Catalytic Test Reaction Research Articles

Application of experimental design in the synthesis of 1-butanol from ethanol on mixed oxide catalysts at different mg/al molar ratios

1-Butanol, primarily sourced from petroleum, is currently being considered as a viable alternative to gasoline. Various pathways for synthesizing 1-butanol from renewable raw materials have been explored, with a particular focus on the Guerbet reactions. This study aimed to investigate the synthesis of 1-butanol from ethanol using Mg/Al mixed oxides derived from layered double hydroxides with Mg/Al molar ratios of 3:1, 5:1, 8:1, and 10:1. The catalysts were analyzed through X-ray diffraction, X-ray fluorescence, N2 adsorption, scanning electron microscope and energy-dispersive X-ray spectroscopy. Catalytic reaction tests were performed according to a Central Composite Rotatable Design (CCRD) with three replicates at the central point (CP). Among the catalysts tested at CP, the mixed oxides with Mg/Al molar ratios of 3:1 and 5:1 exhibited the most promising results, displaying similar ethanol conversion, and 1-butanol selectivity. This similarity underscores their well-balanced combination of both acidic and basic sites. However, further assessment through a deactivation test revealed that the mixed oxides with Mg/Al molar ratio of 5:1 held the most potential for long-term 1-butanol synthesis from ethanol, thanks to its superior stability and sustained activity. Using this catalyst, other reaction tests were carried out following the CCRD, varying N2 feed flowrate, ethanol molar content in feed flowrate, and temperature. The results indicated that an increase in ethanol conversion directly correlated with higher temperatures, while the 1-butanol selectivity depended on both the N2 feed flowrate, ethanol molar content in feed flowrate, highlighting the importance of a well-balanced combination of both acidic and basic sites.

Structural Control Enables Catalytic and Electrocatalytic Activity of Porous Tetrametallic Nanorods.

Integrating more than one type of metal into a nanoparticle that has a well-defined morphology and composition expands the functionalities of nanocatalysts. For a metal core/porous multimetallic shell nanoparticle, the availability of catalytically active surface sites and molecular mass transport can be enhanced, and the multielemental synergy can facilitate intraparticle charge transport. In this work, a reliable and robust synthesis of such a functional tetrametallic nanoparticle type is presented, where a micro- and mesoporous PdPtIr shell is grown on Au nanorods. The effect of critical synthesis parameters, namely temperature and the addition of HCl are investigated on the hydrodynamic size of the micellar pore template as well as on the stability of the metal chloride complexes and various elemental analysis techniques prove composition of the porous multimetallic shell. Due to the synergistic properties, the tetrametallic nanorods possess extensive negative surface charge making them a promising catalyst in reduction reactions. Dye degradation as well as the conversion of p-nitrophenol to p-aminophenol is catalyzed by the supportless nanorods without light illumination. By depositing the particles onto conductive substrates, the nanostructured electrodes show promising electrocatalytic activity in ethanol oxidation reaction. The nanocatalyst presents excellent morphological stability during all the catalytic test reactions.

Novel biologically active paddlewheel-like palladium thiocyanate complex catalyzed cyanation of alkyl bromide utilizing Q-tube system: A green perspective

A novel paddlewheel-like complex of [Pd(SCN)2(3-Acpy)2], (1) was produced at ambient temperature by adding an aqueous solution of palladium chloride to an aqueous acetonitrile solution of 3-acetylpyridine (3-Acpy) and potassium thiocyanate. Elemental analysis, Fourier-transform infrared (FT-IR), ultraviolet–visible (UV–vis), and nuclear magnetic resonance (NMR) spectroscopic methods were used to characterize complex 1 comprehensively. Single crystal X-ray diffraction was used to analyze the crystal structure of complex 1. The palladium atom is bonded to two 3-Acpy ligands and two thiocyanates groups in trans mode giving square planer geometry in complex 1. The discrete units of paddlewheel-like complex 1 through hydrogen bonding extend to form a 3D supramolecular network structure. The synthesized and characterized new palladium complex 1 was utilized as a precatalyst for the cyanation of alkyl bromide using potassium ferrocyanide as a benign cyanide source reagent. The suggested catalytic test reaction under high-pressure conditions via a Q-tube system in green solvent cyclopentyl methyl ether introduced high yields and a short reaction time. Moreover, the cytotoxic activity of complex 1 was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay against HePG-2 of liver cancer and MCF7 of breast cancer cell lines. According to the findings, complex 1 has significant strong activity against the cancer cell lines HePG-2 and MCF-7. Additionally, the luminescence spectra of complex 1 were investigated.

