Characterization Of Catalysts Research Articles

Novel Insight into the Synergistic Mechanism for Pd and Rh Promoting the Hydro-Defluorination of 4-Fluorophenol over Bimetallic Rh-Pd/C Catalysts.

This study explores the synergistic effect between the Rh and Pd of bimetallic Rh-Pd/C catalysts for the catalytic hydro-defluorination (HDF) of 4-fluorophenol (4-FP). It was found that 4-FP could not be efficiently hydro-defluorinated over 6% Pd/C and 6% Rh/C due to the inherent properties of Pd and Rh species in the dissociation of H2 and the activation of C-F bonds. Compared with 6% Pd/C and 6% Rh/C, bimetallic Rh-Pd/C catalysts, especially 1% Rh-5% Pd/C, exhibited much higher catalytic activity in the HDF of 4-FP, suggesting that the synergistic effect between the Rh and Pd of the catalyst was much more positive. Catalyst characterizations (BET, XRD, TEM, and XPS) were introduced to clarify the mechanism for the synergistic effect between the Rh and Pd of the catalyst in the HDF reaction and revealed that it was mainly attributed to the bifunctional mechanism: Pd species were favorable for the dissociation of H2, and Rh species were beneficial to the activation of C-F bonds in the HDF reaction. Meanwhile, the interaction between Rh and Pd species enabled Rh and Pd to exhibit a more positive synergistic effect, which promoted the migration of atomic H* from Pd to Rh species and thus enhanced the HDF of 4-FP. Furthermore, 1% Rh-5% Pd/C prepared using 20-40 equiv NaBH4 exhibited the best performance in the catalytic HDF of 4-FP. Catalysis characterizations suggested that appropriate Rh3+/Rh0 and Pd2+/Pd0 ratios were beneficial to the dissociation of H2 and the activation of C-F bonds, which caused the more positive synergistic effect between the Rh and Pd of Rh-Pd/C in the HDF reaction. This work offers a valuable strategy for enhancing the performance of catalytic HDF catalysts via promoting synergistic effects.

Plasma-catalytic direct oxidation of methane to methanol over Cu-MOR: Revealing the zeolite-confined Cu2+ active sites

Efficient methane conversion to methanol remains a significant challenge in chemical industry. This study investigates the direct oxidation of methane to methanol under mild conditions, employing a synergy of non-thermal plasma and Cu-MOR (Copper-Mordenite) catalysts. Catalytic tests demonstrate that the Cu-MOR IE-3 catalyst (i.e., prepared by three cycles of ion exchange) exhibits superior catalytic performance (with 51 % methanol selectivity and 7.9 % methane conversion). Conversely, the Cu-MOR catalysts prepared via wetness impregnation tend to over-oxidize CH4 to CO and CO2. Through systematic catalyst characterizations (XRD, TPR, UV–Vis, HRTEM, XPS), we elucidate that ion exchange mainly leads to the formation of zeolite-confined Cu2+ species, while wetness impregnation predominantly results in CuO particles. Based on the catalytic performance, catalyst characterizations and in-situ FTIR spectra, we conclude that zeolite-confined Cu2+ species serve as the active sites for plasma-catalytic direct oxidation of methane to methanol.

Cu-Co Bimetallic Catalyst-based Electrochemical Sensing Platform for Determination of Bisoprolol in Clinical Samples.

Bisoprolol (BIS) is a selective beta-blocker. It has been successfully used to treat hypertension and angina pectoris. An overdose of BIS can lead to serious complications. An overdose is a medical emergency that requires immediate medical attention to overcome the adverse effects of the overdose. Hence, sensitive, reliable, and cost-effective methods are required for the determination of BIS. In this work, a new electrochemical sensing platform based on a bimetallic catalyst was developed for the determination of BIS. The Cu-Co nanocatalyst was easily synthesized by galvanic displacement onto a carbon paste electrode (CPE). Then, field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and cyclic voltammetry (CV) were utilized for the characterization of the Cu-Co catalyst. The galvanic displacement of Cu metal significantly affected the electro-catalytic behavior of the Cu-Co catalyst and the Cu-Co/CPE electrode displayed a very sensitive and accurate response towards BIS. Under optimized conditions, the response was linear in the 3 to 120 μM concentration range, sensitivity of 631.1 μA mM-1 and a detection limit of as low as 0.4 μM using cyclic voltammetry. The simple proposed method was also successfully employed in the analysis of BIS in biological and pharmaceutical samples. The advantages of Cu-Co/CPE are its fast and simple manufacturing and the possibility of a repeated surface regeneration of the sensing platform, as well as its application for the detection of BIS in tablets and biological samples, making Cu-Co significant promise for use in clinical diagnostics. Besides, the synthesized catalysts showed excellent reusability and stability. The presence of Cu metal due to galvanic displacement increased the sensitivity. These findings suggest that the new nanocatalyst has potential applications in sensors and electronics.

