Characterization Of Catalysts Research Articles

Novel Ni/SBA-15 Catalyst Pellets for Tar Catalytic Cracking in a Dried Sewage Sludge Pyrolysis Pilot Plant

Novel Ni/SBA-15 catalysts were synthesised and their activity in the dry reforming of methane process was assessed. These materials were prepared into extrudates shaped like pellets and tested in a pyrolysis pilot plant fitted with a catalytic reactor for sewage sludge pyrolysis tar removal. The Ni/SBA-15 catalyst pellets remained highly active and stable throughout the test’s duration, converting 100% tar in the hot gas to smaller non-condensable gases, thereby increasing the pyrolysis gas fraction and eliminating the problematic tar in the vapour stream. Catalyst characterisation with Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray (EDX) analysis, Transmission Electron Microscopy (TEM), and Thermogravimetric Analysis (TGA) confirmed that both the Ni/SBA-15-powered catalyst and the pellets were resistant to sintering and carbon deposition and remained highly active even with relatively high-level sulphur in the feed stream. The Ni/SBA-15 catalyst extrudates were prepared by mixing the powdered catalyst with varied amounts of colloidal silica binder and fixed amounts of methyl cellulose and water. The highest mechanical strength of the extrudates was determined to be of those obtained with 36% of the inorganic binder. The physical properties and catalytic activity of Ni/SBA-15 pellets with 36% colloidal silica were compared with the original powdered Ni/SBA-15 catalyst to assess the binder inhibitory effect, if any. The results confirmed that colloidal silica binder did not inhibit the desired catalyst properties and performance in the reaction. Instead, enhanced catalytic performance was observed.

Alkylation of Aniline with Benzyl Alcohol by Using Ni/O‐Clay: Kinetic Studies

AbstractThis study investigates the alkylation of aniline using benzyl alcohol over a Ni (30)/O‐clay catalyst, focusing on optimizing reaction conditions and understanding the reaction kinetics. The catalyst demonstrated 70% conversion of aniline with 75% selectivity toward benzylideneaniline (BDA) at 343 K in a 6‐hour reaction time. Catalyst characterization was performed using BET, NH3‐TPD, XRD, and FE‐SEM techniques, revealing a mesoporous structure with strong and medium acidic sites that enhance catalytic activity. Key parameters influencing the reaction, including temperature, molar ratio, catalyst loading, oxidants, and solvents, were systematically investigated. The Weisz‐Prater criterion confirmed the absence of mass transfer resistance, and kinetic studies validated the Langmuir‐Hinshelwood‐Hougen‐Watson (LHHW) mechanism. The activation energy was calculated and found to be 37 kcal/mol. The Ni (30)/O‐clay catalyst exhibited excellent reusability, maintaining activity and selectivity up to four reaction cycles. This work highlights the potential of Ni‐organoclay catalyst for green, cost‐effective synthesis of alkylated aniline derivatives, paving the way for sustainable and efficient industrial processes. The results emphasize the importance of heterogeneous catalysts in enhancing selectivity and minimizing by‐products in environmentally friendly chemical transformations.

Tutorial review on catalyst characterization and materials preparation for x-ray powder diffraction analysis

Tutorial review on catalyst characterization and materials preparation for x-ray powder diffraction analysis

Synthesis, characterization, and performance evaluation of different sulfonated lignin-based carbon catalysts for upgrading waste vegetable oil to biodiesel

Synthesis, characterization, and performance evaluation of different sulfonated lignin-based carbon catalysts for upgrading waste vegetable oil to biodiesel

Integration of Pt/Fe‐silicalite‐1 and acidic zeolite as a bifunctional catalyst for boosting ethane dehydroaromatization

