coating of structured catalytic reactors by plasma assisted polymerization of tetramethyldisiloxane. - stainless steel name plate

Three main types of reactors are used in industrial heterogeneous catalytic technology
Fluidized bed reactor
Bed Reactor and recovery unit.
They all provide a large internal surface area and a high free volume, but despite these advantages, there are also some disadvantages, such as low
Heat transfer coefficient (packed bed)
Erosion/wear of catalyst powder (fluidized bed)
It should also be noted that (1), (2).
Compared with the classical industrial reactor, the hot reactor technology is expected to bring several advantages to chemical production (3), (4).
For example, in the case of a strong heat release reaction such as selective oxidation of hydrocarbons, the packed bed reactor does not allow the heat to be fully dissipated.
The resulting hot spot clue toan low selective thetargeted product for the deactivation of the early pd/c catalyst due to composition-products.
To overcome these problems, a possible solution is to use a structured reactor with a coated catalytic Wall (5).
Therefore, the catalyst is deposited as a film (
A few microns)
On metal walls or structurescoatingmethod.
However, once deposited, the catalytic oxide film must be mechanically and chemically stable and exhibit catalytic properties similar to the corresponding powder.
So far, Al (6)or Al-
Alloys such as Kanthal or FeCralloy are expensive.
Therefore, if technical solutions based on cheap substrates are found, the development of structured reactors will become possible.
Stainless Steel (SS)
This is a common material for reactors (7)
In order to allow oxide adhesion of similar catalysts, modifications must be made.
Another drawback is that under the reaction, iron from SS may spread to the active phase and poison it (8). To by-
Through this inconvenience, one method is to deposit the primer layer on the basis of the plasma polymerization technology.
Although the traditional way of polymerization requires organic compounds with polymerization structures, any organic or inorganic compounds can be used in the framework of the auxiliary plasma polymerization process.
In this case, polymerization occurs because the active species of the plasma have enough energy to produce free radicals, and the composite involves the growth of the film, that is, plasma polymer films that can be deposited on various substrates.
When a discharge plasma is involved, the deposition rate is usually very low.
Because this plasma is characterized by charged particles with high concentrations, there is competition between deposition and etching induced by electron and ion bombardment.
This work involves cold remote nitrogen plasma (CRNP)
Located far away from the discharge, the mechanism produced is free of charged particles, so the etching effect is very low and the deposition rate reaches 100 times that obtained by the discharge plasma.
The process is a cold plasma-assisted polymerization based on TMDSO for the preparation of Asia-
Similar layers on the stainless steel substrate can ensure the mechanical stability of the active phase (9-11)
, Acts as a barrier to prevent corrosion and Fe diffusion during the catalyst reaction, and also acts as a binding layer for active phase deposition.
In order to achieve this goal, the full mineralization of the deposited plasma polymerization membrane-
Also known as plasma polymer TMDSO (ppTMDSO)film--
Abuse is needed.
In this article, the process is applied to two stainless steel-free substrates: Laminate and foam with the aim of ensuring the mechanical stability of the active phase, such []VO. sub. x]/[TiO. sub. 2].
[Grafting]TiO. sub. 2]
Support with two substrates.
The interest of metal foam is to use its roughness and 3D dimensions to increase the useful surface area, which is a very important parameter for catalytic reactions.
Experimental device for remote nitrogen plasma assisted polymerization reactor in experimental plasma polymerization process as shown in Fig. 1. The nitrogen (grade 99. 99%)
The flow is stimulated by microwave discharge (2450 MHz-200 W)
In a miscellaneous silicon tube
By continuous pumping (
Roots pump)
, Re-activated flow from discharge to deposition area located at 1 m of discharge.
The main reaction species in this region that do not have charged particles are atomic nitrogen in the ground electron Staten ([. sup. 4]S).
TMDSO monomer (
Sigma Aldrich, level 97%)
Pre-mixing of oxygen (grade [
Greater than or equal to]99. 5)
, Introduction of CRNP through coaxial syringe.
The flow of dinitrogen, dioxygen and tmdso at 1800, 25, and 5 seems (
Standard cubic centimeters per minute)
The quality control through MKS is 550 Pa-Flowcontroller.
Measurement of deposition rate by He-in-situ interference
Ne laser and photoelectric detector.
The process consists of several steps: first, pre-treat the substrate to be coated with singleCRNP for 5 minutes to clean it and resolve contaminants.
