Stainless Steel Catalyst Research Articles

A novel additive manufacturing strategy with high hydrogen production for ordered-porous stainless steel catalyst support

This paper proposes to improve hydrogen production performance of ordered-porous stainless steel by increasing its forming structure parameters. Firstly, selective laser melting additive manufacturing of ordered-porous stainless steel is carried out through designed orthogonal experiment table, to obtain its forming structure parameters under different manufacturing process parameters. Then, different forming structure parameters of ordered-porous stainless steel are converted into a comprehensive index by grey relation theory, which is grey relational degree (GRD). When powder thickness, scanning speed, scanning space and laser power are 30 μm, 800 mm/s, 90 μm and 60 W, respectively, the highest GRD of 0.930 is obtained, when those are 40 μm, 1200 mm/s, 70 μm and 60 W, respectively, the lowest GRD of 0.410 is gained. Finally, catalyst bonding strength and hydrogen production performance of the ordered-porous stainless steels with the above GRDs are verified. It is found that the ordered-porous stainless steel with the highest GRD has higher catalyst bonding strength and higher hydrogen production performance. When 12 mL/h injection rate of methanol–water solution and 250 ℃ reaction temperature are used, CH3OH conversion, H2 flowing rate and CO selectivity of the above ordered-porous stainless steel are 64.3%, 0.396 mol/h and 6.75%, respectively.

Pyrolysis–catalysis upcycling of waste plastic using a multilayer stainless-steel catalyst toward a circular economy

Current un-sustainable plastic management is exacerbating plastic pollution, an urgent shift is thus needed to create a recycling society. Such recovering carbon (C) and hydrogen (H) from waste plastic has been considered as one practical route to achieve a circular economy. Here, we performed a simple pyrolysis-catalysis deconstruction of waste plastic via a monolithic multilayer stainless-steel mesh catalyst to produce multiwalled carbon nanotubes (MWCNTs) and H2, which are important carbon material and energy carrier to achieve sustainable development. Results revealed that the C and H recovery efficiencies were as high as 86% and 70%, respectively. The unique oxidation-reduction process and improvement of surface roughness led to efficient exposure of active sites, which increased MWCNTs by suppressing macromolecule hydrocarbons. The C recovery efficiency declined by only 5% after 10 cycles, proving the long-term employment of the catalyst. This catalyst can efficiently convert aromatics to MWCNTs by the vapor-solid-solid mechanism and demonstrate good universality in processing different kinds of waste plastics. The produced MWCNTs showed potential in applications of lithium-ion batteries and telecommunication. Owing to the economic profits and environmental benefits of the developed route, we highlighted its potential as a promising alternative to conventional incineration, simultaneously achieving the waste-to-resource strategy and circular economy.

Promoting surface reconstruction of low-cost stainless steel catalyst for efficient oxygen evolution reaction.

The development of cost-effective transition metal catalysts for oxygen evolution reaction (OER) is critical for the production of hydrogen fuel from water splitting. Low-cost and efficient stainless steel-based catalysts are expected to replace the scarce platinum group metals for large-scale energy applications. Here in this work, we report the conversion of commonly available inexpensive and easily accessible 434-L stainless steel (SS) into highly active and stable electrodes by corrosion and sulfuration strategies. The NixFe1-xS layer as a pre-catalyst and S-dopedNixFe oxyhydroxides in situ formed on the catalyst surface are the true active species for OER.The optimized 434-L stainless steel-based electrocatalyst exhibits a low overpotential of 298 mV at 10 mA cm-2in 1.0 M KOH with a small OER kinetics (the Tafel slope of 54.8 mV dec-1) and good stability.This work reveals the 434-L alloy stainless steel with Fe and Cr as the main elements can be used as qualified OER catalysts by surface modification, along with a new mentality to solve the energy and resource waste problems.

Stainless steel catalyst for air pollution control: structure, properties, and activity.

