Effective cleanup of CO in hydrogen by PROX over perovskite and mixed oxides

Preferential oxidation of CO (PROX-CO) from hydrogen has been carried out over various oxides and perovskite catalysts namely CeO2, CuLaO2eCeO2, La2CuO4. Further, effect of loading of a small quantity of Pt in catalysts 0.1 wt% Pt/CeO2, 0.1 wt% Pt/La2CuO4, 0.1 wt% Pt/CuLaO2eCeO2 was examined with respect to its activity for PROX-CO. In order to improve the surface area of La2CuO4 a chitosan complex method was used for synthesis. The catalysts were characterized using XRD, SEM and BET-SA techniques. Chitosan complex method results in pervoskite with pure phase, porous structure and higher surface area of 16.3 m2/g compared to that of 3.8 m2/g obtained by co-precipitation synthesis method. La2CuO4 exhibited a considerable activity for CO oxidation with conversion of 91.7%. Whereas, 0.1 wt% Pt/CuLaO2eCeO2 catalyst exhibited CO conversion of 94.1% and selectivity of 87.1% at reaction temperature of 320 �C. The improved CO/H2 selectivity may be attributed to the promotion of water gas shift reaction at the interface of Pt-metal oxide besides the relatively higher oxidation activity of the metal oxides. The catalysts reported in this study with relatively higher CO conversion and selectivity with lower value of l ¼ 0.3 exhibit potential for effective cleanup of hydrogen gas to remove CO for fuel cell applications

Pure phase LaFeO3 perovskite with improved surface area synthesized using different routes and its characterization

Three different wet chemistry routes, namely co-precipitation, combustion and sol–gel methods were used to synthesize LaFeO3 perovskite with improved surface area. The synthesized perovskite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), Brunauer–Emmett–Teller (BET) nitrogen adsorption, ultraviolet diffused reflectance spectroscopy (UVDRS) and Fourier transform infrared (FTIR) spectroscopy techniques. Improved surface area was observed for all three methods as compared to the previously reported values. The perovskite synthesized using sol–gel method yields comparatively pure, crystalline phase of LaFeO3 and relatively higher surface area of 16.5m2 g−1 and porosity. The material synthesized using co-precipitation method yielded other phases in addition to the targeted phase. The morphology of perovskite synthesized using co-precipitation method was uniform agglomerates. Combustion method yields flakes type morphology and that of sol–gel method was open pore type morphology. The selection of method for perovskite synthesis largely depends on the targeted application and the desired properties of perovskites. The results reported in this study are useful for establishing a simple scalable method for preparation of high surface area LaFeO3 as compared to solid-oxide method. Further, the typical heating cycle followed for calcinations resulted in relatively high surface area in the case of all three methods

Catalytic preferential oxidation of carbon monoxide over platinum supported on lanthanum ferrite-ceria catalysts for cleaning of hydrogen

Since hydrogen is produced by reforming of hydrocarbon it contains carbon monoxide (CO). In order to make hydrogen suitable for proton exchange membrane fuel cell application there is need to reduce concentration of CO less than 100 ppm. WatereGas-Shift reactions subsequent to reforming lower CO concentration in H2 to about 1e1.5% by volume. Preferential oxidation of CO (PROXeCO) using a catalyst is therefore important for further cleaning up of CO from H2. The catalyst in this study is platinum supported over lanthanum ferriteeceria (Pt/LaFeO3eCeO2) exhibits excellent activity of 99.8% and selectivity of 95.7% at a relatively lower temperature of 100 �C with an equivalence ratio of 3 for PROX eCO. The concentration of CO is reduced from 1% v/v in feed to ca. 30 ppm in product gas with relatively lower loss of hydrogen is the most significant achievement in this study. The catalyst is selective towards CO oxidation as the hydrogen loss is relatively low (ca. 3.8%) and there is no methane formation. The improvement in catalytic activity and selectivity is attributed to the strong metal support interaction and open morphology of catalyst. The results obtained in this study reveal the excellent catalytic activity by using LaFeO3eCeO2 as support for Pt catalys

Catalytic preferential oxidation of carbon monoxide over platinum supported on lanthanum ferriteeceria catalysts for cleaning of hydrogen