Development of dual-functional materials for integrated CO2 capture and utilization by dry reforming of CH4

Integrated CO2 capture and utilization by dry reforming of CH4 (ICCU-DRM) is an effective way to achieve CO2 emission reduction and resource utilization. However, the process is still in preliminary development stage, and it lacks of efficient and stable dual-functional materials (DFMs) and full understanding of reaction characteristics of ICCU-DRM. In this work, various inert supported Ni/CaO DFMs were synthesized and evaluated by comprehensive adsorption-desorption, catalytic reaction and ICCU-DRM tests. Results show that 5Ni-5Zr/CaO/SBA possesses a very good carbon deposition resistance. Almost no carbon deposition is produced in a continuous ICCU-DRM test for 20 cycles, while the conversion of CH4 and CO2 keeps at 66% and 75%, respectively. Meanwhile, benefiting from the stable micro-structure, 10Ni-CaO-Ca5Al6O14 maintains a high CO2 conversion capacity of 0.44 g g−1 in the stability test with a CO2 and CH4 conversion of 78% and 63%.

Ferrocenophanium Stability and Catalysis.

Ferrocenium catalysis is a vibrant research area, and an increasing number of ferrocenium-catalyzed processes have been reported in the recent years. However, the ferrocenium cation is not very stable in solution, which may potentially hamper catalytic applications. In an effort to stabilize ferrocenium-type architectures by inserting a bridge between the cyclopentadienyl rings, we investigated two ferrocenophanium (or ansa-ferrocenium) cations with respect to their stability and catalytic activity in propargylic substitution reactions. One of the ferrocenophanium complexes was characterized by single crystal X-ray diffraction. Cyclic voltammetry experiments of the ferrocenophane parent compounds were performed in the absence and presence of alcohol nucleophiles, and the stability of the cations in solution was judged based on the reversibility of the electron transfer. The experiments revealed a moderate stabilizing effect of the bridge, albeit the effect is not very pronounced or straightforward. Catalytic propargylic substitution test reactions revealed decreased activity of the ferrocenophanium cations compared to the ferrocenium cation. It appears that the somewhat stabilized ferrocenophanium cations show decreased catalytic activity.

Investigations of mechanism, surface species and support effects in CO hydrogenation over Rh

