Catalytic Support Research Articles

Modulation of the acidity of a vermiculite and its potential use as a catalytic support

The modulation and characterization of the acidity of a vermiculite were carried out, which was modified by delamination by means of hydrothermal and acid treatments with the subsequent incorporation of AlZr and AlCe species to modulate the acidity. The effect of these species was evaluated regarding the structural (XRD, XPS and IR), textural (N2 sortometry) and acidity properties (NH3-TPD, NH3-DRIFTS and CO adsorption at low temperature). The catalytic performance was studied in the dehydration–dehydrogenation reactions of 2-propanol and the hydroconversion of decane, which generate important information about the acidity properties such as the type, number and strength of acidic sites. The correlation between the number, type and acid strength with the catalytic behavior allowed to establish the important effect regarding the nature of the mineral, its method of delamination and the nature of the incorporated cation, thus generating tools for controlled processes for the potentiation of the acidity of new supports from raw vermiculite.

Synthesis, Characterization and Phase Transition of Highly Porous γ - Alumina Nanoparticles

Alumina is an important metal oxide used in a wide range of applications. It is a challenge to synthesize stable γ-alumina nanoparticles because, γ-phase of alumina is not as stable as α phase of alumina. But γ-alumina owns a higher surface area making it a good candidate for many industrial applications such as catalyst, catalytic support for petroleum refining, absorbent, alcohol dehydration, catalytic reduction of automotive pollutants like NOx, CO and hydrocarbons. This research focuses on synthesis, characterization and study of phase identification of pure γ-alumina nanoparticles. Modified “Pechini method”(Danks, Hall, and Schnepp (2016); Huizar-Felix, Hernandez, de la Parra, Ibarra, & Kharisov, 2012; Naskar, 2010; Zaki, Kabel, & Hassan, 2012)was used for the synthesis. Transesterification of citrate and ethylene glycol makes a covalent polymer network with trapped Al atoms. Continuous stirring of the reaction mixture while maintaining an optimum temperature is an important factor affecting this reaction. Calcination was carried out at different temperatures to identify phase transitions of alumina nanoparticles. In order to further reduce the particle size and increase the surface area, reactant ratio of citric acid: aluminum acetate was modified to 1:1, volume of ethylene glycol was increased up to 90% of volume of the solution and Triton X was used as a surfactant. PXRD confirmed the pure γ-alumina phase (JCPDS No. 00-010-0425) in samples calcined at 900 °C. At 1000 °C γ-alumina is converted to α-alumina (JCPDS No. 00-083-2080). After the modifications, γ-alumina was identified at 700 °C. FTIR-ATR analysis shows peaks around 1127 cm-1 indicating the presence of Al-O-Al asymmetric bending modes and the peaks around 500 cm-1-750 cm-1 correspond to γ-AlO6 octahedral sites and 800 cm-1 correspond to AlO4 tetrahedral sites in γ alumina spinel structure. Resulted product of low temperature, pure γ-alumina nanoparticles will facilitate the industrial development in various applications.

Probing Functionalities and Acidity of Calcined Phenylene-Bridged Periodic Mesoporous Organosilicates Using Dynamic Nuclear Polarization NMR, Diffuse Reflectance Infrared Fourier Transform Spectroscopy, and X-ray Photoelectron Spectroscopy

Owing to their high surface area, their high stability, and their hydrophobicity, periodic mesoporous organosilica (PMO) materials represent promising catalytic support for environmentally friendly chemical processes in water. We investigate here how the calcination of PMO material with benzene linkers (PMOB) allows its functionalization. Conventional and dynamic nuclear polarization (DNP)-enhanced NMR spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy, and X-ray photoelectron spectroscopy prove that calcination at 450 {\deg}C results in the oxidation of phenylene bridges into (poly)phenols but also into carboxylic acids. Ketone, aldehyde, as well as allyl and aliphatic alcohol functionalities are also observed, but their amount is much lower than that of carboxylic acids. The calcination also cleaves the Si-C bonds. Nevertheless, N2 adsorption desorption measurements, powder X-ray diffraction, and transmission electron microscopy indicate that the PMOB materials calcined up to 600 {\deg}C still exhibit ordered mesopores. We show that the phenol and carboxylic acid functionalities of PMOB calcined at 450 {\deg}C protonate the NH2 group of 1-(3-aminopropyl)imidazole (API) in water at room temperature, but no formation of a covalent bond between API and the calcined PMOB functionalities has been detected.