Then themonomer /[O. sub. 2]
Add the mixture without air exposure in the deposition step.
Detailed information on the proposed reaction mechanism for monomer decomposition can be found in (12).
Finally, after the TMDSOcoated substratetreated in a [N. sub. 2]/1. 5% [O. sub. 2]
The plasma is remote in 5 minutes. [
Figure 1 slightly]
Stainless steel substrate (AISI 316L)plates (
50mm X 20mm X 0. 5 mm)andfoam (Porvair[R]
, Ppi 40, density 5. 4%)
Used as a substrate.
The surface of the stainless steel plate is shown in the figure. 2a.
Figure 2b and c show the picture after 1 cm X 0 cutting the foam. 7 cm blocks.
Ultrasonic treatment of the substrate with ethanol before use (Sigma-Aldrich 99. 9%)
Remove organic traces in 30 minutes, then ultrasound twice in deionised water for 30 minutes, then dry at 100 [degrees]C for 3h. [
Figure 2:
During the mineralization process, the ppTMDSO film is subjected to the forced convection in the Maton programmable furnace through heat treatment in the air.
Control of Heatingrate with Nelotherm temperature regulator.
In order to remove the remaining carbon traces on the surface sample, . [N. sub. 2]/1. 5% [O. sub. 2]
Finally, remote plasma processing is applied in 5 minutes.
After alkali washing, the position of the mineralised membrane can be evolved into a material with high density silicon alcohol. [TiO. sub. 2]
Soak the Coaling substrate to be coated under stirring in aqueoussusion containing 60 wt % [TiO. sub. 2]
Particles within 5 minutes, withdrawn at a speed of 6 mm/s. [TiO. sub. 2]
Provided by Sigma-Aldrich (10[m. sup. 2]/g, 99.
8% ruiti type with an average particle size of 10 /[micro]m).
After coating, roasting the substrate in the air flow of at110 [degrees]
C in 1 hour and then in 700 [degrees]C during 2 h(
Temperature ramp: 80 [degrees]C/min).
The film was characterized by Fourier transform infrared spectroscopy and Raman spectroscopy (FTIR)Perkin-
Elmer spectrometer
The spectrum was recorded in the mirror reflection mode of the spectral range 4000-400 [cm. sup. -1](resolution 4[cm. sup. -1]). Raman spectra (RS)
Recorded on the LabRAM infinite spectrometer (Jobin Yvon)
With liquid nitrogen detector and frequency-
The Nd: YAG laser that provides the excitation line at 532 nm doubles.
The power applied on the sample is less than 5 mW.
Calibrate the spectrometer daily using the silicon line of 521 [cm. sup. -1]. X-
X-ray electron energy spectrum analysis
Optoelectronic energy spectrum (XPS)
Performed using the escalab 220 XL spectrometer from the vacuum generator.
[Single color AlK]alpha]X-
Using the line source, the electronic energy is measured in the constant analyzer energy mode.
The pass of the measured spectrum can be 100 eV, and the pass of the single element spectrum can be 40 eV.
All XPS binding energy is called the C of 285 eV as the core level.
Angle between event X-
Rays and analyzer are 58 [:degrees]
, Photoelectric collected perpendicular to the surface of the sample.
Before the analysis, embed the sample in the epoxy resin and polish it with an abrasive disc (2400 to 3 [micro]m)granulometry. ABal-
The coated Tec cd005 allows the deposition of thin film carbon films.
Element analysis using wavelength dispersion X-
Rayspectrometer (Cameca SX-
100 micro probe analyzer)
Works under 15kv and 15nA for reverse scattering electrons (BSE)
Images of silicon, titanium and iron X-and 15 kV and 49 nA
Ray profile and mapping.
Si, Fe and TiK [alpha]X-
Light is detected using TAP, leukemia, and PET crystals, respectively.
Scanning electron microscope (SEM)
Hitachi 4100 S is equipped with miniatureanalyzed (EDS)
And field firing guns (FEG).
The operating voltage is 15 kV.
The estimated volume of the analysis is about 1 [micro]m X 1 [micro]I am deep and wide.
Laser interference measurement of the thickness of ppTMDSO films deposited on stainless steel plates measured in situ by He-interference methodNe laser ([lambda]=632. 8 nm)
And photoelectric detectors.
Contact angle measurement using the Kruss computer to evaluate the wetting properties of the deposit layer from the contact angle with the deionized water
Controllable angle meter.
The accuracy of the measurement at room temperature is [+ or -]1[degrees].