AbstractEthane dehydrogenation to aromatics (EDA) is one of the most promising routes to produce aromatics. Herein, the tandem of dehydrogenation component and acidic zeolite are prepared and investigated for EDA. Pt/Fe‐S‐1 coupled with ZSM‐5 of Si/Al of 14 via mixing homogeneously shows excellent EDA performance with 54.0% ethane conversion, 61.5% aromatics selectivity as well as a deactivation rate constant of 0.00010 h−1. According to catalysts characterizations and controlled experiments, it is confirmed the highly dispersed positive Ptδ+ species around Fe species over Pt/Fe‐S‐1 is the active sites for ethane dehydrogenation to ethylene and subsequent naphthenes dehydrogenation to aromatics, Brønsted acid sites of ZSM‐5 and MFI pore are responsible for ethylene oligomerization and cyclization to naphthenes and further naphthenes dehydrogenation to aromatics. The short spatial space between dehydrogenation active sites and acid sites is beneficial for EDA. And the ethylene generation rate is the rate‐determining step of EDA.

Heterogeneous Frustrated Lewis Pair Catalysts: Rational Structure Design and Mechanistic Elucidation Based on Intrinsic Properties of Supports.

ConspectusThe discovery of reversible hydrogenation using metal-free phosphoborate species in 2006 marked the official advent of frustrated Lewis pair (FLP) chemistry. This breakthrough revolutionized homogeneous catalysis approaches and paved the way for innovative catalytic strategies. The unique reactivity of FLPs is attributed to the Lewis base (LB) and Lewis acid (LA) sites either in spatial separation or in equilibrium, which actively react with molecules. Since 2010, heterogeneous FLP catalysts have gained increasing attention for their ability to enhance catalytic performance through tailored surface designs and improved recyclability, making them promising for industrial applications. Over the past 5 years, our group has focused on investigating and strategically modifying various types of solid catalysts with FLPs that are unique from classic solid FLPs. We have explored systematic characterization techniques to unravel the underlying mechanisms between the active sites and reactants. Additionally, we have demonstrated the critical role of catalysts' intrinsic electronic and geometric properties in promoting FLP formation and stimulating synergistic effects. The characterization of FLP catalysts has been greatly enhanced by the use of advanced techniques such as synchrotron X-ray diffraction, neutron powder diffraction, X-ray photoelectron spectroscopy, extended X-ray absorption fine structure, elemental mapping in scanning transmission electron microscopy, electron paramagnetic resonance spectroscopy, diffuse-reflectance infrared Fourier transform spectroscopy, and solid-state nuclear magnetic resonance spectroscopy. These techniques have provided deeper insights into the structural and electronic properties of FLP systems for the future design of catalysts.Understanding electron distribution in the overlapping orbitals of LA and LB pairs is essential for inducing FLPs in operando in heterogeneous catalysts through target electron reallocation by external stimuli. For instance, in silicoaluminophosphate-type zeolites with weak orbital overlap, the adsorption of polar gas molecules leads to heterolytic cleavage of the Alδ+-Oδ- bond, creating unquenched LA-LB pairs. In a Ru-doped metal-organic framework, the Ru-N bond can be polarized through metal-ligand charge transfer under light, forming Ru+-N- pairs. This activation of FLP sites from the framework represents a groundbreaking innovation that expands the catalytic potential of existing materials. For catalysts already employing FLP chemistry to dynamically generate products from substrates, a complete mechanistic interpretation requires a thorough examination of the surface electronic properties and the surrounding environment. The hydrogen spillover ability on the Ru-doped FLP surfaces improves conversion efficiency by suppressing hydrogen poisoning at metal sites. In situ H2-H2O conditions enable the production of organic chemicals with excellent activity and selectivity by creating new bifunctional sites via FLP chemistry. By highlighting the novel FLP systems featuring FLP induction and synergistic effects and the selection of advanced characterization techniques to elucidate reaction mechanisms, we hope that this Account will offer innovative strategies for designing and characterizing FLP chemistry in heterogeneous catalysts to the research community.

Structural Characterization of the Platinum Nanoparticle Hydrogen-Evolving Catalyst Assembled on Photosystem I by Light-Driven Chemistry.

