Article pubs.acs.org/IECR
Nanocomposite MFI-Alumina Hollow Fiber Membranes: Influence of NOx and Propane on CO2/N2 Separation Properties C−H. Nicolas1 and M. Pera-Titus1,2,* 1
University of Lyon, Institut de Recherches sur la Catalyse et l′Environnement de Lyon (IRCELYON), UMR 5256 CNRS/UCBL1, 2 Av. A. Einstein, 69626 Villeurbanne, France 2 Eco-efficient Products and Processes Laboratory (E2P2L), UMI 3464 CNRS/Rhodia, 3966 Jin Du Road, Xin Zhuang Industrial Zone, 201108 Shanghai, China S Supporting Information *
ABSTRACT: This study provides a detailed survey of the effect of moisture, NOx and light hydrocarbons (i.e., propane) on the CO2/N2 permeation and separation properties of MFI-type hollow-fiber membranes in view of on board CO2 capture applications in Diesel vehicles. Five different MFI-alumina samples have been prepared including different degrees of isomorphous boron and germanium substitution, as well as ex framework proton exchange by copper. The quality of the synthesized hollow fibers has been primarily assessed by pure N2 permeation and n-butane/H2 and SF6/N2 separation at room temperature. The different materials show preferential CO2/N2 and CO2/NO selectivity at low CO2 feed concentrations (∼10%) in the temperature range 298−373 K, which can be appreciably promoted under the presence of propane (1 v/v %). The materials show stable and high CO2 permeances even in the presence of large amounts of water in the feed stream. On the basis of the permeation and separation data measured in this study, we present a refined simulation study of a membrane cascade system constituted of two hollow-fiber membrane modules coupled to a DeNox unit for on board CO2 capture and liquefaction/ supercritical storage in heavy vehicles (>40 tn).
1. INTRODUCTION Climate change due to anthropogenic CO2 emissions is a paramount challenge facing our planet in the forthcoming decades. CO2 capture, transport, and long-term storage (CCS) from postcombustion emission sources is visualized as a promising strategy for mitigating CO2 emissions at short and midterm. Among the three steps of the CCS chain, CO2 capture is by far the most expensive one, accounting for 50− 90% of the overall chain cost depending on the emission source.1 Until now, the reported studies and surveyed technologies for postcombustion CO2 capture have focused on stationary sources (e.g., power plants). To our knowledge, no systematic report is still available on technological solutions for postcombustion CO2 capture in mobile sources (e.g., vehicles). Indeed, transport accounted for about 22% of world CO2 emissions in 2009 just after electric and heat generation (41%)2 and this proportion is even larger for countries with intensive nuclear power generation (e.g., France). The development of specific postcombustion CO2 capture solutions for vehicles appears to be a promising option, especially if high-autonomy batteries for electrical engines and efficient hydrogen storage materials for fuel cells become economically discouraged. Moreover, using an on board CO2 capture unit, vehicles could drastically cut CO2 emissions down to the legal limit of 120 gCO2/km set by the EU3 without a dramatic change of propulsion technologies (i.e., internal combustion engines). To become economically feasible, on board CO2 capture technologies should involve reasonable energy costs in terms of power overconsumption, small volume layouts and provide sufficient autonomy to be acceptable for the user. In a previous © 2012 American Chemical Society
study, we have addressed a possible technological solution to meet these requirements for heavy vehicles (>40 tn weight).4 In this concept, the exhaust gas emitted from the vehicle after catalytic CO oxidation and NOx reduction is submitted to a membrane system for CO2 separation and purification. Ideally, the CO2 capture system should allow the removal of at least 75% of the CO2 in the exhaust gas with a purity >95% in the permeate without a significant energy overconsumption (1 μmol·m−2·s −1·Pa−1 at 298 K), robustness and optimal reproducibility of the synthesis protocols unlike other promising zeolite membranes materials (e.g., DD3R5,6) and carbon hollow fibers.7 In a series of studies, we have investigated the genesis and performance of MFI-type membranes in the separation of CO2/N2 mixtures under dry conditions.8−10 To achieve a comprehensive understanding of the performance of such materials for an on-board CO2 capture application, we need indeed to study their separation Received: Revised: Accepted: Published: 10451
