TPR Analysis Research Articles

The impact of transition metals (Cr, Mn, and Co) on the performance of the 10%Ni/Al2O3-10%CeO2 catalysts in combined CO2 reforming and partial oxidation of methane

This study explores the efficacy of Cr, Mn, and Co promoters in enhancing the performance of 10%Ni/Al2O3-10%CeO2 catalysts during methane combined reforming process, emphasizing improved metal dispersion and reduced carbon formation. The supports and catalysts were synthesized through mechanochemical and impregnation methods, respectively, and characterized using XRD, BET, TPR, TPO, and FESEM analyses. The synthesized catalysts exhibited a high BET surface area, ranging from 195 to 172 m2 g-1, along with a mesoporous structure characterized by pore sizes between 2 and 12 nm. The introduction of Cr significantly enhanced catalyst performance, resulting in 70.5 % CH4 and 69.1 % CO2 conversions in dry reforming. TPO analysis indicated reduced carbon deposition on promoted catalysts by enhancing Ni dispersion and carbon reactivity. The 10%Ni–3%Cr/Al2O3-10%CeO2 catalyst demonstrated stability over 440 min at 700 °C, achieving 84.9 % CH4 and 68.1 % CO2 conversions in combined reforming. The TPO analysis indicated an absence of carbon deposition on the catalyst surface during combined reforming, which was corroborated by the FESEM analysis. Furthermore, the influence of operating parameters on catalyst efficiency in both dry and combined reforming processes was investigated. As GHSV increased from 8000 to 24,000 ml/h.gcat, CH4 conversion declined in dry reforming and combined reforming, dropping from 77 % to 66 % and from 86 % to 84 %, respectively. Also, in both processes, increasing the oxidizer contents (CH4: CO2 from 2:1 to 1:2, CH4: CO2: O2 from 1:1:0 to 1:1:0.35) led to an increase in CH4 conversion, while CO2 conversion decreased.

Ni-Ag Catalysts for Hydrogen Production through Dry Reforming of Methane: Characterization and Performance Evaluation

To investigate the influence of Ag and the loading of Ni species, Ni-Ag type catalysts were synthesized with varying Ni/Ag ratios (1, 1.5 and 2) using the coprecipitation method. The catalysts were extensively characterized using various techniques such as TG-DSC-SM, XRD, ICP, BET, SEM-EDX and TPR and subsequently tested in the CH4/CO2 reaction without any pretreatment. Regardless of the ratio employed, a phase mixture containing NiO and Ag was observed after calcination under air between 600 °C and 1200 °C. SEM analysis confirmed the presence of a close interface between Ag and NiO. The specific surface area was found to be significantly higher for the catalyst with lower Ni content (R = 1). TPR analysis demonstrated that the inclusion of Ag facilitated the reduction of Ni at lower temperatures. XRD analyses of the spent catalyst confirmed catalyst reduction during the reaction. Among the samples, a catalyst with Ni/Ag = 1 exhibited superior catalytic activity without any pretreatment under a reduction atmosphere, in which case the conversions of methane and CO2 at 650 °C amounted to 38 and 45 mol%, respectively, with H2/CO = 0.7 and 71 mol% of H2. The presence of Ag species enhances the stability of the Ni catalyst and improves catalytic performance in the dry reforming of methane.

Construction of novel BiOI/CuInS2/ZnO dual S-scheme charge transfer pathway for efficient antibiotic degradation

