Methanol Catalyst Research Articles

Oxidative esterification of 1, 2-propanediol to methyl lactate over Au/CuxAlOy catalysts in methanol without the presence of a base

Oxidative esterification of 1, 2-propanediol to methyl lactate over Au/CuxAlOy catalysts in methanol without the presence of a base

Surface modified graphene materials as improved catalysts for methanol to formaldehyde conversion

Surface modified graphene materials as improved catalysts for methanol to formaldehyde conversion

Facile synthesis of azines by carboxylic acid esters as catalyst and facilitation of intersystem crossing (ISC) in azines by azine chromophore

Development of new organic synthetic methods fascinating the researchers which facilitating the increasing demands of the modern society, environmental friendly with high efficiency and low cost. The introduction of chromophores in an organic molecules facilitating intersystem crossing (ISC) to harvest both singlet and triplet excitons is also currently demanding field. We report a facile synthesis of symmetrical azines from carbonyl compounds and hydrazine hydrate with carboxylic acid esters as catalyst in methanol. This reaction presents a condensation of primary amino groups in hydrazine hydrate and carbonyl compounds took place simultaneously in a very short refluxing time. The prepared azines 1–10 were structurally analysed by various analytical techniques such as LC-MS1, H NMR13, C NMR, UV-Vis, FTIR and single crystal X-ray diffraction. Photoluminescence properties of prepared azines were recorded in CCl4 at 1 × 10−3 M and excitation range from 329 to 362 nm. The photoluminescence analysis results revealed that compounds 1–10 (except 8) were showed delayed fluorescence and 8 was showed fluorescence property. The photophysical properties of compounds 1–10 such as electron density and band gap energies was calculated by density function theory. This results revealed that the intra-molecular charge transfer occurs within the azines. The azine function in the azines enabling intersystem crossing hence, it is showing phosphorescence.

Hydrogen production via steam reforming of methanol on Cu/ZnO/Al2O3 catalysts: Effects of Al2O3 precursors

A series of Cu/ZnO/Al2O3 catalysts were prepared by co-precipitation method. This research focuses on investigating the influence of different Al2O3 precursors on the catalyst structure through thorough structural characterization techniques. Additionally, the catalytic performance of these catalysts in methanol reforming for hydrogen production was systematically evaluated. The results indicate that the simultaneous co-precipitation of Al3+ with Cu2+ and Zn2+ leads to partial substitution of Cu-Zn in the basic carbonates by Al3+. This substitution forms a hydrotalcite-like structure and strengthens Zn-Al interactions. On the contrary, after the co-precipitation of Cu2+ and Zn2+, introducing the Al2O3 precursor has a positive effect on eliminating the adverse effects of Al3+ on Cu-Zn substitution in basic carbonates. This process promotes the Cu-ZnO interaction, facilitates the dispersion of CuO species, and enhances the reducibility of catalysts. It also improves the dispersion of Cu on the surface, and ultimately enhanced the catalytic activity. Notably, the catalyst prepared using pseudo-boehmite as the Al2O3 precursor exhibited the highest activity. Under the conditions of a H2O/CH3OH molar ratio of 1.2 and a reaction temperature of 493 K, methanol conversion reached 94.8%, and the H2 space-time yield was 97.5 mol/(kg·h). The catalyst activity remained relatively stable after continuous operation for 25 h. Even after being heat-treated at 723 K for 10 h, the activity loss of the catalyst was only 5.37%.