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wet spinning process, were supplied by the Fraunhofer Institute for Interfacial Engineering and Biotechnology (IGB, Germany). Only hollow fibers displaying first bubble points above 120 kPa for dry ethanol, corresponding to an average crossing pore size smaller than 0.2−0.3 μm, were used for synthesis. These supports correspond to the A−C categories discriminated in a previous study from xylene separation properties on Al-MFI hollow fibers.9 Aerosil 380 (fumed SiO2), boric acid (H3BO3) and GeO2, supplied by Sigma-Aldrich, were used, respectively, as silica, boron, and germanium sources. Tetrapropylammonium hydroxide (TPAOH, 1 M) was used as template agent. The gases (He, Air, N2, O2, CO2, propane, and NO (5000 ppm in Ar), all with purity >99.9999%, were supplied by Air Liquide. 2.2. Synthesis of (B,Ge,Cu)-MFI Hollow Fibers. The nanocomposite MFI-alumina hollow-fiber membranes were prepared by pore-plugging interrupted hydrothermal synthesis in a Teflon-lined autoclave (15 mL) at 443 K for 89 h using a precursor solution with varying molar composition 1 SiO2/0.45 TPAOH/27.8 H2O/xH3BO3/yGeO2 matured during 3 days at room temperature under mild stirring. More details on the synthesis protocol can be found in previous publications.8,23−25 The samples were labeled as follows: Al-MFI (bare MFIalumina hollow fiber), B-MFI-100 (Si/B = 100), B-MFI-50 (Si/ B = 50) and Ge-MFI-10 (Si/Ge = 10). The indicated B/Si and Ge/Si ratios correspond to the theoretical values in the synthesis solution. After the synthesis, the fibers were washed with distilled water until neutral pH, dried at 373 K for 12 h, and calcined at 773 K for 6 h with heating and cooling ramps of 1 K/min. Cuexchanged MFI samples were prepared by the ion-exchange of parent Al-MFI samples by immersing the fibers in a solution of copper acetate (20−50 mL) at room temperature for 24 h. The as-calcined hollow fibers were immobilized on a supporting dense alumina perforated tube using a homemade low-temperature glaze. The final ensemble was then mounted in a membrane stainless steel module using graphite cylindrical gaskets (Cefilac−Fargraf). Prior to any transport measurement, the hollow fibers were subjected to an in situ high temperature desorption pretreatment at 673 K under 20 cm3(STP)/min N2 flow at both sides with a heating ramp of 1 K/min for at least 4 h to remove adsorbed species following the guidelines of a previous study.26 2.3. Physical Characterization. Some crushed MFIalumina hollow fibers were analyzed by X-ray diffraction (XRD) using a Philips PW1050/81 diffractometer (Cu Kα1+2 radiation) to qualify the structure of the synthesized zeolite material. The morphology of the hollow fibers was inspected by scanning electron microscopy (SEM) using a Hitachi S-800 microscope operating at 15 kV equipped with EDX micropobe analysis (EDAX−Phoenix). Quantitative estimation of the Si/Al and Si/B ratios was performed using inductively coupled plasma atomic emission spectroscopy (ICP−AES) using a flame Perkin-Elmer M1100 spectrometer. For Si analysis, the sample was fused in Li2B4O7 using a Pt−Au crucible by heating up to 1273 K and then dissolved in HCl (20 wt %). For B analysis, the sample was dissolved in a H2SO4 + HNO3 + HF solution and further heated to 393 K for 12 h. Solid-state magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR) was used to characterize the local 29 Si and 27Al environments in crushed MFI-alumina hollow
performance in the presence of pollutants (i.e., moisture, NOx, and hydrocarbons). Unfortunately, the available literature on the permeation and separation properties of MFI membranes under realistic postcombustion CO2 capture conditions is scarce. Bernal et al.11 explored the room-temperature CO2/N2 separation performance (equimolar mixture) of B-ZSM-5 membranes saturated with water vapor. The CO2 permeance decreased about 54% at a feed pressure of 1.7 bar with no remarkable change of the separation factor. Shin et al.12 reported an increase of the CO2/N2 separation factor (from 50 to 60) on a surface-modified ZSM-5 membrane in the separation of a moisture-saturated equimolar CO2/N2 mixture at near-room temperature. It was believed that water blocked partially both the MFI adsorption sites and the intercrystalline nonzeolite pores, overcoming N2 permeation and thus increasing the CO2/N2 separation factor. Our group has recently reported a steady-state decrease of the mixture CO2 and N2 permeances on (Ge)-MFI-alumina membrane tubes with nanocomposite architecture,13,14 becoming more moderate at higher enough temperatures (about 40% at 373 K). All the above stated studies point out the higher hydrothermal stability of MFI membranes compared to SAPO-34 materials, the latter suffering