The present work explored the photocatalytic activity of BiOI–CuInS2–ZnO ternary heterojunction for the photodegradation of the tetracycline (TCl). The bare photocatalysts were prepared via hydrothermal method while the ternary heterojunction was synthesized using simple physical mixing route. The ternary heterojunction of BiOI, CuInS2 and ZnO followed the S-scheme charge transfer pathway exhibiting superior photodegradation ability compared to other synthesized photocatalysts. The attained degradation efficiency of BiOI–CuInS2–ZnO S-scheme ternary heterojunction was 96.75 % within 90 min of light illumination which was much higher than other photocatalysts. Electron spin resonance (ESR) investigations and scavenging experiment indicated that •O2−, and •OH radicals plays an important role in photodegradation of TCl. Furthermore, the structural analysis of synthesized bare photocatalysts was also done via density functional theory (DFT) calculations. The results showed that after the formation of S-scheme heterojunction, the ternary heterojunction showed lower recombination rate (validated via PL analysis) with boosted charge carriers separation rate (confirmed through EIS and TPR analysis) and light absorption ability. This had led to upgradation in photodegradation efficiency of ternary BiOI–CuInS2–ZnO photocatalyst. The reusability test of the photocatalysts confirmed excellent stability of ternary photocatalysts with 90.25 % degradation rate up to five catalytic cycles.

Oxygen donation of alkali earth metal ferrites for biomass chemical looping gasification: A comparative study

This study objectives to compare the oxygen donation properties among a series of alkali earth metal (AEM) ferrites as oxygen carriers (OCs), including MgFe2O4, CaFe2O4, SrFe2O4 and BaFe2O4, in biomass chemical looping gasification (CLG), through fixed bed reactivity tests and several characterizations, including XRD, XPS, TPR and thermogravimetric analysis. It was found that BaFe2O4 possessed the best syngas production performance, owing to its highest reactivity with char and lowest reactivity with CO/H2. Thermogravimetry analysis and TPR tests show that heavier AEM ferrites exhibited higher reactivity with char and lower reactivity with syngas, except for the relationship between SrFe2O4 and CaFe2O4. Fixed bed tests show that the AEM ferrites could be ranked as BaFe2O4 > CaFe2O4 > SrFe2O4 > MgFe2O4 according to their syngas production performance. Other than reactivity, 20-cycle tests demonstrate that BaFe2O4 had the best stability on H2 production compared to other OCs. The advantage of BaFe2O4 may be related to its more sufficient oxygen vacancy and crystal structure. Therefore, BaFe2O4-based OCs were found the most suitable for biomass CLG. The current study filled the gap in screening of AEM ferrite OCs and provided guidance for future OC development, achieving cleaner biomass conversion and enhanced sustainability.

Carbon dioxide conversion to fuel over alumina-supported ruthenium catalysts

In this study, ruthenium-based catalysts were prepared for CO2 hydrogenation. Incipient-wetness-impregnation of the alumina-support with ruthenium (III) nitrosyl nitrate solution to achieve 0.5 wt% Ru loading on supports was used to prepare these catalysts. Potassium (0–3 % wt%) was used to further promote the catalysts. TPR, CO2-TPD, XRD, TEM, XPS, SEM, and EDS analyses were used to characterize catalyst properties. The hydrogenation of CO2 catalytic tests were conducted and the effect of operating conditions (temperature, pressure, and space velocity) were investigated. These studies were conducted in a tubular fixed-bed reactor. The CO2 conversion over these catalysts was found to be low and the dominating product observed was CH4 with a small amount of C2+ forming when K was added to the catalyst. The optimum potassium loading for improved C2+ product yield over Ru/Al2O3 was 1%K for CO2 hydrogenation.

Structural transformation of carbon-encapsulated core-shell CoNi nanoparticles during magnetically induced CO2 reduction into CO

Controlling product distribution in CO2 hydrogenation is of great scientific interest, the selective CO production through the reverse water-gas shift reaction (RWGS) being one of the most investigated processes. Herein, we report the synthesis of new core-shell Co@Ni NPs encapsulated in carbon (Co@Ni@C) to prevent their aggregation at the high-temperatures reached during magnetically induced catalysis. This bifunctional system has been simultaneously used as heating agent and catalyst for the magnetically induced hydrogenation of CO2. While at low magnetic fields Co@Ni@C produces CH4:CO mixtures, at higher field amplitudes it selectively generates carbon monoxide. Indeed, Co@Ni@C has shown to be one of the most active catalysts reported to date, which reaches a maximum conversion of 74.2% with complete selectivity towards CO at 53 mT and 300 kHz. In addition, recycling and cyclability experiments have demonstrated that Co@Ni@C becomes fully selective for CO after being exposed to high field amplitudes (i.e. reaction temperature above 500 °C), even when it exposed to low magnetic fields again. This change in the selectivity is due to an atomic rearrangement of the core-shell structure, as was confirmed by EDX, XAS, TPR and TPD analysis.

