Stepwise Impregnation Research Articles

Effect of promoters on the performance of CuNi catalysts for hydrogen production from methanol decomposition

Abstract Utilizing the exhaust heat from engines to decompose methanol for hydrogen production, and subsequently introducing this hydrogen into the combustion chamber, is one of the crucial approaches for achieving energy savings and emission reductions. The role of an efficient and stable catalyst for methanol decomposition is paramount in this application. Therefore, CuNi-based catalysts modified with promoters such as Zr, La, Mn, and Mg were prepared using a stepwise impregnation method. The developed catalysts were tested using various analytical methods and characterization techniques. The results indicate that the addition of the Zr enhances the dispersion of active components, improves the catalyst’s reducibility. This, in turn, enhances the catalyst’s activity and hydrogen selectivity. The hydrogen yield of the Zr modified catalyst increased by an average of 12% compared to the original catalyst. Furthermore, the Zr modified catalyst exhibits exceptional stability after prolonged use. La can enhance the low-temperature activity of the catalyst but performs poorly at high temperatures. The promoter Mn has a minimal impact on the overall performance of the catalyst. Conversely, the addition of Mg as a promoter inhibits the dispersion of active components, resulting in adverse effects on the catalyst.

Performance of sulfided NiMo catalyst supported on pillared bentonite Al and Ti under hydrodeoxygenation reaction of guaiacol

Bio-crude oil is known to be sustainable, eco-environmentally, and an alternative energy source produced by biomass pyrolysis. However, its quality remains relatively low due to a higher oxygen concentration compared to liquid fuels from fossils. Therefore, an upgrading process is necessary through the catalytic hydrodeoxygenation (HDO) process. This work synthesized pillared bentonite using Al and Ti metals as the pillaring agent to produce Al-PILC and Ti-PILC as catalyst support for sulfided NiMo. Their catalytic activity in HDO reaction using guaiacol as a model compound of bio-crude oil were also evaluated. Characterization of the bentonite-pillared materials, including Al-PILC, Mo/Al-PILC, NiMo/Al-PILC, Ti-PILC, Mo/Ti-PILC, and NiMo/Ti-PILC, was performed using Surface Area Analyzer, X-ray Diffractometer (XRD), Temperature-Programmed Desorption of ammonia (NH3-TPD), X-Ray Fluorescence (XRF), and Scanning Electron Microscope (SEM) techniques. The characterization results confirm the pillarization process of bentonite using Al and Ti metals as the pillaring agent, and the preparation of the NiMo catalyst using the stepwise impregnation method was successfully prepared. The NiMo/Ti-PILC catalyst performs a superior conversion value on the HDO guaiacol reaction than other catalysts. A well dispersion of Mo and Ni metals on the surface support (NiMo/Ti-PILC), thus creating numerous active sites of the catalyst after the sulfidation. Variations in time and temperature during the HDO guaiacol reaction significantly affected the conversion.

Influence of Doping of Niobium Oxide on the Catalytic Activity of Pt/Al2O3 for CO Oxidation

Pt-based alumina catalysts doped with varying niobium contents (i.e., 0, 1.20, 2.84, and 4.73 wt%, denoted as Pt/Nb–Al2O3) were synthesized via stepwise impregnation for catalytic CO oxidation. The effective incorporation of Nb species without altering the fundamental properties of the Al2O3 support was confirmed by the characterization using XRD, Raman, and TEM. Pt metallic particles were uniformly deposited on the niobium-doped alumina (Nb–Al2O3) support. H2-TPR and CO–TPD analyses were performed to reveal the influence of niobium doping on catalyst reduction and CO adsorption properties. The results consistently demonstrate that the doping of niobium affects reducibility and alleviates the competitive adsorption between CO and O2 during the CO reaction. Particularly, when compared to both undoped and excessively doped Pt/Al2O3 catalysts, the catalyst featuring a 2.84 wt% Nb content on Pt1.4/Nb2.8–Al2O3 displayed the most promising catalytic performance, with a turnover frequency of 3.12 s−1 at 180 °C. This superior performance can be attributed to electron transfer at the Pt/NbOx interface.