With the awakening of environmental awareness, the importance of air quality to human health and the proper functioning of social mechanisms is becoming increasingly prominent. The low cost and high efficiency of catalytic technique makes it a natural choice for achieving deep air purification. Stainless steel alloys have demonstrated their full potential for application in a variety of catalytic fields. The diversity of 3D networks or fibrous structures increases the turbulence within the heterogeneous catalysis, balance the temperature distribution in the reaction bed and, in combination with a highly thermally conductive skeleton, avoid agglomeration and deactivation of the active components; corrosion resistance and thermal stability are adapted to highly endothermic/exothermic or corrosive reaction environments; oxide layers formed by bulk transition metals activated by thermal treatment or etching can significantly alter the physico-chemical properties between the substrate and active species, further improving the stability of stainless steel catalysts; suitable electronic conductivity can be applied to the electrothermal catalysis, which is expected to provide guidance for the reduction of intermittent emission exhausts and the storage of renewable energy. The current applications of stainless steel as catalyst or support in the air purification have covered soot particle capture and combustion, catalytic oxidation of VOCs, SCR, and air sterilization. This paper summarizes several preparation methods and presents the relationships between the preparation process and the activity, and reviews its application and the current status of research in atmospheric environmental management, proposing the advantages and challenges of the stainless steel-based catalysts.

Enhancement of Nano Catalyst for an Alkaline Fuel Cells

An alkaline fuel cell, which was developed using nano catalyst (Pt:CNTs) for electrodes. Study has been prepared (Pt:CNTs) nano catalyst, The Structural characteristics were studied through the analysis of X-ray diffraction (XRD) of the prepared nano catalyst for determining the yielding phase and Scanning Electron Microscope (SEM), were used to characterize, Mesh stainless steel catalyst substrate had an envelope structure and a large surface area. In addition, study the characterization of the electrochemical parameters. Electrochemical modelling and nano catalyst led to optimization of cell voltage, current & power densities and the results are found to be 1.76 V, 3.9 A.

Enhancement of Nano Catalyst for an Alkaline Fuel Cells

An alkaline fuel cell, which was developed using nano catalyst (Pt:CNTs) for electrodes. Study has been prepared (Pt:CNTs) nano catalyst, The Structural characteristics were studied through the analysis of X-ray diffraction (XRD) of the prepared nano catalyst for determining the yielding phase and Scanning Electron Microscope (SEM), were used to characterize, Mesh stainless steel catalyst substrate had an envelope structure and a large surface area. In addition, study the characterization of the electrochemical parameters. Electrochemical modelling and nano catalyst led to optimization of cell voltage, current & power densities and the results are found to be 1.76 V, 3.9 A.

Analysis of oxide scales on oxidised EN 1.4509 ferritic stainless steel catalyst support by scanning electron microscopy

This study aims to investigate the oxidation behaviour at high temperature of a commercial ferritic stainless steel EN 1.4509. Tests of high temperature oxidation in air were carried out under isothermal condition (950 ºC) with different exposure times in order to obtain the oxidation kinetics law associated to this material. The surface and cross-section were analysed by scanning electron microscopy and energy-dispersive X-ray spectrometry (SEM/EDS), where the oxide scales proved to be formed by an external Mn-Cr spinel and an inner chromia layer. These oxides were generated by the migration of metallic cations from the stainless steel to the atmosphere. The size of the generated spinel crystals increased when increasing the exposure time as well as the cross-section thickness did. Moreover, the surface modification of ferritic stainless steel EN1.4509 was studied when platinum is deposited on its surface. The feature of this surface-modified ferritic stainless steel against oxidative atmosphere was evaluated by SEM/EDS. This platinum deposition led to reach a different surface morphology in terms of crystal size and nature.