Bridging Dehydrogenation and Hydrogenation in Heterogeneous Catalysis: A Demonstration of a Unified Catalytic Approach.

In the pursuit of enhancing the applications of hydrogen as an energy carrier, this research delved into the utilization of a singular hybrid catalyst capable of performing both dehydrogenation and hydrogenation processes for Liquid Organic Hydrogen Carriers (LOHCs). This study presents the synthesis and characterization of a hybrid catalyst, combining an organometallic pincer complex with Pd-Ru heterostructures supported on γ-alumina. Unlike conventional transition and noble metal nanoparticles, the use of a pincer complex offers exceptional thermal stability due to its aryl backbone, which is advantageous for various endothermic dehydrogenation reactions of hydrocarbons in LOHCs. This pioneering hybrid catalyst is a novel approach, demonstrating a proof of concept. In this study, we utilized the hybrid catalyst to investigate the dehydrogenation and hydrogenation of a lower enthalpic system, specifically the cyclooctane-cyclooctene system. The dehydrogenation of cyclooctane was conducted at 443 K using tertiary butyl ethylene as a sacrificial hydrogen acceptor, while the hydrogenation of cyclooctene reaction catalyzed by Pd-Ru nanostructures occurred at 298 K and 1 atm H2. The results showed successful tandem dehydrogenation-hydrogenation reactions. However, challenges were noted in terms of catalytic activity and recyclability, providing valuable insights for further refinement and optimization.

Low‐Temperature Hydrogenation of Carboxylic Acids to Alcohols over Heterogeneous FeOx‐Modified Ru Catalyst

AbstractSelective hydrogenation of carboxylic acids to alcohols is generally difficult due to the low reactivity of the carboxy group, and the development of effective catalysts enabling high yields of the target alcohols at low reaction temperatures (<473 K) is challenging. Herein, we found that SiO2‐supported FeOx‐modified Ru (Ru−FeOx/SiO2) with the Fe/Ru molar ratio of 0.4 was an effective and reusable heterogeneous catalyst for the hydrogenation of carboxylic acids at a low reaction temperature of 413 K, providing the alcohols in high yields (up to 97 %). The addition of Fe species drastically suppressed the hydrogenolysis of the C−C bond of the alkyl chain to methane, leading to high selectivity to the alcohols. Based on the activity tests and catalyst characterizations, Ru metals were covered by the reduced Fe species, such as Fe metal or Fe2+, and the active site is the interface between the Fe species and Ru metals. From the reactivity comparison of the related compounds, the alcohol is synthesized via the formation of the aldehyde, and the reactivity of the alcohol is very low in the presence of carboxylic acids. As a result, the hydrogenolysis of the produced alcohol is suppressed, leading to the high selectivity of the alcohol.

Understanding the reaction dynamics of glycerol conversion into glycerol carbonate by transesterification of carbonic acid esters over CaO

The conversion of glycerol into value-added products is crucial for reducing waste generation in the biodiesel industry. In this context, glycerol carbonate has emerged as a promising molecule, capable of being produced through various processes, with glycerol transesterification being considered the most environmentally friendly method. In order to investigate the transesterification process comprehensively, this work focused on reactions between glycerol and different carbonic acid esters (dimethyl carbonate, diethyl carbonate, ethylene carbonate, and propylene carbonate), utilizing calcium oxide (CaO) as a basic catalyst. The catalyst was obtained commercially and characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The catalyst characterizations showed that it consisted of nano and micrometric particles with high purity, making it suitable for use without prior pretreatment. The reactions were conducted in a batch reactor using dimethylformamide as a solvent, and the products were analyzed by gas chromatography (GC-FID and GC-MS). Experiments were performed to investigate the effects of different reaction parameters on the formation process of glycerol carbonate and potential co-products. CaO showed moderate catalytic activity in glycerol conversion, which occurred in three steps, forming glycerol carbonate with high selectivity, along with small amounts of co-products, glycidol and glycerol tricarbonate. Thus, considering the results obtained in this and other studies, it was possible to identify that moderately strong basic catalysts favor simple reaction mechanisms, predominantly yielding glycerol carbonate. Conversely, highly basic catalysts induce more complex reaction mechanisms, resulting in significant formation of co-products.

