Production Of Metallic Iron Research Articles

Lunar in-situ ironmaking through laser-assisted flash vacuum pyrolysis of iron oxide

The in-situ metallurgy of lunar regolith minerals for extracting metals and oxygen is a promising approach for the future construction of lunar bases. In this study, a novel laser-assisted flash vacuum pyrolysis (LFVP) method was proposed and developed for the production of metallic iron and oxygen from lunar regolith using iron oxide as raw material. First, the theoretical feasibility of vacuum pyrolysis of FeO was conducted through thermodynamic calculations. Subsequently, an experiment on laser heating of iron oxides was performed, with a reduction rate of FeO of approximately 15.5 % (±0.6 %). Scanning electron microscopy and transmission electron microscopy images revealed that the micronano-level metallic iron exhibited spherical particles, strip-like and irregularly shaped aggregates. The spatial distribution unevenness of the formed metallic Fe, differences in the condensation conditions of gaseous products, and the surface tension effects of liquid metallic iron were mainly attributed to the disparities in the morphology of metallic iron. Meanwhile, the process mechanism of vacuum pyrolysis of FeO was also analyzed. Therefore, LFVP of FeO for producing metallic iron represents a novel ironmaking technology, offering a promising solution for extracting metals and oxygen in situ from lunar minerals for future lunar base construction.

Iron ore reduction using agricultural waste biochar with different carbon to oxygen ratios

BackgroundDuring iron production ferric oxide is reduced to iron, with carbon used as the reducing agent. Traditionally, coke was used as the carbon component, which became a crucial raw material in the iron and steel industry after the industrial revolution. However, coke is the most significant contributor to CO2 emissions due to the source of heat and reducing agent. Thus, shifting to low carbon energy systems, such as those based on biomass, is challenging. Therefore, in this study, we employed the mushroom cultivation residue char (MCRC) as a reducing agent to investigate the feasibility of replacing coke in the production of metallic iron. MethodsAfter carbonization at different temperatures (500 °C, 700 °C and 900 °C), mushroom cultivation residue char (MCRC), were used as a reducing agent in the production of metallic iron. To create the composite pellets, the MCRCs were individually mixed with iron ore at different carbon to oxygen ratios (C/O) (0.7, 0.8 and 0.9) and 1 % of bentonite. The reduction process was undergoing in the electric muffle furnace at different high temperatures (1,000 °C, 1,200 °C and 1,300 °C) to investigate the biomass C/O ratios required for efficient iron production. Significant findingsThe results show that 0.8 was selected as the optimal C/O ratio for mushroom cultivation residue char (MCRC) to be used as a reducing agent. Its metallization rate can reach 31.99 %. The results also indicate that the carbon and volatiles in MCRC play a key role in iron making production using such biochar pellets. In conclusion, MCRC can be used as a reducing agent to increase the sustainability of iron production and reduce agricultural waste.

External moisture enhanced synergistic conversion of biomass and iron sand for the green production of metallic iron

In this study, a novel approach combining chemical looping gasification (CLG) and direct reduced iron (DRI) was proposed for an efficient, sustainable, and green production of metallic iron by enhancing the synergistic conversion between biomass and iron sands via external moisture. In the process, the external moisture acts as a catalyst for pre-gasification of biomass at the early stage while iron sand, as an oxygen carrier (OC) and catalyst, contributes to the later biomass gasification, where biomass is used as a reducing agent for iron ore metallization. The effect of moisture on biomass gasification and roasting effectiveness was investigated, at a reduction temperature of 1080 °C, 10% H2O, and 80 min of roasting time. The total syngas yield was 84.13% and the reduction product with a metallization rate of 97.53% was obtained. The mechanism of synergistic conversion between biomass, external moisture, and iron sand was described. The iron ore and moisture in the initial roasting stage reduced the tar yield, significantly retarded the escape of hydrocarbons, and prolonged the high-pressure maintenance time. Thereafter, the biomass tar and biomass carbon were gasified under the action of oxygen elements from external moisture and iron ore, eventually generating CO and H2 with the final residual carbon being 9.73% comparing to the initial total C element. The reducing gas generated from biomass was used to reduce iron ore, ensuring a high metallization of iron ore and achieving efficient synergistic conversion of biomass and iron ore. Moisture and lattice oxygen of iron ore play significant roles in the gasification of biomass at the early stage. The formed metallic iron and moisture further promoted the gasification of biomass C in the subsequent catalysis. This mutually reinforcing and transformative approach shows great potential in promoting biomass gasification efficiency and reducing carbon emissions from DRI processes.