Development of carbon nanotubes catalyst supported for alkaline fuel cell technology

Study of the development of an activated carbon nanotube catalyst for alkaline fuel cell technology. Through the prepared carbon nanotubes catalyst by an electrochemical deposition technique. Different analytical approaches such as X-ray diffraction (XRD) to determine the structural properties and Scanning Electron Microscope (SEM), were used to characterize, Mesh stainless steel catalyst substrate had an envelope structure and a large surface area. Voltages were also obtained at 1.83 V and current at 3.2 A of alkaline fuel cell. In addition, study the characterization of the electrochemical parameters.

Synthesis of carbon spheres by atmospheric pressure chemical vapor deposition from a serial of aromatic hydrocarbon precursors

Uniform shaped carbon spheres, a material with several potential applications, were synthesized from a serial of aromatic hydrocarbon pyrolysis precursors (benzene, naphthalene, anthracene and pyrene), by chemical vapor deposition at atmospheric pressure, and at moderately low temperatures with stainless steel catalyst. A high carbon sphere yield, without secondary products, was achieved at temperatures above 850 °C. Sphere diameters decrease, in some cases, according to the temperature increments. Field emission scanning electron microscopy images show a completely solid core. Raman and Fourier transform infrared spectra suggest a larger amount of CHx bonds on the sphere surface with major curvature. Spheres are formed by small crystalline graphene flakes, observed by high resolution transmission electron microscopy and confirmed by the G band intensity in Raman spectra and X-ray diffraction signals.

Influence of Stainless-Steel Catalyst Substrate Type and Pretreatment on Growing Carbon Nanotubes from Waste Postconsumer Plastics

This study is concerned with the “up-cycling” postconsumer wastes into the value-added products of multiwall carbon nanotubes (CNTs). It investigated combinations of methods for pretreating different types of stainless-steel catalysts that increase the yield of CNTs form common waste plastics. The polymers were pyrolyzed at 800 °C, in nitrogen, and their gaseous pyrolyzates were passed over fixed catalyst substrates preheated to 800 °C. The substrates consisted of SS-304, SS-316 and SS-316L fine stainless-steel wire-cloths. Therein synthesis of CNTs took place by chemical vapor deposition (CVD). The wire-cloths were used either as-received or chemically etched by acid wash and/or heat-treated in air, nitrogen or helium at 800 °C, and then rapidly air-quenched. Results showed that the catalyst type, composition and pretreatment method, as well as the type of feedstock, are all influential on the yields and physical characteristics of the synthesized CNTs.

SÍNTESIS DE NANOESTRUCTURAS DE CARBONO A PARTIR DE ISOPROPANOL Y ACETATO DE ETILO APLICANDO PRINCIPIOS DE QUÍMICA VERDE

Multiwall carbon nanotubes were grown on a stainless steel AISI 304 core catalyst by chemical vapor deposition in a quartz reactor. The highlight of this research is the use of stainless steel catalyst and organic precursors from renewable feedback for high efficient carbon nanostructures synthesis using green chemistry principles. Isopropanol and ethyl acetate were performing as precursors in the chemical vapor deposition. Raman spectroscopy and electron microscopy were used to analyze the morphology and crystallinity of the synthesized nanostructures. Transmission electron microscopy performed on samples confirms the presence of multiwall carbon nanotubes and metallic particles found on the tip, base and inside the nanotubes demonstrating a mixed growth mechanism. The secondary products found in the samples were carbon nanobars with different interplanar spaces. XRD confirmed the characteristic planes for hexagonal graphite and weak iron and manganese oxides signals. EDS showed a carbon content above 94% and low metals and oxygen contribution. The carbon nanostructures crystallite sizes were calculated from XRD data and compared with the transmission electron microscopy micrographs; the structures obtained from ethyl acetate had major crystallinity. An easy to scale up carbon nanostructures synthesis method applying green chemistry principles is proposed.

Sloughing a Precursor Layer to Expose Active Stainless Steel Catalyst for Water Oxidation.