Directed assembly of abiotic catalysts onto biological redox protein frameworks is of interest as an approach for the synthesis of biohybrid catalysts that combine features of both synthetic and biological materials. In this report, we provide a multiscale characterization of the platinum nanoparticle (NP) hydrogen-evolving catalysts that are assembled by light-driven reductive precipitation of platinum from an aqueous salt solution onto the photosystem I protein (PSI), isolated from cyanobacteria as trimeric PSI. The resulting PSI-NP assemblies were analyzed using a combination of X-ray energy-dispersive spectroscopy (XEDS), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), small-angle X-ray scattering (SAXS), and high-energy X-ray scattering with atomic pair distribution function (PDF) analyses. The results show that the PSI-supported NPs are approximately 1.8 nm diameter disk-shaped particles that assemble at discrete sites with 145 Å separation. This separation is too large to be consistent with NP nucleation and growth at a site adjacent to the FB cofactor site. Instead, we suggest a mechanism for NP growth at hydrophobic sites on the PSI stromal surface. The NPs photoreductively assembled on the PSI stromal surface are found to be analogous to the nanostructures produced by successive cycles of atomic layer deposition (ALD) of platinum onto 40 nm porous anodic alumina oxide supports, although the mechanisms for nucleation appear to differ. This work establishes a foundation for the investigation of the reductive assembly of abiotic metal catalysts at sites connected to photochemically reducing equivalent production in PSI.

The Development of a Novel Aluminosilicate Catalyst Fabricated via a 3D Printing Mold for Biodiesel Production at Room Temperature

Biodiesel production has gained attention as a sustainable alternative to fossil fuels, but challenges related to catalyst recovery and energy consumption remain. In this study, a novel lithium-impregnated aluminosilicate catalyst (LiSA) was developed using a 3D-printed mold, providing precise control over its structure to optimize performance. The structured catalyst featured a cylindrical shape with multiple circular channels, enhancing fluid dynamics and reactant interaction in a fixed-bed reactor. Catalyst characterization by SEM, TGA, XRD, and ICP-MS confirmed high thermal stability and uniform pore distribution. Jatropha curcas oil was used as feedstock, with diethyl ether (DEE) acting as a cosolvent to improve methanol solubility and enable transesterification at room temperature. The process achieved a high fatty acid methyl ester (FAME) yield, averaging 97.1% over 508 min of continuous operation, demonstrating the catalyst’s stability and sustained activity. By reducing mass transfer limitations and energy demands, this approach highlights the potential of 3D-printed catalysts to advance sustainable biodiesel production, offering a scalable and efficient pathway for green energy technologies.

Synthesis and characterization of zirconium oxide-based catalysts for the oxygen reduction reaction via the heat treatment of zirconium polyacrylate in an ammonia atmosphere

Synthesis and characterization of zirconium oxide-based catalysts for the oxygen reduction reaction via the heat treatment of zirconium polyacrylate in an ammonia atmosphere

H2O2 Mediated Photoreduction of Nitrates to Ammonia by Iron Filings under Ambient Conditions.

Herein, a simple ambient conditioned sunlight promoted photochemical reduction reaction is demonstrated for the of nitrate (NO3-) conversion to ammonia (NH3) with the maximum conversion yield of ∼16 mM using iron filings (f-Fe) in the presence of H2O2. Based on a radical scavenging study of reactive species and the characterization of catalyst f-Fe before and after the reaction, a plausible mechanism has been proposed for the ambient conditioned synthesis of NH3. The results associated with the NH3 synthesis have been verified using the 15N isotopic labeled nitrate (15NO3-), which supports the simpler viability of the reported procedure.

Synthesis and characterization of a novel catalyst based on magnetic chitosan beads for oxidoreductase enzyme biomimetic immobilization

Synthesis and characterization of a novel catalyst based on magnetic chitosan beads for oxidoreductase enzyme biomimetic immobilization

A multi-molecular beam/infrared reflection absorption spectroscopy apparatus for probing mechanisms and kinetics of heterogeneously catalyzed reaction from ultrahigh vacuum to near-ambient pressure conditions.