COMPREHENSIVE WASTE-FREE PROCESSING TECHNOLOGY OF COPPER SMELTING SLAGS

More than 140 million tons of slag have been accumulated in the dumps of copper smelting enterprises of the Russian Federation. Maintaining dumps require significant expenses, which makes it necessary to dispose these production wastes as completely as possible. At the same time, these slags contain valuable elements, in particular, iron, copper, zinc, selenium, arsenic and some others; their extraction can make disposal cost-effective. Among these elements iron has the highest cost, which content is at the level of more than 40%; it is almost at the level of some iron ores used in ferrous metallurgy. However, the use of this iron-containing material in conventional ferrous metallurgy processes is complicated by the high (up to 0.6%) copper content. In addition, the extraction of iron by conventional methods does not solve the problems of disposal of newly formed slag. In this work, the technological methods of processing copper-smelting slags by solid-phase reduction of iron in the Tamman reduction furnace, smelting of reduction products in induction furnaces with the production of metallic iron and propants from the slag residue are proposed and worked out in laboratory conditions. The slags and slurries of the Karabash Copper Smelting Plant, where the main component of is iron, were used as the research material. The properties of cast iron grinding media, as well as ceramic proppants for the use in the oil industry, were investigated. As a result, the influence of elements passing into metal (silicon, carbon, copper and sulfur) on the hardness of grinding balls and the influence of the chemical composition of the slag on the strength of the obtained propants was clarified. A technological scheme of complex slag processing has been developed and a set of serially manufactured equipment has been selected. The economic efficiency of the organization of production is estimated.

A biorefinery approach for high value-added bioproduct (astaxanthin) from alga Haematococcus sp. and residue pyrolysis for biochar synthesis and metallic iron production from hematite (Fe2O3)

The present study aimed to investigate a biorefinery approach on natural astaxanthin production from the microalgae Haematococcus lacustris and biomass residue for biochar production through pyrolysis. Further, the biochar obtained from the H. lacustris residue was explored for iron oxide reduction using hematite iron ore through a thermogravimetric analyzer (TGA). The alga H. lacustris cultivated in a low-cost polythene made photobioreactor (PBR) for a period of 32 days. During cultivation, several parameters were optimized for the enhanced biomass and astaxanthin accumulation. The results revealed that the highest biomass productivity of 3 g L−1 was found in acetate amended culture medium. Similarly, the addition of an extra carbon source (acetate) supported the highest astaxanthin productivity of 203 mg L−1, and it was observed during the red phase on day 32. The PBR volumetric biomass productivity of H. lacustris was estimated at up to 79.8 tonnes/acre/year. In this study, the alga H. lacustris grown in polythene made PBR produced the highest natural astaxanthin yield of 6.76%/cell dry weight (CDW). Further, the residual biomass was pyrolyzed through a non-catalytic process to obtain the maximum biochar yield. A mini pellet was synthesized using H. lacustris biochar and hematite (Fe2O3), and it was taken for metallic iron production under a nitrogen atmosphere. The results revealed that the biochar was supported for maximum metallic iron (Fe) production at ≥975 °C. This is the first study demonstrating the utilization of microalgae H. lacustris for natural astaxanthin production and biomass residue for metallic iron (Fe) production at low-cost methods.

Production of Metallic Iron from the Pudo Magnetite Ore using End-of-Life Rubber Tyre as Reductant: The Role of an Underlying Ankerite Ore as a Fluxing Agent on Productivity

This research work investigated the nature of a nonmagnetic ore from Pudo in the Upper West Region of Ghana and its fluxing effect on the extent of reduction of the Pudo titaniferous magnetite ore using pulverised samples of charred carbonaceous materials generated from end-of-life vehicle tyres (ELT) as reductants. Reduction studies were conducted on composite pellets of the Pudo titaniferous magnetite iron ore containing fixed amounts of charred ELT and varying amounts (0%, 10%, 15%, 20%, 30%, 40% and 50%) of the nonmagnetic fluxing material in a domestic microwave oven and the extent of reduction was calculated after microwave irradiation for 40 minutes. Analyses by XRF, SEM/EDS and XRD of the nonmagnetic ore revealed an Ankerite type of ore of the form Ca0.95Fe0.95Mn0.1 (CO3)2. From the microwave reduction studies it was observed that premium grade metallic iron could be produced from appropriate blends of the Pudo iron ores using ELT as reductant, with a measured extent of reduction up to 103.8%. Further, the extent of reduction was observed to increase with an increase in the amount of the nonmagnetic fluxing material (Ankerite) that was added as fluxing agent.
 