The Rh-catalyzed CO hydrogenation to hydrocarbons and C2-oxygenates over Rh/ZrO2 and Rh/SiO2 was studied. Catalytic reaction tests show a support effect with a faster steady state reaction rate over Rh/ZrO2 compared to Rh/SiO2. Temperature programmed hydrogenation (TPH) experiments reveal that the CO dissociation on the metal surface is rate limiting, and the support effect thus accelerates the CO dissociation on the metal. Combined TPH and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies after low-temperature CO pre-adsorption reveal a H-assisted C-O bond breakage through CH3O species on the Rh surface. Transient measurements indicate that this mechanism is also likely to be in operation during the steady state reaction at higher temperatures, although here the methoxide is too short-lived to be detected at steady state. This hydrogen-assisted CO activation can help to explain that previous studies have observed an inverse H/D isotope effect for Rh despite CO dissociation being the rate limiting step. TPH studies show that both CO pre-adsorption at 30 ℃ and CO/H2 exposure at 250 ℃ lead to so high CO coverages that it restricts the CO activation, which only starts once part of the CO has desorbed. The near-complete CO coverage on the working Rh surface is restricting the rate, but is essential for the selectivity towards oxygenates. Studies of acetaldehyde conversion in various atmospheres over Rh/SiO2 and Rh/ZrO2 catalysts show that acetaldehyde decomposes over a bare Rh surface with a rate that greatly exceeds the oxygenate formation rate in CO hydrogenation. In the presence of CO the acetaldehyde decomposition is strongly inhibited. The high CO coverage on the surface of the working Rh catalysts thus prevents oxygenate decomposition and is therefore essential for the ability to produce oxygenated products. The reaction temperature is observed to play a role for the establishment of the high coverage. During exposure to CO/H2 at reaction temperatures (>200 ℃) an activated process occurs whereby both the stability and coverage of the CO adlayer increases. This activated stabilization of the CO adlayer shifts the CO activation up in temperature in a subsequent TPH. The results contribute to a fundamental understanding of the reaction mechanism and support effects in the Rh-catalyzed CO hydrogenation, which can assist the formulation of improved Rh-based catalysts. The results, such as the identification of a H-assisted mechanism of CO hydrogenenation via methoxide, could also be of general relevance for the understanding of CO hydrogenation over other metals.

Investigating the effects of synthesis procedures on textural and catalytic properties of nickel/magnesium silicate catalyst in glycerol dry reforming

• The synthesis method affects the structural properties of the Ni/MgO.SiO 2 catalyst. • The structural features of the Ni catalyst affect catalytic performance significantly. • The Ni/MgO.SiO 2 catalyst prepared by one-pot method showed better performance. • The one-pot method has resulted in the highest textural properties of the Ni/MgO.SiO 2. Ni-based catalysts supported on magnesium silicate were synthesized using various synthesis procedures and were then investigated for the first time in the glycerol-DR (dry reforming) process. In general, synthesis procedures for catalyst supports included co-precipitation and hydrothermal, and nickel as active metal was attached to the support simultaneously with support preparing and impregnation technique. The results of characterizations of Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), hydrogen temperature-programmed reduction (TPR-H 2 ), temperature-programmed oxidation (TPO), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) element mapping, Fourier transform infrared (FTIR), thermogravimetric analysis (TGA-DTA), and the catalytic glycerol-DR reaction tests illustrated that the preparation route of Ni/MgO.SiO 2 catalyst is effective in the structural and physicochemical features of the sample. It was observed that the catalysts with various synthesis methods exhibited different activity and stability during the glycerol-DR reaction. However, the highest glycerol conversion (31–50%) and the yield of both H 2 and CO were achieved over the Ni/MgO.SiO 2 (I) catalyst at all reaction temperature ranges (600–750 °C). The high catalytic performance of the Ni/MgO.SiO 2 (I) sample in the glycerol-DR reaction was related to its textural properties such as surface area (411 m 2 g −1 ), the crystallite size (8.5 nm), and active species dispersion, which were superior for this catalyst in comparison with other samples. This sample also exhibited better catalytic stability during the reaction. Furthermore, synthesis gas (syngas) was produced for all catalysts with an H 2 /CO ratio of less than 1.6. These results clearly show a significant impact of the sample synthesis procedure on the catalyst's final physical and chemical properties. The Ni/MgO.SiO 2 catalyst prepared with a one-step method showed high potential as a glycerol-DR catalyst for syngas production.

