The electrochemical reduction of carbon dioxide (CO 2 ) to hydrocarbons is a potential option to achieve carbon neutrality. Although copper (Cu) shows the highest activity for the CO 2 reduction reaction (CO 2 RR) to hydrocarbons among metals, high reaction overpotentials and significant H 2 production limit its use. We investigate single-atom alloys (SAAs) of ten metals (Ag, Au, Fe, Ir, Ni, Pd, Pt, Rh, Ru, Al) on Cu(111), which is the most-favored facet on Cu for methane production, using density functional theory. We examined the dopants' ability to lower the free energy of the elementary reaction, *CO to *CHO, which is the potential-determining step (PDS). Out of the SAAs studied, only Al-doped Cu demonstrated a lowering of the PDS free energy. Additionally, weaker adsorption energies of *CO and *H on AlÀ Cu(111) suggest a preference for C 1 hydrocarbons and inhibition of H 2 evolution. Finally, activation barrier calculations for the PDS on AlÀ Cu(111) involving an explicitly hydrated proton indicated better intrinsic activity for C 1 hydrocarbons compared to pure Cu(111). We also confirmed the stability of AlÀ Cu SAA compared to small Al clusters. Through a comprehensive study of both thermodynamics and kinetics, our study presents AlÀ Cu SAA as a promising catalyst for CO 2 electroreduction to C 1 hydrocarbons.

Ind. Eng. Chem. Process Des. Dev. 1983, 22, 477-482 y = dimensionless amount adsorbed (= q/qo), dimensionless 2 dimensionless axial position in the column (= kpG/u), z = axial position in the column, m or cm ZE = column length, m or cm Greek Letters Subscripts in = value at the column inlet out = value at the column outlet dimensionless = value at equilibrium Registry No. CH,Br, 74-83-9; C, 7440-44-0. 477 t = void fraction of the bed, dimensionless { = dimensionless parameter (= kfR/5De), dimensionless 0 = dimensionless time (= kp,(t -('/u)z)/pb(qo/co)), di-I.L = viscosity of the gas, g/cm s [ = dimensionless radial position (= r / R ) , dimensionless pb = bulk density of the bed, g/cm3 pf = density of the gas, g/cm3 ps = particle density, g/cm3 r = dimensionless parameter (= kp,(u/ V)/Pb(qo/Co)), di-mensionless m e n s i o n 1 e s s Literature Cited Carberry, J. J. AIChE J . 1960, 6 , 460. Chang, F. H. I.; Tan, K. S.; Spinner, I. H. AZChE J . 1973, 79, 188, Chu, J. C.; Kaiii, J.; Wetteroth, W. A. Chem. Eng. Rog. 1953, 49, 141. Cooney, D. 0.; Shieh, D. AIChE J. 1972, 78, 245. Hashimoto, K.; Miwa, K.; Negate, S. J. W m . Eng. Jpn. 1975, 8 , 367. Mor, L.; Mor, L. A.; Sldeman, S.; Brandes, J. Chem. Eng. Sci. 1980, 35, 725.The discovery that cuprous chloride can effect specifically the aerobic coupling of aqueous phenol under mild reaction conditions ( T < 60 O C , Po? < 1 atm) has led us to propose a novel dephenoiization scheme for high strength phenolic wastewaters. As envisioned In the proposed scheme, aqueous phenols will be converted aerobically and catalytically into insoluble coupling products which may then be easily separated from the wastewaters. The recovered soli organics may be disposed of as a fuel. The low costs of cuprous chloride and oxygen, the simplicity of the scheme, and the fuel value of the recovered organics make the scheme highly promising. Kinetic studies with ammoniacal phenol solutions indicate that the coupling reaction is first order with respect to cuprous chloride catalyst, half order with respect to oxygen, approximately 1.7th order with respect to phenol, and second order with respect to base. At 26 O C and pH 9.7, the rate constant is such that the half-life of a 0.05 M aqueous phenol solution in the presence of 1.58 g/L of capper catalyst and 1 atm oxygen pressure is about 2 h. The reaction activation energy is 12.5 kcal/g-mol. Humic acids are believed to the the major components of the coupling products. A preliminary study with actual coal gasification wastewater confirms the promising nature of the proposed coupling-dephenolization scheme.Fault detection and diagnosis are Wustrated by application of on-line parameter estimation techniques to a nonlinear chemical reactor. An extended Kalman filtering algorithm was successfully used to estimate both the states and time varylng parameters corresponding to faults in a lumped parameter system. Trajectories of parameter estimates were compared with predetermined confidence limits established under normal operating conditions. The ...

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