Complete Removal Of CO Research Articles

Support Effect and Stability of Inverse Fe1(OH)x/Pt Single-Site Interfacial Structured Catalysts for Preferential CO Oxidation in H2

Preferential oxidation of CO in hydrogen (PROX) has been regarded as a promising method for removing a trace amount of CO to a parts-per-million (ppm) level to provide pure hydrogen fuel for polymer-electrolyte membrane fuel cells. Recently, we reported that SiO2-supported Pt nanoparticles with atomically dispersed Fe1(OH)x decoration exhibited exceptional CO removal in a very broad temperature window of −75–107 °C in the PROX reaction because of enriched interfaces and remarkably high reducibility of the iron species. Here, we further investigated the support effect on the catalytic performance of this inverse Fe1(OH)x/Pt single-site interfacial structure, as well as their stabilities under high-temperature redox atmospheres. We found that Fe1(OH)x/Pt on nonreducible supports such as SiO2 and Al2O3 is more favorable for efficient CO removal than those on reducible supports (e.g., Fe2O3 and TiO2) in the PROX reaction. The inferior performance of the latter case is attributed to the creation of additional active interfaces to initiate competing H2 oxidation. High-temperature redox pretreatments of the optimized SiO2-supported Fe1(OH)x/Pt catalyst up to 500 °C did not cause any noticeable changes of the temperature window of complete CO removal, indicating that the inverse Fe1(OH)x/Pt single-site interface structure has high thermal stability against sintering. Further increasing the H2 concentration did not change the temperature window either. The above results suggest that the inverse Fe1(OH)x/Pt catalyst is very robust with high potential for practical applications and other catalytic reactions.

Nanostructured Co‐Free Layered Oxide Cathode that Affords Fast‐Charging Lithium‐Ion Batteries for Electric Vehicles

AbstractThe development of Co‐free Li[NixMn1−x]O2 cathodes for lithium‐ion batteries (LIBs) that can supersede Co‐containing Li[NixCoyMn1−x−y]O2 and Li[NixCoyAl1−x−y]O2 cathodes is considered a priority as Co is associated with price volatility, environmental concerns, and human rights violations. However, the complete removal of Co from cathodes for LIBs is difficult because Co‐free cathodes suffer from structural instability and inferior capacity. In this study, a morphology‐engineering approach is used to develop a Co‐free Li[Ni0.9Mn0.1]O2 cathode with a Ni‐rich core–Mn‐rich shell structure to overcome the limitations of Co‐free Li[NixMn1−x]O2 cathodes. The engineered morphology of the Co‐free Li[Ni0.9Mn0.1]O2 cathode particles effectively dissipates internal strain caused by state‐of‐charge heterogeneity and fracture toughening the cathode. Owing to the effective dissipation of internal strain and chemical protection provided by the Mn‐rich shell, the Co‐free cathode demonstrates excellent long‐term cycling stability; it retains 78.5% of its initial capacity after 2000 cycles at 1 C charge and 0.8 C discharge rates, and retains an unprecedented 79.5% after 1000 cycles under fast‐charging conditions (3 C charge and 1 C discharge). The proposed Co‐free layered oxide cathode represents a next‐generation cathode that affords fast‐charging and durable LIBs, which are more cost effective than LIBs featuring commercial Co‐containing cathodes.

Blocking the non-selective sites through surface plasmon-induced deposition of metal oxide on Au/TiO2 for CO-PROX reaction