AlCl3 modified Pd/Al2O3 catalyst for enhanced anthraquinone hydrogenation

Anthraquinone hydrogenation to produce H2O2 is an economically interesting reaction with great industrial importance. Here, we report a series of Pd/xAl catalysts with different AlCl3 contents by a conventional stepwise impregnation method. The optimal Pd/1.0Al catalyst exhibits a higher performance toward anthraquinone hydrogenation with 8.3 g·L−1 hydrogenation efficiency, 99.5% selectivity and good stability, obviously superior to that of Pd/Al2O3 catalyst (5.2 g·L−1 and 97.2%). Detailed characterization demonstrates that AlCl3 can be grafted on the γ-Al2O3 support to obtain a modified support with abundant surface weak acid and Lewis acid, which can adsorb and activate anthraquinone. Meanwhile, its steric hindrance could isolate and disperse active metals to form more active sites. The synergies between metal sites and acid sites promotes the anthraquinone hydrogenation. Furthermore, the good stability after grafting AlCl3 could attribute to the enhanced metal-support interaction inhibiting metal particles agglomeration and leaching.

Fabrication of Hierarchically Porous CuBTC@PA-PEI Composite for High-Efficiency Elimination of Cyanogen Chloride.

Cyanogen chloride (CNCl) is highly toxic and volatile, and it is difficult to effectively remove via porous substances such as activated carbon due to the weak interaction between CNCl and the adsorbent surface. Developing a highly effective elimination material against CNCl is of great importance in military chemical protection. In this work, a new metal-organic framework (MOF) CuBTC@PA-PEI (polyacrylate-polyethyleneimine) composite was prepared and exhibited excellent CNCl elimination performance in the breakthrough tests. PEI was used for the functionalization of PA with amino groups, which is beneficial to anchor with metal ions of MOF. Afterward, the growth of MOF occurred on the surface and in the pores of the matrix by molecular self-assembly via our newly proposed stepwise impregnation layer-by-layer growth method. Breakthrough tests were performed to evaluate the elimination performance of the composites against CNCl. Compared with the pristine CuBTC powder, the CuBTC@PA-PEI composite exhibited better adsorption capacity and a longer breakthrough time. By compounding with the PA matrix, a hierarchically porous structure of CuBTC@PA-PEI composite was constructed, which provides a solution to the mass transfer problem of pure microporous MOF materials. It also solves the problems of MOF molding and lays a foundation for the practical application of MOF.

Fabrication of PA-PEI-MOF303(Al) by Stepwise Impregnation Layer-by-Layer Growth for Highly Efficient Removal of Ammonia.

NH3 is a typical alkaline gaseous pollutant widely derived from industrial production and poses great risks to humans and other biota. Metal-organic frameworks (MOFs) have excellent adsorption capacities relative to materials traditionally used to adsorb NH3. However, in practice, applications of MOFs as adsorbents are restricted because of its powder form. We prepared a polyamide (PA) macroporous polyester substrate using an emulsion template method and modified the surface with polyethylenimine (PEI) to improve the MOF growth efficiency on the substrate. The difficulty of loading the MOF because of the fast nucleation rate inside the PA macroporous polyester substrate was solved using a stepwise impregnation layer-by-layer (LBL) growth method, and a PA-PEI-MOF303(Al) hierarchical pore composite that very efficiently adsorbed NH3 was successfully prepared. The PA-PEI-MOF303(Al) adsorption capacity for NH3 was 16.07 mmol·g-1 at 298 K and 100 kPa, and the PA-PEI-MOF303(Al) could be regenerated repeatedly under vacuum at 423 K. The NH3 adsorption mechanism was investigated by in situ Fourier transform infrared spectroscopy and by performing two-dimensional correlation analysis. Unlike for the MOF303(Al) powder, the formation of multi-site hydrogen bonds between Al-O-Al/C-OH, N-H, -OH, C=O, and NH3 in PA-PEI-MOF303(Al) was found to be an important reason for efficient NH3 adsorption. This study will provide a reference for the preparation of other MOF-polymer composites.

Effect of Gallium as an Additive Over Corresponding Ni-Mo/γ-Al2O3 Catalysts on the Hydrodesulfurization Performance of 4,6-DMDBT.