Simultaneous Removal of Gas-Phase Pollutants CO and NO Using Ni-Fe Bimetallic Oxides Catalyst

Many studies have been conducted on methods to remove air pollutants. Among them, a representative commercial technology for reducing nitrogen oxides (NO<sub>X</sub>) is selective catalytic reduction (SCR) using NH<sub>3</sub> as a reductant. However, the NH<sub>3</sub>-SCR technology has problems, such as the need for additional NH<sub>3</sub> gas (Active-SCR), the fact that unreacted NH<sub>3</sub> (slipped-NH<sub>3</sub>) in the reaction process can be re-oxidized to NO<sub>X</sub>, and the facility system cost according to the added NH<sub>3</sub> gas. In order to solve these problems, CO gas that is naturally generated in industrial processes can be used, and NO and CO can be removed at the same time using passive-SCR technology that does not require a separate injection of a reductant. In this study, transition metals Ni and Fe were used as catalytic materials to replace expensive precious metals. The results confirmed that both NO<sub>X</sub> and CO removal efficiencies were about 90% or more in the catalyst with combined Ni-Fe, compared to the single catalyst. The addition of Ni to the Fe catalyst increased the catalytic reducing power, which also affected the increase in acid sites. Therefore, it is expected that this catalyst can simultaneously remove NO and CO without the use of NH<sub>3</sub> gas. These results could be explained through XRD, FT-IR, TEM, BET, H<sub>2</sub>-TPR and CO-TPD analyses, and compared to single catalysts, it was confirmed that the catalyst had higher low-temperature desorption ability for CO as a reductant and reducing capability.

Rare Earth Metal (La, Ce, Nd, Eu) Doped Cu/Zr-PILC Catalysts for the Efficient NH3-SCR at Low Temperature

ABSTRACT A series of RE-3Cu/Zr-PILC (RE = La, Ce, Nd, Eu) catalysts were prepared via an impregnation method and activities for NH3-SCR were evaluated. The physicochemical properties of each catalyst were explored using XRD, BET, H2-TPR, NH3-TPD, XPS and in-situ DRIFTS techniques. The doping of RE had enhanced the NH3-SCR efficiency of 3Cu/Zr-PILC. Among them, the 6Ce-3Cu/Zr-PILC sample demonstrated exceptional performance, achieving NO conversion rates exceeding 90% within the temperature range of 250–350°C. Moreover, it reached its peak NO conversion rate of 96.3% at 300°C while maintaining an impressive resistance to SO2. According to the results of TPR, TPD and XPS analysis, the modification of RE (especially Ce) enhanced the redox properties, the surface acidity, the atomic ratio of Cu2+/Cu+ and the amount of surface chemisorbed oxygen in the 3Cu/Zr-PILC samples, all of these are favorable for the NH3-SCR reaction. Furthermore, in-situ DRIFTS analysis reveals that the NH3-SCR reaction of RE-3Cu/Zr-PILC samples at low temperatures is governed by the Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) mechanisms, with the L-H mechanism being the predominant factor.