CO preferential oxidation (PROX) in excess hydrogen is a promising strategy for CO removal in hydrogen-rich reformate. However, the CO conversion and CO 2 selectivity in the PROX reaction dramatically decrease with rising temperature, resulting in a major challenge to complete CO removal across a wide temperature window. Here, we developed a photoexcited deposition of metal oxide (PDMO) method based on surface plasmonic resonance of Au nanoparticles, which can tune the interfacial properties by depositing lead oxide at the Au-TiO 2 interface. The interface modified Pb 3 O 4 /Au/TiO 2 catalyst can successfully eliminate CO in a wide temperature range (70°C–140°C) and exhibit superior stability in the PROX reaction. Further experiments demonstrated that the improved PROX performance is due to the severely depressed hydrogen oxidation through simultaneously inhibiting the activation of hydrogen and oxygen. The results further reveal that the interface of Au/TiO 2 is the superactive but non-selective site for H 2 and CO oxidation. • Photoexcited deposition of metal oxide method is employed for interface engineering • Interface-engineered Au-TiO 2 helps to identify the active site in CO and H 2 oxidation • Blocking the non-selective sites greatly improves the CO-PROX performance • Interface anchoring with inert lead oxide enhances long-term thermal stability Against the background of the carbon-neutral era, the liquid sunshine industry is booming due to the consumption of greenhouse gas (CO 2 ) and the solution of storage and transportation of H 2 energy. However, before the terminal application of H 2 energy, CO must be removed in the H 2 -rich reformate to avoid poisoning the noble metal catalysts. Gold-catalyzed CO preferential oxidation (PROX) has great potential in the removal of CO from H 2 -rich reformate. The competition oxidation of CO and H 2 at the interface of gold support always results in a decrease in CO oxidation conversion and selectivity, especially at high temperature. However, it is a major challenge to distinguish the interfacial sites from the other parts of nanoparticle surface. We show here that the interface of Au-TiO 2 is modified by our photoexcited deposition of metal oxide (PDMO) method, which greatly affects the performance of the CO-PROX reaction. The interfacial area of metal support is the ultrahigh active site in catalysis. However, the ultrahigh active sites are normally adverse for chemoselective oxidation or hydrogenation reaction. Interface-engineered catalyst is prepared based on a selective photoexcited deposition of metal oxide method and shows greatly improved performance in CO preferential oxidation in H 2 -rich stream (PROX reaction).

Hydrogen purification of actual syngas streams for energy applications: Au-Cu supported over nano-shaped CeO2 as stable catalysts for the carbon monoxide removal

Nano-shaped CeO2 (i.e., polyhedra, rods and cubes) and CeO2 without defined morphology were compared as supports of AuCu/CeO2 catalysts in the CO removal of actual syngas streams. Catalyst characterization indicates that oxygen vacancies, exposed CeO2 crystal planes, surface area and the interaction between active metals and support translate into changes in the catalytic performance on each nano-shape of CeO2. CeO2 nano-polyhedra and nano-rods show the higher activity and selectivity due to their high surface area and the presence of both {111} and {100} lattice planes. However, nano-rods are susceptible of losing CO2-selectivity under continuous operation due to the presence of an additional and unstable {110} lattice plane. Therefore, an AuCu catalyst supported on nano-polyhedra CeO2 ensures complete CO removal (i.e., <100 ppm) from an actual syngas stream for 48 h. These results are a contribution to the development of a simple, continuous and robust system for fuel-cell grade H2 production.

Versatile application of wet-oxidation for ambient CO abatement over Fe(OH)x supported subnanometer platinum group metal catalysts

The efficient and stable abatement of CO pollutant under ambient conditions is of great significance; however, it remains a formidable challenge. Herein, we report the versatile application of wet oxidation over Fe(OH) x supported subnanometer Pt group metal (PGM) catalysts for the complete removal of CO under ambient temperature and humidity conditions. Typically, the 1.8 wt% Rh/Fe(OH) x catalyst exhibited better durability during a ∼1400 min run for wet oxidation than for dry CO oxidation. Multiple characterization results including HR-TEM, H 2 -TPR, and in-situ DRIFTS suggested that Fe(OH) x , with good reducibility, promoted by the subnanometer Rh clusters, provided sites for the adsorption and reaction of O 2 and H 2 O to form OH species. Subsequently, these OH species reacted with the adsorbed CO on Rh sites with a considerably lower activation energy (9 kJ mol −1 ) than that of dissociated O species (22 kJ mol −1 ), thus rationalizing the outstanding performance of Rh/Fe(OH) x for wet oxidation. Extended experiments with other PGMs revealed a good generality for the application of wet oxidation in the efficient abatement of CO under humid conditions with Fe(OH) x as the support. Versatile CO abatement under ambient conditions is achieved by wet-oxidation over Fe(OH) x supported subnanometer Pt group metal catalysts owing to the facile formation and reaction of hydroxyl groups.

