Conventional CO2 capture and sequestration (CCS) is a very energy-consuming process in amine solutions (CCS) is very energy intensive. We have developed an advanced technology which adsorbs CO2 from flue gas and catalytically converts it to synthetic natural gas with our patented dual functional material (DFM). The DFM is composed of nano- dispersed CaO and Ru sites, respectively functioning as the CO2 adsorbent and methanation catalyst. For industrial applications, the influences of effluent gas environment (temperature, flow rate, O2, steam, composition, impurities, pressure drop and life) on the catalytic performance needs to be understood. The present project is focused on the scale-up study of CO2 utilization in various industrial applications. Various catalyst synthesis methods for industrial mass production, and reaction process parameters for optimum catalytic performance a are under investigation. Enhanced materials are also being sought.
Modern three way catalysts (TWC) for automotive emission control, are composed of bimetallic Rh-Pd catalysts deposited on stabilized Al2O3. TWC experiences catalyst deactivation during fuel shutoff, an engine operational mode (e.g. coasting down hill) for enhancing fuel economy. A subsequent switch to fuel rich mode allows catalyst regeneration and the maintenance of catalyst performance. Different deactivation and regeneration effects were observed with supported Rh and Pd model TWCs. The research focuses on the influences of the two simulated processes on the Rh- and Pd-based TWC catalyst systems. The studies highlight the examination of catalyst redox chemistry, surface physicochemistry, and regenerability with metal-support interactions.
The research work demonstrates a new process for steam reforming (SR) sulfur-containing hydrocarbons such dodecane (C12H26) as a model compound for diesel fuel. The reaction is catalyzed by Rh-Pt supported on a sulfur tolerant carrier (SiO2-ZrO2). The study highlights the influence of various process parameters such as the steam to carbon (S/C) ratio, sulfur concentration, time on stream (TOS), and preemptive air regeneration on the catalytic performance (activity and stability) and the nature of the coke formed.
It was shown Nb-doped ZrO2-CeO2-Y2O3 solid solution (Nb-ZrCeYO) samples had enhanced oxygen storage (OS) capacity compared with Nb-free solid solutions. However, after several days of exposure to ambient air, the OS behavior of the Nb-doped samples shows significant degradation. This degradation was slowed for samples stored in evacuated glass tubes. Nb segregation to the surface under oxidizing conditions is hypothesized as the cause of the degradation. This hypothesis was shown to be consistent with the analysis of the temperature programmed reduction data. After impregnation with Pt, the enhancement of the OS capacity of Nb-doped oxygen storage component (OSC) relative to the Nb-free OSC was restored. The electrons supplied by metallic Pt mimic reducing conditions, which are known to result in migration of Nb away from the surface and re-dispersion into the bulk solid solution. Nb-doped samples impregnated with Pt showed stable, time-independent OS performance.
Figure 1: CO conversions as a function of temperature in CO oxidation reactions over 20%CuO/Nb2O5, and 20%CuO/Al2O3, both calcined at 300˚C for two hours in air. CO: 1.5vol.%, O2: 14.5vol.%, catalysis volume: 0.1 ml, the total flow rate: 6.5 L/h, GHSV: 65,000 h-1. Each sample was measured twice. For these testing, a fresh sample was used from the same batch of 20%CuO/Nb2O5 or 20%CuO/Al2O3.
Figure 2: XPS Cu 2P3/2 of 20%CuO/Nb2O5, calcined at 300˚C for two hours in air. Cu1+/Cu0 species cannot be differentiated by Cu 2p3/2.
Figure 3: CO conversions as a function of temperature for CO oxidation reaction for 2%CuO/Nb2O5 (red), 6%CuO/Nb2O5 (blue), 10%CuO/Nb2O5 (pink), 20%CuO/Nb2O5 (green), each calcined at 300˚C for two hours in air. 1%Pt/Al2O3 calcined at 500˚C for two hours in air (orange). CO: 1.5vol.%, O2: 14.5vol.%, catalysis volume: 0.1 ml, GHSV: 65,000 h-
Figure 1 shows CO oxidation conversions of 20%CuO/Nb2O5 and 20%CuO/Al2O3. The Nb2O5 sample showed better activity compared with the Al2O3 sample. Analysis of the X-ray Photon Spectroscopy of Cu 2P3/2 revealed that a mixture of Cu1+ and Cu2+ species exist on the surface of a Nb2O5 carrier (Figure 2). Auger LMM confirmed that the majority of Cu species were Cu1+ with little or no Cu0. The presence of Cu+1 leads to an enhancement of CO oxidation activity. The Cu on Al2O3 sample only shows Cu2+. In figure 3 one can see that 6%CuOx/Nb2O5 has comparable activity to 1%Pt/Al2O3. However this advantage is lost as the aging temperature is increased.