C5 C18 Research Articles

Study of the influence of the gas circulation ratio on the production of C5–C18 alkenes in the Fischer–Tropsch synthesis

The process of producing C5+ hydrocarbons, including unsaturated ones, on a zeolite-containing catalyst Сo-Al2O3 /SiO2 /ZSM-5/Al2O3 in flow and flow-circulation modes of operation at a temperature of 250 °C, a pressure of 2.0 MPa, GHSV 1000 h–1 has been studied , H2 /CO ratio = 1.70 in the source gas and circulation ratios of 4, 8 and 16. It was determined that the process indicators (selectivity and productivity for C5+ products) pass through a maximum at a circulation ratio of 8. The use of gas circulation in comparison with flow synthesis mode allows you to regulate the composition of products. An increase in the circulation ratio in the range of 4–16 leads to an increase in the proportion of formed olefins with a hydrocarbon chain length containing 5–20 carbon atoms, from 53.9 wt.% up to 65.7 wt.%. The use of a zeolite-containing catalyst intensifies the formation of C8–C12 alkenes in comparison with the Co-Al2O3 /SiO2 catalyst by 3,3 times – the content increases from 13,5 wt.% up to 44.2 wt.% at similar values of circulation ratio, pressure and H2 /CO ratio = 1.70 in the source gas. It was found that as the circulation ratio increases, the rate of deactivation of the zeolite-containing catalyst decreases, which may be caused by a decrease in the partial pressure of water in the reaction volume.

Molecular coupling behavior of relay catalytic upgrading of heavy oil fast pyrolysis vapor to produce light olefins

The relay catalytic upgrading of vacuum residue (VR) fast pyrolysis vapor process, which combines the VR fast pyrolysis and pyrolysis vapor catalytic cracking on the molecular level, is proposed to produce the chemicals. In this research, the composition and molecular distribution of Changqing vacuum residue (CQ-VR) pyrolysis vapor at 550–650 °C are investigated firstly. In the pyrolysis vapor, the alkanes and alkenes which have high catalytic cracking reactivity are both distributed from C5–C18, whereas the aromatics with high adsorption capacity is consist of monocyclic and polycyclic aromatics. For further catalytic cracking, the optimal reaction temperature for CQ-VR pyrolysis process is 600 °C due to the fact that the pyrolysis vapor at this temperature contains more alkenes and less aromatics. Then, the pyrolysis vapor is catalyzed over FCC catalyst, ZSM-5 catalyst, ZSM-5/calcium aluminate composite catalyst (Z-C catalyst), and ZSM-5/FCC composite catalyst (Z-F catalyst), which has different pore structure and acidity, respectively. The yield of light olefins after catalytic cracking of pyrolysis vapor over Z-C catalyst is 43.26%, which is higher than that over FCC, ZSM-5, and Z-F catalysts. Coupling the molecular distribution of pyrolysis vapor with the composition structure of catalyst can achieve the maximum conversion of CQ-VR to light olefins, and realize the efficient conversion of inferior heavy oil.

Effects of Zn Addition into ZSM-5 Zeolite on Dehydrocyclization-Cracking of Soybean Oil Using Hierarchical Zeolite-Al2O3 Composite-Supported Pt/NiMo Sulfided Catalysts.

Zn-exchanged ZSM-5-Al2O3 (ZA) composite-supported Pt/NiMo (NM) sulfided catalysts were prepared using the conventional kneading method and were tested for dehydrocyclization-cracking of soybean oil. The effects of Zn addition on the activity and selectivity of products were investigated under moderate-pressure conditions of 0.5 and 1.0 MPa H2 in the temperature range of 420–580 °C. At the temperature 500 °C and higher, most of the sample soybean oil was converted at both the pressures of 0.5 and 1.0 MPa. At 1.0 MPa and 500 °C, the effects of Zn addition appeared and increased the yields of aromatics, while the catalyst without Zn produced larger amounts of products with more than C18. Further, at 0.5 MPa and 580 °C, the gas formation was inhibited in comparison to the cases of 1.0 MPa and the effects of the Zn addition also appeared and increased the yields of aromatics, while the catalyst without Zn produced larger amounts of products with more than C18. The Pt/NM/Zn(122)ZA test catalyst produced more than 63% of liquid fuels in the range C5–C18, and the yield of aromatics was 13%, the maximum value in the present study. The following reaction routes were proposed. The structure of triglyceride is converted by hydrocracking to three molecules of aliphatic acids and propane on the surface PtNiMo sulfide on Al2O3 support. The converted aliphatic acids are decomposed through decarboxylation to hydrocarbon fragments, which are further decomposed by cracking on the acid sites of the catalyst, the surface of NiMo sulfide, Al2O3, or ZSM-5. Finally, the formed C3 and C4 olefins are transformed to aromatics through the Diels–Alder reaction on the Zn species of ZnZSM-5. On the other hand, although gases were relatively small in amount, aromatic compounds were formed significantly, suggesting that cyclization might directly occur without conversion to gaseous hydrocarbons to some extent.