Hydrodynamics and Heat Transfer Characteristics of a Double Gradient Microchannel Porous Model: Fixed Gradients and Variable Gradients Structures

AbstractHydrogen production from fluid fuel catalytic reaction is currently a hot research topic and catalyst carriers are the core of the hydrogen production process. The relationship between variable gradient structure and fixed gradient structure is still unclear. The hydrodynamics and heat transfer characteristics of double gradient and fixed gradient microchannel porous models are investigated. A strategy of using a uniform interpolation method to investigate the laws of a continuity equation is developed. There are three major findings. First, the internal fluid velocity of the variable gradient model is greater than the internal fluid velocity of the fixed gradient model. Second, the overall temperature change of the variable gradient structure is greater than the temperature change of the control group. Third, the formula of the macroscopic average temperature change of the area‐based fluid is found to be theoretically reliable. These findings may contribute to improving the catalytic efficiency of microchannel porous catalytic supports.

Kinetic models for Fischer-Tropsch synthesis for the production of clean fuels

Abstract A comprehensive review of the kinetic models for Fischer-Tropsch synthesis with cobalt and iron catalysts was developed. Various kinetic models have been proposed to predict the Fischer-Tropsch synthesis (FTS) reaction behavior, as well as to study the products distribution under the use of cobalt and iron-based catalysts, with different configurations of catalytic supports and promoters. The kinetic models that have been addressed today range from the simplest based on the power-law formulation to the most complex ones based on the formulation of rigorous reaction mechanisms, such as those of Langmuir-Hinshelwood-Hougen-Watson.

COx-free hydrogen generation via decomposition of ammonia over al, Ti and Zr−Laponite supported MoS2 catalysts

There is a need for more efficient, stable and cost-effective catalytic support for efficient catalysts to meet the increasing demand for large production and transportation of hydrogen energy. Laponite RD, a synthetic clay mineral was used to prepare Al, Ti and Zr grafted Laponite by a post grafting method at room temperature (RT). The acid-functionalized Al, Ti and Zr−Laponite were utilized as a support for the preparation of MoS2 catalyst under the hydrothermal method by a soft chemical approach using thiourea as a sulphur source. Even though it contained almost the same amount of MoS2, it exhibited enhanced ammonia conversion due to the type of heteroatom influence on the support. Detailed characterization of the catalysts illustrated that MoS2/Zr−Laponite shows good acidic/basic properties, H2 desorption properties and reducibility of MoS2 on the support. Moreover, the support enables a large surface area providing a maximum MoS2 dispersion. These structural features make MoS2/Zr−Laponite as a promising catalyst that is cost-effective and requires a simple preparation procedure. Physicochemical properties of the catalyst were characterized by high-angle XRD, N2 sorption analysis, NH3, CO2 and N2 temperature programmed reduction (TPD), H2 temperature programmed reduction (TPR) and TPD, HR-TEM, HR-SEM and XPS techniques.

The Potentiality of Rice Husk-Derived Activated Carbon: From Synthesis to Application

Activated carbon (AC) has been extensively utilized as an adsorbent over the past few decades. AC has widespread applications, including the removal of different contaminants from water and wastewater, and it is also being used in capacitors, battery electrodes, catalytic supports, and gas storage materials because of its specific characteristics e.g., high surface area with electrical properties. The production of AC from naturally occurring precursors (e.g., coal, biomass, coconut shell, sugarcane bagasse, and so on) is highly interesting in terms of the material applications in chemistry; however, recently much focus has been placed on the use of agricultural wastes (e.g., rice husk) to produce AC. Rice husk (RH) is an abundant as well as cheap material which can be converted into AC for various applications. Various pollutants such as textile dyes, organic contaminants, inorganic anions, pesticides, and heavy metals can be effectively removed by RH-derived AC. In addition, RH-derived AC has been applied in supercapacitors, electrodes for Li-ion batteries, catalytic support, and energy storage, among other uses. Cost-effective synthesis of AC can be an alternative for AC production. Therefore, this review mainly covers different synthetic routes and applications of AC produced from RH precursors. Different environmental, catalytic, and energy applications have been pinpointed. Furthermore, AC regeneration, desorption, and relevant environmental concerns have also been covered. Future scopes for further research and development activities are also discussed. Overall, it was found that RH-derived AC has great potential for different applications which can be further explored at real scales, i.e., for industrial applications in the future.