Three-component NiO/Fe3O4/rGO nanostructure as an electrode material towards supercapacitor and alcohol electrooxidation

A nanocomposite made of nickel oxide and iron oxide (NiO/Fe3O4) and its hybrid with reduced graphene oxide (rGO) as a conductive substrate with a highly functional surface (NiO/Fe3O4/rGO) was synthesized using a simple hydrothermal approach. This study addresses the challenge of developing efficient materials for energy storage and alcohol fuel cells. After confirming the synthesis through structural analysis, the potential of these nanocomposites as supercapacitor electrodes and catalysts for methanol and ethanol oxidation in alcohol fuel cells were evaluated. The synergy of combining the two metal oxides and adding rGO to the composite structure led to excellent electrocatalytic activity in alcohol oxidation. For the modified NiO/Fe3O4/rGO electrode in the methanol oxidation reaction (MOR), a current density of 450 mA/cm2 at 0.67 V and excellent catalyst stability of 98.7 % over 20 h in chronoamperometric analysis were observed. In the ethanol oxidation reaction (EOR), an oxidative current of 235 mA/cm2 at a peak potential of 0.76 V was seen, with catalyst stability of 96.4 % after 20 h. As a supercapacitor electrode, the NiO/Fe3O4 composite demonstrated a specific capacitance of 946 F/g, while NiO/Fe3O4/rGO showed 1155 F/g. The stability of these electrodes after 10000 GCD cycles was 83.6 % and 90.6 %, respectively. These findings suggest that the proposed structures are cost-effective and reliable alternatives for energy storage and production, suitable for alcohol fuel cells and supercapacitors.

Unique fatty acid composition of coriander seed biodiesel

Biodiesel is a renewable and environmentally friendly alternative fuel that can be used in diesel engines without modification. In this study, biodiesel production from coriander seed oil obtained through a two-stage transesterification process using the cold pressing method was carried out in the Konya region. First, the oil's acid value was reduced through acid-catalyzed pretreatment to form coriander seed oil methyl esters, and then biodiesel was produced using standard transesterification with methanol and sodium methoxide catalyst. Coriander (Coriandrum sativum) contains an unusual fatty acid not previously reported as a major component in biodiesel fuels: petroselinic acid (6Z-octadecenoic acid; 68.5% by weight). Coriandrum sativum seed oil methyl ester was evaluated to have properties suitable for diesel engines, complying with EN 14214 and ASTM D6751 standards, with a unique fatty acid composition and excellent oxidative stability.

Influence of Solid Alkaline Photocatalysts Irradiated with UV Light on Fuel Properties of Palm Oil Biodiesel.

TiO2 nanoparticles are full of porosity that can be impregnated with a strong alkaline catalyst CH3ONa to form a TiO2/CH3ONa catalyst. TiO2 of the anatase phase, which is a semiconductor material, has been a prominent photocatalyst due to its excited photocatalyst activity, chemical and biological stability, and nontoxicity. The CH3ONa compound has been widely used as a catalyst for transesterification. Although the synthesized photocatalyst TiO2 powder with CH3ONa is anticipated to greatly enhance the transesterification efficiency, leading to improving biodiesel properties, relevant studies have not been found. After the photocatalyst was prepared, a reactant mixture of palm oil, methanol, and heterogeneous catalyst TiO2/CH3ONa was illuminated by ultraviolet (UV) light from light-emitting diode (LED) lamps. The experimental results revealed that the formation of fatty acid methyl esters was significantly increased to 98.4% with ultraviolet-light illumination for the molar ratio of methanol/palm oil equal to 6 and 3 wt % catalyst addition. The decrease of the catalyst amount to 2 wt % resulted in a slight decrease of the fatty acid methyl esters to 97.06 wt %. The lowest kinematic viscosity and acid value and the highest distillation temperature, heating value, and cetane index were observed under the above reaction conditions. The distillation temperature and cetane index were increased while the acid value was decreased under ultraviolet illumination on the reactant mixture. Consequently, the optimum preparing conditions for biodiesel production were 6 and 3 wt % for the molar ratio of methanol/palm oil and catalyst addition under UV-light irradiation.