from aging after long exposure to a wet atmosphere.15 Some other studies have surveyed the effect of NOx and hydrocarbons on the permeation properties of zeolite membranes. Hedlund and co-workers16 reported recently a marked reduction of the N2 permeance in the presence of 500− 4000 ppm of NOx. These authors attributed this observation not only to the preferential but weak adsorption of NOx over Na+ cations at near-room temperature, but also to the formation of more strongly bound surface complexes at higher temperatures by reaction with surface silanol groups and adsorbed water in the zeolite, resulting in a partial reduction of NO2 to NO.17 In a series of studies, Noble and Falconer have shown that the gas permeation properties can be strongly affected by crystal swelling in zeolite films, blocking intercrystalline pathways.18−21 As a result, defective zeolite layers can still show gas separation properties.22 While the above stated studies report the influence of humidity, NOx, and hydrocarbons on the CO2 and N2 permeation properties of MFI membranes, to our knowledge no exhaustive study has been devoted to the combined effect of such pollutants on the membrane separation properties. Taking into account the relevant adsorption capacity and strength of such species in MFI-type zeolites, their competitive adsorption/ diffusion in MFI membranes could affect the CO2 separation properties. The present study is intended to elucidate such effects, with an insight into possible means for boosting CO2/ N2 separation factors as an attempt to conceive membranebased technological solutions for on board CO2 capture in vehicles. Five different topical zeolite hollow fibers have been prepared with different degrees of isomorphous substitution by boron and germanium to tune the acidity and hydrophilic behavior of the samples, and Cu-exchange to conceive catalytic applications for DeNox. Relying on the results obtained, we present in the Discussion section a revised version of our onboard CO2 capture concept for heavy vehicles (>40 tn) in the presence of moisture with combined DeNox treatment.
2. EXPERIMENTAL SECTION 2.1. Materials. The ceramic hollow fibers used in this study (o.d., 1.65 mm; i.d., 1.44 mm; porosity, 43%), prepared by a 10452
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membrane. The permeate was swept with an He flow (80 mL(STP)/min). The feed was kept at about 200 kPa, while the transfiber differential pressure was kept at 50 kPa. Some experiments were carried out at different water compositions in the range 1−20%. The separation of a 10 CO2/1 propane/2 O2/0.5 NO/86.5 N2 mixture was also tested in view of simultaneous CO2 and NO separation and HC-SCR catalytic applications. These tests were performed in WK configuration in the range 300−723 K by feeding 500 cm3(STP)/min (Ar) to the inner side of the fibers and 200 cm3(STP)/min to the permeate side. The pressure at the retentate sides of the membrane was kept at 200 kPa, while the transfiber differential pressure was kept at 50 kPa. The permeance of a target species was defined as the permeation flux divided by its corresponding log-mean differential partial pressure, while the separation factor (Sfi/j) was defined as the enrichment factor of one component to another in the permeate, as compared to the feed composition ratio
fibers. The 29Si NMR spectra were recorded on a Bruker DSX 400 spectrometer operated at 79.4 MHz with a 90° pulse length of 3.5 μs, a spinning rate of 10 kHz without cross-polarization, and a repetition time of 40 s between acquisitions, the chemical shifts being referenced to Si(CH3)4 (TMS). The 27Al-NMR spectra were recorded at 104.3 MHz using a Al(NO3)3 (1 M) reference solution with a 15° pulse length of 1.8 μs, a spinning rate of 10 kHz without cross-polarization and a repetition time of 500 ms between acquisitions. 2.4. Adsorption Isotherms. CO2 and propane isotherms were measured on crushed MFI-alumina hollow fibers using a BelSorp HP microvolumetric apparatus, while water isotherms were measured on a BelSorpMax. All the isotherms were measured at 303 K. Prior to the adsorption measurements, the samples were desorbed at 523 K and 10−5 Pa for 4 h to remove any adsorbed species. 