Showing papers on "Temperature-programmed reduction published in 2011"
TL;DR: In this paper, a two-stage fixed bed reaction system with Ni/MCM-41 mesoporous catalyst supports was used for wood sawdust pyrolysis-gasification.
Abstract: The steam pyrolysis-gasification of biomass, wood sawdust, was carried out with a Ni/MCM-41 catalyst for hydrogen production in a two-stage fixed bed reaction system. The wood sawdust was pyrolysed in the first reactor and the derived products were gasified in the second reactor. The synthesised MCM-41 mesoporous catalyst supports were impregnated with different Ni loadings (5, 10, 20 and 40 wt.%), which were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature programmed reduction (TPR), transmission electron microscopy (TEM) and temperature-programmed oxidation (TPO). NiO particles were homogeneously dispersed inside the pores of 5, 10, and 20 wt.% Ni/MCM-41 catalysts; however, more bulkly NiO particles (up to 200 nm particle size) were detected outside the pores with an increase of the Ni loading up to 40 wt.%. Gas production was increased from 40.7 to 62.8 wt.%, hydrogen production was increased from 30.1 to 50.6 vol.% of total gas composition when the Ni loading was increased from 5 to 40 wt.% during the pyrolysis-gasification of wood sawdust. This work showed low coke deposition (from 0.5 to 4.0 wt.%) with valuable bio-oil by-products using the Ni/MCM-41 catalyst. The highly efficient conversion of renewable biomass resource to hydrogen and bio-oil with very low coke deposition indicates that biomass gasification on Ni/MCM-41 catalysts via two-stage reaction is a promising method for the development of the biorefinery concept.
181 citations
TL;DR: In this article, the catalytic roles of Co0 and Co2+ during steam reforming of ethanol were investigated over Co/MgO catalysts, and the Co0 fraction was quantified by temperature programmed reduction and in situ X-ray photoelectron spectroscopy (XPS).
Abstract: The catalytic roles of Co0 and Co2+ during steam reforming of ethanol were investigated over Co/MgO catalysts. Catalysts with different Co0/(Co0+Co2+) fraction were prepared through calcination and/or reduction at different temperatures, and the Co0 fraction was quantified by temperature programmed reduction (TPR) and in situ X-ray photoelectron spectroscopy (XPS). Higher temperature calcination of Co/MgO allowed us to prepare catalysts with more nonreducible Co2+ incorporated in the MgO lattice, while lower calcination temperatures allowed for the preparation of catalysts with higher Co0/(Co0+Co2+) fractions. The catalytic tests on Co0, nonreducible Co2+, and reducible Co2+ indicated that Co0 is much more active than either reducible or nonreducible Co2+ for C−C cleavage and water gas shift reaction. In addition, catalysts with a higher Co0 surface fraction exhibited a lower selectivity to CH4.
97 citations
TL;DR: The results showed that the 4-NP was completely degraded using the high efficiency MECD method within 15 min under [H(+)] = 1.0M, T = 40 °C, and C = 200 ppm over nickel oxide.
94 citations
TL;DR: In this paper, the catalytic activities of three spinel ferrospinels (Co, Ni, Cu) were evaluated for high temperature sulfuric acid decomposition reaction, and copper ferrite was found to be the most active catalyst for the reaction with ∼78% conversion at 800°C.
92 citations
TL;DR: The best catalytic performance was observed on Ni/MgO due to the strong interaction between NiO and MgO via the formation of Ni-Mg-O solid solution, and the highest dispersion of Ni particle in the basic environment.
87 citations
TL;DR: In this paper, double impregnation (DIM), liquid phase reductive deposition (LPRD), and ultrasonication (US) was used to load Au nanoparticles on commercial oxide supports.
