煤炭中CHNS/O元素检测方案(有机元素分析)

Dr. Liliana Krotz and Dr. Guido GiazziThermo Fisher Scientific. Milan， Italy Keywords Coal， Coke， Carbon Black，Graphite， CHNS/O， Heat Value This application note reports dataon CHNS/O determination oncarbon samples needed for qualitycontrol purposes， performed withthe FlashSmart EA. Carbon occurs as a variety of allotropes. There are two crystalline forms，diamond and graphite， and a number of amorphous (non-crystalline) forms，such as charcoal， coke， and carbon black. The most common use of carbonblack is as a pigment and reinforcing phase in automobile tires. Coke is thesolid carbonaceous material derived from destructive distillation of low-ash，low-sulfur bituminous coal. Coke is also used as a fuel and as a reducingagent in smelting iron ore in a blast furnace. For quality control purposes， the organic elements in carbon need to bedetermined. For the determination of carbon， hydrogen， nitrogen， sulfur andoxygen， the combustion method is used. The Thermo Scientific"FlashSmart Elemental Analyzer (Figure 1) allowsthe quantitative determination of carbon， hydrogen， nitrogen and oxygen incarbon. The FlashSmart EA based on the dynamic flash combustion of thesample， provides automated and simultaneous CHNS determination in asingle analysis run and oxygen determination by pyrolysis in a second run.To perform total sulfur determination at trace levels， the analyzer has beencoupled with the Flame Photometric Detector (FPD). For CHNS determination， the FlashSmart EA operatesaccording to the dynamic flash combustion of thesample. Liquid samples are weighed in tin containersand introduced into the combustion reactor via theThermo ScientificMAS Plus Autosampler. Samplescan be directly injected， with a syringe via the ThermoScientificAS 1310 Liquid Autosampler. In both cases aregulated amount of oxygen was used. After combustion，the resultant gases are carried by a helium flow to alayer filled with copper， then swept through a GC columnthat separates the combustion gases. Finally they aredetected by a Thermal Conductivity Detector (TCD). Totalrun time is less than 10 minutes (see Figure 2). For tracesulfur determination， the gases produced by combustionare carried by a helium flow to a layer filled with copper，then swept through a water trap， a short GC columnbefore the sulfur is measured by the Flame PhotometricDetector (FPD). Total run time is 5 minutes (Figure 3). For oxygen determination， the system operates inpyrolysis mode. Samples are weighed in silver containersand introduced into the pyrolysis chamber via theMAS Plus Autosampler or directly injected via the Al 1310or AS 1310 Autosamplers. The reactor contains nickelcoated carbon at 1060 ℃. The oxygen in the sample，combined with the carbon， forms carbon monoxidewhich is then chromatographically separated from otherproducts and detected by the TCD Detector (Figure 2).A complete report is automatically generated by theThermo ScientificEagerSmart Data Handling Software. Results Different carbon samples were chosen to show thereproducibility obtained with the system. Coal， coke，graphite， lignite and carbon black samples werehomogenized by a ball mill. Tables 1 and 2 show CHNS/O and CHNS determinationof different matrices. Instrument calibration wasperformed with 2-3 mg of BBOT (2， 5-Bis (5-ter-butyl-benzoxazol-2-yl) thiophene). No matrix effect wasobserved when