Novel Fe3O4@TiO2 core–shell nanostructure catalyst for NO removal through heterogeneous Fenton processes

Diverse Fe3O4@TiO2 catalysts, featuring a range of core-shell ratios, were employed within an H2O2 catalytic activation system to facilitate the oxidation of NO. These catalysts underwent comprehensive structural characterization, including XRD, TEM, BET, XPS, VSM and TPR analysis. Experimental investigations were conducted with the specific goal of assessing the catalytic efficiency of Fe3O4@TiO2 core-shell catalysts and Fe3O4/TiO2 supported catalysts in the contexts of desulfurization and denitrification. The results demonstrated that catalysts featuring a core-shell ratio of 1:2 exhibited the highest catalytic efficiency. Moreover, the core-shell catalysts outperformed their supported counterparts with the same molar ratio in terms of physicochemical properties, removal efficiency, and stability. Notably, the core-shell catalysts possessed exceptionally favorable pore structures and substantial specific surface areas, facilitating enhanced H2O2 activation for NO oxidation through synergistic interactions between the core and shell components. This research holds the potential to guide future endeavors in the development of catalysts aimed at achieving superior H2O2 catalytic efficiency.

Mapping the substrate-binding subsite specificity of a Porphyromonas gingivalis Tpr peptidase.

Calcium-dependent peptidases of the calpain family are widespread in eukaryotes but uncommon in prokaryotes. A few bacterial calpain homologs have been discovered but none of them have been characterized in detail. Here we present an in-depth substrate specificity analysis of the bacterial calpain-like peptidase Tpr from Porphyromonas gingivalis. Using the positional scanning hybrid combinatorial substrate library method, we found that the specificity of Tpr peptidase differs substantially from the papain family of cysteine proteases, showing a strong preference for proline residues at positions P2 and P3. Such a degree of specificity indicates that this P. gingivalis cell-surface peptidase has a more sophisticated role than indiscriminate protein degradation to generate peptide nutrients, and may fulfil virulence-related functions such as immune evasion.

Glycerol Hydrogenolysis to Bio-Propanol: Catalytic Activity and Kinetic Model for Ni/C Modified with Al(H2PO4)3

The aim of the present research is to investigate the effect of different operation variables in the hydrogenolysis of glycerol to 1-propanol and to develop a simple kinetic model useful for the design of the reactor. For this purpose, a carbon-based composite was impregnated with 4 wt.% of Al(H2PO4)3 (CPAl) and used as a support to prepare a Ni catalyst. The support and the catalyst were characterized by BET, XRD, NMR, potentiometric titration, isopropanol decomposition reaction, TEM and TPR analysis. The catalytic tests were carried out at 220–260 °C and 0.5–4 MPa of H2 initial pressure varying the glycerol concentration in aqueous solutions between 30 and 80 wt.%. The presence of aluminum phosphates in the Ni/CPAl catalyst moderates the surface acidity and the formation of Ni2P leads to a high selectivity towards 1-propanol. In this sense, the Ni/CPAl catalyst showed total glycerol conversion and 74% selectivity towards 1-propanol at 260 °C and 2 MPa of H2 initial pressure using 30 wt.% glycerol aqueous solution and 8 h of reaction time. A slight increase in particle size from 10 to 12 nm was observed after a first reaction cycle, but no changes in acidity and structure were observed. Based on these results, a power-law kinetic model was proposed. For glycerol consumption, partial orders of 0.07, 0.68 and −0.98 were determined with respect to glycerol, H2 and water, and an apparent activation energy of 89 kJ mol−1 was estimated. The results obtained indicate that the model fits the experimental concentration values well and can predict them with an average error of less than 7%.

Effect of Ni-Co addition on Pd promoted Al2O3 catalysts for dry reforming of methane