Experiments were carried out to research the different contents of Ga2O3 modification effects on the hydrodesulfurization (HDS) performance of 4,6-dimethyldibenzothiophene (4,6-DMDBT) catalyzed by the stepwise impregnation method. Characterization techniques such as XRD, BET, HRTEM, NH3-TPD, and Py-FTIR were performed to determine the effects of each modification of the catalyst by Ga on the properties of the prepared supports and catalysts. The catalytic effect of gallium is reflected in the fact that the empty d-orbitals of Ga elements participate in the formation of molecular orbitals in the active center and change their orbital properties, thus generating a direct desulfurization active phase suitable for complex sulfides for endpoint adsorption. The characterization results indicated that the introduction of Ga2O3 with appropriate content (2 wt.%) promoted Ni and Mo species to disperse uniformly and doping of more Ni atoms into the MoS2 crystals, which also increased the average stacking number and the length of MoS2. As a result, more NiMoS active phases were favored to form in the system. The specific surface area and the amounts of acid sites were increased, facilitating the adsorption of reactant molecules and the HDS reactions. The HDS results also suggested the effects of Ga modification play a very important role in the catalytic performance of the corresponding catalysts. The catalyst Ga–Ni–Mo/Al2O3 exhibited the highest conversion rate towards 4,6-DMDBT HDS when the amount of Ga2O3 loading was 2 wt.% with an LHSV of 2.5 h−1 at 290°C and Ga modification also can effectively improve the direct desulfurization (DDS) route selectivity in varying degrees.

Experimental and in situ DRIFTs studies on confined metallic copper stabilized Pd species for enhanced CO2 reduction to formate

Understanding the basic principle of Pd-based bimetallic catalysts design is essential in CO2 hydrogenation to formate. In this work, Cu partially replaced the bivalence position in MgAl hydrotalcite structure was developed for achieving the highly confined Cu species, whose interaction with Pd species was systematically studied and compared with the traditional co-impregnation or stepwise impregnation method. The stable and maximum formate formation rate of 12.8 mmol/h/gmetal was obtained on Pd0.4 @CuMgAlOx catalyst under 100 °C, 4.0 MPa, H2/CO2 ratio of 3, being about double of the sum of formate production rate over the monometallic Cu and Pd catalysts. Strong synergetic interaction between Pd and the confined Cu species was observed with Cu/Pd atomic ratios of 14–181. Extensive characterization using TEM, XPS, XANES, coupled with kinetic study and in situ DRIFTs analysis revealed that the superior performance of Pd0.4 @CuMgAlOx was attributed to the confined PdCu nanoparticles with electron-rich PdCu surface.

Molybdenum oxide decorated Ru catalyst for enhancement of lignin oil hydrodeoxygenation to hydrocarbons

Herein, the catalysts of ruthenium and molybdenum oxide nanoparticles supported on activated carbon (AC) were synthesized by precursor stepwise impregnation and employed for the hydrodeoxygenation (HDO) of lignin oil. The XRD, TEM, XPS and NH3-TPD-MS result of RuMoOx/AC catalysts confirm that the method of loading molybdenum precursor before ruthenium precursor is advantageous for the MoOx and Ru nanoparticles high dispersion and the reduction of MoOx species enhance the amount of acidity of catalyst. Meanwhile, the reduction temperature of RuMoOx/AC-1-T catalysts could effectively regulate the MoOx species that determine the activity and product distribution of HDO. The conversion of aromatic monomers/dimers were up to 96% with high selectivity of hydrocarbon over RuMoOx/AC-1-350 catalyst at 160 °C and 30 bar H2. Which is attributed to the MoO3 and Ru species possess the excellent activity of benzene ring deep hydrogenation, ether bond breaking and acid dehydration. The RuMoOx/AC-1-350 catalyst effectively converted lignin oil (from the depolymerization of cornstalk hydrolysis residue) into hydrocarbons (56.9 wt%) and cyclohexanol/ethers (18.7 wt%) under 280 °C and 3 bar H2. The durability of the RuMoOx/AC-1-350 catalyst for HDO of lignin oil was also investigated and showed that the RuMoOx/AC-1-350 catalyst had good stability, regenerability and repeatability.

The One‐pot Encapsulation of Palladium Complexes into Covalent Organic Frameworks Enables the Alkoxycarbonylation of Olefins

AbstractIn this study, palladium‐based heterogeneous catalysts were successfully prepared by encapsulating the palladium diphosphine complexes into an imine‐linked 2D‐COF (TPB‐DMTP‐COF) through a one pot self‐assembly approach. It not only prevents the oxidation of phosphine‐based ligand during the stepwise impregnation but also suppresses the coordination of imine linkers at the COF host to the palladium guest, thus enabling highly efficient encapsulation of the active bidentate phosphine chelated palladium complex by the widely explored imine‐linked COF. Besides, the dosage of diphosphine ligand (Xantphos‐SO3H, L) and the ratio of palladium to L in the preparation of [Pd]@COF hybrids can be readily adjusted under such one pot procedure to satisfy the requirement of crystallinity, porosity, active sites, and CO adsorption capacity for the catalytic performance in the methoxycarbonylation of olefins. The resultant [Pd]@COF‐A‐0.25‐0.5 provides satisfied catalytic performance for both aliphatic and aromatic olefins with total esters up to 92.1 % under optimized conditions. These findings provide the basis for a novel design concept to design heterogeneous catalysts with high efficiency for reaction processes comprising the alkoxycarbonylation of olefins.