Synergetic effect of photocatalysis and ozonation for enhanced tetracycline degradation using highly macroporous photocatalytic supports

Photocatalysis and ozonation have limited efficiency for the degradation of persistent pollutants as well as the mineralization of byproducts. In this work, we intensify the degradation processes by using simultaneously both processes in macroporous catalytic supports under mild reaction conditions, for degradation of tetracycline. The total organic carbon removal reached up to 90% after 180 min of photocatalytic ozonation reaction, achieving this record value using mild conditions. A comparison among processes showed the synergetic effect of photocatalysis and ozonation carried out in the macroporous support, which presents a kinetics increase of ≈20% greater than the sum of the separated processes. About 100% of tetracycline degradation was achieved with a high total organic carbon removal. This effect is attributed to synergy with the porous structure, which promote better O3 and O2 species mass transfer, due to the tortuosity and turbulence developed within the structure channels, coupled with a augmented residence time of the reactants. The gas-liquid mixture moves slower inside the porous channels, the apparent relative viscosity of a bubble train can be orders of magnitude larger than the viscosity of the pure liquid within the channels. In this work conditions were estimated as 10 times greater per bubble. The better species distribution, the increased residence time, and e−/h + recombination hindering along an increase of free hydroxyl radicals improved the overall degradation of tetracycline, avoiding the use of free catalysts and allowing the direct reuse of the system.

Tuneable Acidity in Fluorinated Al-SBA-15 Materials for the Esterification of Valeric Acid to Alkyl Valerates.

The acidity of Al-SBA-15 materials functionalized by ball milling with several niobium loadings (0. 25–1 wt.%) as well as with several fluorine loadings (by wet impregnation using NH4F as a precursor) was characterized and materials investigated in the esterification of valeric acid to alkyl valerates. The parent Al-SBA-15 support as well as the modified materials loaded with Nb and/or F have been catalysts synthesized characterized by X-ray diffraction (XRD), N2 physisorption measurements, and diffuse reflection infrared spectroscopy (DRIFT) among others. A special interest was paid on the acidity of the materials that was investigated by temperature-programmed desorption of pyridine. Interestingly, the characterization results for the materials containing fluorine showed up an increase in the acidity strength despite of a reduction in the number of acid sites. The catalytic performance of the as-prepared catalysts was investigated in the microwave-assisted esterification reaction of valeric acid to valerate esters. Thus, while the materials modified with niobium exhibited a lower catalytic activity as compared with the catalytic support (Al-SBA-15), the materials loaded with fluorine either onto Al-SBA-15 or on Nb1%/Al-SBA-15 materials presented enhanced conversion values of valeric acid. Therefore, it can be said that the new acid sites with enhanced strength formed by the incorporation of fluorine boost the esterification of valeric acid with alcohols to form the respective valerate ester.

Synthesis, Characterization and Phase Transition of Highly Porous γ -Alumina Nanoparticles

Alumina is an important metal oxide used in a wide range of applications. It is a challenge to synthesize stable γ-alumina nanoparticles because, γ-phase of alumina is not as stable as α phase of alumina. But γ-alumina owns a higher surface area making it a good candidate for many industrial applications such as catalyst, catalytic support for petroleum refining, absorbent, alcohol dehydration, catalytic reduction of automotive pollutants like NOx, CO and hydrocarbons. This research focuses on synthesis, characterization and study of phase identification of pure γ-alumina nanoparticles. Modified “Pechini method”(Danks, Hall, and Schnepp (2016); Huizar-Felix, Hernandez, de la Parra, Ibarra, & Kharisov, 2012; Naskar, 2010; Zaki, Kabel, & Hassan, 2012)was used for the synthesis. Transesterification of citrate and ethylene glycol makes a covalent polymer network with trapped Al atoms. Continuous stirring of the reaction mixture while maintaining an optimum temperature is an important factor affecting this reaction. Calcination was carried out at different temperatures to identify phase transitions of alumina nanoparticles. In order to further reduce the particle size and increase the surface area, reactant ratio of citric acid: aluminum acetate was modified to 1:1, volume of ethylene glycol was increased up to 90% of volume of the solution and Triton X was used as a surfactant. PXRD confirmed the pure γ-alumina phase (JCPDS No. 00-010-0425) in samples calcined at 900 °C. At 1000 °C γ-alumina is converted to α-alumina (JCPDS No. 00-083-2080). After the modifications, γ-alumina was identified at 700 °C. FTIR-ATR analysis shows peaks around 1127 cm-1 indicating the presence of Al-O-Al asymmetric bending modes and the peaks around 500 cm-1-750 cm-1 correspond to γ-AlO6 octahedral sites and 800 cm-1 correspond to AlO4 tetrahedral sites in γ alumina spinel structure. Resulted product of low temperature, pure γ-alumina nanoparticles will facilitate the industrial development in various applications.