Kinetics, thermodynamics, and optimization analyses of lipid extraction from discarded beef tallow for bioenergy production

ABSTRACT The wide expansion of the meat industry generated tremendous amounts of animal-based waste. Discarded beef tallow (DBT) is one of those prevalent lipid-rich wastes disposed of by slaughterhouses, meat processing units, and tanneries. The current study utilized the advanced technology of supercritical CO2 (SC-CO2) to extract lipid content from DBT for biodiesel production through transesterification. The effects of SC-CO2 parameters on the extraction rate were investigated over ranges of (32–80°C) for temperature, (10–50 MPa) for pressure, and (15–150 min) for treatment time. Using response surface methodology (RSM), both processes of SC-CO2 and transesterification were optimized. The highest extraction rate was 86.10%, obtained at the experimental conditions of 60°C for temperature, 30 MPa for pressure, and 120 min for treatment time. For the transesterification, the maximum yield of biodiesel was 95.15%, obtained at the reaction conditions of 1:7.5, 1.16 wt%, 58°C, and 72 min for lipid to methanol molar ratio, catalyst ratio, temperature, and time, respectively. The outcomes of the kinetic and thermodynamic analyses showed that the SC-CO2 extraction was an endothermal, unspontaneous, and temperature-dependent process. The characteristics of the synthesized biodiesel largely comply with the ASTM D6751 and EN 14,214 standards. The findings of the current study confirm the viability of SC-CO2 to extract lipids from DBT as a low-cost feedstock for biodiesel production.

γ-aminobutyric acid-assisted fabrication of plate-like ZSM-5 zeolite for efficient propylene production from methanol conversion

Plate-like ZSM-5 zeolites offering a short diffusion pathway along the b-axis are highly desirable catalyst for methanol to propylene (MTP) reaction. Herein, we successfully developed a simple synthetic strategy toward reducing the thickness along b-axis of ZSM-5 zeolite by combing a preliminary aging process and the addition of γ-aminobutyric acid. In particular, γ-aminobutyric acid adopted as a zeolite growth modifier was firstly proposed to prepare plate-like ZSM-5 zeolite with a short thickness of b-axis, and the minimum thickness can reach ∼50 nm. The shortened diffusion length in plate-like ZSM-5 zeolites could significantly improve the transport efficiency of molecules to and away from the active sites and finally leads to a better catalytic performance in the MTP reaction. Particularly, the plate-like ZSM-5 zeolite with an impressively shortened diffusion length (P-ZSM-5–0.3#0.3) displayed greatly improved catalytic performances (higher propylene selectivity and longer lifetime) than conventional ZSM-5 with a thicker dimension along the b-axis.

Promoted stability of Cu/ZnO/Al2O3 catalysts formethanol production from CO2 hydrogenation by La modification

Deactivation of Cu/ZnO/Al2O3 catalysts in CO2 hydrogenation to methanol reaction is one of the main reasons limiting their application. We synthesized a series of La modified Cu/ZnO/Al2O3 catalysts by adding different contents of La to improve the stability. In the 100 h short-term stability test at 200 °C under 3 MPa with a GHSV of 12000 mL/(g·h), the unmodified Cu/ZnO/Al2O3 catalysts degraded obviously over 100 h. In sharp contrast, the stability was significantly promoted by the addition of La. The best activity was achieved with 5% La added samples (4% CO2 conversion and 85% methanol selectivity),which also showed impressive stability over 1000 h except about 17% deactivation during the initial 190−220 h. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results revealed that the addition of 5% La improved the dispersion of Cu and Zn, inhibited the sintering of Cu, stabilized the Cu0/+ species and retarded oxidation of Cu in catalysts, which attributed to the high stability of the catalysts.