Catalytic Performance of CuZnAl Hydrotalcite-Derived Materials in the Continuous-Flow Chemoselective Hydrogenation of 2-Methyl-2-pentanal toward Fine Chemicals and Pharmaceutical Intermediates.

Hydrotalcite-derived materials are eco-friendly, cheap, and efficient catalysts of different reactions. However, their application in liquid-phase hydrogenation could be more extensive. Hence, this work concerns the application of three hydrotalcite-derived materials with different CuZnAl molar ratios in the liquid-phase continuous-flow hydrogenation of 2-methyl-2-pentenal (MPEA) at a wide range of temperature (298-378 K) and pressure (1 × 106-6 × 106 Pa). The catalytic investigations were supported by catalysts characterization by ICP-OES, TPR, in situ XRD, XPS, NH3-TPD, CO2-TPD, and TEM measurements on different stages of their biography. It was shown that the catalytic activity of these samples is related to the Cu0/Cu+ ratio. Depending on the reaction conditions, selectivity control is possible. All catalysts were 100% selective to 2-methylpentanal (MPAA)-sedative drug precursor, with low conversion, at temperatures ≤ 338 K at every pressure. However, the selectivity of the second desired product, fragrance intermediate, 2-methyl-2-penten-1-ol (MPEO), increased significantly at higher temperatures and pressures. It reached the unique value of 54% with 60% substrate conversion at 378 K and 6 × 106 Pa for the catalyst with the highest Cu loading. It was revealed that the production of significant amounts of MPEO is related to the reaction conditions, the Cu+ predominance on the surface, the hydrogen spillover effect, and the acid-base properties of these systems.

Sustainable Production of Dialkoxymethane Ethers and Related Acetals Using CO2, H2 and Alcohols or Diols

Dialkoxymethane (DAM) ethers, so‐called oxymethylene ethers (OMEs), are compounds constituted by a CH2‐unit bound to two identical alkoxy substituents. These compounds have showcased interesting technological applications as fuel additives or fuels, as a consequence of their interesting properties such as their low vapor pressure, high viscosity, cetane number and oxygen content. Moreover, they are also employed as environmentally benign solvents and bulk compounds useful in fine‐chemical industry. In addition, DAM ethers are considered formaldehyde surrogates. Industrially, dimethoxymethane (DMM) is still produced via two‐step protocol involving toxic formaldehyde that consists of a first step of methanol oxidation (Formox process). Hence, the development of more sustainable protocols for their synthesis is highly desired. Among the different strategies reported for DAM synthesis, its production from CO2/H2 and alcohols constitutes a practical, green and attractive alternative route. In this concept, a careful discussion of the developed catalytic protocols for synthesizing DAM from CO2/H2 or formic acid/H2 and alcohols/diols will be summarized. A special emphasis will be performed on the reaction mechanisms involved and the catalyst nature design and characterization.

Preparation of Ni/ZSM-5 and Mo/ZSM-5 catalysts for hydrotreating palm oil into biojet fuel

With the increasing demand for fuel for global usage and CO2 emissions, greener alternatives are needed, especially in biojet fuel production. Catalyst preparation involves the impregnation of Ni and Mo metals into H-ZSM-5 using a dry impregnation method with spray deposition, resulting in Ni/ZSM-5 and Mo/ZSM-5 catalysts. Catalyst characterization utilizes FT-IR, XRD, SAA, SEM-EDX, XRF, and NH3-TPD instruments. The activity and selectivity tests of the catalysts were conducted in the hydrotreating of palm oil using Ni/ZSM-5 monolayer, Ni/ZSM-5 bilayer, Mo/ZSM-5 monolayer, Mo/ZSM-5 bilayer, as well as Ni/ZSM-5 bottom-layer and Mo/ZSM-5 top-layer arrangements. The result showed double-layer Ni/ZSM-5 as the best catalyst in activity and selectivity in producing biojet fuel fractions with consecutive conversion, selectivity, and yield of 29.71%, 84.76%, and 24.34%, respectively. The layers of catalyst affected the catalytic activity and selectivity, resulting in a higher yield.