Nanocellulose/nanobentonite composite anchored with multi-carboxyl functional groups as an adsorbent for the effective removal of Cobalt(II) from nuclear industry wastewater samples

A novel adsorbent, poly(itaconic acid/methacrylic acid)-grafted-nanocellulose/nanobentonite composite [P(IA/MAA)-g-NC/NB] with multi carboxyl functional groups for the effective removal of Cobalt(II) [Co(II)] from aqueous solutions. The adsorbent was characterized using FTIR, XRD, SEM–EDS, AFM and potentiometric titrations before and after adsorption of Co(II) ions. FTIR spectra revealed that Co(II) adsorption on to the polymer may be due to the involvement of COOH groups. The surface morphological changes were observed by the SEM images. The pH was optimized as 6.0. An adsorbent dose of 2.0g/L found to be sufficient for the complete removal of Co(II) from 100mg/L at room temperature. Pseudo-first-order and pseudo-second-order models were tested to describe kinetic data and adsorption of Co(II) follows pseudo-second-order model. The equilibrium attained at 120min. Isotherm studies were conducted and data were analyzed using Langmuir, Freundlich and Sips isotherm models and best fit was Sips model. Thermodynamic study confirmed endothermic and physical nature of adsorption of the Co(II) onto the adsorbent. Desorption experiments were done with 0.1MHCl proved that without significant loss in performance adsorbent could be reused for six cycles. The practical efficacy and effectiveness of the adsorbent were tested using nuclear industrial wastewater. A double stage batch adsorption system was designed from the adsorption isotherm data of Co(II) by constructing operating lines.

Construction of ultrafine and stable PtFe nano-alloy with ultra-low Pt loading for complete removal of CO in PROX at room temperature

Rational design of highly effective catalysts based on the understanding of structure–activity relationship is becoming more and more important in heterogeneous catalysis. In this study, we have designed and successfully prepared a highly active PtFe nano-alloy catalysts with ultra-low Pt loading for the preferential oxidation of CO, over which CO can be completely removed at room temperature. As compared to the previously reported Pt@Fe quasi-core–shell catalysts with similar performance, the Pt loading of the as-prepared PtFe/Al2O3 nano-alloy catalysts can be decreased by a factor of 6 due to the increased Pt utilization. Based on in situ diffuse reflectance infrared spectroscopy (DRIFTS) and quasi-in situ XPS, it can be concluded that O2 is activated over ferrous iron on the PtFe/Al2O3 nano-alloy catalysts, leading to the high performance towards preferential oxidation of CO. Under reaction conditions, the active species will be oxidized to ferric oxide, thus O2 activation ability and catalytic activity decrease. Based on the above understanding, we further constructed a highly stable catalyst by supporting PtFe nano-alloy particles onto TiO2, which can help to activate O2 and stabilize the lower valence Fe species.

Development of monolithic adsorbent via polymeric sol–gel process for low-concentration CO2 capture

Abstract The objective of this research was to develop a new high-performance CO 2 adsorbent with a simple method. Amine hybrid resorcinol–formaldehyde/silsesquioxane composite aerogel (AH-RFSA) was developed through polymeric sol–gel process and supercritical drying (SCD) technique. CO 2 adsorption performances of AH-RFSA in 1% CO 2 gas mixture (CO 2 + N 2 ) were investigated. A rise in adsorption temperature negatively affects the total CO 2 adsorption capacity of AH-RFSA. However, the useful adsorption capacity does not change with adsorption temperature. Water is more positive to useful CO 2 adsorption capacity than to total CO 2 adsorption capacity. The total CO 2 adsorption capacity achieved with the new adsorbent at 30 °C under dry and humid 1% CO 2 is 3.57 and 4.43 mmol/g, respectively. The useful CO 2 adsorption capacity for complete removal of CO 2 from 1% CO 2 is as high as 3.56 mmol/g. The adsorbent preparation method is inspiring and its resulting adsorbent is exceptional in capacity and regenerability.

