Synthesis and evaluation of novel and efficient Ni-based dual functional materials (DFMs) for integrated CO2 capture and hydrogenation

Abstract

We report on the synthesis and evaluation of novel, highly active and stable bimetallic DFMs for simultaneous CO2 adsorption and subsequent hydrogenation to value added products. The DFMs contain various combinations of Ni (5–15 wt%) and Cu (5–15 wt%) with Na2O (5–15 wt%) as adsorbent supported on alumina (γ-Al2O3). The DFMs were synthesized via sequential incipient wetness impregnation method and were thoroughly characterized by combination of various surface sensitive and bulk sensitive analytical tools such as XRD, XPS, BET surface area, HR-TEM and H2-TPR. The DFMs were evaluated for CO2 capture and subsequent hydrogenation in a fixed-bed quartz tubular reactor connected with an online gas analyzer. The results demonstrated that at an operating temperature of 320℃, the DFM with a composition of 10 wt%Ni5wt%Cu/10 wt%Na2O.Al2O3 resulted in exceptionally high CO2 adsorption (310.84 μmol/g) and subsequent hydrogenation to methane (249.2 μmol CH4/gDFM). The XPS analysis revealed that this DFM contains comparatively larger percentage of highly ionized and/or induced Ni2+ as well as Cu+1 species. The results of H2-TPR also clearly indicated improvement in its reducibility. Moreover, the TEM analysis results revealed the presence of well-dispersed and smaller metal oxide particles in the bimetallic 10 wt%Ni5wt%Cu/10 wt%Na2O.Al2O3 DFM. In this regards, the exceptional high performance of the 10 wt%Ni5wt%Cu/10 wt%Na2O.Al2O3 DFM was attributed to the synergistic effects of the bimetallic combination of Ni with Cu resulting in enhanced physicochemical properties and thus demonstrated exceptionally higher performance.