 Keywords: Ankerite, End-of-life Rubber Tyres, Fluxing Agent, Extent of Reduction

The Correlation between Palm Shell Char Properties and the Production of Metallic Iron in EAF Steelmaking Slag Reduction Reaction

Palm shells wastes generated from oil palm processing are in abundance in landfills every year thereby posing environmental problems. Enormous amount of wastes generated by agro-industry has previously studied as carbon source in steelmaking hence providing solution to environmental problems. This paper studied on the conversion of palm shell waste into carbon material via physical and chemical activation method for metallic iron extraction. Physical char was prepared by pyrolyzed in nitrogen atmosphere at 450ºC while chemical char was impregnated in phosphoric acid before pyrolyzed. Composite pellets of EAF slag (43.18 %Fe2O3) with physical and chemical char were rapidly heated at temperature 1550ºC within 20 minutes under argon flow. All reduced samples were analyzed on the weight loss, degree of reduction, iron recovery and phase analysis using X-ray diffraction (XRD). The results indicated that chemical/slag showed higher weight loss (38.8%) and excellent degree of reduction (29.94%) compared to physical/slag due to higher volatile matter content (9.8%) and larger surface area (562.14m2/g). It was found that the production of metallic iron particles after the reduction process and indicated that chemical char achieved higher iron recovery (15.48%) compared to physical char due to higher total carbon content (60.28%). XRD and Rietveld refinement analysis confirmed that the iron phase was a major component in metallic iron particles for physical/slag and chemical/slag samples. This elucidated that the iron oxides in EAF slag was completely reduced into iron by using palm shell chars as carbon materials. This finding indicates that palm shell chars potentially act as carbon materials in steelmaking applications according to their good characteristics.

Electrolytic Iron Production from Alkaline Bauxite Residue Slurries at Low Temperatures

Primary iron metallurgy is characterised by significant direct carbon dioxide emissions, due to the carbothermic reduction of the iron ore. This paper deals with the electrification of primary iron production by developing a new and innovative process for the carbon-free production of metallic iron from bauxite residue which is a byproduct of the alumina industry. It is based on the electroreduction of iron oxides from bauxite residue suspensions in concentrated sodium hydroxide solutions, at low temperature and normal pressure. The iron oxide source used in the present study is bauxite residue provided by MYTILINEOS SA, Metallurgy Business Unit-Aluminium of Greece. The research study is a preliminary screening of bauxite residue as a potential raw material for iron production by performing experiments in a small-scale electrolysis cell. The first results presented here show that iron can be produced by the reduction of iron oxides in bauxite residue with high Faradaic efficiency (>70%). Although significant optimisation is needed, the novel process shows great promise.

Production of Iron Nuggets from the Akpafu-Todzi Iron Ore and Artisanal Ferrous Slag using Post Consumer Thermosets (Waste Electrical Sockets) as Reductants

AbstractPost-consumer thermosets are difficult to recycle because, unlike thermoplastics, they cannot be remoulded to create other items as a result of the extensive cross-linkages in their structure. The increased production of thermoset blends and composites in recent years has greatly increased the amount of waste materials. However, higher levels of carbon and hydrogen present in thermosets make them a potential reductant in the iron extractive industries. In this research work, postconsumer thermoset was transformed into carbon resource through a charring process. The resulting carbonaceous material from the thermoset was used as reductant in the production of metallic iron from the Akpafu-Todzi iron ore and artisanal slag using the microwave technology through the composite pellet approach at varying firing times. Analyses by XRF, XRD and SEM/EDS showed that the Akpafu Todzi iron ore is comprised of the iron oxides hematite (Fe2O3) and wustite (Fe0.942O), while the artisanal slag was predominantly fayalite (Fe2SiO4). Complete reduction of the ore was attained after 120 min reduction but the maximum extent of reduction was 78.84% for the slag, demonstrating the potential of postconsumer thermosets to function effectively as a reductant in the iron extractive industry. Keywords: Reduction; Akpafu-Todzi Iron Ore; Post Consumer Thermosets; Waste Electrical Sockets

Multistep reduction kinetics of Fe3O4 to Fe with CO in a micro fluidized bed reaction analyzer

