University of Tabriz. From the SelectedWorks of Hosein Afshary. Hosein Afshary, University of Tabriz. Winter February, 2010

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γ-al2o3 during catalytic oxidation of some oxygen containing VOCs in a tubular

1 University of Tabriz From the SelectedWorks of Hosein Afshary Winter February, 2010 Investigation of deactivation of transition metal oxide catalysts supported on γ-al2o3 during catalytic oxidation of some oxygen containing VOCs in a tubular reactor Hosein Afshary, University of Tabriz Available at:

2 Investigation of deactivation of transition metal oxide catalysts supported on γ-al 2 O 3 during catalytic oxidation of some oxygen containing VOCs in a tubular reactor Supervisor Dr.A. Niaei Advisors Dr. D. Salari Researcher Hosein Afshary february 2010

3 Outline Volatile organic compounds(vocs) Catalyst deactivation Experimental section Results and discussion 2

4 VOCs What is the VOC? According to European Union definition A VOC is any organic compound having an initial boiling point less than or equal to 250 C measured at a standard atmospheric pressure of kpa and can do damage to visual or audible senses. 3

5 VOCs Environmental problems: greenhouse effect creation of smog damage to the ozone layer Groundwater pollution Soil pollution 4

VOCs Abatement methods VOCs Removal techniques Modification of equipments and process double technique control destruction recovery biological Filter oxidation

6 VOCs Abatement methods VOCs Removal techniques Modification of equipments and process double technique control destruction recovery biological Filter oxidation Penetration Compressio adsorption membranous absorbs ion n separation Thermal oxidation Catalytic oxidation RFR Adsorption by active carbon Adsorption by zeolites 5

7 VOCs Catalytic oxidation is preferred Advantages: Higher conversion efficiency Lower energy usage (economical justification) Less by-products 6

8 Catalyst deactivation What is the deactivation? catalyst loss of activity with time-on-stream It is both of chemical and physical nature It is inevitable but it can slowed or prevented 7

9 Catalyst deactivation Deactivation types Poisoning Coking Sintering Solid state transformation masking pore blockage Others volatilization attrition crushing 8

10 Catalyst deactivation Deactivation mechanisms Parallel deactivation Octave Levenspiel Series deactivation Side-by-side deactivation 9

Experimental section Aims of this work Preparation of catalysts ( Mn/ γ-al 2 O 3 and Cr/ γ-al 2 O 3 ) Characterization of prepared catalysts (XRD, SEM, FT-IR) Time on stream studies in catalytic

11 Experimental section Aims of this work Preparation of catalysts ( Mn/ γ-al 2 O 3 and Cr/ γ-al 2 O 3 ) Characterization of prepared catalysts (XRD, SEM, FT-IR) Time on stream studies in catalytic oxidation of some O-VOCs Comparing the results with industrial Pt/ γ-al 2 O 3 Investigation of the effect of metal species on deactivation Investigation of the effect of VOC species on deactivation determination of the type of deactivation 10

12 Experimental section catalysts: 1. Pt / γ-al 2 O 3 (an industrial catalyst) 2. Mn / γ-al 2 O 3 (4% wt) 3. Cr / γ-al 2 O 3 (4% wt) 11

13 Experimental section O-VOCs: 1. Isopropanol 2. Benzyl alcohol 3. Ethyl acetate 12

14 Experimental section Catalyst preparation: Impregnation method was carried out γ Al 2 O 3 M (NO 3 ) 2 1 M Stirring (24 hr ) Centrifuge and filtration drying 105 C 24 hr M = Mn, Cr M/γ Al 2 O 3 calcinations 450 C 13

15 Experimental section Reactor configuration N 2 air 14

16 Experimental section Reaction constant conditions: Reactor temperature: 350 C o Pressure: 1 atm Total gas flow: M 3 /S Catalyst weight: 0.2 gr Catalyst bed length: 7 cm Reactor diameter: 11 mm 15

17 Experimental section Analyses: Products quantitative analysis: GC (FID) Products qualitative analysis: GC-MS Determination of particle size and surface species : XRD Catalysts morphological analysis: SEM Catalysts surface elemental analysis: EDS Coke species analysis: FT-IR 16