Results and discussion in the first method, the process of allowing the obtaining of homogeneous [TiO. sub. 2]
Layers of Dip deposition
The coating of SS-on the mineralised ppTMDSO film was studied316L plates.
The process is then used on metal foam.
According to the thickness of the film, the deposition rate of the pptmdso film was evaluated by two methods with an interference measurement of a thickness less than 12 [micro]
M and BSE images with thickness greater than 5 [micro]m.
Figure 3 shows 30-[micro]m thick film.
Under the experimental conditions of this study, the deposit interest rate is 1. 0 [+ or -]0. 1 [micro]
M/min, thickness from 1 to 35 [excellent linearity]micro]m.
The two methods are well agreed.
PpTMDSO films were analyzed with FTIRspectroscopy to determine their chemical properties, similar to those reported in previous studies (9-12).
The spectrum shows a decrease in the strong band of 2145 [cm. sup. -1](see Fig. 4)
This is a feature of Si--
H stretch key in TMDSO (13)
To provide evidence through atomic nitrogen attacks (12).
In the range of 1200-1000[cm. sup. -1]
, Enhancement of double peaks, which is characteristic of asymmetric elongation of Si--O--
Si bonds in the polymerization conformations, and Si--C. [
Figure 3 slightly][
Figure 4 slightly]
Our goal is to find a protocol that allows the conversion of the ppTMDSOfilm into a uniform fully mineralised membrane and in-situ heat treatment of the ppTMDSO membrane in the air. The 15-[micro]
Thick film M-
In [5 minutes]N. sub. 2]/[O. sub. 2]
The plasma glow was submitted to the air heat treatment carried out by 5 [degrees]
C/minheating rate up to 650 [degrees]C.
The final temperature remains unchanged within 1 hour.
As shown in the figure, the protocol leads to a complete burst of layers.
5a, this is also confirmed by the presence of Fe2p photopeak at 710.
68 eV was detected by XPS.
This layer cannot resist physical and chemical constraints induced by the selected conditions.
Therefore, the influence of film thickness (t), the post-treatment (p-t)
Temperature slope (t-r)
A study was carried out to solve this problem.
The response of each experiment was evaluated by BES images. As shown inFig. 5a-
D. Film thickness and rear
Processing is the most important parameter.
For films with outposts, the best results are obtainedtreatment.
Shown before (9), (14)
After Plasma assist
Treatment led to the formation of a quasitwo-
One is the layman's material [SiO. sub. 2]
Another layer of ppTMDSO that was assimilated as unmodified.
During the heat treatment process in the air, the carbon oxygen base of ppTMDSO reacts with oxygen, resulting in the formation [CO. sub. 2]and [H. sub. 2]O (15). [
Figure 5 Slightly]
5-good results were obtained[micro]
1 [m thick filmdegrees]
C/min, no posttreatment.
Under these conditions, a uniform membrane is obtained (Fig. 5d)
, Completely covered SS board.
Figure 6 shows the distribution of Si and Fe concentrations obtained from Electron Probe Microanalysis (EPMA)
Sample analysis of this case.
XPS analysis showed that the carbon level was low and the chemical composition was [SiC. sub. 0. 05][O. sub. 1. 8]
The Raman spectrum also proves this (see Fig. 7). The remaining[CH. sub. 3]
[Effective removal of traces that may not be convenient for further deposition of active stages]N. sub. 2]/[O. sub. 2]
The plasma glow is carried out in 5 minutes.
After this post
After treatment, the surface composition obtained by XPS is [SiO. sub. 0. 01][O. sub. 1. 82](Called again [SiO. sub. x]).
In the course of treatment, the completely modified pptmdso membrane from [contraction]
About equal to]75%.
Check the good adhesion and mechanical stability [SiO. sub. x]
Layer, the sample is immersed in n-
N-gengane ultrasonic bath in 1 minute. No peel-Off was observed.
[Before coatingTiO. sub. 2]
, Immerse the plate in the basic solution within 4 hours (
3 g sodium hydroxide, 4 ml ethanol, 3 ml water).
After this treatment, the contact angle measured by water is 29 [degrees].
Equal to [87]degrees]
Naked SS disc, 104 【degrees]
PpTMDSO/SS and 34 [degrees]for [SiO. sub. x]/SS.
So the comprehensive treatment in [N. sub. 2]/[O. sub. 2]
Plasma and base washing improved the wetting properties of the next [board]TiO. sub. 2]coating step.