Highly efficient aerobic epoxidation of styrene using mesoporous Co-Ni catalysts

This work reports the synthesis and characterization of mesoporous cobalt-nickel mixed metal oxide catalysts with varying Co:Ni ratios using an inverse micelle template self-assembly method. Their structural and morphological properties and catalytic performance in styrene epoxidation were evaluated. Among them, the 73CoNi-250 catalyst (Co: Ni70:30 mol/mol%, calcined 250°C) exhibited a unique flower-like morphology and the highest surface area, which XPS analysis linked to a higher concentration of oxygen vacancies. Notably,73CoNi-250 demonstrated exceptional catalytic activity for styrene epoxidation, achieving near-complete styrene conversion (>99 %) and high selectivity (94 %) for styrene epoxide under mild reaction conditions without the need for oxidants such as peroxides. Furthermore, the catalyst exhibited excellent reusability (≥ 4 cycles) without significant activity loss or changes in mesoporosity. Kinetic studies revealed a first-order reaction profile and a significantly enhanced rate constant compared to the best-reported values (fivefold) in the literature, further underlining the catalyst's efficiency, and emphasizing the environmentally friendly approaches in chemical synthesis.

Copper-supported hydroxyapatite catalysts for bio-isobutanol synthesis from sustainable short-chain alcohols

Developing high-performance catalysts for the direct production of isobutanol through the Guerbet reaction is a challenge today, due to the potential of isobutanol as fuel. The present study describes the synthesis and characterization of Cu-supported hydroxyapatite catalysts. The synthesis of isobutanol has been investigated through batch experiments and in a continuous-flow reactor operating in a gas-solid phase. This study used ethanol and methanol as the primary feedstock for the synthesis process. It was found that Cu supported hydroxyapatite catalysts are capable of catalyzing the formation of isobutanol from CH3OH and C2H5OH at temperatures (300–500 ºC) and 1 atm in a continuous flow reactor. Notably, the highest selectivity to isobutanol was observed at 400 ºC. The use of Cu10/HAP 1.65 catalyst in a batch reactor greatly enhances the selectivity of iBuOH in the liquid phase, increasing it from 18 % (vapor-phase) to 65 %. The data showed that the reaction of ethanol/methanol was limited by the 1-propanol-to-isobutanol reaction, which is a secondary reaction of the key intermediate. A reaction scheme has been proposed.

Highly Efficient Low‐loaded PdOx/AlSiOx for Ethylene Dimerization

Ethylene dimerization is an industrial process that is currently carried out using homogeneous catalysts. Here we present a highly active heterogeneous catalyst containing minute amounts of atomically dispersed Pd. It requires no co‐catalyst(s) or activator(s) and significantly outperforms previously reported catalysts tested under similar reaction conditions. The selectivity to C4‐ and C6‐hydrocarbons was about 80% and 10% at 42% ethylene conversion at 200°C using an industrially relevant feed containing 50 vol% ethylene, respectively. Our kinetic and catalyst characterization experiments complemented by density functional theory calculations provide molecular insights into the local environment of isolated Pd(II)Ox species and their role in achieving high activity in the target reaction. When the developed catalyst was rationally integrated with a Mo‐containing olefin metathesis catalyst in the same reactor, the formed butenes reacted with ethylene to propylene with a selectivity of 98% at about 24% ethylene conversion.

Highly Efficient Low-loaded PdOx/AlSiOx for Ethylene Dimerization.

Ethylene dimerization is an industrial process that is currently carried out using homogeneous catalysts. Here we present a highly active heterogeneous catalyst containing minute amounts of atomically dispersed Pd. It requires no co-catalyst(s) or activator(s) and significantly outperforms previously reported catalysts tested under similar reaction conditions. The selectivity to C4- and C6-hydrocarbons was about 80% and 10% at 42% ethylene conversion at 200°C using an industrially relevant feed containing 50 vol% ethylene, respectively. Ourkinetic and catalyst characterization experiments complemented by density functional theory calculations provide molecular insights into the local environment of isolated Pd(II)Ox species and their role in achieving high activity in the target reaction. When the developed catalyst was rationally integrated with a Mo-containing olefin metathesis catalyst in the same reactor, the formed butenes reacted with ethylene to propylene with a selectivity of 98% at about 24% ethylene conversion.