18 Experimental section Examples of GC analyses propene toluene isopropanol Isopropanol Impurity of solvent Toluene 17

19 Experimental section An example of GC-MS analyses (detection of propen in product) 18

20 Experimental section 1. Oxidation of isopropanol Bp: 82.5 C 0 saturator condition: ice-water bath(0 C 0 ) Feed concentration: ppm Main reaction: Isopropanol + O 2 CO 2 + H 2 O By reaction: Isopropanol propene + H 2 O 19

21 Experimental section 2. Oxidation of Benzyl alcohol bp: C o saturator condition: boiling water bath(95 C o ) Feed concentration: 130 ppm Main reaction: Benzyl alcohol + O 2 CO 2 + H 2 O By reaction: not observed 20

22 Experimental section 3. Oxidation of Ethyl acetate bp: 77.1 C 0 saturator condition: ice-water bath(0 C 0 ) Feed concentration: 14077ppm Main reaction: Etoac + O 2 CO 2 + H 2 O By reactions: Etoac AcOH + EtOH Etoac Acetaldehyde Etoac Acetone 21

23 Results and discussion Time on stream studies a) Oxidation of benzyl alcohol Total conversion total conversion (%) oxidation over Cr/Al2O3 oxidation over Pt/Al2O3 oxidation over Mn/Al2O time on stream (h) 22

24 Results and discussion Time on stream studies b) Oxidation of isopropanol Total conversion 100 Total conversion (%) oxidation over Pt/Al2O3 oxidation over Mn/Al2O3 oxidation over Cr/Al2O Time on stream (h) 23

25 Results and discussion Time on stream studies b) Oxidation of isopropanol Yield of by product(propen) 100 yield of propene (%) oxidation over Pt/Al2O3 oxidation over Mn/Al2O3 oxidation over Cr/Al2O Time on stream (h) 24

26 Results and discussion Time on stream studies c) Oxidation of Ethyl acetate Total conversion total conversion(%) oxidation over Pt/Al2O3 oxidation over Mn/Al2O3 oxidation over Cr/Al2O time on stream(h) 25

Results and discussion Time on stream studies c) Oxidation of Ethyl acetate Yield of by products 100 yield of by products(%) 90 80 70 60

27 Results and discussion Time on stream studies c) Oxidation of Ethyl acetate Yield of by products 100 yield of by products(%) oxidation over Pt/Al2O3 oxidation over Cr/Al2O3 oxidation over Mn/Al2O time on stream(h) 26

28 Results and discussion XRD patterns 1. Fresh catalysts intensity (a.u) (c) (b) a) Al 2 O 3 b) Cr/Al2O3 c) Mn/Al2O3 (a) θ intensity industrial Pt/Al 2 O θ 27

29 Results and discussion XRD patterns 2. Used catalysts a. Oxidation of isopropanol intensity (a.u.) (b) a) fresh Mn/Al 2O 3 a) used Mn/Al 2 O 3 (a) intensity (a.u.) a) fresh Pt/Al2O3 b) used Pt/Al2O3 (b) θ a) fresh Cr/Al 2 O 3 b) used Cr/Al2O3 (a) θ intensity(a.u) (b) (a) ? 28

30 Results and discussion XRD patterns 2. Used catalysts b. Oxidation of ethyl acetate intensity (a.u.) a) fresh Mn/Al 2 O 3 b)used Mn/Al 2 O 3 (a) (b) a) fresh Pt/Al 2 O 3 b) used Pt/Al2O θ (degree) intensity (a.u.) (b) (a) θ (degree) intensity (a.u.) (b) (a) a) fresh Cr/Al 2 O 3 b) used Cr/Al 2 O θ (degree) 29

31 Results and discussion FT-IR results 1. Oxidation of isopropanol absorbance (a. u.) a) fresh Cr/Al 2 O 3 b) used Cr/Al 2 O 3 (b) (a) absorbance (a. u.) a) fresh Pt/Al 2 O b) used Pt/Al2O 3 wavenumbers (cm -1 ) 3300 OH 2300 (b) (a) wavenumbers (cm -1 ) absorbance (a. u.) a) fresh Mn/Al 2 O 3 b) used Mn/Al 2 O 3 (b) 3400 (a) wavenumbers (cm -1 )

