(101f) Dual Cu(I) Active Site for CO Adsorption with Elevated Adsorption Capacity

Carbon monoxide (CO) is a toxic gas that has brought up climate change, ozone depletion, acid rain, and other environmental concerns. Many chemical products such as acetic acid, formic acid, methanol, liquid hydrocarbon fuels, plastics, and fibers are produced using CO as the raw material. The processes for production of these products require separation of CO that contributes up to 70% of total production cost. Adsorption is a cost and energy-effective method of separation that can provide high CO adsorption capacity and selectivity with correct selection of adsorbent. Usually adsorbents are chemically modified with copper salts to form Cu(I) on the surface since copper is cheap and readily available. However, Cu(I) suffers from instability and offers lower adsorption capacity in comparison to other active adsorbent materials such as palladium. In this work, we report a dual Cu(I) active site (DAS) with enhanced CO adsorption capacity and stability. The dual-active-site was synthesized through a facile two-step route (reduction-modification). The formation of this site was confirmed using various characterization techniques. Single component adsorption isotherm of CO over the DAS was measured at 20 °C to determine the equilibrium adsorption capacity. DAS showed 117% and 320% increase in CO uptake than CuCl and Cu2O single sites, respectively, which is attributed to binding CO to two active sites with different anions (O and Cl). The effect of Cu(I) loading on heterogeneity and adsorption capacity of the DAS was investigated using the affinity distribution function. The results also indicate the high stability of the DAS by retaining its 95% of adsorption capacity after storage in ambient conditions for 3 days.