Highly selective hierarchical ZSM-5 from kaolin for catalytic cracking of Calophyllum inophyllum oil to biofuel

Upgrading the inferior properties of Calophyllum inophyllum oil via catalytic cracking into biofuel required a porous heterogeneous acid catalysts. Hierarchical ZSM-5 (Hi-ZSM-5(K)) produced from desilication of kaolin-derived ZSM-5 was employed as catalyst and the activity was compared with hierarchical ZSM-5 obtained from templating method (Hi-ZSM-5(T)). Catalytic cracking of Calophyllum inophyllum oil was carried out in one-pot reaction at 475 °C for 120 min under the flow of H2 and the products analysed using GC-MS were consisted of the mixtures of alkane, alkene, oxygenated carbon and aromatics compound. The advantages of desilication method for the formation of highly selective hierarchical ZSM-5 was observed when the catalyst exhibited enhanced acidity with mesopores diameter of 2–5 nm to give 93% conversion and high selectivity towards light C7–C9 hydrocarbons. However, Hi-ZSM-5(T) showed low acidity to give only 43% conversion, and selectivity towards C11–C12 hydrocarbons due to the mesopores diameter of 3–12 nm. The activity of hierarchical ZSM-5 was also compared with microporous ZSM-5 that produced biofuel with approximately equal distribution of C5–C18 hydrocarbons. The role of hierarchical structures was further discussed on the composition of aromatics compound, oxygenates content and alkene/alkane ratios of the biofuel.

Dependence of mesomorphism on flexibility of lateral and terminal groups of chalconyl esters

ABSTRACTA novel liquid crystalline homologous series of chalconyl vinyl esters with a lateral bromo substituent RO─C6H4─CH═CH─COO─C6H3─(Br)─CO-CH═CH─C6H4─C12H25(n) has been synthesized and studied with a view to understanding and establishing the relation between the molecular structure and liquid crystal (LC) behavior in terms of molecular flexibility of the lateral and terminal groups. The novel homologous series consists of thirteen (C1–C18) homologues, whose enantiotropic nematic and smectic mesomorphism commences from the C4, (C4–C18) and the C5, (C5–C18) homologue, respectively. The rest of the homologues (C1, C2, C3) are nonliquid crystals (NLC). Mesomorphism and transition temperatures were examined using an optical polarising microscope (POM) equipped with a heating stage. Textures of nematic phase are threaded or Schlieren and those of the Smectic-A or Smectic-C are focal conic. Analytical, thermal and spectral data supported molecular structures of the novel homologues. Thermal for smectic and nematic are 87.5°C and 101.1°C, respectively, whose, total mesophase length ranges from 17°C to 30°C at C14 and C7 homologue, respectively. The mesomorphic transition temperature ranges are between 70°C and 113°C.

Mesomorphism dependence on halogenated chalconyl esters in terms of molecular flexibility/rigidity

ABSTRACTVinyl carboxy central group containing a novel chalconyl ester homologous series: RO.C6H4.CH ˭ CH.COO.C6H4.CH ˭ CH.CO.C6H4.I (para) have been synthesized and studied with a view to understand and establish the relation between thermotropic liquid crystalline (LC) behaviors and the molecular structure. Novel chalconyl ester homologous series consists of thirteen homologs (C1–C18). C1–C3 homologs are nonmesogenic, C4 homolog is enantiotropic nematogenic and the rest of the homologs (C5–C18) are enantiotropically smectogenic plus nematogenic. Phase transition temperatures and textures of LC phase were determined by an optical polarizing microscopy (POM) equipped with a heating stage. Cr-M/I, Sm-N, N-I transition curves in a phase diagram behaved in normal manner. Sm-N and N-I transition curves exhibited odd-even effect from C4–C10 or nearby C10 homolog. Textures of nematic phase are threaded or Schlieren and that of the smectic phase are of the type smectic A or C. Analytical and spectral data confirms the molecular structure of homologs. Thermal stabilities for smectic and nematic mesophases are 155.0 and 180.7, respectively, and their corresponding mesophaselengths are varied from minimum to maximum at 17.0°C–39.0°C as well as 15.0°C–30.0°C. Thus, it is middle ordered melting type series. The group efficiency orders derived on the basis of smectic and nematic thermal stabilities are as under: Sm: -C6H4.I > -C6H4.Cl > -C4H3S and N:- C6H4.I > -C6H4.Cl > -C4H3S from comparative study of structurally similar analogous series