2.5. n-Butane/H2 and SF6/N2 Quality Tests. n-Butane/H2 and SF6/N2 separations were carried out for quality testing. Both separations were performed in Wicke−Kallenbach (WK) mode with increasing temperature, the gases being diluted in dry N2 (15 v/v %) and He (15 v/v %), respectively. The feed was kept at 104−125 kPa with a transfiber differential pressure of 0.4 kPa. The flow rate in the feed and permeate streams were kept both at 80 cm3(STP)/min in both separations using mass flow controllers (Brooks 5850 TR). The composition at the retentate and permeate sides of the membrane was analyzed using a HP 5890/series II GC equipped with a Porapak Q column and a TCD detector. The separation factor of n-butane over H2 and SF6 over N2, SfC4H10/H2 and SfSF6/N2, respectively, were calculated as the permeate-to-feed composition ratio of n-butane (or SF6), divided by the same ratio for H2 (or N2). The separation factor was measured at steady state and room temperature. In all the separations, mass balances were performed with an accuracy better than 5%. 2.6. Pure and Mixture CO2/N2/NO Permeation Tests. The setup used for carrying out the pure and mixture CO2, N2, and NO permeation tests in the presence of vapors has been described elsewhere.13 In all the tests, gas flows and feed compositions were controlled by mass flow controllers (Brooks, types 5850TR and 5850E). The overall permeation fluxes were measured using a volumetric flowmeter (DryCal, Bios). On the one hand, the CO2 and N2 composition at the feed, retentate, and permeate streams was analyzed online using a μGC (Agilent 3000) equipped with two columns (PPU+MS5A and PPQ+PPU) and two thermal conductivity detectors (TCD) using Ar and He as carrier gases. On the other hand, the NOx permeance was measured in WK mode by feeding a 500mL(STP)/min NO mixture (5000 ppm in Ar) to the inner side of the fiber and 200 mL(STP)/min of Ar to the outer permeate side. The NOx composition was analyzed by chemiluminescence using a CLD 822 Mh equipement (Ecophysics). Two regulation valves at the outlet of the retentate and permeate streams were used to adjust, respectively, the feed and transmembrane pressures. The desired water humidity in the feed stream was introduced by heating a pressurized liquid water stream with the corresponding flow rate controlled using a liquid mass flow controller (Bronkhorst Hi-Tech). A hygrometer equipped with a probe was used for monitoring the relative humidity in the feed and permeate streams. Binary CO2/N2 and ternary CO2/N2/NO separations were performed by feeding 500 cm3(STP)/min (10 CO2: 90 N2 and 10 CO2: 89 N2: 0.5, respectively) to the inner side of the
Sfi / j =
(yi /yj )permeate (xi /xj)feed
(1)
where xi and xj and yi and yj are, respectively, the molar fractions of species i and j in the retentate and permeate streams.
3. RESULTS 3.1. Quality of the Synthesized MFI-Alumina Hollow Fibers. The XRD patterns of the crushed (B,Ge)-MFI hollow fibers (not shown) show characteristic diffraction peaks in the range 7−9° and 23−25° belonging to the MFI unit cell, reflecting the formation of pure MFI phases for all the membrane samples. Within the limits of the experimental error, no detectable variation of the unit cell size can be deduced from the shift of the peaks upon B or Ge incorporation to the MFI framework. This observation opposes the slight peak deviation of about 0.2% reported by van de Water et al.27 for the reflection at 2.0107 Å (2θ = 45.050°) on Ge- ZSM-5 (Si/Ge = 9) samples. The SEM micrographs of the materials (not shown) confirm in all cases the formation of genuine nanocomposite architectures, namely no zeolite film is formed on top of the support, most of the MFI material being hosted in the large central cavities. The average Si/Al ratio at about 50-μm depth for the Al-MFI sample is about 13 (including the alumina support) as measured by EDX analysis, corresponding to small pores. The Si/Al ratio of the MFI phase measured from 29Si and 27Al MAS NMR lies in the narrow range 23−30 for the AlMFI and boron-substituted samples (3.6−4.0 Al atoms/uc) and a value of 150 (0.6 Al atoms/uc) for the Ge-MFI-10 hollow fiber. Detailed NMR spectra are depicted in the Supporting Information (see Figure SI1 and Table SI1). The B/Si ratio for samples B-MFI-100 and B-MFI-50 are about 107 and 73, while the Ge/Si ratio for sample Ge-MFI-10 is about 18. These ratios involve, respectively, B and Ge loadings ca. 0.9 and 1.3 B atoms/uc and 4.8 Ge atoms/uc. The crystal morphology in the gel evolves from the typical needle-like hexagonal shape for (B)-ZSM-5 to a pseudospherical shape with a higher degree of twinning for the Ge-modified sample. This latter observation is in good keeping with the results reported by Kosslick et al.28 on Ge-ZSM-5 powders. 10453
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Table 1. Main Characteristics of the Samples Prepared in This Study ref Al-MFI B-MFI-100 B-MFI-50 Ge-MFI-10 Cu-MFI a
% substituted (atoms/uc) 300
30 32
Me=B, Ge, Cu with Si/Me ratio measured from ICP-AES. bMeasured from 29Si and 27Al MAS NMR. cRoom-temperature pure gas permeance.