This study investigates the effectiveness of x Ni – (5 – x) Co / 5 Pd – Al2O3 (where x=0, 1.25, 2.5, 3.75, and 5) bimetallic catalysts and the influence of the Pd on their activity in the dry reforming of methane. Comprehensive characterization techniques including XRD, TPR, TPD, SEM, TGA, and Raman analysis are employed to examine the catalysts. XRD analysis of the calcined catalysts reveals the presence of multiple oxides such as NiO, CoO, Co3O4, and PdO. The metal-support interaction and the particle sintering of the catalysts depend on the amount of Co loading, for higher Co loadings (> 2.5 wt%) resulted in weakened metal-support interaction as indicated by TPR analysis. Also, the particle sintering was observed with an increase in Co loading observed from SEM and TEM analysis. The activity analysis demonstrates that the 5 Ni / 5 Pd – Al2O3 catalysts exhibit superior performance in terms of both CH4 (59%) and CO2 (64%) conversions, as well as stability, compared to the Ni-Co bimetallic catalyst. The addition of Co leads to decreased activity, Furthermore, TGA analysis indicates minimal carbon deposition on the 5 Ni / 5 Pd – Al2O3 catalyst during the 7-hour activity study. Notably, Raman analysis reveals a lower presence of graphitic carbon on the catalyst, which contributes to its stable catalytic activity. The presence of Pd in the 5 Ni catalyst reduces carbon deposition and enhances its activity. However, in the case of the Ni-Co bimetallic catalyst, the promotional effect of Pd appears to be negligible. Overall, these findings emphasize the promising potential of the 5 Ni / 5 Pd – Al2O3 catalyst for efficient and stable dry reforming of methane.

Obtaining hydrogen by steam reforming of residual glycerol from biodiesel production using Ni/La2O3-CeO2 catalysts

Ni/La2O3-CeO2 catalysts derived from perovskite-type precursors, with La1−xCexNiO3 composition (x = 0, 0.1, and 0.2), were prepared by the precipitation method, without and with the use of Pluronic F-127 surfactant. The materials were characterized using techniques including thermogravimetric analysis, nitrogen physisorption, scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and temperature programmed reduction with H2. The presence of Ce and use of the surfactant resulted in samples with smaller NiO crystallites and lower reduction temperature, with the catalysts A2 (La0.9Ce0.1NiO3 + P) and A6 (LaNiO3 + P) showing the highest percentages of the LaNiO3 phase, according to XRD and TPR analyses. The glycerol conversions were high (above 96%) and similar for all the catalysts, except A5 (LaNiO3). Although the samples prepared with Ce addition did not show the best selectivity towards H2, their use led to lower carbon formation during the reaction (%C = 2.2), compared to the sample with the best catalytic performance (%C = 8.0). Overall, the materials studied here were stable and active during 5 h of reaction, with low coke formation in all cases. The findings indicated that perovskite-type catalysts synthesized with the addition of surfactant are promising for application in the steam reforming of glycerol for hydrogen production.

Synthesis and evaluation of the cobalt-promoted NiO/CaO.2Al2O3 catalysts in CO2 methanation reaction: Effect of different promoters

This work is concentrated on designing of CO2 methanation process over nickel-based catalysts doped by different promoters (CuO, Cr2O3, Co3O4, Fe2O3, and MnO2) supported on CaO.2Al2O3 powder. The CaO-Al2O3 powder was fabricated by mechanochemical method, and catalysts were synthesized via a wet impregnation procedure. The characterization properties of all samples were tested by XRD, BET, TPR, FESEM, and EDS-mapping analyses. The optimum amount of NiO was selected at 10 wt% along with CaO:Al2O3 as support with the molar ratio of 1:2. The Co-doped catalyst showed the lowest pore size (9.4 nm) and the highest surface area (106 m2.g−1) among the promoted catalysts. The results exhibited that the Co3O4(3)-NiO(10)/CaO.2Al2O3 catalyst possessed superior catalytic performance in the CO2 methanation reaction. The results illustrated that the increase in cobalt oxide percentage up to 3 wt% improved catalytic performance. However, further augmentation in the Co3O4 from 3 to 7 wt% diminished the specific surface area. According to the performance tests, carbon dioxide conversion and methane selectivity were 83.1% and 99.5% at 450 °C under operating conditions (GHSV = 18,000 ml.gcat−1.h−1 and H2:CO2 = 4:1) over this catalyst. The processing conditions including calcination temperature, reduction temperature, GHSV, feed ratio, and long-term stability test were also examined over the selected catalyst. Outcomes revealed that CO2 conversion increased with a decrement in calcination temperature from 650° to 450°C. Also, chosen catalyst reduced at 650 °C showed the highest performance. Besides, catalytic performance enhanced by raising feed ratio (H2:CO2) from 2:1 to 5:1 and decreased with augmentation of GHSV from 12,000 to 30,000 ml.gcat−1.h−1. Moreover, Co3O4(3)-NiO(10)/CaO.2Al2O3 catalyst possessed high stability during 14 h time on stream.