Figure 8 shows a 12 [micro]
M thick coating [SiO. sub. x]/SS plate.
WDS profile of Si, Ti and Fe.
9 evidence of the continuous layer is given. ThisTiO. sub. 2]/[SiO. sub. x]
/SS composites remain fairly stable, even at n-
The heptaane ultrasonic bath proved its good mechanical stability in 1 minute. [
Figure 6 slightly][
Figure 7 Slightly][
Figure 8:[
Figure 9 omitted
Stainless steel foam coating due to its large surface volume ratio, the foam presents the advantages of increased mass and increased heat transfer, which must be controlled in the catalytic heat release reaction.
In order to make a uniform coating of the foam with ppTMDSO, there are two configurations (A and B)
Adequate support is designed (see Fig. 10).
In configuration A, the sample has just precipitated on the base plate support, so the reaction gas flows through the foam through diffusion and is consumed before reaching the sample core.
No more coatings were observed (Fig. 11d)beyond3.
5mm from the top surface of the sample.
In configuration B, the active gas flows through the foam.
The pre-cycle transport is then ensured through the entire foam volume.
Uniform layer is observed by foam with an entire thickness above or equal to 15 [micro]m (Figs. 11e-h)
, Evaluated by EPMA along the z direction.
Generate 【SiO. sub. x]
On a layer of metal foam, the sample is decomposed under the conditions of the previously determined plate (no post-treatment, 1[degrees]
Heating rate C/min, final temperature 650 [degrees]C during 1 h).
EPMA images show that it is possible to obtain a uniform calcined ppTMDSO only if the film thickness is less than 7 [micro]m (see Fig. 12).
After Plasmapost-
Processing steps and chemical treatment in sodium hydroxide [TiO. sub. 2]
Coating as described above. EPMA image (Fig. 13)
And electron probe analysisFig. 14)as well as X-ray mapping (see Fig. 14)
Provide evidence for these two consecutive layers. [
Figure 10 slightly][
Figure 11 omitted][
Figure 12:[
Figure 13:[
Figure 14 omitted]
Conclusion in the literature, polymer plasma TMDSO film was first deposited on the entire surface of stainless steel foam by plasma assisted polymerization process.
This film can easily become stable, viscous, uniform [1 [. SiO. sub. x]
Layer after roasting in air.
This result is very interesting in the field of non-homogeneous catalytic industrial applications. Indeed,[SiO. sub. x]
Effectively acts as a binding layer for the deposited oxide catalyst. The [TiO. sub. 2]
A scaffold on which vanadiumisopropoide is grafted by dip-depositioncoating in[TiO. sub. 2]-
Trititanium water suspension. [SiO. sub. x]
Is expected to serve as a primer and a barrier against [poisoning]VO. sub. x]/[TiO. sub. 2]
A catalyst made of iron from a substrate.
The catalytic experiment of this coating foam is in progress.
These catalysts/structural reactors have been successful and their active phase is-
Known for its applications in the chemical industry and pollution reduction, this may help promote the use of new reactors with enhanced heat transfer and mass transfer. [
Figure 15 omitted]
Confirm M. Frere and L.
Gengembre is thanks for the XPS measurements. S.
Thanks for Bellayer's analysis. REFERENCES (1. )H.
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To: Brigitte muttle; e-mail:brigitte. mutel@univ-lillel.
Fr contract award sponsor: national airlineANR-MILLICAT);
Contract award number: 06-BLAN-0126-01.
Online release in the Wiley Online Library (
Wileyonlinelibrary. com). [C]
2011 Institute of Plastic Engineers Adil Essakhi ,(1)
Brigitte muttle (2)
Philip Supiot ,(2)AxelLofberg, (1)
Paul ,(1)
Veronik courtova (1)ValerieMeille,(3)
Pitault, Beibei ,(3)
Elizabeth BoulderRichard (1)(1)
The catalyst of unity and other de Chimie du Solide (UCCS)
University of Science and Technology, Lille 1, France, 8181 villeneuved' asq cedex, UMR 59655 (2)IEMN -
UMR 8520, Groupe BioMEMS, team report P2M-
University of Science and Technology, Lilai 1, France, 59655 teseneuve d. Ascq cedex (3)
Laboratoire de elves des Procedes domtiques CPE Lyon 43Boulevard du 11 nov novembre 1918, BP 82077, 69616 verleban cedex, mountain month, France. 1002/pen.