3D‐Printed Acidic Monolithic Catalysts for Liquid‐Phase Catalysis with Enhanced Mass Transfer Properties

AbstractThe thriving research and development in additive manufacturing and especially 3D printing in chemical engineering and heterogeneous catalysis enables novel and innovative approaches for the shaping of catalysts. In this work, tailor‐made monoliths with complex transport pore channels are designed and printed by fused deposition modelling (FDM) from polystyrene filament. Subsequently, sulfonic acid groups are introduced by sulfonation for a catalytic functionalization of the structured monoliths’ accessible inner surface. As a catalytic test reaction, the aqueous phase hydrolysis of sucrose was chosen. For this reaction the functionalized monoliths exhibited a superior catalytic performance in both batch and continuous reaction mode in comparison to a macroporous sulfonic acid‐functionalized ion exchange resin as commercial benchmark catalyst. This is due to the higher accessibility of the sulfonic acid groups on the surface of the monoliths’ pore channels and hence, enhanced effective reaction kinetics by decreased mass transfer limitations.

From Catalytic Test Reaction to Modern Chemical Descriptors in Zeolite Catalysis Research

AbstractFor the successful implementation of catalysts in industrial processes, three overall goals are optimized: activity, selectivity, and stability. This review will address the role of chemical descriptors in aiding and guiding the development of optimal zeolite catalyst designs with the above performance criteria in mind. It will focus on both gas‐phase and liquid‐phase catalysis with a special focus on methanol to hydrocarbon, and biomass valorization reactions. By way of preface, the research on constraint and spaciousness indices is discussed. These indices can be considered the original chemical descriptors of catalysis research.

Rare earth–porphyrin complex catalysts for transforming CO2 into cyclic carbonate under mild conditions

AbstractA series of rare earth metal complexes RE(TPP)(acac) (RE = NdIII, YbIII, EuIII, ErIII, PrIII, and LuIII; TPP = 5,10,15,20‐tetraphenylporphyrin) were synthesized and characterized via UV–vis, IR, and elemental analyses. Their catalytic activities on the synthesis of cyclic carbonates from carbon dioxide and epoxides under different reaction conditions (temperature, pressure, and reaction time) were investigated. Catalytic reaction tests showed that the complex Lu(TPP)(acac) could significantly enhance the catalytic reactivity under mild conditions without any co‐solvent.

Evolution of Structure and Active Sites during the Synthesis of ZSM-5: From Amorphous to Fully Grown Structure

Lately, to considerably reduce the diffusion constraints in the catalysis performed by zeolites, there has been significant interest in syntheses of partially formed zeolites with extremely accessible active sites, named embryonic zeolites. Their preparation relies on stopping the crystallization of conventional micron-sized zeolites before the zeolites reach full crystallization, as detected by X-ray diffraction. In this current study, ZSM-5 zeolites were synthesized by using the same starting batch without organic template and different times, obtaining amorphous, ill-crystalized, and fully-grown structures that were characterized by various physicochemical methods and used in two catalytic test reactions. Using this synthesis strategy, two significant features of zeolites in catalysis are highlighted: (1) the accessibility of their inner pores for reactants and (2) the confinement effect, the ability of zeolites to stabilize transition states in some catalytic reactions. As the ZSM-5 was being formed, ...

Preparation of Efficient TS‐1 with Small Particle Size and Enhanced Framework Ti

AbstractCrystal size and framework Ti content are two main factors which influence catalytic performances of TS‐1 catalysts. Control over the crystal size and framework Ti of TS‐1 through the synthesis of TS‐1 in the presence of polyethylene glycol (PEG) is reported. The crystal size of TS‐1 sample synthesized in the presence of PEG, TS‐1‐PEG was 230 nm. However, the size of TS‐1 synthesized without PEG, standard sample, was 290 nm. The TS‐1‐PEG possess higher amount of framework Ti content and less anatase TiO2 in comparison with TS‐1. The catalytic reaction tests showed superior activity of TS‐1‐PEG toward hydroxylation of phenol and oxidation of dibenzothiophene, deep desulfurization of fuels, as a result of cooperative effects of smaller particle size and higher framework Ti content. Consequently, using safe and un‐expensive PEG polymer is a powerful approach to synthesize TS‐1 with small crystal size and high framework Ti content to make efficient TS‐1 catalyst.

