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Creating innovative composite materials to enhance thekinetics of CO 2 capture by hydroquinone clathrates

Romuald Coupan, Frédéric Plantier, Jean-Philippe Torré, ChristopheDicharry, Pascale Senechal, Fabrice Guerton, Peter Moonen, Abdel Khoukh,

Sid Ahmed Kessas, Mehrdji Hemati

To cite this version:Romuald Coupan, Frédéric Plantier, Jean-Philippe Torré, Christophe Dicharry, Pascale Senechal, etal.. Creating innovative composite materials to enhance the kinetics of CO 2 capture by hydroquinoneclathrates. Chemical Engineering Journal, Elsevier, 2017, 325, pp.35-48. �10.1016/j.cej.2017.05.038�.�hal-02065960�

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This is an author’s version published in: http://oatao.univ-toulouse.fr/21530

To cite this version:

Coupan, Romuald and Plantier, Frédéric and Torré, Jean-Philippe and Dicharry, Christophe and Sénéchal, Pascale and Guerton, Fabrice and Moonen, Peter and Khoukh,

Abdel and Kessas, Sid Ahmed and Hemati, Mehrdji Creating innovative composite materials to enhance the kinetics of CO 2 capture by hydroquinone clathrates. (2017) Chemical Engineering Journal, 325. 35-48. ISSN 1385-8947

Official URL: https://doi.org/10.1016/j.cej.2017.05.038

Open Archive Toulouse Archive Ouverte

with a low molecular weight, such as carbon dioxide (CO2),methane (CH4) and nitrogen (N2), can be trapped as guest molecules in a clathrate structure. A variety of host molecules, such aswater, phenol and hydroquinone (HQ), have been studied in recentyears and are described in literature [2]. Scientists have been fascinated by gas clathrates for more than a century, but these solidcompounds are now the focus of even greater attention owing totheir possible practical applications such as CO2 capture andsequestration. This new interest arises from their capacity to storelarge quantities of gases, more or less selectively depending on theclathrates considered and the gas mixture used.

To begin with, the most studied clathrate compounds are ‘‘gashydrates” [3], which generally form at high pressure (a few MPa)and low temperature (a few K above 273 K) with water and gas.For the past 15 years or more, they have been the focus of manystudies [4], which included adding chemical promoters or usingdifferent multiphase contactors [5 7] to overcome the many critical limitations that prevent hydrate based gas separation processes from being deployed, from pilot to industrial scale.However, the use of gas hydrates to separate CO2 from gas mixtures such as CO2/CH4 and CO2/N2 is still hindered by the followingmain obstacles: (i) the overall cost of the process is not competitivecompared to others such as reactive absorption [8], except whenthe raw gas is already pressurized (as the gas compression costsare prohibitive in most cases); (ii) the difficulties in handling, contacting and transporting a multiphase mixture composed of atleast three phases that have to coexist (water or water/oil mixture,gases and solids) for the reaction to take place; (iii) the necessity tomaintain a relatively low temperature in the apparatus for the gashydrates to form (generally slightly above 273 K); and (iv) the lowrate of hydrate formation and insufficient selectivity of gashydrates toward CO2 in certain gas mixtures, particularly CO2/CH4 [9,10].

Secondly, HQ is a solid hydroxy aromatic compound recentlyidentified in literature as a potential innovative clathrate candidatefor gas storage and separation [11 13]. Interestingly, for differentgas mixtures such as CO2/N2, CO2/H2 and CO2/CH4 [14,15], theenclathration reaction with HQ seems to be highly selective toCO2. The thermodynamic pressure temperature conditions (i.e.the clathrate phase equilibria) in which some HQ clathrates formand dissociate are mentioned in literature [16 19] and the equilibrium data and detailed characterization of CO2 HQ clathrates wererecently published [20 21]. But although HQ clathrates seem veryinteresting for practical applications such as CO2 separation bydirect gas/solid reaction (i.e. without using any solvent), the gasclathrate formation kinetics need to be improved before thesecompounds can be used on an industrial scale. Previous studiesinvolving tests carried out using powdered HQ have alreadyattempted to do so [14,15,22]. But very fine HQ particles wouldbe difficult to handle in an industrial gas solid contactor (such asa fixed bed reactor) for several reasons: (i) the gas circulatingthrough the HQ powder causes a significant pressure drop that insome cases could be excessive, (ii) the very fine particles can beblown into the process equipment, and (iii) operators must applystringent safety measures when handling large quantities of a finepulverulent material such as HQ during loading and unloading ofthe reactor. Indeed, reactivity is limited by the contact areabetween the gas and the solid HQ, and depends on the specific areaof the reactive medium used. Consequently, in an attempt toenhance the gas solid enclathration reaction, we developed a composite material made of porous particles impregnated with HQ thatcan be used as a reactive medium in a clathrate based gas separation process.