Catalytic pyrolysis of polypropylene waste for liquid fuels production using Ni/Al-MOF-derived catalysts

Waste plastics pose significant environmental risks due to their non-biodegradable nature and accumulation in the environment. The pandemic has exacerbated this issue by increasing the production of plastic medical waste such as surgical masks. This study developed Ni/Al-MOF-derived catalysts for pyrolysis, an effective plastic waste utilization technology. By optimizing conditions, the study successfully converted waste surgical masks, made primarily of polypropylene, into gasoline or diesel range chemicals. The oil yield from polypropylene waste reached 72.8 % using Ni/Al-MOF-derived catalysts with 5 % Ni loading at 450°C, while surgical masks yielded 58.9 % oil under the same conditions. Catalyst characterization revealed a high surface area and evenly distributed Ni particles in MOF-derived Al2O3, maximizing catalytic performance. This catalyst provides a promising solution for converting waste surgical masks into liquid fuels, reducing the environmental impact of plastic products, and promoting plastic waste recycling.

Study on the reducible metal oxide carriers to regulate the catalytic reaction performance of CO2 with ethane

Aiming at the resource utilization of CO2 and the value-added catalytic conversion of ethane, different reducibility oxide carriers were used to study. Through catalytic reaction experiments, catalyst characterization and kinetic analysis, the interaction between reducible carriers and active metals and their regulation on the catalytic reaction performance of ethane with CO2 were revealed. Fe1.5Ni0.5/CeO2 has the highest ethylene selectivity of 87% near 650 °C, and is a good catalyst for the CO2-assisted ethane oxidative dehydrogenation to ethylene reaction. The strong interaction between the reducible CeO2 and ZrO2 carriers and active metals makes the Fe–O–Ce and Fe–O–Zr covalent bonds on the Fe1.5Ni0.5/CeO2 and Fe1.5Ni0.5/ZrO2 catalysts stronger than Fe–O–Ti and Fe–O–Al covalent bonds on Fe1.5Ni0.5/TiO2 and Fe1.5Ni0.5/γ-Al2O3 catalysts. The lattice oxygen on the reducible catalyst is more readily involved in the reaction. The strong interaction between the active metal and the carrier results in the reduction of the FeOx species and the formation of new active sites, resulting in a high reactivity of the catalyst. The mutually promoted redox cycle between the active species Fe3+/2+-Ni2+/0 and the reducible carrier variable metal Ce4+/3+ species improves the catalytic performance for the reaction of ethane awith CO2.

Rhodium-doped iron oxides promoted by sodium for highly selective hydrogenation of CO2 to ethanol and C2+ hydrocarbons

Hydrogenation of CO2 to produce high-value C2 + products has gained great interest, but catalyst design for highly selective ethanol still remains a challenge. Herein, bifunctional catalysts of iron oxide promoted with rhodium and sodium, Na-Rh-FeOx and Rh-FeOx-Na, were prepared by using simple methods of incipient wetness impregnation (IWI) and coprecipitation. The former catalyst prepared via IWI, Na-Rh-FeOx, is remarkably efficient for the hydrogenation of CO2 to ethanol with high selectivity of 91 % at 200 °C in the liquid fraction. The latter catalyst synthesized solely through the coprecipitation in a sodium-containing medium, Rh-FeOx-Na, displayed the synergy effect to perform a better CO2 conversion of 23 % at 200 °C. Characterization of catalysts via XRD, XPS, N2 physisorption, CO2-TPD, and gas pulse-chemisorption reveals that different preparation methods influenced the dispersion of sodium particles. This property, in turn, impacts the ratio of hydrogen-activating sites to CO-adsorption sites, directly related to the balance between dissociative- and non-dissociative CO* intermediates, which is crucial for ethanol formation. Adding alkali metal facilitates the formation of iron carbide Fe5C2, known to be active for C–C propagation. Integrating Na-Rh-FeOx with ZSM-5 support further increased ethanol selectivity up to 97 % in liquid phase and 90 % in gas phase. By selecting a proper route for introducing alkali metals and combining with supports, the catalyst properties can be effectively tailored, thereby regulating the catalytic activity and selectivity.