Abstract: Au has been loaded (1% wt.) on different commercial oxide supports (CuO, La2O3, Y2O3, NiO) by three different methods: double impregnation (DIM), liquid-phase reductive deposition (LPRD), and ultrasonication (US). Samples were characterised by N2 adsorption at −196 °C, high-resolution transmission electron microscopy, selected area electron diffraction, energy dispersive X-ray spectrometry, high-angle annular dark-field imaging (Z-contrast), X-ray diffraction, and temperature programmed reduction. CO oxidation was used as a test reaction to compare the catalytic activities. The best results were obtained with Au loaded by DIM on the NiO support, with an activity of 7.2 × 10−4 molCO·gAu−1·s−1 at room temperature. This is most likely related to the Au nanoparticle size being the smallest in this catalyst (average 4.8 nm), since it is well known that gold particle size determines the catalytic activity. Other samples, having larger Au particle sizes (in the 2–12 nm range, with average sizes ranging from 4.8 to 6.8 nm), showed lower activities. Nevertheless, all samples prepared by DIM had activities (from 1.1 × 10−4 to 7.2 × 10−4 molCO·gAu−1·s−1, at room temperature) above those reported in the literature for gold on similar oxide supports. Therefore, this method gives better results than the most usual methods of deposition-precipitation or co-precipitation.
Open image in new window
78 citations
TL;DR: In this article, a single step polymerization method was used to synthesize catalysts containing NiO/MgO/ZrO 2 mixtures, which were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR) and physisorption of N 2 (BET) and then tested in the reforming of a model biogas.
Abstract: Catalysts containing NiO/MgO/ZrO 2 mixtures were synthesized by the polymerization method in a single step. They were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR) and physisorption of N 2 (BET) and then tested in the reforming of a model biogas (1.5CH 4 :1CO 2 ) in the presence of air (1.5CH 4 + 1CO 2 + 0.25O 2 ) at 750 °C for 6 h. It was observed that the catalyst Ni20MZ performed better in catalytic processes than the well known catalysts, Ni/ZrO 2 and Ni/MgO, synthesized under the same conditions. The formation of solid solutions, MgO–ZrO 2 and NiO–MgO, increased the rate of conversion of reactants (CH 4 and CO 2 ) into synthesis gas (H 2 + CO). The formation of oxygen vacancies (in samples containing ZrO 2 and MgO) seems to promote removal of the coke deposited on the nickel surface. The values of the H 2 /CO ratio were generally found to be slightly lower than stoichiometric, owing to the reverse water–gas shift reaction occurring in parallel.
74 citations
TL;DR: In this paper, the effect of Pd on activity enhancement of perovskite catalysts for oxidation of CH4 and CO emitted from natural gas fueled vehicles is investigated using a synthetic stoichiometric exhaust gas mixture.
Abstract: The effect of Pd on activity enhancement of perovskite catalysts for oxidation of CH4 and CO emitted from natural-gas fueled vehicles is investigated using a synthetic stoichiometric exhaust gas mixture. Various LaBO3 and LaBPd0.05O3 (B = Mn, Fe, Co and Ni) perovskite-type nanocatalysts were prepared via a solution combustion synthesis, calcined at 700 °C for 5 h, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), BET specific surface area measurement, H2 temperature programmed reduction (TPR) and O2 temperature programmed desorption (TPD). XRD results, confirms the presence of PdO in Pd-containing samples, which is highly active for CO and CH4 oxidation. TPR and TPD results show that Pd significantly facilitates the reducibility of B in LaBPd0.05O3 pervoskites and enhances the mobility of lattice oxygen in the prepared samples, which results in activity enhancement for Pd-containing catalysts. Oxidation activity results reveal that Pd effect is more pronounced for CO oxidation as compared to that for CH4, probably due to the Pd transition from PdO to metallic Pd and/or its incorporation into the pervoskite structure occurred at elevated temperatures, which both seem to reduce its activity. Among the prepared samples, LaFePd0.05O3 catalyst shows the highest activity for CO and CH4 oxidation, T90 of which occur at 165 and 558 °C, 191 and 40 °C lower than that for LaFeO3 respectively.