There are two procedures for impregnation: wet impregnation(abbreviated as WI below) and dry impregnation (abbreviated asDI below) in a fluidized bed. Creation of a composite material by

WI consists of a dip coating method involving several steps:impregnation, filtration and drying [23]. DI in a fluidized bed waspreviously developed in the Laboratoire de Génie Chimique (chemical engineering laboratory) of Toulouse and patented by the INPTand the CNRS in 2001 [24]. Unlike WI, creation of a compositematerial by DI in a fluidized bed is a ‘‘one pot process” in whichthe stages of impregnation, filtration and drying are carried outin just one apparatus. This technique consists in spraying a solution containing the organic precursor onto a warm fluidized bedof porous particles chosen as the support material for the precursor. This condensed technique was initially used for depositingmetal nanoparticles on porous supports (such as silica gel, aluminaand activated carbon) and has shown that in operating conditions:(i) the deposition efficiency is close to 100%, (ii) the deposit is quasiuniform, and (iii) the size of the supported metal nanoparticles iscontrolled by the pore diameter [25 29]. In the present work, thecomposite materials synthesized by the two procedures (i.e. WIand DI) are evaluated as reactive media for CO2 capture. Both thegas storage capacity of the reactive media and data on the CO2 capture kinetics were measured and compared to the results obtainedwith pure powdered HQ. All experiments were performed at3.0 MPa and 323 K by means of a gravimetric method using a magnetic suspension balance. These experimental conditions werechosen for two main reasons: (i) CO2 HQ clathrates can form underrelatively high temperature (e.g. 323 K) and pressure [20] conditions, which could be economically very advantageous when theraw gas is already hot and pressurized, the case for example of aproduction gas containing CO2/CH4; (ii) CO2 HQ clathrates mayreach their maximum capacity when the formation pressure isclose to 3.0 MPa [30], justifying the operating pressure chosen forthese tests.

2. Experimental section

2.1. Materials

The organic precursor used in this study is HQ (purity of99.5 mol%) provided by Acros Organics. The solvent used in WIand DI is absolute ethanol (purity greater than 99 mol%). Thischoice was motivated by the high solubility of HQ in this solvent(e.g. 0.2063 mol% at 308.2 K) [31] and its low boiling temperatureof 351 ± 2 K (calculated mean values obtained from the NIST) thatfacilitates the drying step. The N2, CO2 and helium (He) used for theexperiments (minimum mole fraction purity of 99.995%) are purchased from Linde Gas SA. The porous supports used are silica particles provided by SiliCycle. The experiments are conducted withtwo types of silica particles: high grade irregular silica particles(SiliaFlash�, referred to as SF below) and high purity analyticalgrade spherical silica particles (SiliaSphere�, referred to as SSbelow) with tight particle size distribution. Information concerningnative SF and SS particles is given in the Supplementary Material.

2.2. Experimental set up and methods

Prior to impregnation, a saturated solution of HQ in ethanol wasprepared at 308 K based on the solubility data and a correlationproposed by Li and coworkers [31]. Before each experiment, thesolid particles were dried for 24 h at 423 K in a muffle furnace(from Nabertherm).

2.2.1. Wet impregnationWI is performed in hermetic glass vessels. An oven (model 800,

from Memmert) is used to maintain the temperature at a constantvalue with an accuracy of ±0.5 K. A vacuum filtration system composed of a Buchner funnel connected to a vacuum pump is used for

same way as for the global capture capacity and reaction kineticsby using this type of composite material.

Acknowledgments

We would like to acknowledge the entire work group involvedin the ORCHIDS project and the Carnot Institute ISIFoR (Institutefor the Sustainable engIneering of Fossil Resources). We extendour thanks to the staff of the Service Analyse et Procédés of theUniversity of Toulouse for their help. We also wish to thankMathieu Molinier, Victor Cabrol and Sofiane Bekhti for their technical assistance and the Total E&P, ‘‘Gas Solutions” departmentfor its financial backing. We would also like to thank Total for providing UMS 3360 DMEX with the Zeiss Xradia Versa 510 used tocarry out the tomographic acquisitions reported in this article.

Appendix A. Supplementary data

Supplementary data associated with this article can be found, inthe online version, at http://dx.doi.org/10.1016/j.cej.2017.05.038.