Novel multineedle-to-cylinder plasma coupled with bimetallic catalysts for efficient removal of sulfides and ammonia in odor gases

Dielectric barrier discharge (DBD) plasma is a promising technology for treating odor gases. This study developed an innovative multineedle-to-cylinder (MC) configuration DBD plasma reactor and investigated its synergistic effect with bimetallic catalysts. The results demonstrated that MC-DBD plasma achieved complete elimination of ammonia and organic sulfides, while the removal efficiencies of inorganic H2S and CS2 reached 44.0 % and 53.0 % respectively. Compared with conventional plasma, the specific energy input (SEI) of MC-DBD was significantly reduced to 4.44 J/L. Furthermore, with the incorporation of Mn-Ce/ZSM-5 catalyst, optimal removal efficiencies of H2S and CS2 were significantly improved to 82.6 % and 90.7 %, and the SEI was reduced by 18 %. The electrical performance revealed that the low energy consumption was mainly attributed to stable fast-pulse micro-discharge channels and significantly enhanced inhomogeneous electric fields achieved by the filament discharge mode. Catalyst characterization (X-ray photoelectron spectroscopy and O2-temperature programming desorption) confirmed that surface catalytic reaction mainly follows the Mars-van Krevelen mechanism, where increased lattice oxygen content and the electron transfer between Mn and Ce play crucial roles in enhancing malodor degradation performance. This work proposes an efficient solution for degrading mixed malodors and provides an experimental and theoretical basis for optimizing plasma structure as well as researching treatment of mixed pollutants.

The application of diatomic catalysts in advanced oxidation Fenton-like water treatment technology:A mini review

In the past few years, there has been a widespread utilization of diatomic catalysts in the catalysis sector because of their distinct benefits. In this review, we specify the application of diatomic catalysts based on carbon and carbon nitride in the Fenton-like field. This paper focuses on the synthesis and characterization of homonuclear and heteronuclear diatomic catalysts and methods to improve the catalytic performance by optimizing d-band structure, tuning charge transfer, and constructing spin states. There is no doubt that diatomic catalysts have bright prospects in the Fenton-like field.

ENHANCED PREDNISONE REMOVAL BY CATALYTIC WET AIR OXIDATION USING SEWAGE SLUDGE DERIVED CATALYST

Sewage sludge-based catalysts have been used for the first time for the catalytic wet air oxidation (CWAO) of prednisone, a glucocorticoid pharmaceutical pollutant present in various aquatic environmental matrices. This research focuses on transforming dry sludge into carbonaceous catalysts through pyrolysis and post-treatment. Various parameters have been considered for the synthesis, finding that pyrolysis temperature and acid washing are determinant for specific surface area development. The sewage sludge derived catalysts exhibit high catalytic activity in the CWAO of prednisone (Dcat= 0.3g·L-1, T= 100 °C, P= 15bar). The development of porosity enhances their catalytic properties, the C-750-N catalysts demonstrated the highest activity for prednisone with 66% TOC reduction, initial reaction rate 0.0092mg·s-1 and 66% CO2 selectivity. The study provides valuable insights into the synthesis, characterization, and application of sewage sludge-derived catalysts, offering a sustainable solution for wastewater treatment and pharmaceutical pollutant removal. Our present study indicates that catalysts with unique reforming properties may be potentially applicable for prednisone treatment and industrial applications.

Probing Basal and Prismatic Planes of Graphitic Materials for Metal Single Atom and Subnanometer Cluster Stabilization.

Supported metal single atom catalysis is a dynamic research area in catalysis science combining the advantages of homogeneous and heterogeneous catalysis. Understanding the interactions between metal single atoms and the support constitutes a challenge facing the development of such catalysts, since these interactions are essential in optimizing the catalytic performance. For conventional carbon supports, two types of surfaces can contribute to single atom stabilization: the basal planes and the prismatic surface; both of which can be decorated by defects and surface oxygen groups. To date, most studies on carbon-supported single atom catalysts focused on nitrogen-doped carbons, which, unlike classic carbon materials, have a fairly well-defined chemical environment. Herein we report the synthesis, characterization and modeling of rhodium single atom catalysts supported on carbon materials presenting distinct concentrations of surface oxygen groups and basal/prismatic surface area. The influence of these parameters on the speciation of the Rh species, their coordination and ultimately on their catalytic performance in hydrogenation and hydroformylation reactions is analyzed. The results obtained show that catalysis itself is an interesting tool for the fine characterization of these materials, for which the detection of small quantities of metal clusters remains a challenge, even when combining several cutting-edge analytical methods.