacity, and transmission electron microscopy-energy dispersive X-ray analysis. Modifications of the structural and redox properties of these materials were evaluated in relation to their catalytic performances. Particularly, the relationship between the active oxygen sites of the catalysts and their catalytic performances was investigated. The interaction between active metals (Ni and Co) and Ce x Zr 12x O 2 support was found to be very important for catalytic performance. The active oxygen site of Ce x Zr 12x O 2 can considerably improve catalytic performance. Appropriate Co metal addition also remarkably enhanced the catalytic stability and activity. Moreover, PEG-6000 addition can improve the Brunauer-Emmett-Teller surface area and active metal dispersion of catalysts to improve their performances. The nanosized catalyst 15 wt % Ni-5 wt % Co/Ce 0.25 Zr 0.75 O 2 prepared by adding 5 wt % PEG-6000 achieved almost 85% CO 2 conversion and 98% selectivity to methane at 280 C when the gas hourly space velocity was 10,000 h 21 .

A novel W-doped Ni-Mg mixed oxide catalyst for CO2 methanation

“…The stability enhancement over their catalysts was attributed to the 'anchoring' of metallic Ni by surface defects on the support, which were formed at the vicinity of the reduction sites of Ni species located in the Ni-Mg solid solution. Furthermore, the incorporation of a third component, such as Ru [23], Sr [29], Co [30] has been investigated to improve the stability of Ni-based catalysts for CO 2 methanation. Recently, a synergistic effect between Ni and W in mixed Ni-W-Ce oxide catalysts has been reported, which displayed significant effectiveness in minimizing the coke formation and stabilizing the metal particles for ethanol steam reforming [31].…”

Nickel supported on iron-bearing olivine for CO2 methanation

“…It has been suggested that the unreduced iron oxides supply adsorbed carbonate species for the CO 2 hydrogenation to occur more efficiently [29]. In addition, the reducible support were reported to greatly affect the activity and stability of supported catalysts by electronical modification and SMSI [16,20,21]. As shown in Fig.…”

“…The catalytic performance of nickel supported on Al 2 O 3 , SiC, SiO 2 , MgAl 2 O 4 , Ce x Zr 1Àx O 2 , rice husk ash, etc. has been studied [8,10,11,13,15,16]. It was found that the lattice mismatch between the small Ni 0 particles and the support g-Al 2 O 3 leads to the formation of an additional thin interface composed by mixed Ni-NiC x or Ni 3 C in Ni/g-Al 2 O 3 , which could result in the detachment of the Ni-particles from the support during methanation of biomass-derived synthesis gas [18].…”

“…Support matching with the supported metal was suggested to be a key factor in developing supported nickel catalyst with excellent stability [19]. Besides, the activity and stability of the supported catalysts could be improved by the supports via electronical modification and strong metalsupport interaction (SMSI) [16,20,21], characterized by reducible supports and reduction treatment under high temperature (typically above 723 K). Based on the reducible nature of CeO 2 and TiO 2 , M/CeO 2 and M/TiO 2 catalysts exhibiting some sort of SMSI effect were widely studied and used in various applications [22e25].…”

“…Based on the reducible nature of CeO 2 and TiO 2 , M/CeO 2 and M/TiO 2 catalysts exhibiting some sort of SMSI effect were widely studied and used in various applications [22e25]. Catalytic methanation of carbon dioxide by active oxygen material Ce x Zr 1Àx O 2 supported NieCo catalyst was reported by Hongwei Zhu et al [16]. It was suggested that modifications of the structural and redox properties of the support could affect the catalytic performance, in particular, the active oxygen site of Ce x Zr 1Àx O 2 can considerably improve the catalytic activity.…”