三元催化剂中AutoCatalyticConverter_hirez_2012July18检测方案(能散型XRF)

Part of Thermo Fisher Scientific Determination of Platinum， Palladium， andRhodium in Spent Automotive CatalyticConverters with Thermo Scientific Niton XL3tSeries Analyzers Introduction More than ever， highly variable compositions andvolatile prices of platinum (Pt)， palladium (Pd)， andrhodium (Rh) are important factors in the purchaseand recycling of spent catalytic converters. In 2010，the global sales of Pt， Pd， and Rh totaled， respectively，245， 299，and 27.2 tons. About 46% of the total Pt，57% of the total Pd， and 77% of the total Rh wereconsumed by the automotive catalyst industry. Thatsame year， 33.7 tons of Pt， 41.2 tons of Pd， and 7.3tons of Rh were recovered from the recycling of spentcatalytic converters [1]， representing a total value of$3 billion at the 2010 cumulative average price of finemetals. Depending on the supply， the demand， and speculation，the price of these three elements has fluctuatedstrongly over the last 20 years (see Figure 1).Thesefluctuations， as well as the tightening of emissionlegislation， have had a direct correlation on thecomposition of the catalysts， which themselves havehad a strong influence on the demand. The average concentration and the ratio of Pt andRh were more or less constant 20 years ago [2]，so a simple weighting was sufficient to arrive ata good estimation of the precious metal content.Currently， the composition，which depends on thecubic capacity of the engine and the type of fuel used，varies dramatically. The formulation can consist ofonly Pt， or various ratios of Pt-Pd-Rh， Pt-Rh， andPd-Rh [2].Today's recycled catalytic converterscome from cars manufactured， on average， 10 to 15years ago [3]. Further， the amounts of recoverablePt， Pd， and Rh in each can range from 1-2 grams fora small car to 12-15 grams for a big truck in the US. The corresponding value in precious metals rangesfrom $25 to a few hundred dollars per vehicle [4].Moreover， the trade of ground-up material sold ascatalysts can be very dangerous because of possiblealterations， which can mean inclusion of lead or spentnickel-cadmium batteries. To avoid considerable financial losses， there is adefinite advantage in having the ability to determinequickly and accurately the contents of Pt， Pd， andRh in spent catalytic converters at the collector’s siteor in the refineries. Thermo Scientific Niton XL3tx-ray fluorescence (XRF) Series analyzers are the idealinstruments for achieving this objective. Thermo Scientific Niton XL3t and Niton XL3t GOLDD+Handheld XRF AnalyzersOur advanced， NitonQ XL3t Series analyzers werethe first handheld XRF instruments equipped with a Figure 1： Pt， Pd， and Rh prices from 1992-2011 (data collected from references[3] and [5]) Materials are pulverized to a maximum 250um and loaded in XRF samplecups or sample bags for analysis. high-performance x-ray tube (50 kV/100pA max.)，enabling them to quantify rare earth elements (REEs)such as cerium， lanthanum， praseodymium， andneodymium based on their interference-free K-lines.Fundamental Parameter (FP) analysis， an algorithmthat corrects using theoretical constants for theinfluence of all elements contained in the sample， isused to measure catalyst composition. FP is suitablein the analysis of the spent catalytic materials， whichshow unprecedented variability in their composition.The correct knowledge of the rare earth element， aswell as zirconium， lead， and other elements that arepotentially present at high levels in spent catalysts is akey factor in using FP to obtain accurate results for Pt，Pd， and Rh. Additionally， the Niton XL3t GOLDD+ analyzer withThermo Scientific Geometrically Optimized LargeArea Drift Detector (GOLDDTM) technology andhigher performing x-ray tube (50 kV/200pA max.)has light element capabilities (Mg， Al， Si， P) and bettersensitivity. Methodology Automotive catalyst material is made either of aceramic substrate， mostly cordierite coated witha precious metal containing a wash coat， or of ametallic substrate with an aluminum oxide washcoat also containing precious metals. There is notechnique for analyzing non-homogeneous materialslike catalytic converters directly without samplepreparation. Therefore， the collected catalystswith ceramic substrate undergo a“de-canning”operation， which is the extraction of the ceramicwith a honeycomb structure from the steel case. Allof the ceramic is then sorted crushed， milled， andmostly blended with other catalysts [2]. In contrast，converters with a metallic substrate are first shreddedor milled， and then the metallic parts are separatedusing magnets and winnowing from the wash coatpowder containing precious metals [2]. Because of this enrichment， the precious metal content of thesewash coat samples is usually much higher than thatfor milled ceramics. In both cases， the materials arepulverized to a maximum 250pm and loaded in XRFsample cups or sample bags for analysis. The total measurement time for the Niton XL3tanalyzer and Niton XL3t GOLDD+ analyzer was120s respectively. Pt was measured with the mainfilter for one half of the total measurement time.whereas Pd and Rh were measured with the highfilter for the second half. Results The results for the analysis of three commerciallyavailable certified reference materials (CRMs) areshown in Table 1. The values of Pt， Pd， and Rhmeasured with the