32 Results and discussion FT-IR results 2. Oxidation of ethyl acetate a) fresh Pt/Al 2 O 3 absirbance (a. u.) a) fresh Cr/Al2O3 b) used Cr/Al2O3 (b) absorbance (a. u.) b) used Pt/Al 2 O 3 (b) (a) 3400 (a) wavenumbers (cm -1 ) a) fre sh M n/al 2 O 3 b) use d M n/al 2 O 3? wavenumbers (cm -1 ) 300 absorbance (a. u.) (b) (a ) wav e numbe rs (cm -1 )

33 Results and discussion SEM images and EDS results a. Fresh catalysts 1. Industrial Pt/Al2O3 Spectra: Pt Element Series unn. C norm. C Atom. C [wt.-%] [wt.-%] [at.-%] Oxygen K series Aluminium K series Platinum M series Gold M series Total: % 32

34 Results and discussion SEM images and EDS results a. Fresh catalysts 2. Mn/Al 2 O 3 Spectra: Mn Element Series unn. C norm. C Atom. C [wt.-%] [wt.-%] [at.-%] Oxygen K series Aluminium K series Manganese K series Gold M series Total: 91.8 % 33

35 Results and discussion SEM images and EDS results a. Fresh catalysts 3. Cr/Al 2 O 3 Spectra: Cr Element Series unn. C norm. C Atom. C [wt.-%] [wt.-%] [at.-%] Oxygen K series Aluminium K series Chromium K series Gold M series Total: % 34

Results and discussion SEM images and EDS results b. Used catalysts 1. Pt/Al2O3 (oxidation of ethyl acetate) Spectra: Pt-Et Element Series unn. C norm. C Atom. C [wt.-%] [wt.-%] [at.

36 Results and discussion SEM images and EDS results b. Used catalysts 1. Pt/Al2O3 (oxidation of ethyl acetate) Spectra: Pt-Et Element Series unn. C norm. C Atom. C [wt.-%] [wt.-%] [at.-%] Carbon K series Oxygen K series Aluminium K series Platinum M series Gold M series Total: % 35

Results and discussion SEM images and EDS results b. Used catalysts 2. Mn/Al 2 O 3 (oxidation of ethyl acetate) Spectra: Mn-Et Element Series unn. C norm. C Atom. C [wt.-%] [wt.-%] [at.

37 Results and discussion SEM images and EDS results b. Used catalysts 2. Mn/Al 2 O 3 (oxidation of ethyl acetate) Spectra: Mn-Et Element Series unn. C norm. C Atom. C [wt.-%] [wt.-%] [at.-%] Carbon K series Oxygen K series Aluminium K series Manganese K series Gold M series Total: 80.8 % 36

Results and discussion SEM images and EDS results b. Used catalysts 3. Cr/Al 2 O 3 (oxidation of ethyl acetate) Spectra: Cr-Et Element Series unn. C norm. C Atom. C [wt.-%] [wt.-%] [at.

38 Results and discussion SEM images and EDS results b. Used catalysts 3. Cr/Al 2 O 3 (oxidation of ethyl acetate) Spectra: Cr-Et Element Series unn. C norm. C Atom. C [wt.-%] [wt.-%] [at.-%] Carbon K series Oxygen K series Aluminium K series Chromium K series Gold M series Total: % 37

39 Results and discussion SEM images b. Used catalysts 4. Pt/Al 2 O 3 (oxidation of isopropanol) 38

40 Results and discussion SEM images b. Used catalysts 5. Mn/Al 2 O 3 (oxidation of isopropanol) 39

41 Results and discussion SEM images b. Used catalysts 6. Cr/Al 2 O 3 (oxidation of isopropanol) 40

42 Results and discussion Results XRD patterns showed structures XRD patterns showed coke and phase transformation Time on streams showed deactivation properties (selectivity and activity) SEM and EDS results showed the deactivation types FT-IR results showed the absorbed and surface species For isopropanol oxidation: Cr/ γ-al 2 O 3 For ethyl acetate oxidation: Mn/ γ-al 2 O 3 For benzyl alcohol oxidation: Cr/ γ-al 2 O 3 = Mn/ γ-al 2 O 3 41

43 Suggestions for future works Study of other VOCs or O-VOCs Study of other transition metals Study of deactivation kinetics Study of promoter effects on catalyst deactivation Study of by metallic catalysts deactivation Modeling of deactivation 42

44 43

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