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Creating innovative composite materials to

enhance the kinetics of CO2 capture by

hydroquinone clathrates

Romuald COUPAN 1, Frédéric PLANTIER 2, Jean-Philippe TORRÉ 1,*, Christophe

DICHARRY 1, Pascale SÉNÉCHAL3, Fabrice GUERTON 3, Peter MOONEN 1,3, Abdel

KHOUKH 4, Sid Ahmed KESSAS 5, Mehrdji HEMATI 5

AUTHOR AFFILIATIONS:

1. CNRS/TOTAL/UNIV PAU & PAYS ADOUR, Laboratoire des Fluides complexes et leurs Réservoirs-

IPRA, UMR5150, 64000, PAU, France

2. CNRS/TOTAL/UNIV PAU & PAYS ADOUR, Laboratoire des Fluides complexes et leurs Réservoirs-

IPRA, UMR5150, 64600, ANGLET, France

3. UNIV PAU & PAYS ADOUR, CNRS, DMEX-IPRA, UMS 3360, 64000, Pau, France

4. UNIV PAU & PAYS ADOUR, CNRS – UMR 5254 – Institut des Sciences Analytiques et de Physico-

Chimie pour l’Environnement et les Matériaux (IPREM), Hélioparc, Avenue du Président Pierre Angot,

Pau F-64000, France.

5. Université de Toulouse – Paul Sabatier, CNRS – UMR 5503 – Laboratoire de Génie Chimique (LGC),

ENSIACET, INPT, 5 rue Paulin Talabot, BP 1301, Toulouse F-31106, France.

* CORRESPONDING AUTHOR: Jean-Philippe TORRE. Address: CNRS/TOTAL/UNIV PAU & PAYS

ADOUR, Laboratoire des Fluides complexes et leurs Réservoirs-IPRA, UMR5150, 64000, PAU, France. Tel.

+335 40 17 51 09. Email: jean-philippe.torre@univ-pau.fr

SUPPLEMENTARY MATERIAL

1. INFORMATION CONCERNING THE NATIVE SUPPORT MATERIALS

The native support materials − SiliaFlash® (SF) and SiliaSphere® (SS) silica particles − used

in this study underwent particle size characterization and gas porosimetry in order to

experimentally determine their textural parameters. Our experimental data and those provided

by the supplier are given in Table SI1 and Table SI2 respectively. As the batch of SF particles

presented a large size dispersion (i.e. from 200 to 1,000 µm), it had to be separated into two

fractions to allow homogenous fluidization: a low fraction of particles from 200 to 500 µm

(called L-SF below) and a high fraction of SF particles from 500 to 1,000 µm (referred to as

H-SF below).

Note that the SS particles were not evaluated by gas porosimetry, as the PSD was out of the

measurement range of the equipment. For the native SF particles, the PSD analysis revealed

mesopores of about 38 ± 5 nm, in good agreement with supplier data (pore diameter of 33 nm

provided).

Table SI1. Textural parameters of native SiliaFlash® (SF) and SiliaSphere® (SS).

Support material L-SF H-SF SS

d10 (µm) 127 478 183

d50 (µm) 326 748 249

d90 (µm) 587 804 341

Mean particle diameter (µm) 306 710 242

Mean pore diameter (nm) 38 -

Porous volume (cm3/g) 0.89 -

Specific area (m2/g) 144 -

Table SI2. Physical properties of native SiliaFlash® (SF) and SiliaSphere® (SS) given by the

supplier.

Support material SF SS

Particle diameter (µm) 200 – 1,000 200 – 500

Mean pore diameter (nm) 33 99

Porous volume (cm3/g) 1.28 0.83

Apparent density (g/ cm3) 0.583 0.790

Particle density (g/ cm3) 2.29 2.29

Porosity fraction 0.75 0.64

Specific area (m2/g) 155 57

pH 4.3 7.4

The operating conditions applied for developing the composite materials by Dry Impregnation

(DI), particularly the minimum fluidization velocities of the particles obtained at room

temperature, are listed in Table SI3.

Table SI3. Operating conditions applied for the DI of SiliaFlash® (SF) and SiliaSphere®

(SS).