Cost‐effective bio‐derived mesoporous carbon nanoparticles‐supported palladium catalyst for nitroarene reduction and Suzuki–Miyaura coupling by microwave approach

A new heterogeneous catalyst was synthesized by immobilizing Pd on areca nut kernel‐derived carbon nanospheres (CNSs). The CNSs, without any further activation processes, accommodated 3% of Pd on their surface. The new Pd/CNS material was used for the reduction of nitroarenes and Suzuki–Miyaura coupling of bromoarenes with aryl boronic acids. The reactions were conducted under microwave irradiation at 160 °C using 12 mol% of Pd/CNS (0.36% actual Pd content). The reduction of nitroarenes into their respective amino compounds was achieved in 10–20 min (conversion up to 100%); by contrast, the Suzuki–Miyaura reactions yielded up to 98% at 150 °C with 10 mol% of Pd/CNS catalyst. The products were identified using gas chromatography and nuclear magnetic resonance spectroscopy. The catalyst was isolated from reaction mixture and reused without any significant loss in the activity. Thus, the present work introduces one‐pot‐derived porous CNSs as efficient catalytic support to Pd, establishing an alternative to existing Pd/C in terms of cost and efficiency.

Pt-based catalyst decorated by bimetallic FeNi2P with outstanding CO tolerance and catalytic activity for methanol electrooxidation

Subjected to CO poisoning and weak catalytic performance, there are still large barriers to the effective use of direct methanol fuel cells. Therefore, bimetallic FeNi2P/C hybrid is synthesized by a facile hydrothermal method and low temperature phosphorization process. Subsequently, the as-synthesized FeNi2P/C is employed as catalytic support to load Pt nanoparticles. Due to the existence of phosphorus and the difunctional effects of Fe and Ni, electrochemical results demonstrate that the prepared Pt–FeNi2P/C compound exhibits an outstanding catalytic activity of 1125 mA·mg-1 Pt during methanol oxidation in acid solution, tower over that of Pt–FeP4/C (721 mA·mg-1Pt), Pt–Ni2P/C (588 mA·mg-1Pt) and Pt/C-JM (284 mA·mg-1Pt), separately. Significantly, bimetallic Pt–FeNi2P/C hybrid shows the optimal anti poisoning tolerance, which onset potential is negatively shifted 0.2 eV in comparison of Pt/C-JM. Hence, Pt-based catalyst decorated by bimetallic phosphides with excellent anti poisoning tolerance would be a superb material to flourish the catalytic field.

Accessing Basic Sites on Modified CoFe2O4 Nanoparticles: Addressing the Selective e 4 Oxidation of Benzyl Alcohol and Unraveling the Au:Pd Ratio Effects by XPS

AuPd nanoparticles have gained substantial attention due to their application in selective oxidation of alcohols. However, due to the radical nature of the oxidation of benzyl alcohol, under specific conditions, even without a catalyst, the reaction occurs and affects the selectivity of the system. Therefore, we aimed to develop a catalyst that enables the control of the oxidation leading to higher reaction selectivity. To accomplish this, we have prepared a catalytic support comprised of CoFe2O4 nanoparticles impregnated with Sr(OH)2 that presented a significant control of the reaction selectivity without any metal or external base addition. After the impregnation of AuPd nanoparticles in a specific ratio, the reaction reached a selectivity of > 99% for benzaldehyde, in 3.5 h, with a recycle regime of five runs without loss of activity and selectivity. Our results show that the judicious choice of the ratio of the metals prevents the necessity of manipulating the reaction conditions to improve the performance of the system. Additionally, studies under N2 and O2 environments, with or without water, confirmed the role of the O2 in the system. Holding all this information, we propose a possible mechanism for the prepared system.

Efficient synthesis of highly dispersed ultrafine Pd nanoparticles on a porous organic polymer for hydrogenation of CO2 to formate.

Precise design of catalytic supports is an encouraging technique for simultaneously improving the activity and stability of the catalyst. However, development of efficient heterogeneous catalysts for transforming CO2 into formic acid (FA) is still a big challenge. Herein, we report that Pd nanoparticles (NPs) based on a porous organic polymeric support containing amide and pyridine functional groups (AP-POP) can be an efficient catalyst for selective hydrogenation of CO2 to form formate with high efficiency even under mild reaction conditions (6.0 MPa, 80 °C). Electron density of the active Pd species modulated via the interaction between pyridine nitrogen and Pd play important roles in dramatic enhancement of catalytic activity and was indicated by X-ray photoelectron spectroscopy (XPS) along with CO chemisorption. This work provides an interesting and effective strategy for precise support design to improve the catalytic performance of nanoparticles.