Important factors of the A-site deficient Mn perovskites design affecting the CO oxidation activity

A-site deficient La0.4Sr0.4MnxTi1−xO3 (LSMT, x = 0, 0.4, 0.6, 0.8) perovskites were investigated for their structural change and effect on CO oxidation activity. The XRD, XPS, TPR and O2-TPD analysis represent the change in Mn concentration, known as an active species in oxidation, affecting the crystal structure, oxidation state of the B-site cation (Mn), number of oxygen vacancies, and the reducibility of the catalysts. The shift in the main perovskite diffraction peak in XRD spectra of the perovskites with a change in Mn content represents the formation of cationic vacancies. At the lower temperature (<200 oC), CO oxidation efficiency of LSMT perovskite catalysts was found to be almost identical. This can be attributed to their similar perovskite structure and surface area. Compared to the higher temperature (>200 oC) CO oxidation activity, the LSMT catalyst with lower Mn content of 0.4 shows relatively better performance than the higher Mn content samples, which signifies the active role of the Mn oxidation state and lattice oxygen species of the perovskite catalysts. Moreover, the LSMT4446 catalyst shows stable activity for more than 12 h with an average CO conversion of 80 %. From these results, we found that the factors of the Mn oxidation state and the type of oxygen species are crucial when designing an Mn-based perovskite catalyst for catalytic applications.

Response surface methodology for optimizing the activity of bimetallic Ni–Co–Ce/Al2O3 catalysts in the steam methane reforming

Hydrogen is being explored as a potential energy carrier for power and heat production, as well as energy storage, making it one of the most significant basic chemicals. In this work, steam methane reforming (SMR) over Ce-promoted Co–Ni/Al2O3 catalysts were employed to produce hydrogen, and the response surface method (RSM) based on an optimal custom method was used to examine the interplay between synthetic and operational factors affecting methane conversion, hydrogen yield and H2/CO molar ratio. Several independent factors were considered, including the catalyst Co/Ni mass ratio (0, 0.5, 1), Ce loading (0, 1.5, 3.0), operation temperature (600, 650, 700 °C), steam to methane (S/M) molar ratio (1.5, 2.5, 3.5), and support type (bulk and hollow Al2O3). Among the two determined optimized results in Design Expert, the hollow 0.17Co–Ni-1.26Ce@Al2O3 catalyst was the best choice, depicting 96.20% methane conversion, 96.89% hydrogen yield and 6.57H2/CO molar ratio. The stability test of both hollow and bulk optimized catalysts was compared in optimal conditions (S/M molar ratio and temperature) over a 12-h SMR reaction. The physical properties and morphology of the optimized catalysts were determined before and after the steam reforming reaction using FESEM, XRD, N2 physisorption, TPR, and TGA analyses.

In situ impregnated Ni/Al2O3 catalysts prepared by binder jet 3D printing using nickel nitrate-containing ink

The binder jetting printing technique enables in situ impregnation of alumina using a Ni(NO3)2-containing ink (NI), facilitating omission of impregnation. NI was compared to wet impregnation (WI). Full characterization by quasi-in situ XPS, XAS and TPR revealed the presence of Ni as NiAl2O4 spinel. TPR analysis identified surface NiO and NiAl2O4 species with facilitated reduction by NI, in addition to the respective species in bulk form. Post-processing affects active site accessibility by coverage. 3D printing limited the Ni loading, but XPS revealed higher metal dispersion by NI. CO2 hydrogenation confirmed active Ni/Al2O3 catalysts with enhanced activity by NI.