A novel multi-molecular beam/infrared reflection absorption spectroscopy (IRAS) apparatus is described, which was constructed for studying mechanisms and kinetics of heterogeneously catalyzed reactions following a rigorous surface science approach in the pressure range from ultrahigh vacuum (UHV, 1 × 10-10mbar) to near-ambient pressure (NAP, 1000mbar) conditions. The apparatus comprises a preparation chamber equipped with standard surface science tools required for the preparation and characterization of model heterogeneous catalysts and two reaction chambers operating at different pressure ranges: in UHV and in the variable pressure range up to NAP conditions. The UHV reaction chamber contains two effusive molecular beams (flux up to 1.1 × 1015 molecules cm-2s-1), a quadrupole mass spectrometer, a Fourier-Transform (FT) IRA spectrometer, and a molecular beam monitor for beam aligning. This combination of the methods allows us to independently dose different reactants on the surface in a highly controlled way while simultaneously monitoring the evolution of gaseous products by QMS and recording the evolution of the surface species by FT-IRAS. The second reaction chamber operating in the variable pressure range is equipped with polarization-modulation-IRAS and three gas dosers and is designed as a small reactor, which can be operated in a continuous flow mode. The sample prepared under well-controlled UHV conditions can be in situ transferred between all chambers, thus allowing for investigations of structure-reactivity relationships over model surfaces. In this contribution, we provide a detailed description of the apparatus and the test measurements of the different crucial parts of the apparatus in the variable pressure range.

Ketonization of Valeric Acid to 5‐Nonanone Over Metal Oxides Catalysts

AbstractValeric acid (VA), readily obtainable in the biorefinery from sugary biomass streams, can be upgraded to 5‐nonanone, a versatile chemical building block with numerous applications. This study investigates the performance of nine metal oxide catalysts (SnO2, SiO2, Y2O3, CeO2, ZrO2, TiO2, La2O3, Cr2O3, and Al2O3) in the gas‐phase ketonization of VA to 5‐nonanone in the 350–450 °C range. The screening reveals a correlation between the metal oxides lattice energy and their catalytic activity for valeric acid ketonization. ZrO2, TiO2, and La2O3, characterized by high lattice energy, demonstrate the highest catalytic activity, whereas Y2O3, SnO2, and SiO2, showing low lattice energy, are barely active. However, exceptions to this trend were observed: Cr2O3 and Al2O3 displayed poor catalytic performance despite their elevated lattice energy. The comprehensive characterization of the catalysts, encompassing XRD, N2‐physisorption, NH3‐TPD, and CO2‐TPD analyses, has unveiled the crucial role of important parameters including acid–base properties in addition to lattice energy. Only oxides showing amphoteric properties can catalyze the reaction effectively. Interestingly, low‐lattice energy and amphoteric oxides such as SnO2 (showing poor performance) become significantly active at higher temperature (500 °C). Analysis of by‐products by online GCMS and spent catalyst characterization indicated that in this case the ketonization mechanism changed from the so‐called surface mechanism to the so‐called bulk mechanism.

Temperature and Cr-Co ratio on Production of Diethyl Ether from Ethanol Dehydration using Cr-Co/γ-Al2O3 Catalyst

The running down of fossil fuels and rising environmental concerns, there is an increasing emphasis on identifying eco-friendly alternative energy sources. Diethyl ether (DEE) is considered one such additive fuel that can replace fossil fuels. In this study, DEE was synthesized through the reaction dehydration of ethanol using γ-alumina catalysts impregnated with chromium and cobalt. The dehydration of ethanol performed in a fixed bed reactor using Cr-Co/γ-Al2O3catalysts loading. The effect of metal ratio of Cr-Co was examined. Catalyst characterization was carried out using XRD, BET, and SEM-EDX analyses. The dehydration reaction was conducted in a fixed-bed reactor at temperatures 100 to 200 ºC, with nitrogen gas flowrates between 200 and 600 mL/min as the carrier gas. The findings revealed that the increase chromium contents, and the temperature were augmenting the diethyl ether yield. And the increase of nitrogen flow rate is slightly increasing the yield of DEE and conversion of ethanol. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