A New Class of MnCeOx Materials for the Catalytic Gas Exhausts Emission Control: A Study of the CO Model Compound Oxidation

The effects of cerium addition on the physical–chemical properties and CO oxidation activity of nanocomposite MnCeOx catalysts (0 ≤ χCe ≤ 1) have been assessed. The kinetics of the CO oxidation on a typical nanocomposite MnCeOx catalyst (M5C1) were probed by temperature programmed catalytic reaction tests in the range of 293–533K. A systematic study of the interaction pattern of the catalyst with reagent and product molecules shows easy reactivity of surface oxygen to CO, low mobility of lattice oxygen and weak surface affinity to CO2. Systematic evidences on mechanism and intermediates signal an extrafacial redox path, triggered by the abstraction of oxygen atoms in the neighbouring of surface-active MnIV sites, and sustained by O2 species adsorbed on the resulting O-vacancies. A Langmuir–Hinshelwood (L–H) type reaction mechanism leads to a formal kinetic model fully predicting the CO oxidation functionality of the MnCeOx catalysts.

MgAl-Layered Double Hydroxide Solid Base Catalysts for Henry Reaction: A Green Protocol

A series of MgAl-layered double hydroxide (MgAl-HT), the calcined form at 500 °C (MgAlOx), and the rehydrated one at 25 °C (MgAl-HT-RH) were synthesized. Physicochemical properties of the catalysts were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Surface area of the as-synthesized, calcined, and rehydrated catalysts was determined by N2 physisorption at −196 °C. CO2 temperature-programmed desorption (CO2-TPD) was applied to determine the basic sites of catalysts. The catalytic test reaction was carried out using benzaldehyde and their derivatives with nitromethane and their derivatives. The Henry products (1–15) were obtained in a very good yield using MgAl-HT-RH catalyst either by conventional method at 90 °C in liquid phase or under microwave irradiation method. The mesoporous structure and basic nature of the rehydrated solid catalyst were responsible for its superior catalytic efficiency. The robust nature was determined by using the same catalyst five times, where the product % yield was almost unchanged significantly.

Structure and Dynamics of Zr6O8 Metal-Organic Framework Node Surfaces Probed with Ethanol Dehydration as a Catalytic Test Reaction.

Some metal-organic frameworks (MOFs) incorporate nodes that are metal oxide clusters such as Zr6O8. Vacancies on the node surfaces, accidental or by design, act as catalytic sites. Here, we report elucidation of the chemistry of Zr6O8 nodes in the MOFs UiO-66 and UiO-67 having used infrared and nuclear magnetic resonance spectroscopies to determine the ligands on the node surfaces originating from the solvents and modifiers used in the syntheses and having elucidated the catalytic properties of the nodes for ethanol dehydration, which takes place selectively to make diethyl ether but not ethylene at 473-523 K. Density functional theory calculations show that the key to the selective catalysis is the breaking of node-linker bonds (or the accidental adjacency of open/defect sites) that allows catalytically fruitful bonding of the reactant ethanol to neighboring sites on the nodes, facilitating the bimolecular ether formation through an SN2 mechanism.

Henry Reaction between Benzaldehyde and Nitromethane over Solid Base Catalysts: A Green Protocol

The development of environmentally benign solid base catalysts instead of the soluble bases for C-C bond formation in organic reactions especially Henry reactions with nitroalkanes compounds is of intense research activity in the bulk and fine chemical chemistry in order to achieve the selectivity of the desired product and the reduction of the salts formed due to soluble bases neutralization. While using of LDHs catalysts in the synthesis of nitro alcohols is of great interest because LDHs (double layered hydroxides) is of unique properties and an excellent catalytic property. The nitroalcohols are obtained in a very good yield while using catalyst either by conventional at 90°C in liquid phase, microwave or sonoenergy without solvent methods, and the results yields are compared. A series of different nitro alcohols from (a - o) were prepared, the catalytic test reaction were carried out using benzaldehyde and their derivatives with nitromethane and their derivatives. A series of LDHs catalysts were prepared also and studying of the catalytic effect on the reactions was carried out. Properties of the compounds prepared were characterized by IR, MNR, and GC-MS.

