Automobile Catalysts Research Articles

Application of a Novel Phosphonium-Based Ionic Liquid to the Separation of Platinum Group Metals from Automobile Catalyst Leach Liquor

The recovery of platinum group metals (PGMs) from automotive exhaust catalysts is important, and hydrometallurgical extraction is an effective approach. In the present study, a newly designed phosp...

Rare earth elements, U and Th in tunnel dusts of São Paulo city, Brazil

São Paulo is one of the most populated cities in the world, with about 20 million inhabitants in its metropolitan area, more than 12 million motor vehicles and intense industrial activity. Given its importance as a major urban center in South America and the lack of information concerning urban dust composition, the present study aimed to determine rare earth elements (REEs), U and Th mass fractions in tunnel dust, collected in the Jânio Quadros Tunnel, and to assess their possible sources. The study of REEs distribution in urban environments has become of interest over the last decades, due to the increasing industrial use of these elements. The REEs, that are as common as the most familiar metals, are found in metallurgical additives, fluid cracking catalysts and automobile converter catalysts, among other applications. In this study, which employed Instrumental Neutron Activation Analysis (INAA) as analytical technique, the mass fractions of eight REEs were determined and normalized to the chondrite concentration values. The results showed that major concentrations were found for light REEs, following the sequence Ce > La > Nd > Sm > Yb > Eu > Tb > Lu. The pattern of the results pointed to a natural origin for these elements. Regarding U and Th concentrations, the results varied between 1.0 – 9.4 µg g-1 and 3.3 – 35.9 µg g-1, respectively. Since there is almost no information about the concentration of these elements in this kind of matrix in São Paulo city, these data are important to support further investigations.

Recovery of platinum from waste effluent using polyethyleneimine-modified nanocelluloses: Effects of the cellulose source and type

Nanocellulose is a promising biosorbent for the recovery of precious metals from waste streams. A variety of nanocelluloses exhibit significant different properties that depend on the natural source and type. In this study, cellulose nanofibrils(P-CNF) and cellulose nanocrystals(P-CNC) obtained from hard wood pulp and CNF from tunicates(T-CNF) were evaluated for their ability to recover platinum(Pt) after modification with polyethyleneimine(PEI). The PEI grafting density on each nanocellulose was distinct, resulting in significant variations in the Pt adsorption performance. The Pt adsorption capacity of the PEI-modified nanocelluloses followed the order T-CNF>>P-CNC > P-CNF. The inherent characteristics of T-CNF, that is, the negative charge and high surface area caused by open porous structure, were found attributed to the grafting of ≈40% PEI and the excellent Pt adsorption capacity(≈600 mg/g). Also PEI-modified T-CNF exhibited high selectivity towards Pt in the presence of other metals. Finally, PEI modified T-CNF was applied for Pt recovery from simulated spent automobile catalyst leachate to prove feasibility in a real application.

Current State and Problems of Analytical Control of Spent Automobile Catalysts (Review)

Abstract—Spent Automobile Catalysts (SACs) hold a special place among secondary raw materials containing precious metals. Accurate determination of platinum group metals in SACs plays an important role influencing the economic efficiency of the utilization process. In this work, we review the methods of analysis of SACs available in the literature, as well as methodological developments of the Giredmet Institute in collaboration with Anserteko and NUST “MISiS”. The main emphasis is placed on the use of modern tools for chemical preparation of hard-to-break objects like SACs, including autoclave and microwave opening of the samples. The advantages of the assay concentration method based on developments at the Yekaterinburg Non-Ferrous Metals Processing Plant for analysis of SACs are considered. We discuss certified spectroscopic and chemical methods which have been developed for analysis of spent automobile catalysts and outline the ways of their further improvement.