Support material H-SF L-SF SS

Fluidized bed temperature (K) 308 308 308

Initial mass of support material (g) 310 330 345

Minimal fluidization velocity (m/s) 0.110 0.021 0.017

Fluidization gas flow-rate (m3/h) 7.80 7.80 7.38

Spraying gas flow-rate (Nm3/h) 1.2 1.2 1.2

HQ mass fraction of solution 0.31 0.31 0.31

Mass of sprayed solution (g) 383 198 556

Theoretical precursor content (gHQ/ gsupport) 0.38 0.19 0.50

Figure SI1. SEM images of native silica particles: (a) SS particles; (b) H-SF particles. Images

obtained with a tabletop microscope HITACHI TM3000 equipped with an EDS SwiftED3000

detector from Oxford Instruments.

2. TECHNICAL DETAILS OF ANALYTICAL TECHNIQUES

The mean particle diameter and particle size distribution were evaluated by sieving and by

using a laser diffraction particle size analyzer from Malvern Instruments (model Mastersizer

2000). The laser diffraction particle size analyzer works for particles of about 0.02 µm to

2,000 µm.

The morphology of the particles was obtained using a field emission gun scanning electron

microscope (SEM-FEG) from JEOL (model JSM 7100F TTLS). This SEM is equipped with

an energy dispersive X-ray (EDX) spectrometer. The EDX technique detects X-rays emitted

by the sample while it is being bombarded by an electron beam and is able to characterize the

elemental composition of the surface analyzed.

The precursor content, defined as the mass of HQ per unit mass of support, was determined

by thermogravimetric analysis (TGA) by measuring the mass loss rate of the sample subjected

to a temperature ramp from ambient temperature to 773 K in an oxidizing atmosphere (air).

The thermal signature of the impregnated compound was verified by differential scanning

calorimetry (DSC). A Model Q600 analyzer from TA Instruments was used to perform both

TGA and DSC.

The attrition resistance was determined by a simple attrition test. A sample of the composite

material was sieved for 3 hours and its precursor content was measured by TGA. The value

obtained was compared with the precursor content of the original sample.

The textural parameters – specific area, total pore volume, and pore size distribution (PSD) –

were estimated from N2 adsorption–desorption isotherms at 77 K using an automatic

Micromeritics TriStar II 3020 system. This system can be used to evaluate mesoporous

materials (i.e. materials with a pore size of 2 to 50 nm) with a specific area reaching several

thousands of m2/g. Before the measurements were taken, samples were purified at 308 K and

10 Pa for 24 hours. Specific areas were determined based on the Brunauer-Emmett-Teller

(BET) method [Brunauer, S., Emmett, P.H., Teller, E., 1938. Adsorption of gases in

multimolecular layers. J. Am. Chem. Soc. 60, 309-319]. Both the total pore volume and the

pore size distribution were calculated using the Barrett-Joyner-Halenda (BJH) method

[Barrett, E. P., Joyner, L.G., Halenda, P.P., 1951. The determination of pore volume and area

distributions in porous substances. I. Computations from nitrogen isotherms. J. Am. Chem.

Soc. 73, 373–380] applied to the desorption branch of the N2 isotherm.

Structural data were obtained by cross-polarization / magic angle spinning (CP/MAS) solid-

state 13C NMR experiments using a Bruker Avance 400 spectrometer. The sample was placed

in a zirconia rotor of 7 mm and the spectra were collected at ambient temperature at a

resonance frequency of 100.61 MHz and a magic angle spinning rate of 7 kHz. The contact

time and pulse delay were 3.8 ms and 5 s respectively. Chemical shifts were referenced to

tetramethylsilane at 0 ppm and carbonyl signal of glycine at 176 ppm as external reference.

The three-dimensional microstructure was obtained by X-ray tomography using a Zeiss

Xradia Versa 510. Samples were subjected to the ambient test conditions (28°C) for at least

24h prior to each scan to ensure thermal equilibrium. For each scan, 2001 16 bit radiographs

are acquired, while rotating the sample over 360°. The acquisition settings were selected

based on the recommendations of the manufacturer of the tomograph [Zeiss, 2016. Zeiss

Xradia Versa User’s Guide]. 3D tomographic reconstruction was performed using the filtered

back projection algorithm, as implemented in XMReconstructor [Zeiss, 2016. Zeiss Xradia

Versa User’s Guide], using a Gaussian filter with a unit kernel width. Data analysis and

visualization was performed using Fiji [Schindelin J., Arganda-Carreras I., Frise E., Kaynig

V., Longair M., Pietzsch T., Preibisch S., Rueden C., Saalfeld S., Schmid B., Tinevez J. Y.,

White D. J., Hartenstein V., Eliceiri K., Tomancak P., Cardona A., 2012. Fiji: an open-source

platform for biological-image analysis. Nat Methods, 9, 676-682].