Rhenium modification on NiMo/Al2O3 catalyst and effects on the hydrodesulfurization reaction route selectivity of 4,6-dimethyldibenzothiophene

A series of Re modified NiMo/Al2O3 hydrodesulfurization (HDS) catalysts with different contents of Re2O7 were successfully synthesized by stepwise impregnation method and co-impregnation method respectively. The effects of Re modification and impregnation methods on the physical-chemical properties of the prepared catalysts were determined by the characterization techniques such as XRD, N2 physical adsorption-desorption, NH3-TPD, Py-FTIR and HRTEM. Finally, the effects of the Re modification and the impregnation methods on the catalytic activity and the HDS reaction route selectivity were evaluated using 4,6-dimethyldibenzothiophene (4,6-DMDBT) as a probe. The results show that the crystal morphologies and pore structures of the synthesized catalysts varied with the contents of Re2O7 and the impregnation methods and the amounts of acid sites can be modulated by the incorporation of Re2O7 and the impregnation methods. Moreover, Re modification was conducive to the formation of the “type II” Ni-Mo-S active phase by changing the morphology of the Ni promoted MoS2 slabs. The HDS evaluation of 4,6-DMDBT results show that Re modification can effectively improve the 4,6-DMDBT conversions, DDS route selectivity and even 3,3′-dimethylcyclohexanebenzene (3,3′-DMCHB) selectivity in varying degrees, and compared with that of co-impregnation method, the Re modification by stepwise impregnation method exhibited a more prominent effect. In general, 1 wt% Re2O7 content was the most favorable to the HDS reaction since excessive Re2O7 content has very little promoting effect.

Hydrogen- and Methane-Rich Clean Producer Gas from the Reforming of Bio-oil with Fe/AC Catalyst Prepared by a Stepwise Impregnation Method

Hydrogen- and Methane-Rich Clean Producer Gas from the Reforming of Bio-oil with Fe/AC Catalyst Prepared by a Stepwise Impregnation Method

Tuning the interactions among Ce, Pd and Rh over Ce-modified Pd-Rh three-way catalyst for exhaust treatment of natural gas vehicles

Three Ce-modified Pd-Rh bimetallic catalysts for exhaust purification of natural gas vehicles (NGVs) under stoichiometric conditions were prepared by deposition-precipitation (DP), stepwise impregnation (SI) and co-impregnation (CI) methods, respectively. It demonstrated that before and after aging the catalyst prepared by DP technique displayed much higher activity for the conversions of CH4 and NO than the other two catalysts, especially at high temperatures (about 410–550 °C). X-ray diffraction, CO-chemisorption, hydrogen temperature-programmed reduction and X-ray photoelectron spectroscopy analyzes demonstrated that there were smaller CeO2 particles, higher metal dispersion, stronger reducibility and more surface metallic Pd species over the catalyst prepared by DP method. This might be due to the stronger Pd-Ce but weaker Pd-Rh interactions over the catalyst prepared by DP mean. Moreover, in situ diffuse reflectance infrared Fourier transform spectroscopy of CO adsorption analysis implied that the electronic structures of Pd in the three catalysts were different, which may be also induced by the different interactions among Rh, Ce and Pd in these catalysts. The results indicated that the performance of Pd-Rh three-way catalyst for NGVs exhaust purification can be enhanced by modulating the interactions of Pd-Rh and Pd-Ce. Our work may provide a new strategy for the preparation of three-way catalyst with high efficiency for NGVs.

Enhancement of catalytic activity in NH3-SCR reaction by promoting dispersibility of CuCe/TiO2-ZrO2 with ultrasonic treatment