73 citations
TL;DR: In this article, two heterogeneous catalysts were prepared by impregnating a raw-clay, a montmorillonite-rich material, with iron oxides, in order to be used in oxidative reactions of toluene.
73 citations
TL;DR: In this article, the catalytic gas phase hydrogenation of m-dinitrobenzene (1 atm, 423 K) over laboratory synthesized (1 mol%) Au supported on Al2O3, TiO2, Fe 2O3 and CeO2 and a reference Au/TiO2 (World Gold Council) has been investigated.
71 citations
TL;DR: In this article, the highly porous Co 3 O 4 nanorods are prepared by a simple hydrothermal method, in which CO(NH 2 ) 2 is employed as precipitating agent, and K60 (PVP, polyvinylpyrrolidone) is used as surfactant to improve the stability of the nanoparticles.
Abstract: The highly porous Co 3 O 4 nanorods are prepared by a simple hydrothermal method, in which CO(NH 2 ) 2 is employed as precipitating agent, and K60 (PVP, polyvinylpyrrolidone) is used as surfactant to improve the stability of the nanoparticles. For comparison, the bulk Co 3 O 4 is prepared by thermal decomposition of cobalt nitrate. The samples are characterized by field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (ED), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, N 2 adsorption, Thermogravimetric analysis (TG), H 2 -temperature programmed reduction (TPR), CO-, CH 4 -, and O 2 -temperature programmed desorption (TPD). The catalluminescence (CTL) and catalytic properties of the samples are investigated extensively. The results show that the Co 3 O 4 nanorods are composed of nanoparticles, and have a large number of pores with a narrow pore size distribution (1.5–7 nm). Compared with the bulk Co 3 O 4 , the porous nanorods have a higher CTL intensity of CO oxidation, and a higher activity of CH 4 combustion especially at a higher gas hourly space velocity (GHSV), which has been ascribed to its porous structure and larger surface area.
TL;DR: In this article, a series of Cu/ZnO/Al2O3 catalysts were used for steam reforming of methanol and ethanol, and they were characterized using N2 physisorption, X-ray diffraction (XRD), temperature programmed reduction (TPR) techniques, N2O decomposition, high resolution transmission electron microscopy (HR-TEM), and thermogravimetric analysis (TGA).
Abstract: Hydrogen production by steam reforming of methanol and ethanol is studied over a series of Cu/ZnO/Al2O3 catalysts prepared by different coprecipitation procedures and modified with the introduction of Ni and Co The catalysts are characterized using N2 physisorption, X-ray diffraction (XRD), temperature programmed reduction (TPR) techniques, N2O decomposition, high resolution transmission electron microscopy (HR-TEM) and thermogravimetric analysis (TGA) Despite the influence of the preparation method on the texture and structure of Cu/ZnO/Al2O3 catalysts, their catalytic behavior appears not significantly affected While Cu/ZnO/Al2O3 shows poor H2 selectivity in the ethanol steam reforming reaction, the presence of a second metal (Ni or Co) significantly improves the reforming reaction Although coke deposition remains a drawback for these systems, formation of an alloy between Ni and Cu appreciably reduces carbon deposition with respect to the Co/Cu-based system
TL;DR: In this article, a template-assisted precipitation method was used to construct a doped Ce 1− x M x O catalysts for the oxidative dehydrogenation of ethylbenzene (EB) to styrene.
Abstract: Mesostructured doped Ce 1− x M x O catalysts (M = Al, Sn, Zr, Mn, and Ni) with large surface area prepared via template-assisted precipitation method have been tested for the oxidative dehydrogenation (ODH) of ethylbenzene (EB) to styrene. Several techniques including N 2 desorption–adsorption, X-ray diffraction, H 2 -temperature programmed reduction (H 2 -TPR), total oxygen storage capacity (OSC), and X-ray photoelectron spectroscopy (XPS) were applied to characterize the physicochemical properties of the as-synthesized materials. Of the Ce 1− x M x O catalysts tested, the CeNiO composite containing 10 mol% Ni demonstrates the highest ST yield of 55% with long-term stability for ODH of EB under 450 °C. By analysis of H 2 -TPR and total OSC characterization profiles, the superior performance of Ce 0.90 Ni 0.10 O catalyst can be attributed to the dramatic improvement in oxygen mobility and storage capacity of the ceria materials, resulting from the introduction of Ni species into ceria cubic structure and hence a further shrinkage of ceria lattice. A catalytic mechanism via a simple surface redox cycle has been tentatively proposed based on the XPS results.