The multiple step reduction kinetics of Fe3O4 to Fe with CO was investigated to understand the reaction mechanism for the production of metallic iron from hematite. The experiments were carried out in a micro fluidized bed reaction analyzer at different temperatures and CO concentrations using mass spectrometer analysis to determine the composition of the off gas. The overall kinetic parameters were then investigated based on the conversion obtained as a function of the oxygen loss, which can be calculated from the concentrations of CO and CO2 in the off gas. According to the analysis of the activation energy, a transformation of the reaction mechanism was identified at the conversion of 0.1. Considering that the reduction involves reactions in series, i.e., Fe3O4→FeO→Fe, it could be concluded that the FeO→Fe step was only involved beyond this transfer point, while the Fe3O4→FeO step occurred during the entire lifetime of Fe3O4. Meanwhile, the reaction rate for the reduction of Fe3O4 to FeO was controlled by the phase boundary, whereas the reduction of FeO to Fe was controlled by the phase boundary and diffusion. The reaction rate of the overall reduction process was determined by FeO→Fe, and the rate increased with increasing temperature from 600 °C to 720 °C and then decreased at approximately 720 °C until it reached a minimum value, and then increased again from 760 °C to 800 °C. Furthermore, the apparent activation energies of Fe3O4→FeO at 600–800 °C, FeO→Fe at 600–720 °C, and FeO→Fe at 760–800 °C were determined to be 35.01 ± 3.53 kJ/mol, 42.83 ± 0.25 kJ/mol, and 14.27 ± 1.69 kJ/mol, respectively.

Cultivation of microalgae Chlorella sp. in municipal sewage for biofuel production and utilization of biochar derived from residue for the conversion of hematite iron ore (Fe2O3) to iron (Fe) – Integrated algal biorefinery

This study demonstrated the utilization of municipal sewage for high biomass production at large scale and achieved highest biomass yield of 46.3 tons and the lipid yield of 13.7 metric tons per acre in a year. The extracted crude lipid was analyzed for biodiesel production, and the yield attained was 92.5 wt% with respect to initial lipid weight. Furthermore, the lipid extracted residue obtained from two different algal biomass such as Chlorella sp. and Sargassum sp. were explored for biochar production through a slow pyrolysis technique at 400 °C. The hematite iron ore reduction with algal biochar was performed non-isothermally at 1100 °C under nitrogen atmosphere. The metallic iron synthesis from hematite iron ore involves three major steps, and they were as follows (1) in this step the Fe3O4 was synthesized from Fe2O3 at the temperature of 350–450 °C; (2) this step contain the formation of FeO from Fe3O4 at the temperature of 700–850 °C; (3) finally the formation of metallic iron (Fe) was observed at higher temperature of 850–1100 °C. Herein, we established a novel low-cost microalgae-based biorefinery approach for the production of bioenergy and residue for metallic iron production from municipal waste.

Investigation of Balling Characteristics of Mixture of Iron Oxide Bearing Wastes and Iron Ore Concentrates

Iron oxide bearing wastes in form of dust and sludges are hard to handle because of their micron size particles and moisture content in case of sludge. More often they are stockpiled in large quantities that can occupy large area of real and agricultural estates and cause pollution. Balling or palettization, an agglomeration process was used to process the wastes in order to address the problem of micron size particles and to make them fit for recycling back into metallic iron production route like blast furnace. Balling or green pelletization is the process of forming nearly spherical shaped granules by tumbling moistened particulates with or without binders in balling drums or discs disc. For a pellet to be effective either for being transported or for being recycled in blast furnace to produce metallic iron without disintegrating to dust its balling characteristics should measure up to required standard. Most outstanding of those balling characteristics include Drop Number, Green or Wet Compression Strength, Dry Compression Strength, Abrasion and Tumbler Indices. In this work iron oxide bearing wastes was mixed with iron ore concentrates in various proportions. These mixes were taken through balling or wet pelletization process using Radicon Balling Disc. The balls formed balls were taken through Drop number tests adopting the Free Fall method, where balls are made to fall freely from a height of 50 mm on steel surface, Green compression and Dry compression tests using a 5 kN Universal Testing Machine (INSTRON Corp., model 1011 UK) System while Abrasion and Tumbler indices tests were conducted using Tumbler Index cylinder or drum and adopting ASTM method. It was found that Drop number as high as 7.8 times, Green compression strength and Dry compression strength up to 11.7 N/pellet and 25.99 N/pellet respectively were attained by some of the pellets. The Tumbler and Abrasion indices recorded were up to above 95% and 5% respectively. These values are higher than the minimum recommended.