The Characteristics of Hydrodeoxygenation of Biomass Pyrolysis Oil over Alumina-Supported NiMo Catalysts

The hydrodeoxygenation (HDO) of biomass pyrolysis oil (BPO) was evaluated in the presence of two commercial alumina-supported transition metal catalysts, NiMo/alumina-1 (NM1) and NiMo/alumina-2 (NM2). The study explored two characteristic aspects: how HDO reaction conditions affected the oxygen content, density, and boiling point distribution of BPO with varying temperature and HDO reaction time, and the roles of catalysts. Characterizations of HDO-treated oils included elemental analysis, GC-MS, SIMDIS, 13C NMR, and 1H NMR, and characterizations of catalysts included NH3-TPD, XRF, and TPO-MS analysis. The results show that both NM1 and NM2 catalysts removed oxygenated compounds effectively, which led to decreases in density and shifts toward higher boiling point distributions of BPO. Compared to the NM1 catalyst, NM2 had a higher acidity and enhanced HDO activity. The best HDO reaction performance was achieved in the presence of the NM2 catalyst at 300 °C. Furthermore, HDO reactions showed a significant amount of CO2, CH4, C2H6, and C3H8, which suggests that HDO reactions proceeded via a series of reactions of decarboxylation, water–gas shift, and methanation. In addition, hydrocarbon fraction tests suggested a favorable potential for the blending of HDO-treated biomass pyrolysis oil (HDO-BPO) with petroleum-derived fractions.

Use of aldol condensation between furfural and acetone for biofuel production: A review

The continued reliance on fossil fuels and the associated environmental challenges have spurred the development of renewable energy sources, with biorefineries emerging as a prominent solution for converting biomass into valuable fuels and platform chemicals. Among these, the production of furfural, derived from C5 sugars in lignocellulosic materials, holds particular significance. Extended-chain hydrocarbon fuels and intermediates, such as 4-(2-furyl)-3-buten-2-one (FAc, C8) and 1,4-pentadiene-3-one-1,5-di-2-furanyl (F2Ac, C13), are synthesized via aldol condensation between furfural and acetone, followed by hydrogenation and hydrodeoxygenation processes. This study emphasizes the critical role of catalysts, particularly heterogeneous catalysts, in increasing the efficiency and selectivity of these reactions. Solid catalysts, compared to their homogeneous counterparts, offer substantial advantages, including ease of recovery, reusability, and increased sustainability. Advances in analytical techniques, such as gas chromatography-mass spectrometry (GC-MS) and other state-of-the-art methods, have been instrumental in refining the characterization of heterogeneous catalysts, ensuring improved product quality and process optimization. Additionally, the study explores cutting-edge methodologies for catalyst characterization, utilizing tools such as field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and inductively coupled plasma optical emission spectroscopy (ICP-OES) to obtain precise quantitative and qualitative insights. This review provides a detailed analysis of the integration of these technologies into biofuel production, highlighting the critical role of innovative catalysts—particularly bifunctional systems under controlled conditions—and the development of optimized conversion routes. These strategies are essential for advancing industrial efficiency, improving process selectivity, and contributing to the sustainability of the energy sector.

Preparation and Characterization of Ni-based Catalysts Supported on Metal Organic Frameworks (MOFs) for CO2 Conversion to Value-added Chemicals

Preparation and Characterization of Ni-based Catalysts Supported on Metal Organic Frameworks (MOFs) for CO2 Conversion to Value-added Chemicals

Non-thermal plasma synergistic Ni/Al2O3 for ammonia synthesis: Configuration and optimization of a double dielectric barrier discharge reactor