Estimation of the radiation dose of 107Pd in palladium products and preliminary proposal of appropriate clearance level

ABSTRACT The effective radiation dose of palladium under the assumption that it is contaminated with 107Pd (1 Bq/g) is estimated through four exposure pathways: the inhalation of airborne particles emitted from an automobile exhaust control catalyst, ingestion via food or drinking water, ingestion of palladium in saliva after release from a dental application, and inhalation exposure of dust in the work place. The highest dose (3.17 × 10−9 μSv/y) was estimated in adult workers manufacturing palladium products. Considering variations in parameters and possible exposure pathways, it is concluded that this is the critical group for determining the clearance level of 107Pd. The clearance level, which is defined as a 107Pd concentration providing less than 10 μSv/y in any exposure pathway, is calculated as 3.16 × 103 Bq/g.

Recovery of Platinum and Palladium from Spent Automobile Catalyst by Solvent-Impregnated Resins

ABSTRACTSeparation of platinum and palladium, using solvent-impregnated resin (SIR) impregnating di-hexylamine (DHA), di-n-octylamine (DOA), or di-hexyl sulfide (DHS), coated by polyvinyl alcohol crosslinked by glutaraldehyde, was investigated. Coating of the SIR successfully suppressed leakage of the extractant during adsorption. The coated SIR was applied to chromatographic recovery of the two metals and quantitative adsorption–elution was performed via the frontal analysis mode. The adsorption of Pt and Pd was achieved, while adsorption of the co-existing metals in the leaching solution was suppressed. Separation of Pt and Pd was achieved by employing sequential chromatography system together with the quantitative elution of Pt from DHA-SIR with the mixture of 0.5 mol/L thiourea and 0.5 mol/L HCl and that of Pd from DHS-SIR with the mixture of 0.1 mol/L thiourea and 0.5 mol/L HCl solution. Finally, elementary Pt was then obtained from the eluent of sequential chromatography system by simultaneous precipitation and reduction of Pt with sodium borohydride with 99.2% purity.

Influence of H2O2 and O3 on PGM Extraction from Used Car Catalysts

Influence of H2O2 and O3 on PGM Extraction from Used Car Catalysts

Recovery of Platinum Group Metals from Spent Catalysts Using Iron Chloride Vapor Treatment

The recovery of platinum group metals (PGMs) from spent automobile catalysts is a difficult process because of their relatively low contents in the scrap. In this study, to improve the efficiency of the existing recycling techniques, a novel physical concentration method involving treatment with FeCl2 vapor has been examined. The reactions occurring between typical catalyst components and FeCl2 vapor are discussed from the thermodynamic point of view, and the validity of the proposed technique was experimentally verified. The obtained results indicate that the vapor treatment at around 1200 K (927 °C) can effectively alloy PGMs (Pt, Pd, and Rh) with Fe, resulting in the formation of a ferromagnetic alloy. It was also confirmed that cordierite and alumina (the major catalyst components) remained unreacted after the vapor treatment, while ceria species were converted into oxychlorides. The samples simulating the automobile catalyst were also subjected to magnetic separation after the treatment with FeCl2 vapor; as a result, PGMs were successfully extracted and concentrated in the form of a magnetic powder. Thus, the FeCl2 vapor treatment followed by magnetic separation can be utilized for recovering PGMs directly from spent catalysts as an effective pretreatment for the currently used recycling methods.

Real life experimental determination of platinum group metals content in automotive catalytic converters

The real life experimental protocol for the preparation of spent automobile catalyst samples for elemental analysis is thoroughly described in the following study. Collection, sorting and dismantling, homogenization and sample preparation for X-Ray fluorescence spectroscopy and Atomic Adsorption Spectroscopy combined with Inductive coupled plasma mass spectrometry are discussed in detail for both ceramic and metallic spent catalysts. The concentrations of Platinum Group Metals (PGMs) in spent catalytic converters are presented based on typical consignments of recycled converters (more than 45,000 pieces) from the Greek Market. The conclusions clearly denoted commercial metallic catalytic foil contains higher PGMs loading than ceramic honeycombs. On the other hand, the total PGMs loading in spent ceramic catalytic converters has been found higher than the corresponding value for the metallic ones.

