456834 Supported Cobalt Catalysts with Preferentially Exposed Crystal Facets for CO2 Hydrogenation

Thursday, November 17, 2016: 4:35 PM
Imperial B (Hilton San Francisco Union Square)
Cun Wen1, Juan Jimenez1, Jason Hattrick-Simpers2, Jochen Lauterbach2 and Maryorie C. Santos1, (1)Chemical Engineering, University of South Carolina, Columbia, SC, (2)Department of Chemical Engineering, University of South Carolina, Columbia, SC

Supported Cobalt Catalysts with Preferentially Exposed Crystal Facets for CO2 Hydrogenation.

Cun Wen, Juan Jimenez, Maryorie Santos, Jason Hattrick-Simpers, Jochen Lauterbach,*

University of South Carolina, Columbia, SC, 29208, USA

*Corresponding author: lauteraj@cec.sc.edu

Global climate change has been widely acknowledged to be a result of rising CO2 concentration in the atmosphere.1-3 However, curbing CO2 emission is hindered by the high thermodynamic stability of CO2, which leads to low reactivity in most reactions.4 Our recent studies have demonstrated that by tuning the surface crystal facets of Cobalt catalysts, catalysts with {110} facets have superior activity toward CO2 hydrogenation compared with Co with {111} and {001} facets. More importantly, our previous studies have shown that the Co catalysts with {110} facets have an unprecedented self-healing functionality during a hydrogenation reaction.5 Similar to other faceted catalysts reported in literature, the highly active and stable Cobalt catalysts are not supported and lack the capability to meet industrial requirements for high heat and mass transfer, facilitated reactor packing, mechanic strength, and so on. Here, a novel methodology leading to supporting the faceted Co catalysts without sabotaging the referentially exposed surface crystal facet will be discussed in this presentation.

In this study, Co catalysts for CO2 hydrogenation are based on series of cobalt oxide catalysts that we have recently published for CO hydrogenation.5 The Co nanorods, for instance, have predominant {110} and {001} facets, while the Co nanoparticles have {111} and {001} facets. The Co nanorods start to show activity toward CO2 hydrogenation (130‹C) at 95 ‹C lower than that (225 ‹C) for Co nanoparticles. For practical applications, the faceted Co catalysts needs to be supported to meet industrial specifications. As a proof or principle, Al2O3 supported Co3O4 nanorods are synthesized and tested for CO2 hydrogenation. The Al2O3 supported Co3O4 nanorods have comparable catalytic activity and product selectivity to that of pure Co3O4 nanorods, as shown in Fig. 1. This result indicates that after supporting the faceted Co3O4 nanorods with metal oxide, the superior catalytic performance can be preserved. More detailed structure characterizations, including XRD, STEM-HAADF, BET, and ICP, indicate that the preferential crystal facets exposure is preserved after supported on Al2O3.

Figure 1. Comparison between the catalytic performance of a) Co nanorods and b) Co nanorods@Al2O3 in CO2 hydrogenation.

References

1. T.F. Stocker, A. Schmittner, Nature, 388 (1997) 862-865.

2. M. Meinshausen, N. Meinshausen, W. Hare, et al., Nature, 458 (2009) 1158-1162.

3. E. Dlugokencky, P. Tans, in, NOAA/ESRL.

4. H. Arakawa, M. Aresta, J.N. Armor, et al., Chem Rev, 101 (2001) 953-996.

5. C. Wen, D. Dunbar, X. Zhang, et al., Chem Commun, 50 (2014) 4575-4578.

 


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