Dual-layer BaCe0.8Y0.2O3-δ-Ce0.8Y0.2O2-δ/BaCe0.8Y0.2O3-δ-Ni hollow fiber membranes for H2 separation

Ceramic ion-conducting membrane technology is one of the promising options for hydrogen separation to replace the conventional expensive cryogenic distillation methods. In order to achieve high H2 permeation flux, designing multi-phase membranes possessing high mixed protonic and electronic conductivities in asymmetric structure with a thin dense separating layer is an important strategy for future novel membrane development. Multi-phase dual-layer BaCe0.8Y0.2O3-δ (BCY)-Ce0.8Y0.2O2-δ (YDC)/BCY-Ni hollow fiber membrane with excellent hydrogen permeability was developed by a single-step co-extrusion technique in this work. The thickness of the dense layer of the membrane can be controlled by the powder content of BCY-YDC in the spinning suspension. When the content of BCY-YDC was lowered from 65 to 45 wt%, the thickness of the dense layer was decreased from 33.5 to 14.5 μm. The thin dual-phase BCY-YDC dense layer determines the H2 permeation and the porous BCY-Ni support layer provides the mechanical strength and catalytic effect for surface exchange reactions. Compared to the BCY-YDC single-layer membrane, the H2 flux of such dual-layer asymmetric membrane with dense layer of 17.0 μm was improved significantly by a factor of 2 reaching 0.566 mL cm−2 min−1 at 900 °C under the hydrogen partial pressure difference of 50 kPa. A long term permeation test for 240 h confirmed the high operational stability of the prepared dual layered hollow fiber membrane. The good membrane performance is directly sourced from the excellent integration of the dual layers prepared in one step and thin thickness of the densified separating layer with catalytic porous support.

Anchoring Co3O4 nanoparticles on MXene for efficient electrocatalytic oxygen evolution

Rational design and controllable synthesis of efficient electrocatalysts for water oxidation is of significant importance for the development of promising energy conversion systems, in particular integrated photoelectrochemical water splitting devices. Cobalt oxide (Co3O4) nanostructures with mixed valences (II,III) have been regarded as promising electrocatalysts for the oxygen evolution reaction (OER). They are able to promote catalytic support of OER but with only modest activity. Here, we demonstrate that the OER performance of cubic Co3O4 electrocatalyst is obviously improved when they are anchored on delaminated two-dimensional (2D) Ti3C2 MXene nanosheets. Upon activation the overpotential of the hybrid catalyst delivers 300 mV at a current density of 10 mA cm−2 in basic solutions, which is remarkably lower than those of Ti3C2 MXene and Co3O4 nanocubes. The strong interfacial electrostatic interactions between two components contribute to the exceptional catalytic performance and stability. The enhanced OER activity and facile synthesis make these Co3O4 nanocubes-decorated ultrathin 2D Ti3C2 MXene nanosheets useful for constructing efficient and stable electrodes for high-performance electrochemical water splitting.

Heterogeneous interfacial engineering of Pd/TiO2 with controllable carbon content for improved direct synthesis efficiency of H2O2

Series of heterogeneous interfacial engineered TiO2 (C-TiO2) with controllable carbon content were facilely synthesized by incipient-wet impregnation using glucose and subsequent thermal carbonization. The obtained C-TiO2 were used as catalytic supports to load Pd nanoparticles for H2O2 direct synthesis from H2 and O2. The as-prepared samples were systematically studied by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), air isothermal microcalorimeter, temperature-programmed reduction of H2 (H2-TPR), and so on. The catalytic results showed that H2O2 productivity and H2O2 selectivity of Pd/C-TiO2 firstly rose with increasing carbon content and then declined. Pd/C-TiO2 catalyst with 1.89 wt% of carbon content showed the best catalytic performance that had 61.2% of selectivity and 2192 mmol H2O2/gPd/h of productivity, which were significantly better than those of pristine Pd/TiO2 (45.2% and 1827 mmol H2O2/gPd/h). Various characterization results displayed that the carbon species were heterogeneously dispersed on TiO2 surface. Moreover, no obvious geometric transformation in supports and Pd nanoparticles were observed among different catalysts. The superficial hydrophobicity of Pd/C-TiO2 was gradually promoted with increasing carbon content, which led to the corresponding decrease in adsorption energy of H2O2 with catalysts. According to structure-performance relationship analyses, the heterogeneous interfacial engineering of carbon could maintain the interaction of Pd nanoparticles with TiO2 and simultaneously accelerate the H2O2 desorption. Both factors further determined the excellent H2O2 direct synthesis performance of Pd/C-TiO2.