Recycling Waste Polyurethane as a Carbon Resource in Ironmaking

Globally, major avenues available for dealing with waste Poly-Urethane (PU) are disposal at landfill sites and incineration. However, PU contains high levels of carbon and hydrogen that can be recovered for use as reductant in metal extraction processes. In this work the use of post-consumer PU as reductant for the production of metallic iron from iron oxide was investigated in a horizontal tube furnace through the composite pellet approach. Composite pellets were formed from mixtures of iron oxide and post-consumer PU. The iron oxide-PU composites were heated from room temperature to 1200 °C and then between 1200-1600 °C in a continuous stream of pure argon and the off gas was analysed continuously using an infrared (IR) gas analyser. Elemental analyses of samples of the reduced metal were performed chemically for its oxygen content using a LECO oxygen/nitrogen analyser. The extent of reduction was then determined at two temperatures 1200 °C and 1550 °C. Gas emission studies revealed the emission of large volumes of the reductant gas CO along with CO2. It is further demonstrated that post-consumer PU is effective at reducing iron oxide to produce metallic iron with complete reduction achieved in less than 4 min at 1550 °C. Keywords: Polyurethane, Composite Pellets, Infrared gas Analyser, LECO Carbon/Sulphur Analyser

Influence of Reduction Temperatures on Reduction of FeO-Containing Slag by Agricultural Waste

Generally, the conventional carbon sources such coke/coal are used in EAF steelmaking attributed the highest growth rate in energy consumption. A substitute routes striving to improve energy efficiency by providing auxiliary sources is essential. The unique features such high carbon content, surface area, porosity and low sulphur was available in agricultural waste clearly have the potential to be used as reducing agent in steelmaking process. The present study investigated the reduction behavior of EAF slag and production of metallic iron by reduction process. The carbon materials, coke and palm char (pyrolyzed via chemical activation) were used as reducing agent composite with EAF slag respectively. The reduction reaction was conducted in horizontal tube furnace at different reduction temperatures (1250°C, 1350°C, 1450°C and 1550°C) under argon gas (flow rate 0.01L/min) within 20 minutes. The reduced sample was examined by X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) to understand the reduction behavior of both composite samples. Palm char showed more efficient due to improvement in degree of FeO reduction which was 57.72% compared to coke, 26.72%. The phase movement from iron oxide to iron was influenced by the reduction temperatures. XRD pattern revealed that the metallic iron was initiating appeared at temperature 1250°C and completely reduced at temperature of 1550°C . Predominant peak of metallic iron and the other oxides was clarified by EDS spectra. This study found that palm char has viability to be used as carbon sources in steelmaking applications.

Production and use of concentrates from polymetallic manganese ore

Polymetallic manganese ore has been discovered in the Altae–Sayansk region. Because of its high content of phosphorus and iron, this ore cannot be used to produce standard alloys without preliminary enrichment. Thermodynamic and experimental data on the enrichment of polymetallic manganese ore permit the identification of basic principles for the extraction of the components and development of an enrichment technology. By the proposed technology, high-quality concentrates of manganese, nickel, iron, and cobalt may be obtained. Optimal enrichment parameters permit high levels of metal extraction from the ore: 95–97% for Mn, 98–99% for Ni, 96–98% for Fe, and 60% for Co. The manganese concentrate may expediently be used to produce metallic manganese and steel with low phosphorus content. That reduces Russia’s dependence on imported manganese ore. A technology for alloying steel with the nickel concentrate from the polymetallic ore has been developed. The replacement of metallic nickel by its concentrate considerably reduces alloying costs. The production of metallic iron by solid-phase reduction from the iron concentrate permits reduction in harmful impurities in the steel.

Production of Metallic Iron from Iron Oxide (Fe<sub>2</sub>O<sub>3</sub>) Using End-of-Life Rubber Tyre and its Blends with Metallurgical Coke as Reductants

The production of metallic iron from iron oxide using end-of-life tyres (RT) and its blends with metallurgical coke as reductants has been investigated through experiments conducted in a laboratory scale horizontal tube furnace. Composite pellets of iron oxide (96.89 % Fe2O3) with RT, coke and coke/RT blends (in four different proportions) were rapidly heated at 1500 °C under high purity argon gas and the off gas was continuously analysed for CO and CO2 using an online infrared gas analyser (IR). The extent of reduction after ten minutes, level of carburisation of the reduced metal and the total amount of CO2 emissions were determined for each carbonaceous reductant. The results indicate that metallic iron can be effectively produced from Fe2O3 using RT and its blends with coke as reductant. The extent of reduction and level of carburisation are significantly improved when coke is blended with RT. Blending of coke with RT resulted in significant decrease in CO2 emissions.