Niton XL3t and Niton XL3tGOLDD+ analyzers show excellent agreement withthe certified values. Figures 2 through 4 show thecorrelation curves for certified results (fire assay+ICP)vs. measured concentrations for Pt， Pd， and Rh. Thecoefficient of determination (R) for each element isprovided in the figures. The Rvalue is a measure ofhow closely the data sets correlate with each other，where a perfect correlation would have an R of 1.For all the elements determined in 130 samples， thereis an excellent linear correlation over a wide range ofconcentration between certified and measured values：both the slopes and the coefficients of determinationR are close to 1. The average of the relative differencebetween certified and measured value was 4.1% forPt， 2.8 % for Pd，and 3.7% for Rh. These resultsdemonstrate the robustness of the analysis againstconsiderable matrix changes and sometimes veryhigh concentrations of relevant concomitant elementssuch as cerium， lanthanum， zirconium， lead，iron， orchromium that were found in the 130 samples (seeFigure5). Materials/Elements XRF Analyzer Value(ppm) Certified Value (ppm) NIST SRM 2557 Pt 1110±20(2o) 1131±11 Pd 230±10(20) 233.2±1.9 Rh 130±10(2o) 135.1±1.9 NIST SRM 2556 Pt 690±30(20) 697.4±2.3 Pd 310±10 (2o 326±1.6 Rh 40±10(20) 51.2±0.5 BAM ERM-504 Pt 1720±60(20) 1777±15 Pd 290±10(20) 279±6 Rh 330±20(2o) 338±4 Table 1. Results of analysis for commercially available automotive catalystCRMs Limits of detection (LODs) for Pt， Pd， and Rh in purecordierite are given in Table2 for both the Niton XL3tanalyzer and the Niton XL3t GOLDD+ analyzer.Thesuperior sensitivity of Niton XL3t GOLDD+ enabledus to achieve a higher sample throughput whilehalving the measurement time. Element Niton XL3t GOLDD+(30s/filter) Niton XL3t(60s/filter) The limits of detection depend on the testing time， theinterferences/matrix， the level of statistical confidence Pt 10 ppm 16 ppm Pd 5 ppm / ppm Rh 5 ppm 6 ppm Table 2. LODs (3a) of precious metals in pure cordierite (common ceramicsubstrate of catalysts) Conclusions Exploration catalysts from gasoline engines withvarious ratios of Pt-Pd-Rh， Pt-Rh， or Pd-Rh， as wellas catalysts from diesel engines containing higheramounts of Pt only or wash coats from catalystswith metallic substrates were all analyzed with goodaccuracy. The analysis results were comparable tolab assays， showing that Niton XL3t Series XRFanalyzers can be used successfully in the field toprovide a good estimation of the value of spentcatalytic converters. Important benefits derived from using Niton XL3tSeries analyzers include： · Analyses take only one or two minutes vs.time-consuming lab assays · Ease of use with little training vs. lab analysisrequiring specialized knowledge · Robust FP-calibration is insensitive to matrixchanges ·Cost efficient with reduced price per analysis To discuss your particular applications andperformance requirements， or to schedule an on-sitedemonstration， please contact your local ThermoScientific portable XRF analyzer representative orcontact us directly by email at niton@thermofisher.com， or visit our website at www.thermoscientific.com/niton. Figure 2. Correlation curve for Pt-CRM vs. Niton XL3t Series analyzers Figure 3. Correlation curve for Pd -CRM vs. Niton XL3t Series analyzers Figure 4. Correlation curve for Rh - CRM vs. Niton XL3t Series analyzers In addition to these offices， Thermo FisherScientific maintains anetwork of representativeorganizationsthroughout the world. Americas Boston， MA USA +1 9786707460 niton@thermofisher.com EuropeMunich， Germany+49 89 3681 380niton.eur@thermofisher.com Asia PacificNew Territories， Hong Kong+8522885 4613niton.asia@thermofisher.com www.thermoscientific.com/niton Figure 5. Range of concentration for Pt， Pd， Rh and relevant matrix elements found in the investigated samples ( References ) @2012 Thermo Fisher Scientific Inc. All rights [1] Loferski， P.，“Platinum-Group Metals，" in 2010 Mineral Yearbook， US Geological Survey， 2011. reserved. All trademarks are the property of Thermo [2] Hageluken， C.，"Der Kreislauf der Platinmetalle- Recycling von Katalysatoren，"Autoabgaskatalysatoren，Expert Verlag， 2005. [3] Hageluken， C.， The PGM-markets and their interdependencies with the autocatalyst. Presented at the CTI Forum Material in Exhaust GasTechnology， Stuttgart， Germany. May 2008. Available at http：//www.autocatalyst-recycling.umicore.com/ [4] Tollefson， J. ， Worth its weight in platinum， Nature 450， 2007， 334-335. Fisher Scientific Inc. and itssubsidiaries.Specifications， terms andpricing are subject tochange. Not all products areavailable in all countries.Please consult your local salesrepresentative for details. ( [5] http：//www.kitco.com ) 8-316 07/2012 More than ever, highly variable compositions andvolatile prices of platinum (Pt), palladium (Pd), and rhodium (Rh) are important factors in the purchase and recycling of spent catalytic converters. In 2010, the global sales of Pt, Pd, and Rh totaled, respectively, 245, 299, and 27.2 tons. About 46% of the total Pt, 57% of the total Pd, and 77% of the total Rh were consumed by the automotive catalyst industry. That same year, 33.7 tons of Pt, 41.2 tons of Pd, and 7.3 tons of Rh were recovered from the recycling of spent catalytic converters [1], representing a total value of $3 billion at the 2010 cumulative average price of fine metals.