changing the nature of sample. Table 1 also indicates the Gross Heat Value (GHV inkcal/kg) and Net Heat Value (NHV in kcal/kg) calculatedautomatically by the dedicated EagerSmart Xperiencesoftware. Figure 1. FlashSmart Elemental Analyzer coupled with FlamePhotometric Detector (FPD). Figure 2. CHNS/O configuration with TCD Detector. Figure 3. Sulfur configuration with FPD Detector. Table 1. CHNS/O determination and Heat Value calculation. Sample N% C% H% S% 0% GHV NHV 1.740 73.006 5.389 0.838 12.733 7316 7040 Coal 1.732 72.950 5.358 0.857 12.731 7316 7040 1.747 73.238 5.398 0.828 12.813 7313 7037 RSD% 0.431 0.209 0.390 1.752 0.367 0.024 0.025 1.287 80.137 4.621 0.488 4.903 7957 7720 Hard coal 1.288 80.123 4.513 0.486 5.085 7918 7687 1.329 80.706 4.617 0.497 5.094 8003 7766 RSD% 1.842 0.414 1.336 1.195 2.144 0.535 0.514 1.988 77.258 3.280 0.386 3.730 7131 7145 Brown coal 2.006 77.196 3.266 0.386 3.723 7304 7136 2.028 77.823 3.292 0.397 3.690 7364 7195 RSD% 0.998 0.446 0.397 1.630 0.575 0.442 0.444 0.758 62.281 4.636 0.377 25.202 5589 5357 Lignite 1 0.750 62.357 4.544 0.373 25.540 5574 5343 0.757 62.24 4.377 0.371 RSD% 0.559 0.074 2.899 0.724 0.942 0.184 0.192 Table 2. CHNS determination. Table 3. Trace sulfur determination by FPD Detector. Sample Sulfur Sample Sulfur Nature ppm S RSD% Nature ppm S RSD% 398 46 Coke 404 1.507 Graphite 46 1.264 392 45 Table 3 shows trace level sulfur data obtained whenusing the FPD Detector. Solid samples were weighed intin containers with the addition of Vanadium Pentoxide，a typical“oxygen donor” that allows the total conversionof sulfur. For CHNS/O determination for carbon characterizationsamples， the FlashSmart EA performs accurate analysis.Data were obtained with good reproducibility and nomatrix effect when changing the sample. CHNS determination can be performed in a single runwith the FlashSmart EA. By coupling the FlashSmartEA with the FPD Detector， trace levels of sulfur can beanalyzed. Oxygen determination can also be performed.Alongside with reproducibility of the data， the ElementalAnalyzer offers advantages also in terms of reducedoperational costs and analysis efficiency. Find out more at thermofisher.com/OEA ( C 2017 Thermo F is h er Sc i e ntific Inc. All r igh t s reserved . AST M i s a t r adema r k of t he Ame r ican S o ciety f o r Testing an d M a t eri a ls.N IS T i s a t rademark o f The N a tiona l Institute fo r Standards an d Technol o g y . Al l other t r a de m ar k s ar e th e property of Thermo F i s h erSci e nt i f i c and its subsidia r ies. Thi s in fo rma t ion is presented as a n example o f t h e capabil i ties of The r mo Fisher Sci e ntific products. I t i s not int e n d ed t o e nc ourage u s e of th e se pr o ducts i n a n y ma n n e r s t h at mi g h t infr ing e th e i n t el le ctual pr o perty r ights o f o t h ers. S pec if icatio n s， t er ms and prici ng are su b j e ct to c h an ge. N o t a l l pro d ucts are a v a ilable i n all c oun t rie s .Pl e ase consu lt y o ur loca l sales r e p resentativ e s fo r det ails.A N 42182-EN 0917S ) Thermo FisherSCIENTIFIC 碳以各种同素异形体的形式存在。有两种晶体形式，如钻石和石墨。以及一些无固定形状的（非晶体）， 例如木炭、焦炭和炭黑。碳黑被最常用用于作为汽车轮胎中的一种颜料和增强剂。焦炭是由低灰、低硫烟煤经过破坏性蒸馏得到的固体含碳物质。焦炭也被用作冶炼铁矿石的燃料和还原剂，从质量控制角度，其中的各种有机元素需要测定，使用高温燃烧法的元素分析仪来测定碳、氢、氮、硫和氧的各元素的含量。 热电FlashSmart元素分析仪基于动态+瞬烧闪点技术，可以进行全自动元素分析，一次进样即可得到C,H,N,S的含量，另外O是基于高温裂解进行分析。如果样品中S含量特别低，可以使用选配的FPD火焰光度计进行低浓度S元素的测定。