Morphology and Phase Evolution in Microwave Synthesized Al/Fe3O4 System

Thermite reaction between Al/Fe3O4 raised by microwave (MW) heating under N2 atmosphere has been investigated, and compared with that by the electric furnace. In addition to the stoichiometric ratio for the production of metallic iron and alumina, mixture with slightly lower in Al content is also studied. As thermite reaction is highly exothermic, melting of reaction product and destruction of microstructure may occur, which corresponds to the enthalpy and adiabatic temperature of the reaction. Hence, to avoid this problem, reaction coupled with a smaller driving force by controlling the MW ignition condition at low temperature exotherm has been investigated. The phase and microstructure evolution during the reaction were analyzed by differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Thermogram of the DTA analysis, irrespective of their mole ratio, recorded two exothermic peaks, one at ~ 1310oC and another one at ~ 1370oC. When heated by microwave at 955oC, the main products were identified as Al, FeO and Fe, minor amount of Fe3O4 and some Fe and alumina were detected. When heating to 1155oC, Al and Fe3O4 peaks disappeared, formation of Fe-Al alloy was observed. For sample heated at 1265°C, a porous body was obtained. Micron sized metal particles with complex morphology, irregular in size and shapes were formed, uniformly distributed within the spinel hercynite and/or alumina matrix. In contrast, conventional heating produced no porous products. Formation of alumina is also observed around the metal particles. Controlling of the reaction progress was possible while heating the sample by MW around the low temperature exotherm region, whereas the combustion wave could not be self-propagated.

The reducibility of the Greek nickeliferous laterites: a review

This paper refers to a critical review of the Greek nickeliferous laterites roasting reduction studies for better understanding of the process thermodynamic and kinetic mechanisms, affecting decisively the smelting step in pyrometallurgical extraction of nickel from these ores. From this work, it is deduced that iron and nickel oxide reduction degree does not exceed 33 and 76% respectively, the reductive reactions being stopped within the first 20–30 min. Thus, part of ferric iron is transformed into ferrous iron (in the form of magnetite, wustite or fayalite) instead of metallic iron production. Also, no total conversion to metallic nickel takes place. Variation of roasting temperature (700–850°C), grain size of the ores and type of solid reductants, affect the reduction rates and the final reduction degrees obtained. Diffusion or mixed control mechanisms have been found to prevail during reduction. Low reduction degrees obtained are attributed to kinetic phenomena, such as the formation of fayalite (2FeO.SiO2), which probably covers oxide grains and impedes reduction.

Utilization of Waste Plastic for the Production of Metallic Iron, Hydrogen and Carbon Monoxide without Generating Carbon Dioxide

National legislation within Japan has increased the need for the development of new process technologies that will utilise various waste materials. The present study is aimed at generating some fundamental data with respect to the application of waste plastic as a potential reductant for iron oxide. By using a high frequency induction furnace, mixtures of polyethylene+Fe2O3 were heated very rapidly to temperatures between 1673 and 2073 K in a stream of argon. Gas chromatography, chemical analysis and X-ray diffraction were used to detect reaction products, which consisted of metallic iron, ferrous oxide, char, CO, CO2, H2O, H2 and CH4, depending upon C/O mole ratios within the polyethylene+Fe2O3 mixture and the experimental temperature. The results were in good agreement with values calculated from thermodynamic equilibrium.

A comparison between the precipitation and impregnation methods for water gas shift catalysts

The precipitation and impregnation methods in the preparation of chromium-doped magnetite for water gas shift reaction (WGSR) were compared in this work. This reaction is an important step in the commercial production of highly pure hydrogen from natural gas or naphtha feedstocks. It was found that the preparation method affects both the textural and catalytic properties of chromium-doped magnetite. However, chromium was able to preserve the specific surface area during the WGSR and to delay the metallic iron production, independently of the preparation method. Chromium caused a decrease in activity per area, depending on the preparation method. This fact was assigned to its ability in making the production of Fe 2+ species more difficult, making the catalytic sites less active, because the redox cycle of the reaction becomes more difficult. The most active catalyst was obtained by adding chromium by impregnation, which led to a large amount of total chromium in the solid and then a catalyst with high specific surface area was produced. It was showed that the catalysts can be prepared in the active phase avoiding the reduction step, before reaction.