TL;DR: In this article, four different types of mesoporous silica (SBA-15, MCM-41, MCm-48 and KIT-6) were examined for catalytic reduction of NO with CO in the temperature range of 250-500°C.
Abstract: Copper oxide supported on four different types of mesoporous silica (SBA-15, MCM-41, MCM-48 and KIT-6) were prepared and examined for catalytic reduction of NO with CO in the temperature range of 250–500 °C. Their structural and chemical properties were characterized by N2 adsorption, low angle and wide angle X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), FTIR and temperature programmed reduction (TPR). H2-TPR revealed that MCM-41 and SBA-15 tend to possess a higher quantity of reducible copper species in contrast to MCM-48 and KIT-6. CuO supported on MCM-41 and SBA-15 exhibited higher activity in catalytic reduction of NO than CuO supported on MCM-48 and KIT-6. The superior catalytic activity was attributed to homogeneous dispersion of CuO and availability of the reducible copper ions in the channels of mesoporous materials.
TL;DR: In this article, a carburized Fe-Mn catalyst was tested for Fischer-Tropsch synthesis using a stirred tank reactor at 270 C, 1.21 MPa, and H{sub 2}:CO = 0.7.
Abstract: Fe-based catalysts containing different amounts of Mn were tested for Fischer-Tropsch synthesis using a stirred tank reactor at 270 C, 1.21 MPa, and H{sub 2}:CO = 0.7. Catalyst activation by carburization with 10% CO/He was followed by Temperature Programmed Reduction/X-ray Absorption Spectroscopy (TPR-EXAFS/XANES) from room temperature to 300 C. {gamma}-Fe{sub 2}O{sub 3} was converted into iron carbides, whereas MnO{sub x} was reduced to oxygen deficient MnO. Mn hindered Fe carburization, such that the carburized catalyst displayed higher Fe{sub 3}O{sub 4} content than the catalyst without Mn. EXAFS fitting indicates that the carburized catalyst contained a mixture of Hgg carbide, Fe{sub 3}O{sub 4}, and Mn oxides. Increasing Mn content led to higher CH{sub 4} and light product selectivities, and lower light olefin selectivities. Higher and stable conversions were obtained with a catalyst containing an almost equimolar Fe/Mn ratio relative to the catalyst without Mn. Selectivity trends are attributed to the higher WGS rates observed on the FeMn catalysts, consistent with the structural differences observed.
TL;DR: In this article, the structure-activity relationship and reaction mechanism for selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) in toluene were studied on vanadium oxide domains on TiO 2, Al 2 O 3, Nb 2 O 5, ZrO 2 and MgO and with a wide range of VO x surface densities.
Abstract: The structure-activity relationship and reaction mechanism for selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) in toluene were studied on vanadium oxide domains on TiO 2 , Al 2 O 3 , Nb 2 O 5 , ZrO 2 , and MgO and with a wide range of VO x surface densities. The structures of these catalysts were characterized by X-ray diffrac- tion (XRD), diffuse reflectance UV-vis spectroscopy (UV-vis DRS), and Raman spec- troscopy, and their reducibility was probed by H 2 -temperature programmed reduction. The structures of the VO x domains evolved from monovanadate to polyvanadate structures with increasing the VO x surface densities, and finally to crystalline V 2 O 5 clusters at surface den- sities above one-monolayer capacity. Within one-monolayer capacity, higher VO x surface densities and more reducible supports led to higher reducibility and reactivity of the VO x domains. The support surfaces covered with polyvanadates and V 2 O 5 clusters and the sup- ports with acidity favored the formation of DFF. The correlation between the reducibility and reactivity, together with the kinetic studies, suggests that the HMF oxidation to DFF proceeds via the redox mechanism involving the V 5+ /V 4+ redox cycles and the reoxidation of V 4+ to V 5+ by O 2 as the rate-determining step. These results may provide guidance for the design of more efficient catalysts for the HMF oxidation to synthesize DFF.