Modification of Copper-Ceria Catalyst via Reverse Microemulsion Method and Study of the Effects of Surfactant on WGS Catalyst Activity

Some major drawbacks encountered in the synthesis of copper-ceria (Cu-CeO2)-based Water Gas Shift (WGS) catalyst via the conventional Impregnation (IMP) method are aggregate formation and nanoparticles’ instability. These lead to the poor interaction between Copper and Ceria, thereby impeding the catalytic activity with the inefficient utilization of active sites. To overcome these drawbacks, in this study, we described the synthesis of the Cu-CeO2 catalyst via the Reverse Microemulsion (RME) method with the help of the organic surfactant. This development of insights and strategies resulted in the preparation of porous particles with uniform size distribution and improved interaction within the composites, which were evident through XRD, XPS, BET Surface area, TPR, TEM and SEM analysis results. Remarkably, the optimum 20% Cu-CeO2 catalyst prepared by RME method was found to have superior Water Gas Shift (WGS) catalytic activity than the conventionally Impregnated catalyst when their CO conversion efficiencies were tested in WGS reaction at different feed gas compositions with and without CO2. Moreover, the 20% Cu-CeO2 sample prepared by RME method exhibited sustained catalytic activity throughout the entire 48 h period without any signs of deactivation. This observation highlights RME method as the potential pathway for developing more effective nanoparticle catalysts for hydrogen production, contributing to the growing demand for clean and sustainable energy sources.

Fabrication and catalytic evaluation of Ni/CaO–Al2O3 in glycerol steam reforming: Effect of Ni loading

The present study aims to assess the catalytic activity of the Ni/CaO–Al2O3 catalysts with different Ni loadings (2.5, 5, 10, 15, and 20 wt %) for H2 generation via the glycerol steam reforming (GSR). The support was prepared by the mechanochemical method, and then the various contents of nickel were impregnated on the support surface. The synthesized samples were characterized by BET, XRD, H2- TPR, CO2-TPD, TPO, FTIR, and SEM analyses. High stable catalytic activity was reported for the prepared catalysts. Among the investigated catalysts, 15%Ni/CaO–Al2O3 with the highest reducibility, proper BET area (96.6 m2 g−1), and suitable basicity possessed the highest catalytic performance with glycerol conversion of 99.4% at 700 °C. All the samples had high stability after 5 h, and the 15%Ni/CaO–Al2O3 showed 97.5% glycerol conversion at 550 °C without any decline in glycerol conversion durin 15 h time on stream. It was also found that glycerol conversion decreased with the increase in gas hourly space velocity and calcination temperature.

Investigation of Ba doping in A-site deficient perovskite Ni-exsolved catalysts for biogas dry reforming

This work presents the development of an A-site deficient La0.9−xBaxAl0.85Ni0.15O3 (x = 0, 0.02, 0.04, and 0.06) perovskite oxide catalyst for dry reforming of model biogas. The catalysts are prepared using a citrate sol-gel method and used for biogas dry reforming at 800 °C for feed ratios (CH4/CO2) of 1.5 and 2.0. The fresh and spent catalysts are analyzed using XRD, FTIR, TPD, XPS, FESEM, TEM, TPR, TGA-DTA, and Raman analysis. The XRD analysis exhibits the host perovskite oxide structure and the exsolved Ni phase for all prepared catalysts. The partial doping of Ba improves the metal support interaction and oxygen vacancies that enhance catalytic activity and stability, as revealed by the TPR and XPS analysis. The stability experiment on La0.9−xBaxAl0.85Ni0.15O3, for x = 0 catalyst resulted in reduced activity due to the catalyst deactivation by sintering, as confirmed by XRD and FE-SEM. Among all the catalysts studied, La0.84Ba0.06Al0.85Ni0.15O3 (LB6AN-15) exhibited the highest catalytic stability with CH4, and CO2 conversions are 60% and 93%, respectively, for 40 h time-on-stream due to the strong metal support interactions, high oxygen vacancies, and anti-sintering of exsolved Ni nanoparticles in biogas dry reforming.