Dependence of thermotropic mesomorphism on molecular flexibility of changing tail group

ABSTRACTA novel chalconyl ester homologous series of liquid crystals has been synthesized and studied with a view to understanding and establishing the effect of molecular structure on liquid crystalline properties. Novel series consisted of 13 members (C1–C18) of a series. C1–C4 member of a series is nonliquid crystals and, the rest of the homolog members (C5–C18) are enantiotropically nematogenic with absence of smectogenic property. None of the homolog is monotropically mesomorphic. Transition and melting temperatures were determined by an optical microscope equipped with a heating stage. Textures of nematic phase are threaded or schlieren. Spectral and analytical data of selected members of a series confirms the molecular structures of homologues. Cr-N and N-I transition curves of a phase diagram behaved in normal manner with exhibition of odd-even effect of very short range as observed for N-I transition curve. Thermal stability for nematic is 122.0°C and the nematogenic mesophase ranges from 7.0°C to 38.0°C. Liquid crystal properties of a present series are compared with the structurally similar known homologous series.

Catalytic hydroprocessing of fatty acid methyl esters to renewable alkane fuels over Ni/HZSM-5 catalyst

A series of Ni/HZSM-5 catalysts with different Ni loading and Si/Al ratios were prepared by incipient wetness impregnation. The physicochemical properties of the catalysts were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2-adsorption, temperature-programmed desorption of ammonia (NH3-TPD), and thermogravimetric (TG) analysis. Moreover, their catalytic performance was investigated for the hydroprocessing of long-chain unsaturated fatty acid methyl esters (FAMEs) to renewable alkane fuels using a high-pressure fixed bed reactor system with a facility for online analysis. The different Ni loading and Si/Al ratios of the catalysts, as well as the influence of reaction conditions such as temperature, pressure, H2/oil molar ratio, and liquid hourly space velocity (LHSV), were studied in detail. The NiO aggregates dispersed on the surface of the support clearly increased the acidity after H2 reduction, thus significantly affecting the catalytic performance. Temperature and pressure played crucial roles in the conversion of FAMEs and selectivity for gasoline or jet or diesel alkane. Hydroprocessing over 10wt% Ni/HZSM-5 (Si/Al=25) at 280°C, a H2 pressure of 0.8MPa, an LHSV of 4h−1, and with a highly purified H2/oil molar ratio of 15 led to a high selectivity of 88.2% for C5–C18 liquid alkanes, which includes 8% of gasoline alkane, 32.5% of jet alkane and 47.7% of diesel alkane, along with appropriate isomerization selectivity of 27.0%, while the conversion of FAME reached 85.1%. To demonstrate the potential of this catalyst for practical applications, its stability in the hydroprocessing of FAMEs was also investigated. The conversion of FAMEs decreased to 30.1% over 10wt% Ni/HZSM-5 (Si/Al=25) after operation for 80h. Catalyst deactivation was predominantly caused by the deposition of carbon which causes blockage of the pores for FAMEs as evidence from TG analysis.