A series of CuCe-modified TiO2-ZrO2 catalysts synthesized by stepwise impregnation method and ultrasonic-assisted impregnation method were investigated to research the removal of NO in the simulated flue gas. Results showed that the CuCe/TiO2-ZrO2 catalyst prepared by ultrasonic-assisted impregnation method exhibited the superior NO conversion, in which higher than 85% NO was degraded at the temperature range of 250–400 °C and the highest NO conversion of 94% at 350 °C. It proves that ultrasonic treatment can markedly improve the performance of catalysts. The effect of ultrasonic enhancement on CuCe/TiO2-ZrO2 was comprehensively studied through being characterized by physicochemical characterization. Results reveal that the ultrasonic cavitation effect improves the distribution of active species and the synergistic interaction between Cu with Ce components (Cu+ + Ce4+ ↔ Cu2+ + Ce3+) on the catalysts significantly, thus resulting in better dispersibility as well as a higher ratio of Cu2+ and Ce3+ of the catalysts. Moreover, it was found that the CuCe/TiO2-ZrO2 catalyst prepared by the ultrasonic-assisted impregnation method represented a higher degree of ultrafine metal particles and evenness. The above results were described with the generalized dimension and singularity spectra in multifractal analysis and validated by the comparative test. Therefore, it can be concluded that ultrasonic treatment facilitates the particle size and distribution of active sites on the catalysts.

The effects of MoO3 impregnation order on the catalytic activity for propane combustion over Pt/ZrO2 catalysts: the crucial roles of Pt–MoO3 interfacial sites density

MoO3 promoted Pt/ZrO2 catalysts were prepared by co-impregnation (Pt–Mo/ZrO2) or stepwise impregnation (Pt/Mo/ZrO2 and Mo/Pt/ZrO2) for propane combustion.

Surface configuration modulation for FeOx-CeO2/γ-Al2O3 catalysts and its influence in CO oxidation

The surface configuration of a catalyst, including the present state, coordination environment and related content of the active and additive species, has dominant effect on its physicochemical properties and catalytic performance. Herein, two types of FeCe/Al catalysts with different surface configurations, FeCe/Al-CI (co-impregnation) and FeCe/Al-SI (stepwise impregnation) were synthesized by adjusting the preparation conditions. Both catalysts together with the reference sample Fe/Al and Ce/Al were characterized by means of XRD, BET, TEM, EPR, UV–vis, Mössbauer spectra, H2-TPR and XPS. The results showed that (1) in both impregnation modes, ceria presented as small particles, while the iron species existed in two forms: the isolate state (tetrahedral coordination), cluster state (octahedral coordination); (2) iron species in different existence state can be characterized qualitatively or quantitatively via EPR, UV–vis and Mössbauer spectra, and the contents of FeOx clusters follows: FeCe/Al-SI < FeCe/Al-CI < Fe/Al. (3) With the help of HNO3 leaching operation, FeOx clusters were identified as the main active species for CO oxidation. Although Fe/Al sample contained the highest concentration of active cluster FeOx species, the deficiency of Fe-O-Ce structures led to the lowest number of surface oxygen, Ce3+ and Fe2+ species, which resulted in poor CO oxidation activity for Fe/Al catalyst.

Bioinspired multilevel interconnected networks with porous multiwalled nanotubes built by heterogeneous nanocrystallites

AbstractInspired by fiber‐interwoven eggshell membrane (ESM) with associated specific permeability and transport performance, interconnected nanotube networks are constructed to empolder relevant distinctive properties and functional advantages. In this work, a typical ESM‐templated procedure combined with stepwise impregnation and gradient calcination is developed to accomplish the fabrication of multilevel frameworks from TiO2 nanocrystallites to porous multiwalled nanotubes (NTs) to final interconnected networks. During the impregnation process, in situ mineralization occurs on ESM fiber substrate to generate Ti‐impregnant coating with variant composition and layered structure. Followed by the calcination, anatase TiO2 porous NTs come into being as ESM templates decompose at 500°C, then heterogeneous nanocrystallites are achieved at higher temperature. Thus, the final ESM‐morphic nanocomposites present interconnected networks woven by porous multiwalled NTs. Benefiting from interconnected multichannels of multilevel networks and controllable heterogeneous nanocrystallites, the ESM‐inspired TiO2 would behave higher light‐excitation and transport efficiency, which can achieve more valuable applications such as photocatalytic degradation to some organic pollutants.