TL;DR: In this article, the effect of support composition as well as active metal composition on steam reforming of ethanol in micro-channel reactor was studied at atmospheric pressure, with an ethanol to water molar ratio of 1:6, over a temperature range of 400-600 °C.
TL;DR: In this article, the influence of EDTA on the reducibility and metal-support interactions of SiO2-Al2O3 catalysts was investigated using temperature programmed reduction (TPR) technique.
TL;DR: In this paper, the shape and crystal planes of supporting Co3O4 nanocrystals were tuned for low-temperature methane combustion by tuning the shape of supporting Pd catalysts, and the strong surface interaction between the Co 3O4 unit cell and the PdO unit cell was analyzed by using high resolution transmission electron microscopy and temperature programmed reduction experiments.
Abstract: We report a novel strategy to prepare supported Pd catalysts for low-temperature methane combustion. The structure–property relationship of the catalysts was investigated by tuning the shape and crystal planes of supporting Co3O4 nanocrystals. Pd/Co3O4 nanosheets are more reactive than Pd/Co3O4 nanobelts and nanocubes with the same Pd loading. The strong surface interaction between the Co3O4 unit cell and the PdO unit cell on {112} crystal plane of Pd/Co3O4 nanosheets has been analyzed by using high resolution transmission electron microscopy and temperature programmed reduction experiments.
TL;DR: In this paper, the structures, morphologies, surface compositions and catalytic activities of unmodified and Ce-modified Pd-Ni alloy catalysts have been characterized by XRD, TEM, temperature programmed reduction (TPR) and electrochemical measurements, respectively.
TL;DR: In this paper, carbon nanotube supported nano-size monometallic and noble metal (Pt and Ru) promoted cobalt catalysts were prepared by incipient wetness impregnation (IWI) using solution of cobalt nitrate and characterized by nitrogen adsorption isotherm, X-ray diffraction (XRD), temperature programmed reduction, in situ magnetic method and TEM.
Abstract: Carbon nanotube supported nano-size monometallic and noble metal (Pt and Ru) promoted cobalt catalysts were prepared by incipient wetness impregnation (IWI) using solution of cobalt nitrate and characterized by nitrogen adsorption isotherm, X-ray diffraction (XRD), temperature programmed reduction, in situ magnetic method and TEM. Analysis of the magnetization and H2-TPR data suggested promotion with platinum and ruthenium significantly decreased the cobalt species reduction temperature. TEM and XRD results showed that the presence of noble metal promoters had no significant effect on the size of cobalt for carbon naotube as catalytic support. Promotion of cobalt carbon nanotube-supported catalysts with small amounts of Pt and Ru resulted in slight increase in Fischer–Tropsch cobalt time yield. The Pt and Ru promoted cobalt catalyst exhibited carbon monoxide conversion of 37.1 and 31.4, respectively. C5+ hydrocarbon selectivity was attained at 80.0%. The Pt promoted cobalt supported on carbon nanotube yielded better catalytic stability than that of the monometallic cobalt catalyst. Over carbon nanotube supported cobalt catalyst, the addition of noble promoter significantly decreased the cobalt reduction temperature, but had no significant influence on the cobalt particle size.
TL;DR: In this paper, the authors describe the development of substituted spinel catalysts for low-temperature selective catalytic reduction (SCR) of NOx with NH3 using X-ray diffraction and field emission scanning electron microscopy (FESEM).