Pyrolysis of marine biomass to produce bio-oil and its upgrading using a novel multi-metal catalyst prepared from the spent car catalytic converter

In order to reduce the economic and environmental consequences caused by spent car catalyst, we herein report for the first time a novel promising multi-metal catalyst prepared from spent car catalytic converters to upgrade the pyrolysis bio-oils. The physico-chemical properties of prepared catalyst were characterized by XRD, EDS, FESEM, and FT-IR analyses. The thermal stability of the multi-metal catalyst was studied with TGA. To investigate the activity of the catalyst, Conversion of Cladophora glomerata (C. glomerata) into bio-products was carried out via a fixed bed reactor with and without catalyst at the temperature of 500°C. Although the catalyst didn’t catalyze the gasification reaction, bio-oil was upgraded over the catalyst. The main effect of the catalyst on the bio-oil components is deoxygenating of nitrogen compounds and promotion the ketonization reaction, which converts acid to ketone and declines the corrosive nature of bio-oil.

Eco-threat Minimization in HCl Leaching of PGMs from Spent Automobile Catalysts by Formic Acid Prereduction

Reclamation of spent automobile catalysts via aqueous processing for the efficient recovery of Pt, Pd, and Rh (PGMs) has remained a challenge. In this research, the effect of prereduction by HCOOH ...

Magnetic Concentration of Platinum Group Metals from Catalyst Scraps Using Iron Deposition Pretreatment

Spent automobile catalysts are the most important secondary source of platinum group metals (PGMs). However, effective recovery of PGMs from catalyst scraps is difficult because they are present in only small quantities as chemically stable substances. In this study, in order to improve the efficiency of the existing recycling processes, the authors experimentally investigated a novel physical concentration pretreatment process for PGMs using samples that simulate an automobile catalyst. In order to magnetically separate PGMs directly from the catalysts, ferromagnetic Fe was deposited on the PGM particles (or the porous catalyst layer) using an electroless plating technique. By using a plating bath containing sodium borohydride and potassium sodium tartrate as the reducing and complexing agents, respectively, Fe was successfully deposited on the sample without requiring complicated pretreatments such as sensitization and activation. After Fe deposition and subsequent pulverization, the PGMs could be extracted and concentrated in the form of magnetic powder using a magnet. The proposed magnetic concentration process was demonstrated to be feasible, and it has the potential to make the recycling of PGMs more efficient and environmentally friendly.

A magnetized graphene oxide modified with 2-mercaptobenzothiazole as a selective nanosorbent for magnetic solid phase extraction of gold(III), palladium(II) and silver(I)

This article describes a useful sorbent for separation and preconcentration of trace amounts of gold(III), palladium(II) and silver(I) ions. Graphene oxide (GO) nanoparticles were synthesized by a modified Hummers method and magnetized by MnFe2O4 nanoparticles to give a sorbent referred to as mag-GO. Addition of sodium dodecyl sulfate creates admicelles on the surface of the mag-GO. Then the metal chelating agent 2-mercaptobenzothiazole (MBT) was immobilized on mag-GO to give a mag-GO-MBT type material. This adsorbent was applied to the preconcentration of gold(III), palladium(II) and silver(I) ions. Following ion desorbed with a solution of thiourea, the ions were quantified by flow injection coupled to ICP-OES. Effect of sample pH value, type and volume of eluent, amount of adsorbent, sample volume, time of adsorption and desorption were optimized. Under optimized condition, the calibration plots are linear in the 2.5 to 25,000 μg.L−1 concentration range. The limits of detection range from 0.045 to 0.076 μg.L−1, and enhancement factors are 160, 160 and 140 for gold, palladium and silver ions, respectively. Precisions, expressed as relative standard deviation for 100 μg.L−1 of each ion are <3.1%. The nanosorbent applied to selective adsorption, extraction and preconcentration of Au(III), Pd(II), and Ag(I) from water, ore and automobile catalyst samples.