Table 1 compiles the main characteristics of the fibers prepared in this study. In general terms, the weight uptake and specific surface of the fibers keep invariable upon B or Ge introduction into the MFI framework or after proton exchange by Cu(II) after synthesis. The Si/B and Si/Ge ratios of B- and Ge-modified MFI samples match in each case the theoretical ratios in the synthesis solution, suggesting complete solubility of the corresponding B and Ge precursors. The incorporation of B and Ge into the MFI framework does not alter appreciably the BET specific surface of the crushed MFI-alumina hollow fibers, keeping at a value in the range 30−33 m2/g (MFI +support). The effective MFI thickness of the different materials lies in the narrow range 0.7−1.5 μm, as inferred from Maxwell−Stefan (MS) modeling of pure N2 permeance data (see further details in refs 8 and 23). Figure 1 plots the evolution of the N2 permeance at nearroom temperature with the mean pressure between the feed
Figure 2. Evolution of n-butane and H2 molar fluxes with temperature in the separation of a n-butane/H2 equimolar mixture for the Al-MFI sample. Conditions: feed flow rate, 80 cm3(STP)/min (15 v/v % nbutane, 15 v/v % H2); N2 flow (sweep gas), 80 cm3(STP) /min. The curves are a guide to the eye.
of the n-butane/H2 equimolar separation properties as a function of temperature for the Al-MFI sample. The n-butane flux shows a characteristic maximum at 430 K, while the nbutane/H2 separation factor shows a monotonous decreasing trend with the temperature from an initial value of 25−300 (preferential n-butane permeation) at room temperature to 25 are usually considered acceptable for gas separation purposes.14,29 Figure 3 plots the performance of the Al-MFI sample toward separation of a SF6/N2 equimolar mixture. Despite the much higher kinetic diameter of SF6 compared to N2 (5.5 vs 3.1 Å), the Al-MFI hollow fibers permeate selectively SF6 at room temperature, the SF6/N2 separation factor reaching a value of 5. This observation is attributed to the much higher adsorption affinity of SF6 on the MFI material at low temperature than that of N2. Such behavior has also been observed in the case of MFI nanocomposites prepared on alumina tubes (not shown), but displaying lower fluxes. The evolution of SF6 and N2 fluxes with temperature supports the absence of a significant amount of large defects on the MFI material, in good keeping with the results obtained for n-butane/H2 separation. These results do
Figure 1. Evolution of the room-temperature pure N2 permeance as a function of the mean pressure for the Al-MFI, B-MFI-100, B-MFI-50, Ge-MFI-10, and Cu-MFI hollow fibers. Experimental conditions: feed flow rate, 500 cm3(STP)/min; transfiber pressure, 50 kPa.