A TGA/DTA-MS investigation to the influence of process conditions on the pyrolysis of Jimsar oil shale

The influence of heating rate and pyrolysis temperature on the pyrolysis of Jimsar oil shale was studied. Oil shale samples were pyrolyzed in a TG analyzer (thermogravimetric analyzer) at eight different heating rates (0.5–30 °C/min) up to a temperature of 1000 °C. The decomposition mechanism of oil shale was confirmed through online MS (mass spectrometric) combined with the TGA. Compounds of about 258 atomic mass units in the products were identified and the evolution rates of the compounds were measured. Increasing the heating rate increased the lighter alkanes/heavier alkanes ratio, unsaturated hydrocarbons/respective alkane ratio and benzene/alkyl aromatics ratio. The atomic H/C ratio of derived oil (C5–C18) decreased as the heating rate was increased from 0.5 to 15 °C/min. Then the ratio increased as the heating rate was increased to 30 °C/min. Lighter hydrocarbons evolved at lower temperature and their formation rates were higher. The H/C ratio of derived oil (C5–C18) increased firstly and then decreased with the increase of pyrolysis temperature (<620 °C). The pyrolysis kinetics of oil shale was calculated using Friedman-Carroll method. The reaction order and activation energy were changed with heating rate. And the reliability of the calculated activation energies was verified through DTA (differential thermal analysis).

Core@shell Co3O4@C-m-SiO2 catalysts with inert C modified mesoporous channel for desired middle distillate

Following our previous findings that spatial confinement using core@shell cobalt-based catalysts could regulate the product distribution toward desired distillate. We developed a facile solvothermal method to prepare Co3O4@C-mesoporous SiO2 (Co3O4@C-m-SiO2) catalysts with inert C modified surface of mesoporous channel using PVP polymer as carbon source. High-resolution transmission electron microscopy (HRTEM) characterization result, together with the N2 physisorption, indicated that the Co3O4@C-m-SiO2 catalysts with inert C modified mesoporous channel could be prepared via carbonization of PVP polymer under argon gas instead of calcination and mesoporous silica shell could also be fabricated after inert C modification, and thus higher mesoporous nature contributed to the facile access of the reactant gas to the active Co sites and diffusion of formed product. Hydrogen temperature programmed reduction (H2-TPR) showed that the degree of reduction for the Co3O4@C-m-SiO2 catalysts were enhanced gradually with increase of C modifier content due to weak Co–C interaction instead of strong Co-silica interaction in the Co3O4@m-SiO2 catalysts. As a result, such inert C modified cobalt-based catalyst with core@shell structure, which possessed rigid porous framework to allow free access of syngas and inhibit mesoporous channel collapsing during F–T reaction, showed the higher catalytic activity and stability due to synergetic effect between higher Co dispersion and reducibility. Moreover, hydrophobic channel of the Co@C-m-SiO2 catalysts with different C modifier content, which were likely favorable to the internal transportation of H2O byproduct and spatial confined effect for the formed hydrocarbon, led to a better selectivity toward C5–C18 fraction than that of unmodified Co@m-SiO2 catalysts in the FTS.

Co3O4@Mesoporous Silica for Fischer–Tropsch Synthesis: Core–Shell Catalysts with Multiple Core Assembly and Different Pore Diameters of Shell

A series of core–shell cobalt oxide catalysts were prepared by tuning the pore diameter of mesoporous silica shell and the influence of pore dimensions on Fischer–Tropsch synthesis was studied. TEM images of core–shell 20Co3O4@MSN-x catalysts showed an increase in the silica shell porosity with increasing molar ratio of the swelling agent to tetraethyl orthosilicate used during catalyst preparation. As a result of this porosity increase, the dispersion of congregated core Co oxide particles within the shell increased, resulting in multiple core centers. Reference catalysts were synthesized using conventional supports, and the effects of pore dimensions on the activity and hydrocarbon selectivity of the reference and the prepared core–shell catalysts were compared. In the experiments performed, 20Co3O4@MSN-x catalysts showed an increase in their CO conversion and C5+ selectivity with increasing silica shell porosity. Moreover, the prepared core–shell catalysts demonstrated higher selectivity toward C5–C18 hydrocarbon fractions than SBA–15- and SiO2-supported Co oxide catalysts. This could be due to the comparatively lower diffusion limitations and less probability of readsorption of intermediates in the confined space of the mesoporous silica shell. Further, the core–shell catalysts displayed higher stability (100 h on stream) than the reference catalysts, and this was attributed to their small diffusion length and less probability of metal sintering due to a protective silica shell around Co oxide particles.