High selectivity and extractability of palladium from chloride leach liquors of an automotive catalyst residue by azothiacalix[4]arene derivative

Pd(II) is a noble metal in the platinum group metals (PGMs) and has been used extensively in automobile catalysts. However, its resources are strictly limited; thus, the recovery of Pd(II) from wastes or secondary sources currently has great importance. A new ligand, namely, 11,17,23-tetrakis-[(p-methoxyphenyl)azo]-25,26,27,28-tetrakis[(dimethyl thiocarbamoyl)oxy]thiacalix[4]arene (MADTTCA), was investigated for the extraction of Pd(II) from a hydrochloric acid medium using chloroform as a diluent. Extraction data indicate that the extraction efficiency depends on the concentration of HCl, from 0.1–5.0M. The equilibrium extraction time of MADTTCA was achieved with a short contact time (15min), which made MADTTCA a suitable candidate for industrial applications. Notably, the maximum uptake capacity of MADTTCA for Pd(II) was found to be 417mg/L using 1.0mM MADTTCA. On the basis of the obtained data, the stoichiometric ratio between Pd(II) and MADTTCA was found to be 1:1. MADTTCA was shown to be highly effective at extracting Pd(II) from simulated mixed metal and automotive catalyst residue (ACR) solutions composed of six metal ions (PGMs), such as Pd(II), Pt(IV), Rh(II), Al(III), La(III) and Ce(III). More than 99.9% of the extracted Pd(II) was stripped with 0.1M thiourea in a 1.0M HCl solution. The title extractant was able to be recycled and reused at least five times without a significant loss of its extraction features. All of the obtained results revealed that MADTTCA can be used for the selective recovery of Pd(II) from ACR solutions.

List of Abstracts

. Production efficiency as well as the reduction of energy consumption and waste are the main drivers for the improvement of large-scale production in chemical industry. In addition, the demand for new processes – these days especially related to the chemical energy conversion as basis for the Energiewende – are additional triggers for innovation. Catalysis, well recognized by the public e.g. in form of the 3-way automobile catalyst, plays an important role for about 90% of all processes in chemical industry. The development of new and improved catalysts is a challenge for chemists – as is the search for new structural materials for mechanical engineers. Due to the often-necessary noble and thus expensive metals (e.g. palladium) in many catalysts, structural and chemical function have been developed separately in the two communities. Recent progress in catalytically active materials allows replacing expensive noble metals in selected catalytic processes by significant cheaper elements [1]. This offers the new perspective to combine structural and chemical functionality by innovative materials. Within this area, intermetallic compounds with their peculiar combination of crystal and electronic structure [2], represent an interesting class of materials to address this vision as will be shown in the contribution.

Recovery of palladium from secondary waste using soluble tannins cross-linkedLagerstroemia speciosaleaves powder

BACKGROUND Naturally available biomass can be explored as a potential sorbent for recovery of precious metals. This work evaluates the sorption potential of a biosorbent developed by host soluble tannins cross-linked Lagerstroemia speciosa leaves powder (TLS) for Pd recovery from secondary waste. RESULTS Batch experiments suggest 95% Pd(II) sorption by TLS is achieved over a pH range of 1–6 with a maximum of 99% at pH 2. The experimental data for Pd(II) sorption onto TLS is well explained by pseudo-second-order kinetics and the Langmuir isotherm model with a monolayer sorption capacity of 46.3 mg g−1. Thermodynamic variables indicate that Pd(II) sorption onto TLS is spontaneous, endothermic, and physical in nature. TLS biosorbent was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy (XPS). XPS results reveal the presence of zero-valent Pd and mono or divalent Pd species on the TLS surface, which conclude that Pd(II) removal is governed by a sorption-reduction mechanism. CONCLUSIONS The TLS is effective in Pd(II) recovery from an acid-leached solution of monolithic ceramic capacitors (A-MLCC) and simulated spent automobile catalyst (A-SSAC), which suggests that this biosorbent can be used as a promising material in biotechnological processes for recovery of precious metals from secondary waste. © 2016 Society of Chemical Industry

Development of Combining of Human Bronchial Mucosa Models with XposeALI® for Exposure of Air Pollution Nanoparticles.

