The global warming impacts associated with anthropogenic CO2 emissions from fossil fuel combustion present an enduring problem to achieving energy sustainability. Although conservation measures and carbonless energy technologies may eventually stabilize CO2 emissions from stationary and mobile power sources, a continued reliance on coal, oil and natural gas in the near term necessitates development of strategies to reduce CO2 loadings into the atmosphere. Carbon capture and storage (CCS) is a promising concept in which CO2 is recovered from process gas streams, concentrated to a fraction suitable for pipeline transport, and sequestered in geologic formations or other storage media. Large, stationary point sources, such as fossil fuel electric power plants, are obvious targets for CCS. Improved adsorbents are needed however to reduce the high cost of separating CO2 from other process gases, particularly N2 in the case of (post-combustion) flue gas and H2 in the case of (pre-combustion) gasified coal or oil. Novel porous materials based on metal-organic framework (MOF) chemistries show promise for selective capture of CO2 from gas mixtures. In this paper, we report molecular simulation studies of mixed-gas CO2 adsorption on a copper-bipyridine MOF adsorbent that exhibits highly selective gated adsorption for CO2. Adsorption capacities and selectivities for CO2/H2 and CO2/N2 mixtures were studied via Monte Carlo simulations at 300, 350, and 400 K under realistic process pressures. Monte Carlo simulation results for isosteric heats of adsorption of CO2 and H2 are also presented.