N‐doped Porous ZIF@PDA/Pt Catalysts with Ultra‐Low Pt for Methanol Oxidation

AbstractMetal‐organic frameworks (MOFs) materials, due to their unique porous structure, large surface area, low density, and customizable ligands, have the potential to serve as catalytic carriers. They can address the limitations of pure platinum (Pt), including susceptibility to toxicity and poor stability during catalytic processes. In this study, ZIF‐8@ZIF‐67 derived N‐doped carbon‐loaded ultra‐low Pt catalysts (ZIF@PDA/Pt‐x‐y) were prepared using zeolitic imidazolate frameworks (ZIFs) as carriers. Meanwhile, the effects of dopamine hydrochloride (DA) incorporation and reaction temperature on the topography structure and electrocatalytic properties of the synthesized samples were mainly investigated. The introduction of polydopamine (PDA) relieved the loss of the nitrogen source of ZIF due to high temperature. The electrocatalytic performances of synthetic samples for methanol oxidation were investigated using electrochemical methods, and ZIF@PDA/Pt‐5‐900 exhibited the most favorable catalytic effect. Compared to other samples and the Pt/C catalyst (20 %), ZIF@PDA/Pt‐5‐900 demonstrated the largest electrochemically active surface area (ECSA, 66.25 m2 mgPt−1), higher electrocatalytic amount activity (1719.28 mA mgPt−1) and superior stability. Overall, this finding offers a new approach for preparing catalysts for direct methan ol fuel cells (DMFCs).

Oxygen evolution reaction activity of carbon aerogel supported Pd–Ni–Al catalysts synthesized by microwave irradiation method

The oxygen evolution reaction (OER) is a critical step for oxygen production during the electrochemical splitting of water. Effective OER catalysts support the development of clean energy technologies by increasing the energy efficiency of these processes. In this study, carbon aerogel (CA) was first synthesized as a catalyst support material using sol-gel, supercritical drying, and pyrolysis process. Then, mono-metallic (Pd/CA, Al/CA), bi-metallic (Pd–Al/CA, Pd–Ni/CA), and tri-metallic (Pd–Ni–Al/CA) catalysts were synthesized by microwave irradiation method. Inductively coupled plasma-mass spectrometry (ICP-MS), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy have been made to examine the structural properties of the synthesized catalysts. Electrochemical analysis was carried out through cyclic voltammetry (CV), chronoamperometry, and electrochemical impedance spectroscopy (EIS) in alkaline media (1 M KOH: Methanol) to examine the effect of metal loading of CA support material towards OER performance. All the compositions showed excellent activity toward OER, among all Pd–Ni/CA catalysts showed the highest activity. The OER peak current increased remarkably up to 48 mA cm−2 with methanol addition, which signifies the substantial application of carbon aerogel supported-Pd-Ni-Al catalysts in direct methanol fuel cells (DMFCs). Pd–Ni/CA display high OER performance with maximum diffusion coefficient, Do (6.6 × 10−8 cm2 s−1) and heterogeneous rate constant, ko (4.706 × 10−4 cm s−1), and smaller value of Tafel slope (128 mV dec−1). Electrochemical studies predicted that all the prepared carbon aerogel supported-Pd-Ni-Al catalysts can be used as efficient catalysts for OER and other related electrocatalysis applications.

Atomically dispersed dual iron and manganese anchored nitrogen doped reduced graphene as robust cathode catalyst for direct methanol fuel cell and aluminium air battery

A noble metal-free atomically dispersed dual metal (Fe and Mn) anchored nitrogen (N)-doped reduced graphene oxide (rGO) is synthesized as a high-performance oxygen reduction reaction (ORR) electrocatalyst for alkaline direct methanol fuel cell and aluminium-air battery (AAB). The as-synthesized FeMn-NrGO catalyst exhibits a half-wave potential of 0.84 V for ORR and a low onset potential of 0.96 Vvs (RHE). The theoretical study reveals that the synergetic coupling of Mn and Fe with pyridinic and pyrrolic nitrogen weakening adsorption bond strength of the O* intermediates to the active site of the catalyst, thereby improving the for ORR performance. The synthesized Fe3Mn1-NrGO cathode catalyst assembled alkaline direct methanol fuel cell (DMFC) demonstrates a peak power density of 65 mW/cm2 extending an effective strategy to enhance the ORR kinetics of the non-noble metal-based catalyst for fuel cell application. Furthermore, the synthesized Fe3Mn1-NrGO also exhibits excellent ORR activity in 3.5 wt% NaCl solution and demonstrates a peak power density of 11.2 mW/cm2 aqueous NaCl electrolyte-based AAB system.