Catalytic oxidation of carbon monoxide over supported palladium nanoparticles

Catalytic oxidation of CO with ozone had been studied over Al2O3 and SiO2 supported Pd nanoparticles which was synthesized by two different methods. The polyol method mainly resulted in highly dispersed Pd particles on the support, while the impregnation method resulted in agglomeration Pd particles on the support. Supported Pd nanoparticles synthesized from PdCl2 in the presence of poly (N-vinylpyrrolidone) (PVP) by chemical reduction. The catalysts were characterized by X-ray diffraction, N2 BET surface area, pore size distributions, CO chemisorption, TEM and H2-temperature programmed reduction. The physico-chemical properties were well correlated with activity data. Characterizations of XRD and TEM show that the surface Pd nanoparticles are highly dispersed over Al2O3 and SiO2. The catalytic activity was dependent upon ozone/CO ratio, contact times, and the reaction temperature. The extent of carbon monoxide oxidation was proportional to the catalytically ozone decomposition. The PVP synthesized Pd/A2O3 catalyst had been found to be highly active for complete CO removal at room temperature. The higher activity of the nanocatalyst was attributed to small particle size and higher dispersion of Pd over support.

Novel Co‐Mn‐O nanosheet catalyst for CO preferential oxidation toward hydrogen purification

Co‐Mn‐O composite oxide nanosheet catalyst was successfully prepared using a facile urea‐assisted one‐step hydrothermal method in the absence of organic or organic templating reagent. Co‐Mn‐O nanosheet catalyst was optimized by varying hydrothermal process parameters such as molar ratio of Co‐Mn to urea, hydrothermal temperature, and hydrothermal time. Various characterization techniques including scanning electron microscopy, X‐ray diffraction, nitrogen adsorption, X‐ray photoelectron spectroscopy, Raman spectroscopy, and H2 temperature‐programmed reduction were used to reveal the relationship between catalyst nature and catalytic performance in CO preferential oxidation (CO PROX) in excess H2. The developed Co‐Mn‐O nanosheet catalyst have demonstrated much superior catalytic performance to Co‐Mn‐O nanoparticle, particularly in the low temperature range, and 100% CO conversion over the developed Co‐Mn‐O nanosheet can be achieved in temperature range of 50 to 150°C at 10,000 mL g−1 h−1 of gas hourly space velocity in the standard feed. Furthermore, the almost complete CO removal over Co‐Mn‐O nanosheet at 125°C of low temperature with 94.9% selectivity can be achieved even in the simulated reformed gas. The excellent catalytic performance is ascribed to nanosheet morphology, more surface Co3+, smaller average crystallite size, higher reducibility, and strong Co‐Mn interaction. Catalytic stability investigation indicates the developed nanostructured catalyst exhibits high catalytic stability for CO PROX reaction in simulated gas. The developed Co‐Mn‐O nanosheet catalyst can be a potential candidate for catalytic elimination of trace CO from H2‐rich gas for Proton exchange membrane fuel cell applications. © 2014 American Institute of Chemical Engineers AIChE J, 61: 239–252, 2015

Optimal Ru particle size for selective CO oxidation in H2 over Ru/κ-Al2O3

Ru/κ-Al2O3 catalysts with different Ru dispersions were prepared by controlling the pretreatment conditions, and were applied to selective CO oxidation in H2. The prepared catalysts were characterized by N2 physisorption, transmission electron microscopy, temperature-programmed oxidation, CO chemisorption, and O2 chemisorption. The Ru dispersion decreased with increasing reduction and oxidation temperature of Ru/κ-Al2O3. The turnover frequency for CO oxidation in H2 increased as the Ru particle size increased from 2.2 to 3.6 nm, whereas the apparent activation energy decreased as the Ru particle size increased from 2.2 to 3.4 nm for 1% Ru/κ-Al2O3. However, larger Ru particles were not always favorable for the selective CO oxidation in H2 because H2 oxidation was also promoted by these catalysts. In the case of the 1 wt% Ru/κ-Al2O3 catalyst, Ru nanoparticles of approximately 3 nm appeared to be optimal for the selective CO oxidation in H2 on the basis that they provided the widest temperature window, resulting in complete removal of CO even in the presence of H2O and CO2.