Abstract: The present work describes the development of Mn1–xMxCr2O4 (M = Mg, Ca; x = 0–0.1) substituted spinel catalysts prepared via gel combustion synthesis for the low-temperature selective catalytic reduction (SCR) of NOx with NH3. The catalysts have been characterized by means of X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), field emission scanning electron microscopy (FESEM) and temperature programmed reduction (TPR) analyses, whereas their catalytic activity has been tested in a temperature programmed reaction (TPRe) apparatus over a temperature range of 100–200 °C (W/F = 0.072 g·s·cm–3) in the presence of oxygen. The catalytic activity of alkali earth-metal substituted Mn–Cr spinels is compared with that of the stoichiometric MnCr2O4 in order to assess the effect of the substitutions. All the spinel catalysts have shown both high NO conversion and high selectivity to N2. Mn0.95Ca0.05Cr2O4 has shown the best performance, reaching an NO conversion of 96% and a selectivity to N2 of 97% at 125 °C. All...
TL;DR: In this paper, a method combining conventional temperature programmed reduction (TPR) by hydrogen with reoxidation in N 2 O followed by a second surface TPR (s-TPR), enables discrimination and a quantitative estimation of the Cu oxidation states +2, +1 and 0.
TL;DR: In this article, the application of a redox treatment consisting of a high-temperature reduction with 5%H 2 /Ar in the range 950-1075°C for 0.5-3
Abstract: In this work the application of a redox treatment consisting of a high-temperature reduction with 5%H 2 /Ar in the range 950–1075 °C for 0.5–3 h followed by mild oxidation at 550 °C with 5%O 2 /He was evaluated as a tool for improving the catalytic performance of Ce 0.5 Zr 0.5 O 2 mixed oxide in the combustion of chlorinated compounds. Structural, morphological and physico-chemical changes caused by the redox treatment were analysed by X-ray diffraction, Raman spectroscopy, BET measurements, NH 3 -temperature programmed desorption, temperature programmed reduction with hydrogen, and oxygen chemisorption. Interestingly, after reduction at a temperature as high as 1050 °C during at least 1.5 h, a substantially enhanced redox behaviour was noticed which resulted in a significant promotion of the catalytic activity in comparison with the unmodified parent sample. Hence, the value of temperature of half conversion at 30,000 h −1 decreased from 300 to 275 °C for the combustion of 1,2-dichloroethane, which was selected as a model chlorinated feed. This active performance was assigned to the formation of a new κ-CeZrO 4 phase after redox aging characterised by a markedly increased capacity of providing active oxygen species at low temperatures. For comparative purposes two additional Ce 0.5 Zr 0.5 O 2 samples calcined at 750 and 1000 °C were also characterised and catalytically tested.
TL;DR: In this article, the first evidence of exclusive benzyl alcohol production in the continuous gas phase hydrogenation of benzaldehyde (T =393 K; P = 1 atm) over Au/Al2O3, where activity was largely maintained for up to 15h on-stream.
TL;DR: In this article, the role of metal components in bimetallic catalysts for oxygen-enhanced water gas shift (OWGS), wherein a small amount of O 2 is added to H 2 -rich reformate gas to enhance CO shift.
Abstract: Catalytic hydrogen production and CO removal in a post-reforming process are critical for low-temperature fuel cell applications. The present study aims at clarifying the role of metal components in bimetallic catalysts for oxygen-enhanced water gas shift (OWGS), wherein a small amount of O 2 is added to H 2 -rich reformate gas to enhance CO shift. Among CeO 2 -supported bimetallic catalysts, Pd–Cu and Pt–Cu combinations were found to show strong synergetic promoting effect in OWGS, which leads to much higher CO conversion and higher H 2 yield than WGS at low temperature around 250 °C. Temperature programmed reduction (TPR) showed strong interaction between Pd and Cu in Pd–Cu/CeO 2 by a single reduction peak in contrast to multiple peaks on monometallic Cu/CeO 2 . Extended X-ray absorption fine structure (EXAFS) analysis revealed that such bimetallic Pd–Cu and Pt–Cu form alloy nanoparticles, where noble metal is mainly surrounded by Cu atoms. Oxygen storage capacity (OSC) measurements point to higher resistance of Pd–Cu to oxidation indicating that Pd keeps Cu in reduced state in air pulse condition. From kinetic study, Pd in Pd–Cu was found to promote CO shift, rather than CO oxidation by increasing the number of active sites and by suppressing H 2 activation (that is inherent to monometallic Pd), which minimizes both the inhibition effect of H 2 and the loss of H 2 by oxidation in OWGS. Transient response technique revealed that Cu in Pd–Cu enhances desorption of strongly chemisorbed CO 2 on catalyst surface in contrast to very slow CO 2 desorption from surface of monometallic Pd. Thus, the excellent OWGS activity of Pd–Cu catalyst has been attributed to the complementary roles of the two metals for enhancing CO shift, which is realized by its alloy structure and the accompanying strong interaction between metal components.