Synthesis of TiO2–ZrO2 Mixed Oxides via the Alginate Route: Application in the Ru Catalytic Hydrogenation of Levulinic Acid to Gamma-Valerolactone

In this work, high surface area mono- and binary oxide materials based on zirconia and titania synthetized via the alginate route were applied as supports of ruthenium catalysts used in levulinic acid hydrogenation towards γ–valerolactone. The physicochemical properties of the catalysts were investigated using surface (like time-of-flight secondary ion mass spectrometry (ToF-SIMS), transmission electron microscopy (TEM)) and bulk techniques (temperature-programmed reduction (TPR), X-ray diffraction (XRD)). The obtained results exhibited that the proposed synthesis method allows for modification of the shape, morphology, and surface properties of the studied materials. These catalysts were tested in levulinic acid hydrogenation, in which catalytic support is known to be crucial. The results revealed that the titania-supported catalyst was the most active in the reaction mentioned above, while the highest mechanical stability was observed for zirconia-supported materials.

Influence of catalytic mass content in catalytic combustion of isopropyl alcohol using aerosol nanocatalysis technology

This paper studies the effect of catalytic combustion of isopropyl alcohol according to the principles of aerosol nanocatalysis technology on a vibrating fluidized bed reactor. using a metal oxide catalyst in the form of Fe2O3 The prospects of using isopropyl alcohol as feedstock for catalytic heat generators were considered. The availability of isopropyl alcohol and possible methods for its production were also analyzed. A comparative analysis of the efficiency of aerosol nanocatalysis and heterogeneous catalysis in relation to the processes of deep oxidation of alcohols is carried out. The methodology of experimental studies of oxidation processes using isopropanol as feedstock and using an aerosol nanocatalysis reactor with a vibration layer of the catalytic system was worked out. Catalytic reactions under aerosol nanocatalysis technology eliminate the need for catalytic supports, while implementing in situ a continuous mechanical and chemical activation (MCA) of the catalyst surface by the mobile inert material. The effect of catalytic mass concentration in the reactor was analyzed to ascertain the best mass content of catalyst needed to achieve complete high % volume content of CO2 in the combustion gases product. This study revealed that under this technology, complete combustion can be achieved at a catalytic mass content of 0.0002 grams and 0.0004 grams, as results of the experiment showed that there needs to be a full saturation of the inert material with the catalytic component, for the combustion reaction to be favorable towards CO2 generation. This experiment was conducted by varying the amount of catalytic content being introduced into the reactor, by altering the mass of the catalyst from 0.0001 grams - 0.0005 grams, while using a temperature of 400oC and MCA frequency of 3Hz, the MCA frequency of 3Hz provides the reactant the opportunity to fully interact with the pores of the catalytic surface under mild reactor bed vibrations while under the impact of atmospheric pressure. Prospects for the development of industrial technology based on experimental studies were considered.

Porous carbon fibers for effective hydrogen evolution

Carbon fibers (CFs) with unique physicochemical properties have been considered as a sustainable material for use as a catalytic support for hydrogen evolution reaction (HER). Porous carbon microfibers (PCFs) were generated by utilizing the needle less electrospinning technology (NLE). The first approach involved the formation of porosity in precursor polyacrylonitrile/polyvinylpirolidone (PAN/PVP) fibers by washing out PVP and carbonization of remaining PAN. Although the sufficient porosity was achieved with increasing PVP content, the total bulk porosity was lost. The second approach was simple removal of PVP, based on different polymer degradation process at high temperatures. The most efficient way was utilization of sodium dodecyl sulphate (SDS) as an anionic surfactant. Binding SDS on PVP polymer chain caused the formation of micelles, which formed regular porous structures in the fibrous carbon matrix after carbonization. The formation of porosity and electrocatalytic activity of CFs after carbonization in Ar and H2 reduction atmosphere were studied. The electrocatalytic results have pointed out that the composition of precursor fibers PAN/PVP/SDS heat treated without previous preoxidation process, carbonized in Ar atmosphere and followed in H2 atmosphere can be efficiently used as a porous material platform for different modification and further application as a potential electrocatalysts for HER.