CO2 capture via barium carbonate formation after its absorption with ammonia in a pilot scale column

Abstract This study evaluates the removal and capture efficiency of carbon dioxide (CO 2 ) by aqueous ammonia (NH 3(ac) ) in a packed absorption tower at pilot scale. Initial concentrations of 2, 5, 10 and 15 mol% of CO 2 were used with 0, 1, 3, and 5 mol% of NH 3(ac) . The liquid flows ( L ) were varied between 1 and 3 L/min, and the gas flow ( G ) was kept constant at 80 L/min. The complete removal of CO 2 was achieved when the tower was operated with initial concentrations of CO 2 of up to 10 mol%, NH 3 concentration = 3 mol%, L = 1.7 L/min, G = 80 L/min and 50% flooding. The CO 2 absorbed in the liquid stream was separated by the precipitation of the carbonate ion (CO 3 2− ) with BaCl 2 . The precipitated salt was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and X-ray fluorescence (XRF). These analyses supported the conclusion that the salt consists predominantly of crystalline BaCO 3 , which is stable up to 1000 °C under static air. Based on this information and the modeling of the system in Aspen Plus, a new efficient and low-energy method of CO 2 capture was proposed.

Hierarchically nanoporous Co–Mn–O/FeOx as a high performance catalyst for CO preferential oxidation in H2-rich stream

A novel and highly-efficient hierarchically nanoporous Co–Mn–O/FeOx catalyst fabricated by a hard/soft dual-templating and subsequent deposition–precipitation (HSDT/DP) approach demonstrates unexpectedly high catalytic activity with 100% CO conversion at 75°C and wide temperature window of 75–200°C with complete CO removal for CO preferential oxidation (CO PROX), ascribed to the unique microstructure and strong interaction between finely dispersed cobalt–manganese and FeOx. The excellent catalytic performance allows it to be a practical candidate for CO elimination from H2-rich stream.

Mesostructured Co–Ce–Zr–Mn–O composite as a potential catalyst for efficient removal of carbon monoxide from hydrogen-rich stream

Mesostructured CoxCe0.85Zr0.15MnyOe composites were firstly prepared by a simple one-pot surfactant-assisted co-precipitation (SACP) method and then employed to catalyze the CO preferential oxidation (CO PROX) reaction in an H2-rich stream. Effects of the Co and Mn contents (x and y, respectively) in the formula, as well as the presence of H2O and CO2 in feed were investigated. The as-synthesized Co0.4Ce0.85Zr0.15Mn0.10Oe catalyst showed excellent catalytic performance in the CO PROX reaction: 100% CO conversion could be observed in a wide temperature range of 140–200 °C; even in the simulated syngas, the almost complete CO removal could still be achieved at 175–225 °C; no obvious change in both CO conversion and CO2 selectivity over the catalyst took place during the CO PROX process with simulated syngas as feed. N2 physisorption (BET), temperature-programmed reduction (TPR), X-ray diffraction (XRD), Raman and X-ray photoelectron spectroscopic (XPS) characterization techniques were employed to reveal the relationship between the catalyst nature and catalytic performance. The outstanding catalytic performance in CO PROX reaction was remarkably dependent on a larger specific surface area, more reducible Co3+ and the high dispersity of the Co3O4, affected by the Co and Mn contents through strong Co–Ce–Zr–Mn interactions. The mesostructured Co0.4Ce0.85Zr0.15Mn0.10Oe catalyst prepared by the simple one-pot SACP protocol can be a promising candidate for CO PROX reaction in excess H2.