Rare Earth Porphyrin Complex Catalysts Transforming CO2 Into Cyclic Carbonate under Mild Conditions

A series of rare earth metal complexes RE(TPP)(acac) (RE=NdIII, YbIII, EuIII, ErIII, PrIII and LuIII, TPP=5,10,15,20-tetraphenylporphyrin) were synthesized and characterized via UV-Vis, IR and elemental analyses. Their catalytic activities on the synthesis of cyclic carbonates from carbon dioxide and propylene oxide under different reaction conditions (temperature, pressure and reaction time) were investigated. Catalytic reaction tests demonstrated that the complex Lu(TPP)(acac) could significantly enhance the catalytic reactivity under mild conditions without any co-solvent.

Probing the functionality of nanostructured MnCeOx catalysts in the carbon monoxide oxidation: Part II. Reaction mechanism and kinetic modelling

The kinetics of the CO oxidation on a typical nanocomposite MnCeOx catalyst (M5C1) were probed by temperature programmed catalytic reaction (TPCR) tests in the range of 293–533K, varying reagent partial pressure (i.e., pCO and pO2) between 0.00625 and 0.025atm (P, 1atm) (Arena et al., 2017). Experimental data indicate kinetic orders of 0.6 and 0.4 on pCO and pO2 respectively, with apparent activation energy of 40±3kJ/mol (Arena et al., 2017). A systematic study of the interaction pattern of catalyst with reagent and product molecules shows easy reactivity of surface oxygen to CO, low mobility of lattice oxygen and weak surface affinity to CO2. Systematic evidences on reaction mechanism and surface intermediates signal an extrafacial redox path, triggered by abstraction of oxygen atoms in the neighbouring of active MnIV sites (Arena et al., 2017), and sustained by O2 species adsorbed on those surface oxygen vacancies. A Langmuir-Hinshelwood (L-H) reaction mechanism leads to a formal kinetic model explaining the CO oxidation functionality of bare and promoted MnOx catalysts.

Au Capping Agent Removal Using Plasma at Mild Temperature

To prevent sintering, ozone treatment at mild temperature is used to remove the capping agent from supported Au nanoparticles. The Au nanoparticles are first synthesized as a colloidal solution and then supported on alumina. Fourier Transform Infra Red (FTIR) shows the capping agent is removed completely. Transmission Electron Microscopy (TEM) and catalytic test reactions show the Au does not sinter significantly upon low temperature ozone treatment.

Methane dry reforming using Ni/Al2O3 catalysts: Evaluation of the effects of temperature, space velocity and reaction time

In this study, 15% Ni/Al2O3 and 30% Ni/Al2O3 catalysts were prepared by the wet impregnation method and characterized by flame atomic absorption spectrometry (FAAS) (metal content), N2 physisorption, temperature programmed reduction (TPR), X-ray diffraction (XRD) and temperature programmed desorption of ammonia (TPD-NH3). A continuous flow tubular reactor was built to perform the catalytic reaction tests, and the following reaction variables were analyzed: reaction temperature (600–700°C range), space velocity (WHSV of 15 and 45Lh−1gcat−1) and reaction time (up to 10h). Increasing the reaction temperature in the dry reforming reactions led to higher H2 yields and higher conversions of CH4 and CO2. In general, better conversion rates were achieved in the reactions performed with the 15% Ni/Al2O3 catalyst. In the reactions in which the space velocity was varied, it was observed that increasing the space velocity (WHSV of 45Lh−1gcat−1) decreased CH4 conversion so the reaction rate is also controlled by the bed length and hence favored the dry reforming reaction. The results of the reaction tests performed for 10h indicated that no significant loss of catalytic activity occurred during the reaction, therefore no deactivation occurred by coke deposition or metal sintering.