Hydrogen production by water electrolysis has been regarded as a promising approach to wean away from sourcing energy through fossil fuels, as the produced hydrogen gas can be converted to electrical or thermal energy without any harmful byproducts. However, an efficient hydrogen production is restricted by the sluggish oxygen evolution reaction (OER) at the counter anode. Therefore, the development of new OER catalysts with high catalytic activities is crucial for high performance water splitting. Here, we report a novel sloughing method for the fabrication of an efficient OER catalyst on a stainless steel (SS) surface. A chalcogenide (Fe-S) overlayer generated by sulfurization on the SS surface is found to play a critical role as a precursor layer in the formation of an active surface during water oxidation. Interestingly, a newly exposed catalytic layer after sloughing off the Fe-S overlayer has a nanoporous structure with changed elemental composition, resulting in a significant improvement in OER performance with an overpotential value of 267 mV at a current density of 10 mA cm-2 (in 1 M KOH). Our novel method for the preparation of OER catalyst provides an important insight into designing an efficient and stable electrocatalyst for the water splitting community.

Synthesis of Nanocarbon from Polyethylene Plastic Using Stainless Steel Catalyst via Oxidative Heat Treatment Preparation Method

Synthesis of Nanocarbon from Polyethylene Plastic Using Stainless Steel Catalyst via Oxidative Heat Treatment Preparation Method

Carbon Nanotubes Synthesis from Four Different Organic Precursors by CVD

ABSTRACTCarbon nanotubes (CNTs) were synthesized by Chemical Vapor Deposition (CVD) from diethyl ether, butanol, hexane and ethyl acetate. A quartz tube with a stainless steel tube catalyst core with 0.019 m diameter and 0.6 m large formed the reactor. To avoid combustion, argon was used as the carrier gas. Time process ranged 30 to 60 min. The range of CNTs synthesis temperature was 680-850 °C for different precursors. Scanning Electron Microscopy micrographs have demonstrated tangled CNTs growth in all samples, thus presenting difficult length measurement. The CNTs diameters from diethyl ether are 45-200 nm, butanol diameter range from 55-230 nm, hexane diameter range is 50-130 nm and ethyl acetate range from 100 to 300 nm. Carbon content for all samples was higher than 93 %, CNTs from butanol showed carbon concentration up to 99%. FTIR, Raman and X-Ray Spectroscopies spectra for all samples demonstrated the characteristics signals present in carbon nanotubes. This research proposes a simple, effective and innovative method to synthesize CNTs by CVD on iron stainless steel catalyst in combination with diethyl ether, ethyl acetate, butanol and hexane as precursors by applying the principles of green chemistry, sustainability and its ease to be scaled.

Characterization of Wet Impregnation Method for Catalytic Microcombustor by Using Platinum

The wet impregnation method for catalytic microcombustor was characterized by using platinum as a catalyst. The main purpose of this study is to increase the surface porosity of the catalyst support. A high surface porosity indicates that a high amount of catalyst was deposited within the surface areas. The performance of the catalytic microcombustor improves with increasing catalytic surface area. The stainless steel catalyst support was treated with sulfuric acid solution containing polyvinyl (3.89 wt%) and propargyl alcohol (1.48 wt%). Combustion test was performed using LPG-air to test the performance of the catalyst. The surface support treated with polyvinyl (PVA) showed a higher surface porosity and combustion blow-out limit compared with propargyl alcohol. The combustion mode changes from surface to submerged combustion after the catalyst was deposited in the support surface.