TL;DR: In this article, a perovskite, LaMnO3, was obtained by the citrate method and characterized by means of X-ray diffraction, temperature-programmed desorption of oxygen, temperature programmed reduction, and measurement of specific surface area.
TL;DR: In this article, an in situ solution combustion synthesis (SCS) method was tailored to the preparation of a LiCr0.9O2-catalyzed trap based on a SiC wall-flow monolith.
TL;DR: In this paper, the influence of rare earth elements (La, Nd, Pr, Sm and Y) addition to Ce 0.2 Zr 0.8 O 2 and its supported Pd-only three-way catalysts has been investigated by X-ray diffraction (XRD), N 2 adsorption/desorption, XPS and H 2 temperature programmed reduction (H 2 -TPR) techniques, and that the dynamic oxygen storage capacity has also been evaluated under transient conditions.
Abstract: The influence of rare earth elements (La, Nd, Pr, Sm and Y) addition to Ce 0.2 Zr 0.8 O 2 and its supported Pd-only three-way catalysts has been investigated by X-ray diffraction (XRD), N 2 adsorption/desorption, X-ray photoelectron spectroscopy (XPS) and H 2 temperature programmed reduction (H 2 -TPR) techniques, and that the dynamic oxygen storage capacity (DOSC) has also been evaluated under transient conditions. Special attention was given to the information of structural modification and the effect of doping on the three-way catalytic performance. The phase for all the ceria–zirconia-rare earth ternary solid solution is single tetragonal, irrespective of the treatment temperature applied. The presence of La, Nd and Pr results in enhanced thermal stability, improved reducibility and increased strong metal–support interaction, leading to the relatively higher three-way catalytic activity for all the target pollutants over the corresponding catalysts. The air/fuel operation window is also enlarged due to the increased dynamic oxygen storage capacity.
TL;DR: In this article, the effect of supercritical water gasification (SCWG) on Ni-based Al 2 O 3 catalysts doped with La 2 O3 was investigated to gain a better understanding of the catalyst's role.
Abstract: Demand for low cost and high activity catalysts for use in biomass gasification is gaining significant attention. This study investigated the effect of supercritical water gasification (SCWG) on Ni-based Al 2 O 3 catalysts doped with La 2 O 3 in order to gain a better understanding of the catalyst's role. The investigated micron and nano sized catalysts were characterized both before and after SCWG treatment by temperature programmed reduction (TPR) and oxidation (TPO) for determining metal–support interactions and stability. Temperature programmed desorption (CO 2 -TPD) was measured for CO 2 adsorption to the catalyst surface. Pulse chemisorption was conducted to measure the dispersion and crystalline size of the nickel particles while XRD, TGA and Raman analysis were carried out to examine the crystalline phase and coke deposition. The results showed that exposure to SCWG severely affected the physical and chemical structure of the Ni/Al 2 O 3 catalysts leading to agglomeration of active metals, particularly for nanostructured catalysts. Adding La 2 O 3 to the Ni/Al 2 O 3 catalysts retarded coke formation, especially graphitic type coke by forming lanthanum oxycarbonate species.