CO selective methanation in hydrogen-rich gas mixtures over carbon nanotube supported Ru-based catalysts

Series of carbon nanotube supported Ru-based catalysts were prepared by impregnation method and applied successfully for complete removal of CO by CO selective methanation from H2-rich gas stream conducted in a fixed-bed quartz tubular reactor at ambient pressure. It was found that the metal promoter, reduction temperature and metal loading affected the catalytic properties significantly. The most excellent performance was presented by 30 wt% Ru-Zr/CNTs catalyst reduced at 350 °C. Since it decreased CO concentration to below 10 ppm from 12000 ppm by CO selective methanation at the temperature range of 180–240 °C, and kept CO selectivity higher than 85% at the temperature below 200 °C. Characterization using XRD, TEM, H2-TPR and XPS suggests that Zr modification of Ru/CNTs results in the weakening of the interaction between Ru and CNTs, a higher Ru dispersion and the oxidization of surface Ru. Amorphous and high dispersed Ru particles with small size were obtained for 30 wt% Ru-Zr/CNTs catalyst reduced at 350 °C, leading to excellent catalytic performance in CO selective methanation.

Hemilabile and reversible carbon monoxide binding properties of iron(ii), cobalt(ii) and nickel(ii) complexes containing a new tridentate P–S–N ligand

Several first-row transition metal complexes of the formulation [M(1)(2)](X)(2) {where 1 = Ph(2)PCH(2)CH(2)S(2-C(6)H(4)NH(2)); M = Fe(II), X = BF(4)(-) (2); M = Co(II), X = BF(4)(-) (3), Ni(II), X = ClO(4)(-) (4)} have been prepared by reaction of two equivalents of the new P-S-N ligand Ph(2)PCH(2)CH(2)S(2-C(6)H(4)NH(2)) 1 with one equivalent of the appropriate [M(OH(2))(6)](X)(2) precursor in acetonitrile. In the solid state, complexes 2-4 exist as distorted centrosymmetric octahedral structures featuring facially capping ligands in an all-trans arrangement. Reaction of 2 and 3 with a stream of carbon monoxide (1 atm.) for 5 min in acetonitrile generates iron(II) monocarbonyl species of formulation [Fe(CO)(1)(2)](BF(4))(2)2a, and a cobalt(II) dicarbonyl complex, [Co(CO)(2)(1)(2)](BF(4))(2)3a, which can be isolated in the solid state. Complete removal of CO is achieved by either heating to reflux samples of 2a in acetonitrile for 5 min or by heating solid samples of 3a at 120 °C in vacuo over a period of 4 h. The binding of carbon monoxide is fully reversible for 2 and 3 and can be repeated over multiple cycles. When the same trapping reactions were carried out with very low radiochemical (11)CO concentrations, metal carbonyl species were no longer formed. It is likely that the kinetics of (11)CO adduct formation are too slow to allow for effective trapping under the applied radiochemical conditions.

Effect of quenching temperature on the performance of poly(vinylidene fluoride) microporous hollow fiber membranes fabricated via thermally induced phase separation technique on the removal of CO 2 from CO 2-gas mixture

The capture and utilization of carbon dioxide from flue gases and sweetening of natural gas, is currently a global issue. Hollow fiber membranes contactors are new emerged technology proposed for this purpose. In the present work hollow fiber membranes were fabricated and used as a membrane contactor and utilized in the absorption of carbon dioxide from natural gas. Poly(vinylidene fluoride) (PVDF) was used to fabricate microporous hollow fiber membranes. The fibers were prepared by using glycerol triacetate (triacetin) as solvent, and through thermally induced phase separation technique. The fabricated fiber membranes were investigated at various quenching temperatures. Characterization of the resulting membranes included scanning electron microscopy and differential scanning calorimetry. Microscopic observation showed that the membrane was composed of spherical clusters. The crystallinity increased with the quenching temperature. Permeation performance was also determined, including pure water permeability and gas permeation test. The results showed that at lower quenching temperatures, the structure of the membrane was dense. Therefore the water permeability and gas permeability were low. Complete removal of CO 2 was possible using PVDF hollow fiber membrane contactor enclosed of hollow fiber membranes fabricated at high quenching temperatures.