BackgroundExposure to agents via inhalation is of great concerns both in workplace environment and in the daily contact with particles in the ambient air. Reliable human airway exposure systems will most likely replace animal experiment in future toxicity assessment studies of inhaled agents.MethodsIn this study, we successfully established a combination of an exposure system (XposeALI) with 3D models mimicking both healthy and chronic bronchitis-like mucosa by co-culturing human primary bronchial epithelial cells (PBEC) and fibroblast at air-liquid interface (ALI). Light-, confocal microscopy, scanning- and transmission electron microscopy, transepithelial electrical resistance (TEER) measurement and RT-PCR were performed to identify how the PBEC differentiated under ALI culture condition. Both models were exposed to palladium (Pd) nanoparticles which sized 6–10 nm, analogous to those released from modern car catalysts, at three different concentrations utilizing the XposeALI module of the PreciseInhale® exposure system.ResultsExposing the 3D models to Pd nanoparticles induced increased secretion of IL-8, yet the chronic bronchitis-like model released significantly more IL-8 than the normal model. The levels of IL-8 in basal medium (BM) and apical lavage medium (AM) were in the same ranges, but the secretion of MMP-9 was significantly higher in the AM compared to the BM.ConclusionThis combination of relevant human bronchial mucosa models and sophisticated exposure system can mimic in vivo conditions and serve as a useful alternative animal testing tool when studying adverse effects in humans exposed to aerosols, air pollutants or particles in an occupational setting.

New Heterocyclic Dithioether Ligands for Highly Selective Separation and Recovery of Pd(II) from Acidic Leach Liquors of Spent Automobile Catalyst

The solvent extraction behavior of Pd(II) from a hydrochloric acid solution with heterocyclic dithioether ligands, namely, 1,2-bis((5-methyl-1,3,4-thiadiazol-2-yl)thio)ethane (BMDTE) and 1,2-bis((5-(methylthio)-1,3,4-thiadiazol-2-yl)thio)ethane (BMTDTE) were investigated, for the first time, as potential extractants by using chloroform as diluent. Various experimental parameters such as effects of the concentration of hydrochloric acid, extractant concentration, hydrogen ion, chloride ion, and diluents on the extraction of Pd(II) was also investigated in detail. By comparing the extraction time, BMDTE exhibits a more rapid and quantitative extraction of Pd(II) even within 5 min than BMTDTE (30 min). The loading experiments indicated that the maximum loading capacity of BMDTE and BMTDTE for Pd(II) was determined to be 124 and 118 ppm, respectively. The stoichiometry of the extracted species during extraction was confirmed by 1H NMR and Job’s method analysis. Both of the two extractants exhibit high extract...

ChemInform Abstract: Rh Nanoparticle Anchoring on Metal Phosphates: Fundamental Aspects and Practical Impacts on Catalysis

AbstractReview: [21 refs.

A selective dynamic sorption-filtration process for separation of Pd(II) ions using an aminophosphine oxide polymer

Abstract In order to develop an industrially applicable method for the use of phosphine oxide-based powder material for the capture and concentration of platinum group metals (PGM) from acidic effluents, a two stage process is proposed in this work. The process steps involve coupling the metal sorption on the powder in a continuous stirred tank reactor (CSTR) with a microfiltration PTFE membrane enabling a subsequent stripping of the metals concentrated on the powder material using an acidified solution of thiourea. Using a model solution with 0.6 mM Pd(II) in HCl and common metals as impurities (0.6 mM of Ni(II) and Cu(II) each), the process was conducted for several cycles leading to the final solution containing up to 9.8 mM of Pd(II) with a purity of around 90%. In addition, this process was successfully applied to a leachate of a car catalyst converter, that contained not only palladium, but also platinum, rhodium, as well as large excess of aluminum, cerium and iron. We have thus arrived at a robust process for concentrating effluents containing precious metals, achieving high concentration factors and purities of the final stream, while having low material loss and/or fouling of equipment.