AAO–CNTs electrode on microfluidic flow injection system for rapid iodide sensing

In this work, carbon nanotubes (CNTs) nanoarrays in anodized aluminum oxide (AAO–CNTs) nanopore is integrated on a microfluidic flow injection system for in-channel electrochemical detection of iodide. The device was fabricated from PDMS (polydimethylsiloxane) microchannel bonded on glass substrates that contains three-electrode electrochemical system, including AAO–CNTs as a working electrode, silver as a reference electrode and platinum as an auxiliary electrode. Aluminum, stainless steel catalyst, silver and platinum layers were sputtered on the glass substrate through shadow masks. Aluminum layer was then anodized by two-step anodization process to form nanopore template. CNTs were then grown in AAO template by thermal chemical vapor deposition. The amperometric detection of iodide was performed in 500-μm-wide and 100-μm-deep microchannels on the microfluidic chip. The influences of flow rate, injection volume and detection potential on the current response were optimized. From experimental results, AAO–CNTs electrode on chip offers higher sensitivity and wider dynamic range than CNTs electrode with no AAO template.

The synthesis and characterization of carbon nanotubes grown by chemical vapor deposition using a stainless steel catalyst

Multi wall carbon nanotubes (MWCNTs) were grown on a stainless steel (SS) sheet by chemical vapor deposition without the addition of external metal catalyst. We found that the key for highly efficient growth includes the nanoscale roughness of the SS surface, as shown by scanning tunneling microscopy, that acts as catalyst/template in the nanotube formation. Raman spectroscopy and electron microscopy were used to check the nature and quality of the synthesized nanotubes. We conclude that stainless steel favors a base-growth mechanism. Transmission electron energy loss spectroscopy performed on single metallic particles found inside the nanotubes clarified the atomic nature of the catalytic particles supplied by the steel. Only unoxidized iron was found and no traces of nickel and chromium were detected. In addition, the SS substrate has been used for a second growth process after carefully removing the synthesized CNTs, proving that a continuous production of CNTs from the same substrate is achievable.

Flow injection based microfluidic device with carbon nanotube electrode for rapid salbutamol detection

A microfabicated flow injection device has been developed for in-channel electrochemical detection (ECD) of a β-agonist, namely salbutamol. The microfluidic system consists of PDMS (polydimethylsiloxane) microchannel and electrochemical electrodes formed on glass substrate. The carbon nanotube (CNT) on gold layer as working electrode, silver as reference electrode and platinum as auxiliary electrode were deposited on a glass substrate. Silver, platinum, gold and stainless steel catalyst layers were coated by DC-sputtering. CNTs were then grown on the glass substance by thermal chemical vapor deposition (CVD) with gravity effect and water-assisted etching. 100-μm-deep and 500-μm-wide PDMS microchannels fabricated by SU-8 molding and casting were then bonded on glass substrate by oxygen plasma treatment. Flow injection and ECD of salbutamol was performed with the amperometric detection mode for in-channel detection of salbutamol. The influences of flow rate, injection volume, and detection potential on the response of current signal were optimized. Analytical characteristics, such as sensitivity, repeatability and dynamic range have been evaluated. Fast and highly sensitive detection of salbutamol have been achieved. Thus, the proposed combination of the efficient CNT electrode and miniaturized lab-on-a-chip is a powerful platform for β-agonists detection.

Dry‐Reforming of Ethanol in the Presence of a 316 Stainless Steel Catalyst

AbstractDry‐reforming is a known process for the production of synthetic gas from natural gas or other volatile fossil fuels. Another possible application is the reforming of hydrocarbons contained in the synthetic gas produced from biomass or waste gasification. The absence of wide industrial process applications is mainly due to the high endothermicity of the reactions involved and technical problems associated with carbon formation. In this work, the target reaction is: The principal challenge is that of using a 2D catalyst formulation favouring the target reaction and permitting easy retrieval of deposited carbon while, at the same time, preserving the catalyst's activity and structural integrity.This paper presents the results obtained from the use of a 316 stainless steel catalyst. The catalyst is active in ethanol dry reforming as the yield of hydrogen reached 98% of the theoretical value. Moreover, the co‐product carbon is of a filamentous form and can be easily retrieved without risk of modification to the catalyst properties. This catalyst is recyclable; it can be used several times over in the dry‐reforming of ethanol process without detectable change in its activity and selectivity.