Controlled Preparation of Co3O4@porous-SiO2 Nanocomposites for Fischer–Tropsch Synthesis

Monodispersible Co3O4 nanoparticles were prepared via a facile solvothermal route using polyvinylpyrrolidone (PVP) as capping agent and the porous silica shell was then coated by means of the Stöber process to fabricate Co3O4@porous-SiO2 (Co3O4@p-SiO2) nanocomposites. The particle size of Co3O4 and porous silica shell thickness of Co3O4@p-SiO2 nanocomposites could be easily controlled through changing the amount of PVP and tetraethoxysilane, respectively. The high resolution transmission electron microscopy results, together with the X-ray diffraction results, indicated that monodispersible Co3O4 nanoparticles were successfully prepared and uniformly encapsulated by porous silica. During the growth of silica shell, the PVP was trapped and dispersed in the silica shell. As a result, the porous silica shell was obtained after burning off the PVP and a positive correlation existed between the Brunauer–Emmett–Teller surface area of the porous silica shell and quantity of PVP in the original Co3O4 nanoparticles. Compared with the Co/SiO2 reference catalyst, CO conversion of the Co@p-SiO2 model catalyst was more stable and higher in a period of 240 h, and hydrocarbon selectivity towards C5–C18 fraction was also higher than that of the Co/SiO2 catalyst. The results of analysis for the Co@p-SiO2 catalyst showed that core@shell structure could maintain high dispersion of Co particles so as to provide higher number of Co active sites, and enhance selectivity towards C5–C18 fraction due to confined structure of porous channel in the silica shell. Schematic diagram of the procedure for synthesizing Co3O4@p-SiO2 nanocomposites.

Studies of Cobalt Particle Size Effects on Fischer–Tropsch Synthesis over Core–Shell‐Structured Catalysts

AbstractA series of core–shell‐structured catalysts that consist of different‐sized Co3O4 nano‐particles and silica shells were prepared by an in situ coating method. The reduced catalysts displayed uniform core sizes that ranged from 5.5–12.7 nm as ascertained by TEM, which concurred well with XRD analysis. The BET results revealed the highly mesoporous nature of the silica shell, which contributes to the facile access of the reactant gas to the active sites on the core particles. The degree of reduction of the calcined catalysts studied by H2 temperature‐programmed reduction was enhanced with increased Co particle size. In the Fischer–Tropsch synthesis, a volcano‐like curve was plotted as the CO conversion and Co‐time‐yield revealed a rapid growth if the particle size increased from 5.5 to 8.7 nm and then decreased with further increased particle size to 12.7 nm, which is an effect of the combination of Co dispersion and reducibility. However, the turnover frequency remained invariant for catalysts with particle sizes larger than 8.7 nm. If we consider the product selectivity, generally, larger particles led to a longer chain length of hydrocarbons with a larger chain‐growth probability. The selectivity towards methane decreased and the corresponding heavy hydrocarbons (C19+) increased continuously with the increase of particle size. The catalyst with a particle size of 8.7 nm exhibited the highest selectivity and the maximum space‐time‐yield towards middle distillates (C5–C18) because of the modest chain‐growth probability.

Stereoselective Synthesis of the C5–C18 Fragment of Halichomycin

An efficient and convergent synthesis of the C(5)-C(18) fragment of halichomycin is reported. Butanolide fragment 6 was readily prepared stereoselectively from (R)-Roche ester through catalyst control; dienylic bromide domain 7 was synthesized from (S)-serine by substrate control. C(5)-C(18) fragment 2 was rapidly assembled through a stereoselective alkylation of the butanolide with the dienylic bromide, followed by functional group transformations.

Air‐Stable, Highly Fluorescent Primary Phosphanes

Air‐Stable, Highly Fluorescent Primary Phosphanes

Odd–Even Effect and Unusual Behavior of Dodecyl-Substituted Analogue Observed in the Crystal Structure of Alkyltrimethylammonium–[Ni(dmit)2]− Salts

Abstract A series of [Ni(dmit)2]− (dmit: 1,3-dithiole-2-thione-4,5-dithiolato) salts of alkyltrimethylammonium (Cn: n represents the alkyl chain length; n = 3 and 5–18) have been prepared and analyzed by X-ray structural analysis. All complex salts have been found to be composed of alternate sheets of [Ni(dmit)2]− anions and sheets of cations with a pronounced interdigitation of the alkyl chains. However, molecular arrangement differed between (C3)[Ni(dmit)2] and other (Cn)[Ni(dmit)2] (n = 5–18). Adjacent cations were aligned along the long axis of [Ni(dmit)2]− anion in C3 complex salt, while in others (C5–C18 complex salts), they were aligned toward the short axis. Such a difference in arrangement arose from correlativity between the lengths of the long axis of cation and anion, namely CLCA. Furthermore, relative orientation between the alkyl chain of cation and [Ni(dmit)2]− anion differed between the odd- and even-numbered cations for C10–C18. Whereas the plane of alkyl chain for odd-numbered cation was normal to the plane of [Ni(dmit)2]− anion, that of even-numbered cation was parallel. It was also found that C12 analog behaved like odd-numbered cations. However, in C12 salt, the end methyl group of the dodecyl group adopted unusual end-gauche conformation.