Since hydrogen is produced by reforming of hydrocarbon it contains carbon monoxide (CO). In order to make hydrogen suitable for proton exchange membrane fuel cell application there is need to reduce concentration of CO less than 100 ppm. WatereGas-Shift reactions subsequent to reforming lower CO concentration in H2 to about 1e1.5% by volume. Preferential oxidation of CO (PROXeCO) using a catalyst is therefore important for further cleaning up of CO from H2. The catalyst in this study is platinum supported over lanthanum ferriteeceria (Pt/LaFeO3eCeO2) exhibits excellent activity of 99.8% and selectivity of 95.7% at a relatively lower temperature of 100 _C with an equivalence ratio of 3 for PROX eCO. The concentration of CO is reduced from 1% v/v in feed to ca. 30 ppm in product gas with rela-tively lower loss of hydrogen is the most significant achievement in this study. The catalyst is selective towards CO oxidation as the hydrogen loss is relatively low (ca. 3.8%) and there is no methane formation. The improvement in catalytic activity and selectivity is attributed to the strong metal support interaction and open morphology of catalyst. The results obtained in this study reveal the excellent catalytic activity by using LaFeO3eCeO2 as support for Pt catalyst

Pure phase LaFeO3 perovskite with improved surface area synthesized using different routes and its characterization

Three different wet chemistry routes, namely co-precipitation, combustion and sol–gel methods were used to synthesize LaFeO3 perovskite with improved surface area. The synthesized perovskite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), Brunauer–Emmett–Teller (BET) nitrogen adsorption, ultraviolet diffused reflectance spectroscopy (UVDRS) and Fourier transform infrared (FTIR) spectroscopy techniques. Improved surface area was observed for all three methods as compared to the previously reported values. The perovskite synthesized using sol–gel method yields comparatively pure, crystalline phase of LaFeO3 and relatively higher surface area of 16.5 m2 g−1 and porosity. The material synthesized using co-precipitation method yielded other phases in addition to the targeted phase. The morphology of perovskite synthesized using co-precipitation method was uniform agglomerates. Combustion method yields flakes type morphology and that of sol–gel method was open pore type morphology. The selection of method for perovskite synthesis largely depends on the targeted application and the desired properties of perovskites. The results reported in this study are useful for establishing a simple scalable method for preparation of high surface area LaFeO3 as compared to solid-oxide method. Further, the typical heating cycle followed for calcinations resulted in relatively high surface area in the case of all three methods

Effective cleanup of CO in hydrogen by PROX over perovskite and mixed oxides

Preferential oxidation of CO (PROX-CO) from hydrogen has been carried out over various oxides and perovskite catalysts namely CeO2, CuLaO2eCeO2, La2CuO4. Further, effect of loading of a small quantity of Pt in catalysts 0.1 wt% Pt/CeO2, 0.1 wt% Pt/La2CuO4, 0.1 wt% Pt/CuLaO2eCeO2 was examined with respect to its activity for PROX-CO. In order to improve the surface area of La2CuO4 a chitosan complex method was used for synthesis. The catalysts were characterized using XRD, SEM and BET-SA techniques. Chitosan complex method results in pervoskite with pure phase, porous structure and higher surface area of 16.3 m2/g compared to that of 3.8 m2/g obtained by co-precipitation synthesis method. La2CuO4 exhibited a considerable activity for CO oxidation with conversion of 91.7%. Whereas, 0.1 wt% Pt/CuLaO2eCeO2 catalyst exhibited CO conversion of 94.1% and selectivity of 87.1% at reaction temperature of 320 _C. The improved CO/H2 selectivity may be attributed to the promotion of water gas shift reaction at the interface of Pt-metal oxide besides the relatively higher oxidation activity of the metal oxides. The catalysts reported in this study with relatively higher CO conversion and selectivity with lower value of l ¼ 0.3 exhibit potential for effective cleanup of hydrogen gas to remove CO for fuel cell applications

Efficient hydrogen supply through catalytic dehydrogenation of methylcyclohexane over Pt/metal oxide catalystsEfficient hydrogen supply through catalytic dehydrogenation of methylcyclohexane over Pt/metal oxide catalysts

This paper describes the results of experiments on dehydrogenation of methylcyclohexane over Pt supported on metal oxides (Pt/MO) and Pt supported on perovskite (Pt/Per) catalysts. The reaction is being considered as a means for delivery of hydrogen to fueling stations in the form of more easily transportable methylcyclohexane. Among Pt/MO catalysts, the best activity as determined by the hydrogen evolution rate was observed over Pt/La2O3 catalyst at 21.1 mmol/gmet/min. Perovskite-supported catalysts exhibited relatively higher activity and selectivity, with Pt/La0.7Y0.3NiO3 giving the best performance. This Pt/Per catalyst had an activity of ca 45 mmol/gmet/min with nearly 100% selectivity towards dehydrogenation. The catalysts were characterized using XRD, CO-chemisorption and SEM-EDXA techniques. The present study reports catalysts that minimize the use of Pt and explores tailoring the properties of the perovskite structure