CO Methanation Over Ru–Al2O3 Catalysts: Effects of Chloride Doping on Reaction Activity and Selectivity

The selective CO methanation (CO-SMET) process via Ru–Al2O3 catalysts was investigated as a tool for complete CO removal in fuel processors, when the H2-rich gas so produced is employed for PEM-FCs applications to vehicles, boats, yachts and residential co-generators. CO-SMET seems, in fact, to be a good alternative to the most widely used CO preferential oxidation (CO-PROX) process. The performance of Ru-based catalysts on alumina carrier for efficient CO removal through CO-SMET was studied, exploring the role of two different Ru precursors (chloride and nitrate), and the doping effect of chloride and of Ru load (1%, 3% and 5%). First, two catalytic families (Ru–Al2O3_Cl and Ru–Al2O3_NO3) were prepared by incipient wetness impregnation of alumina powder synthesized via solution combustion synthesis, by varying the Ru load. Then, based on the best obtained results, a third catalytic family was prepared adding chloride to Ru–Al2O3_NO3 catalysts by impregnation. The CO removal performance was determined at catalyst powder level in a fixed bed micro reactor. Better performances were exhibited when Ru was deposited from chloride precursor, but the post-addition of chlorine to fresh Ru–Al2O3 catalysts prepared with nitrate precursor tremendously improved their selectivity toward CO methanation. In particular, with both 1% and 3% Ru–Al_NO3 catalyst chlorine doped, complete CO conversion was reached in a proper temperature range where the CO2 methanation was suitably kept at a low acceptable level.

Ru-based catalysts for CO selective methanation reaction in H 2-rich gases

Even traces of CO in the hydrogen-rich gas fed to PEM-FCs can poison the platinum anode electro-catalyst and dramatically decrease the stack power. The CO selective methanation (CO-SMET) process seems to be a good alternative to the CO preferential oxidation (CO-PROX) one for PEM-FCs applications to vehicles, boats, yachts and residential co-generators, as a CO-SMET reactor is inherently easier to control than the CO-PROX one. The present paper deals with the study on complete removal of CO in H 2-rich gas stream from a reforming process through CO-SMET over Ru-based catalysts supported on Al 2O 3 and CeO 2 carriers. All the catalysts, with Ru load of 1%, 3% and 5%, were prepared by a conventional impregnation method, using two different Ru precursors, chloride and nitrate, and their CO removal performance was determined at the powder level in a fixed bed micro reactor. The Al 2O 3 carrier exhibited performances better than the CeO 2 one, in particular when Ru was deposited from RuCl 3 precursor. The best performance was obtained with 5% Ru–Al 2O 3_Cl as the temperature range of complete CO conversion with acceptably low levels of CO 2 methanation (≤50% of CO molar methanation) was the widest.

CO selective methanation in H2-rich gas for fuel cell application: Microchannel reactor performance with Ru-based catalysts

The present paper deals with the study on complete removal of CO in H2-rich gas stream through CO-SMET over Ru-based catalysts supported on γ-Al2O3 and CeO2 carriers. All the catalysts, loaded with 3% Ru, were prepared by a conventional impregnation method and their CO removal performance was determined at the powder level in a fixed bed micro reactor. The 3% Ru–γAl2O3 catalyst showed the best performance; consequently, it was deposited on microchannel metal plates reactor. With a catalyst load on the microchannel plates of 5mgcm−2 the performance was poor as complete CO conversion was not reached and also CO2 methanation was present. Increasing Ru load to 5%, the performance further worsened, the CO conversion decreased and higher amount of methane was produced.The catalytic activity on microchannel metal plates reactor was improved with the 3% Ru–γAl2O3 catalyst by doubling the its load on the surface (10mgcm−2): the residual CO concentration decreased to about 100–150ppmv at 310°C, but a large amount of methane was formed also by the CO2 methanation, thus reducing catalyst selectivity.