and permeate sides of the membrane for the different MFIalumina hollow fibers prepared in this study. All the materials except the Ge-modified sample show an almost constant trend of the N2 permeance with the mean pressure (i.e., absence of viscous contribution), suggesting the absence of macrodefects. However, the presence of small intercrystalline mesopores promoting Knudsen diffusion mechanisms cannot be ruled out from these tests. In contrast, sample Ge-MFI-10 shows a slightly positive trend of the N2 permeance involving a viscous contribution of about 8% (101 kPa mean pressure), suggesting the presence of a reduced number of intercrystalline macropores or large mesopores. More insight into the intercrystalline microstructure of the as-synthesized MFI-alumina hollow fibers can be gained by measuring the corresponding n-butane/H 2 and SF 6 /N 2 separation properties. Figure 2 shows an example of evolution 10454
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Type V for the Ge-MFI-10 sample, reflecting a higher degree of hydrophibicity of the MFI framework upon Ge incorporation.14 Interestingly, despite the expected lower acidity of B-ZSM-5, the incorporation of boron promotes the hydrophilic behavior of the materials, although this promotion is not apparently linear with the boron loading. 3.3. Pure CO2, N2 and NO Permeances. Figures 4 and 5 show the evolution of the pure CO2/N2 and NO permeances,
Figure 3. Evolution of SF6 and N2 molar fluxes with temperature in the separation of a SF6/N2 10 equimolar mixture for the Al-MFI sample. Conditions: feed flow rate, 80 cm3(STP)/min (15 v/v % SF6, 15 v/v % N2); He flow rate (sweep gas), 80 cm3(STP)/min. The curves are a guide to the eye.
not exclude however the presence of a reduced amount of narrow intercrystalline defects (small mesopores and supermicropores) in the nearby of MFI crystals that might be vanished during the SF6/N2 separation tests by crystal expansion induced by SF6 adsorption.20 3.2. Adsorption Properties of Crushed MFI-Alumina Hollow Fibers. Figure SI2 (see Supporting Information) plots the CO2, propane, and water isotherms measured at 303 K on crushed Al-MFI, B-MFI-100, B-MFI-50, and Ge-MFI-10 hollow fibers. In the former case, the isotherms are represented in the pressure range 0−250 kPa for which no relevant contribution of the support is observed. The CO2 adsorption capacity is not linear with the boron content, this being promoted for the BMFI-100 sample (see ref 10 for further details). This observation is accompanied by a higher Henry’s constant or slope at near-zero pressure for the latter sample (compare the values of 0.0719 and 0.0250 mmol·g−1·kPa−1, respectively, for the crushed B-MFI-100 and Al-MFI hollow fibers). In the case of the Ge-modified sample, the corresponding CO2 isotherm matches the trend obtained for Al-MFI and B-MFI-50 samples. Notwithstanding this fact, the CO2 saturation loading shows an increase of about 30% compared to the crushed Al-MFI hollow fiber, which is somewhat higher within the limits of the experimental error than the variation of density of the MFI framework upon boron incorporation (0.4 μmol·m−2·s−1·Pa−1 at 303 K for the Al-MFI, B-MFI-50, and Cu-MFI samples (>0.7 μmol·m−2·s−1·Pa−1 at 373 K for Al-MFI and Cu-MFI samples). The samples permeate preferentially propane at a level of 1.5 μmol·m−2·s−1·Pa−1 at 303 K. In contrast, the room-temperature CO2/N2 separation factor increases to a value about 6 in the presence of propane compared to the value 100 and L/Db = 2400 > 100, respectively, for modules 1 and 2 are fulfilled.38 Given the flow rate of concentrated CO2 at the permeate stream of module 2, the autonomy of a heavy vehicle (>40 tn) can be estimated as a function of the volume of the CO2 storage tank. According to our estimates, if we consider a storage volume about 750 L, the autonomy of the vehicle for CO2 removal would be about 10 h. The weight increase of the vehicle due to CO2 storage after 10 h including fuel consumption would be about 6.3%. 10459
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Table 3. Main Characteristics of the Different Streams Indicated in Figure 11 stream
T (K)
P (kPa)
flow rate (kmol/h)
yCO2
yN2
yO2
1 2 3 4 5 6 7 8 9 10
523 348 348 373 303 348 303 348 303 303
303 303 303 303 101 30 303 303 30 10100
10.3 7.2 26.0 8.3 8.2 17.7 17.7 16.8 0.94 0.91
0.109 0.123 0.535 0.0359 0.0370 0.768 0.768 0.758 0.945 0.970
0.753 0.854 0.440 0.936 0.952 0.209 0.209 0.220 0.0239 0.0267
0.0202 0.0229 0.0118 0.0251 0.0105 0.0056 0.0056 5884 ppm 641 ppm 713 ppm
■
yNO 2600 3000 1816 3278
ppm ppm ppm ppm
1134 ppm 1134 ppm 1189 ppm 165 ppm 183 ppm
ypropane 3300 ppm 0.0112 156 ppm 0.0163 0.0163 0.0155 0.0304 -
yw 0.119