Methanol Reforming over Cu-Ce-Al Catalysts Prepared by Solution Combustion Synthesis Method

The demand for environmentally friendly types of energy is growing all over the world, which naturally increases the intensity of studies on fuel mixtures that have high contents of hydrogen. In this case, methanol steam reforming is a leading effective research area, as it is a process with low energy consumption. The results of the steam reforming of methanol on synthesized catalysts by the solution combustion synthesis (SCS), self-propagating high-temperature synthesis (SHS), and moisture impregnation capacity methods are presented. A study was conducted to evaluate the activity of Cu-Ce-Al catalysts with varying ratios of components for hydrogen production, comparing the SCS method with the other mentioned methods. The methanol conversion reached 99% and the selectivity of H2 was 88% at 500 °C. The study showed that the replacement of Al3+ ions with Cu2+ and Ce3+ cations leads to the formation of spinels, such as CuAl2O4 and CeAlO3. As a consequence, the CuAl2O4 and CeAlO3 lattice parameters increase because of the difference in the ionic radii of Al3+ (0.53 Å), Cu2+ (0.73 Å), and Ce3+ (1.07 Å). Advantages of SCS catalysts in the process of the steam reforming of methanol have been demonstrated. The goal of this research is to create a new catalyst for methanol’s conversion into hydrogen-containing fuel mixtures, the production of which, in the future, will be a huge step in the transition to more energy-efficient and environmentally friendly methods of their synthesis.

Does Direct Dimethyl Ether Synthesis from Carbon Dioxide and Hydrogen Yield More Valuable Products than the Equivalent Methanol Production? A Review on Recent Work

AbstractDimethyl ether (DME) has promising properties as e‐fuel and platform chemical. Its direct synthesis from CO2 and hydrogen, which is thermodynamically more favorable than the indirect route over methanol, is reviewed. Systematic thermodynamic equilibrium calculations are evaluated and compared to bifunctional catalysis experiments performed with Cu/ZnO/ZrO2 methanol catalyst and ferrierite or heteropolyacid‐coated dehydration catalysts under thermodynamic and kinetic conditions. In the thermodynamic region, the methyl yield of direct DME synthesis is superior over sole methanol synthesis. Significant differences among the solid acids used are absent. However, under kinetic conditions, the heteropolyacid‐coated catalysts show superior performance for dehydration over zeolites.

Recent progress in the deactivation mechanism of zeolite catalysts in methanol to olefins

Recent progress in the deactivation mechanism of zeolite catalysts in methanol to olefins

Ni-Pt-Pd ternary alloy nanoparticles supported on carboxyl-modified carbon nanotubes as highly efficient catalyst for methanol and ethanol electrooxidation

Pt-based catalysts are currently the most efficient anode catalysts in alcohol fuel cells. However, their widespread commercialization is hindered by their high cost. In this study, a straightforward method was employed to deposit Ni-Pt-Pd ternary alloy nanoparticles onto carboxyl-modified multi-walled carbon nanotubes (CNTs) and subsequently annealed the synthesized catalysts at different temperatures to adjust the surface composition and alloying degree. The Ni-Pt-Pd alloy exhibits a synergistic effect between Pt and Ni. The presence of Ni effectively modulates the d-band center of Pt, thereby enhancing the electrochemical performance of for alcohol oxidation. The synergistic effect of Pt-Pd alloy is harnessed to enhance both catalytic activity and stability of the catalyst for oxidation of methanol or ethanol. Density functional theory (DFT) calculations demonstrated that alloying Pt with Pd and Ni effectively reduced the Gibbs free energy during EOR and MOR reactions. The resulting catalysts, denoted as Ni6Pt6Pd6 NPs/CNTs-M2, exhibited exceptional catalytic oxidation performance for both ethanol and methanol. Specifically, their electrochemical mass activity for ethanol oxidation reaction (EOR) reached 2345 mA mg-1Pt+Pd, which was 15.5-fold and 2.56-fold higher than that of commercial Pt/C and Pd/C catalysts respectively. Moreover, their mass activity for methanol oxidation reaction (MOR) was measured at 2995 mA mg-1Pt+Pd, which was 8.2-fold and 5.3-fold higher than that of Pt/C and Pd/C catalysts respectively.