The design of efficient reaction units and the use of efficient catalysts for green and non-polluting ammonia synthesis is an important and challenging issue. In this paper, we design a high-efficiency reaction device, a coaxial double dielectric barrier discharge plasma reactor, which produces a more uniform plasma discharge during operation, changes the discharge characteristics, promotes the physicochemical reactions of ammonia synthesis, improves the efficiency of ammonia production, and reduces the energy consumption. The use of transition metal Ni and its metal oxide NiO loaded on the carrier as catalysts. The catalyst was comprehensively characterized by X-ray photoelectron spectroscopy, X-ray diffraction, and scanning electron microscope. The reaction mechanism of plasma-catalyzed ammonia synthesis was studied in detail by combining discharge characteristics, optical emission spectroscopy, and catalyst characterization. The reaction conditions and discharge parameters of the dielectric barrier discharge plasma reactor were optimized, which greatly improved the energy efficiency and synthesis rate, which could reach 1002 μmol g−1 h−1 under the optimal conditions. Based on the experimental results, we analyzed how different conditions and parameters affect the reaction of ammonia synthesis.

Synthesis and Characterization of Aluminosilicate Catalysts from Volcano Mud for Biofuel Production with Different Feedstocks

The increasing awareness of sustainable development goals has led to the intensive development of biofuel as a substitute for fossil fuels. This study investigates the potency of volcano mud (VM) as the precursor in synthesizing aluminosilicate catalysts for biofuel production. Three catalysts were synthesized, A3, A3T, and A5, in a manner to investigate the effect of tetrapropylammonium hydroxide (TPAOH) addition and hydrothermal time on the crystallinity, Si/Al ratio, and textural properties of the catalysts. The catalytic activity of the synthesized catalysts was evaluated in two different qualities of feedstock, i.e., oleic acid (OA) and waste cooking oil (WCO). It is found that A5 which is synthesized with longer hydrothermal of 5 h has desirable properties, a high mesoporous surface area of 159 m2/g, and a high acidity of 0.263 mmol/g. Catalyst A5 is proven to have similarly high catalytic activity in both WCO and OA feedstock, achieving a liquid yield of 93% with FAME selectivity of 95% for WCO and 95% liquid yield and FAME selectivity of 99% for OA feedstock. These results suggest that A5 is a versatile catalyst in biofuel production from either high or low-quality feedstocks.

Hierarchical micro-meso-macroporous xAIL@HP UIO-66-NH2 catalysts used for efficient biodiesel production from low-grade acidic oils

The utilization of hierarchical porous supports to fabricate an efficient solid catalyst is a feasible strategy due to their remarkable merit in ameliorating the diffusion of reactants on the catalyst surface and increasing the exposure of active species in particular for the bulky molecule-involving reactions. In this research, to abatement the mass transfer resistance of large triglycerides, the hierarchical porous solid catalyst (xAIL@HP UIO-66-NH2) was prepared by grafting acidic ionic liquid (AIL) with double acidic sites of -SO3H and HSO4- onto micro-meso-macroporous metal-organic gels (HP UIO-66-NH2) through acid-base interactions between -NH2 moiety of HP UIO-66-NH2 and acidic moiety of AILs. The catalyst characterization results showed that the xAIL@HP UIO-66-NH2 catalyst owned the hierarchical porous structure and double Brønsted-Lewis acid centers with large BET surface area and pore volume. This catalyst was adopted for efficient biodiesel production from low-grade acidic oils, exhibiting high catalytic activities for triglyceride transesterification and free fatty acid (FFA) esterification reactions. By using acidic oils as feedstocks, the oil transesterification conversion could reach 91.3 % and the FFAs were completely converted to biodiesel under the conditions of 130 °C for 8 h at methanol-to-oil molar ratio of 35: 1 and catalyst dosage of 8 wt%. Based on the kinetic study, the activation energy Ea of this catalyst was 56.6 kJ/ mol, and the reaction complied with pseudo-first-order kinetics. This solid catalyst demonstrated satisfactory acid and water resistance, with good reusable performance, posing great potential in the efficient biodiesel preparation by the one-pot method using the low-grade acidic oils.