Modification of Y‐Zeolite with Zirconium for Enhancing the Active Component Loading: Preparation and Sulfate Adsorption Performance of ZrO(OH)2/Y‐Zeolite

AbstractNowadays, several techniques have been utilized to remove sulfate from industrial sewage. The method using ZrO(OH)2 to adsorb sulfate is highly efficient and environmentally friendly, however, nano‐powdered ZrO(OH)2 is hard to be recycled owing to its great loss in the adsorption process, which brings enormous difficulties to industrial applications. In this research, to prevent adsorbents from losing, Y‐zeolite was modified with zirconium, including the incorporation of zirconium as heteroatoms into zeolite frameworks and ion‐exchange of Zr4+ into the cages of zeolite, and then used as carrier to load ZrO(OH)2 to fabricate adsorbent via the stepwise impregnation treatment. The as‐prepared supported adsorbent ZrO(OH)2/Y‐zeolite has a high SO42− adsorption capacity, a strong adsorption selectivity to SO42− and good adsorption‐regeneration circulation performances. The saturated SO42− adsorption capacity of 284.22 mg/g can be obtained under the following adsorption conditions: SO42− concentration of 10 g/L, the pH value of 1.5, the temperature of 25 °C. After five adsorption‐regeneration circulations, its adsorption capacity has decreased only about 10%. The adsorption‐ desorption of sulfate over ZrO(OH)2/Y‐zeolite adsorbent proceeds according to the ion‐exchange mechanism between sulfate and the surface hydroxyl groups.

Preparation of copper-based catalysts by ultrasonic co-impregnation to catalyze the hydrogenation of sec-butyl acetate

Four different impregnation methods, namely ultrasonic co-impregnation, ultrasonic stepwise impregnation, co-impregnation and stepwise impregnation, were used to prepare Cu/B/Ca/Al2O3 catalyst. The effects of ultrasonic-assisted impregnation on the physicochemical properties, morphology and hydrogenation performance of sec-butyl acetate were investigated, and the difference between ultrasonic co-impregnation and ultrasonic stepwise impregnation was further explored. The catalysts were characterized by inductively coupled plasma atomic emission spectrometry, X-ray diffraction, scanning electron microscopy, Transmission electron microscope and N2 physical adsorption-desorption. The results indicate that ultrasonic-assisted treatment can reduce the agglomeration of copper particles, and that the active components are uniformly dispersed on the surface of the catalyst, expanding the specific surface area and, thus, increasing the conversion of sec-butyl acetate from 79.6% to 99.8%, and the selectivity of sec-butanol from 63.5% to 70.2%. In addition, the reaction pressure is reduced from 8 MPa to 5 MPa compared to the conventional impregnation.Ultrasonic co-impregnation is more advantageous than ultrasonic stepwise impregnation, since it can shorten the catalyst preparation cycle, avoid loss of B2O3 and CaO components during the secondary impregnation, expand the effective contact area between Ca and Cu species, increase the electron transfer rate from Ca to Cu, avoid the increase of Cu+/Cu and finally ensure the hydrogenation activity of the catalyst. The catalyst has the highest reactivity at an ultrasonic power of 80 W and within the duration of 0.75h. However, continued increase in ultrasonic power and time leads to catalyst deactivation. A long term test for catalyst stability which lasted for 200h had been run at 226 °C, 5 MPa H2, space velocity = 0.5h−1.

Mild Ammonia Synthesis over Ba-Promoted Ru/MPC Catalysts: Effects of the Ba/Ru Ratio and the Mesoporous Structure

A series of novel mesoporous carbon-supported, Ba-promoted, Ru catalysts with Ba/Ru ratios of 0.1–1.6 and a Ru loading of 10 wt% (denoted as 0.1–1.6Ba-10Ru/MPC) were prepared via stepwise impregnation of Ru and Ba precursors on the mesoporous carbon materials. The catalysts were applied to mild ammonia synthesis and compared to reference materials, including an analog of the prepared catalyst with a Ba/Ru ratio of 1.6 and a Ru loading of 10 wt% (denoted as 1.6Ba-10Ru/AC). Characterization by X-ray diffraction (XRD), nitrogen physisorption, and electronic microscopy revealed that the 0.1–1.6Ba-10Ru/MPC catalysts contained Ru particles (approximately 2 nm) that were well-dispersed on the mesoporous structure and nanostructured Ba(NO3)2 species. These species decomposed into amorphous BaOx species, acting as a promoter on the metallic Ru particles forming catalytically active sites for ammonia synthesis. All the 0.1–1.6Ba-10Ru/MPC catalysts showed a synergistic effect of the active Ba and Ru species, which were stabilized in the mesoporous carbon framework with fast molecular diffusion and could effectively catalyze mild ammonia synthesis (280–450 °C and 0.99 MPa) even under intermittently variable conditions, particularly for those with Ba/Ru ratios of &gt;0.5. In contrast, the 1.6Ba-10Ru/AC analog showed poor activity and stability for ammonia synthesis due to the sintering of Ba and Ru particles on the outer surface of the microporous carbon framework, resulting in low molecular diffusion and weak synergistic effect of the catalytically active sites.