Silylated Co3O4-m-SiO2 catalysts for Fischer–Tropsch synthesis

Silylated Co3O4-mesoporous SiO2 catalysts were prepared by a surface organic modification to understand the influence of a hydrophobic surface on their performance in the Fischer–Tropsch synthesis (FTS). Fourier transform infra-red (FT-IR) spectra showed that the reaction of the surface silanol groups with hexamethyldisilazane (HMDS) took place effectively, and X-ray diffraction (XRD) indicated that such a modification did not affect Co3O4 crystallite size. Furthermore, hydrogen temperature programmed reduction (H2-TPR) illustrated a higher extent of reduction for silylated Co3O4-m-SiO2 catalysts. As a result, such a silylated core–shell structured Co catalyst showed the higher catalytic activity and better selectivity towards C5–C18 fraction than the unsilylated Co3O4-m-SiO2 catalyst in the FTS, which was likely favorable to the internal transportation and their hydrophobic shell.

Solvothermally derived Co3O4@m-SiO2 nanocomposites for Fischer–Tropsch synthesis

Monodispersible Co3O4 nanoparticles were prepared via a facile solvothermal route using polyvinylpyrrolidone (PVP) as the capping agent. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) results, together with the N2 physisorption, indicated that those as-made Co3O4 nanoparticles of about 17 nm could be used as cores to prepare [email protected] nanocomposites with mesoporous silica shell. Such monodispersible Co3O4 nanoparticles were observed to be coated completely by mesoporous silica shell, and showed the higher catalytic activity and selectivity towards C5–C18 fraction than Co/mesoporous SiO2 (Co/m-SiO2) in the Fischer–Tropsch synthesis (FTS).

Textural Structure of Co-based Catalysts and their Performance for Fischer–Tropsch Synthesis

Both mono- and bi-modal Co-based Fischer–Tropsch Synthesis (FTS) catalysts were prepared by incipient-wetness impregnation (IWI). XRD and N2 physisorption revealed that the catalyst with a bi-modal distribution of 2.5–17 nm had the smallest size of cobalt crystal. In this case, the Raman absorbance shifted toward lower frequencies due to the size quantization effect. Furthermore, H2-TPR indicated a lower reducibility originated from the interaction between small crystalline cobalt and silica. Such bi-modal structure catalysts showed a better FTS performance, and particularly the bi-modal mesopores catalyst presented the lowest methane selectivity, the highest activity and the highest selectivity to C5–C18 hydrocarbons, which might be due to the confinement of mesopore to the cobalt particles. The catalyst with a bi-modal distribution of 2.5–17 and 2.5–65 nm showed a better FTS activity, lower methane selectivity than mono-modal catalyst, particularly the bi-modal mesoporous catalyst presented the highest selectivity to C5–C18 hydrocarbons

Analysis of trifluoroacetic acid and other short-chain perfluorinated acids (C2–C4) in precipitation by liquid chromatography–tandem mass spectrometry: Comparison to patterns of long-chain perfluorinated acids (C5–C18)

A method has been developed to measure 29 perfluorinated acids (PFAs) including short-chain perfluorocarboxylates (PFCAs) such as trifluoroacetic acid (TFA; C2) and long-chain PFCAs, perfluoroalkylsulfonates, fluorotelomer acids, and two perfluorooctylsulfonamides in water matrices. The method involves solid phase extraction (SPE) using a weak anion-exchange (WAX) cartridge, an ion-exchange high-performance liquid chromatography (HPLC) column separation, and tandem mass spectrometry (MS/MS) detection. To our knowledge, this is the first HPLC–MS/MS method to determine TFA in water at sub-ng L −1 concentrations. The method is selective, simple, and robust, capable of measuring 29 PFAs in a single analysis, with overall recoveries of the target analytes ranging from 75% to 132%. The method was applied to the analysis of rainwater samples collected from two cities in Japan. TFA and several short-chain PFAs were the major compounds found in rainwater.