One-pot CO2-to-olefins via methanol over In2O3-ZrO2/SAPO-34 catalysts mixtures with different spatial arrangements

The one-pot CO2 hydrogenation to lower olefins involves the integration of two catalytic reactions in a single reactor: the conversion of CO2 into methanol (CTM) and its subsequent conversion into lower olefins (MTO). This approach requires two catalysts cooperating in the same reactor, posing different challenges in terms of synergies and interactions between the two active phases. In this work, we investigate the effect of process conditions and arrangements between In2O3-ZrO2 (CTM catalyst) and SAPO-34 (MTO catalyst) on the lower olefins yield. We show that the distance between CTM and MTO active sites, studied by assessing different catalyst arrangements spanning from an intimate mixture obtained through mortar mixing to a complete segregation of the catalysts (i.e., consecutive beds), plays a key role in driving the products distribution. However, the thermodynamic equilibrium of the reverse water gas shift limits CO2 conversion in the investigated conditions. Finally, we discuss the stability of the catalytic performances: the characterization of the spent samples after ∼400 h on stream indicated the deactivation of the catalytic materials in all investigated cases, with In sintering on the methanol catalyst, and SAPO-34 losing both P and Al due to hydrothermal aging; indications of In migration on SAPO-34 were also observed when the two catalyst are in contact.

Pd/TiO2 decorated carbon fibers as an efficient anode catalyst for methanol electro‐oxidation

AbstractIn this study, Pd/TiO2 decorated carbon nanofibers (Pd/TiO2@CNFs) and Pd@CNFs were prepared by the impregnation method for application in direct methanol fuel cells (DMFCs). Pd and TiO2 particles were supported on the surface of carbon fibers. Noticeably, When the mass fraction of PdCl2 added is 4%, the Pd@CNFs catalyst (Pd‐4@CNFs) showed higher electrocatalytic activity and stability, which were about 28.4 and 13.2 times higher than those of commercial Pd/C catalyst, respectively. On the basis of Pd‐4@CNFs catalyst, TiO2 with a mass fraction of 10% was added to produce Pd/TiO2@CNFs catalyst (Pd‐4/TiO2‐10@CNFs). The electrocatalytic activity of Pd‐4/TiO2‐10@CNFs increased to 3,850.4 A·g−1, which was 31.9 times higher than that of commercial Pd/C catalysts. These results demonstrated that the novel Pd/TiO2@CNFs catalyst is expected to be an efficient and durable catalyst for DMFC.

MoO3/WO3/rGO as electrode material for supercapacitor and catalyst for methanol and ethanol electrooxidation.

The potential of metal oxides in electrochemical energy storage encouraged our research team to synthesize molybdenum oxide/tungsten oxide nanocomposites (MoO3/WO3) and their hybrid with reduced graphene oxide (rGO), in the form of MoO3/WO3/rGO as a substrate with relatively good electrical conductivity and suitable electrochemical active surface. In this context, we presented the electrochemical behavior of these nanocomposites as an electrode for supercapacitors and as a catalyst in the oxidation process of methanol/ethanol. Our engineered samples were characterized by X-ray diffraction pattern and scanning electron microscopy. As a result, MoO3/WO3 and MoO3/WO3/rGO indicated specific capacitances of 452 and 583 F/g and stability of 88.9% and 92.6% after 2000 consecutive GCD cycles, respectively. Also, MoO3/WO3 and MoO3/WO3/rGO nanocatalysts showed oxidation current densities of 117 and 170 mA/cm2 at scan rate of 50 mV/s, and stability of 71 and 89%, respectively in chronoamperometry analysis, in the MOR process. Interestingly, in the ethanol oxidation process, corresponding oxidation current densities of 42 and 106 mA/cm2 and stability values of 70 and 82% were achieved. MoO3/WO3 and MoO3/WO3/rGO can be attractive options paving the way for prospective alcohol-based fuel cells.