Enhanced Acidic and Catalytic Properties of Modified Sulfonic Acid Resins. D R Brown, H E Cross and P F Siril

Transcription

1 Enhanced Acidic and Catalytic Properties of Modified Sulfonic Acid Resins D R Brown, E Cross and P F Siril Department of Chemical and Biological Chemistry, University of uddersfield

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4 1 omogeneous Acid Catalysts: AlCl 3, 2 S 4, F - DISPSAL!! 2 eterogeneous Acid Catalysts A) Rigid Solid Acids 1 nm pores X 10 nm pores K B) Non-Rigid Solid Acids Solvent Gel e.g. Sulfonated Polystyrene Resins S 3 S 3

5 Sulfonated polystyrene S 3 S 3 C 3 S 3 S 3 [ +] 4.9 mmol g -1 S 3 S 3 S 3 [ +] 2.9 mmol g -1 p-toluenesulfonic acid S 3 S 2 S 3 S 3 S 3 S 3 [ +] 5.4 mmol g -1

6 Surface Acidity Characterisation Base Temperature Programmed Desorption Base Adsorption Calorimetry NMR direct or with probe (eg triethylphosphine) IR direct or with probe ammett Indicators (eg dicinnamalacetone pka -3.0 benzalacetophenone pka -5.6)

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8 Enthalpy of N 3 Adsorption (as a measure of acid site strength) o ads (N 3 ) = -150 kj mol-1 N 3 + Solid- N Solid -

9 Enthalpy of N 3 Adsorption (as a measure of acid site strength) o ads (N 3 ) = -150 kj mol-1 N 3 + Solid- N Solid - - o (PA Solid - ) o (Binding) Solid Solid - + N N 3 o PA (N 3 ) = kj mol-1 N 4 +

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11 40 30 eat flow /mw eat Flow /mw Time /s Time /s -125 Δ o ads (N 3 )/ kj mol -1 ads(n3) /kj mol CT-175, 4.90 mmol g -1 CT-275, 5.40 mmol g -1 CT-375, 5.52 mmol g -1 Sulfonated Polystyrene Resins S 3 S D4034, 0.74 mmol g -1 SP21-51, 1.82 mmol g -1 AMB15, 4.74 mmol g Average Coverage /mmol g -1 N 3 Coverage /mmol g -1

12 Molar enthalpy of adsorption of N 3 vs. amount of N 3 adsorbed on macroporous sulfonated polystyrene beads at 100 C CT-275, ads(n3) /kj mol CT-175, 4.90 mmol g mmol g -1 CT-375, 5.52 mmol g D4034, 0.74 mmol g -1 SP21-51, 1.82 mmol g -1 AMB15, 4.74 mmol g Average Coverage /mmol g -1

13 CT-275, ads(n3) /kj mol CT-175, 4.90 mmol g mmol g -1 CT-375, 5.52 mmol g D4034, 0.74 mmol g -1 SP21-51, 1.82 mmol g -1 AMB15, 4.74 mmol g Average Coverage /mmol g -1 + (- 2 ) + Catalyst Reaction Specific Selectivity/ Rate Activity [exene] [Ether] /10-2 μmol /10-3 μmol converted converted g -1 h -1 mmol -1 (-S 3 ) h Amb15 ([ + ] = 4.7 mmol g -1 ) CT-175 ([ + ] = 4.9 mmol g -1 ) CT-275 ([ + ] = 5.4 mmol g -1 )

14 Catalyst Reaction Specific Selectivity/ Rate ACTIVITY [exene] [Ether] /10-2 μmol /10-3 μmol converted converted g -1 h -1 mmol -1 (-S 3 ) h Amb15 ([ + ] = 4.7 mmol g -1 ) CT-175 ([ + ] = 4.9 mmol g -1 ) CT-275 ([ + ] = 5.4 mmol g -1 )

15 + + S S S S S S S S I II III

16 N 3 Adsorption from e eat flow / mw st th Amb15 Sulfonated polystyrene A eat flow / mw th B -ZSM th th th Time / s th Time / s Exo Endo The shape of the calorimeter signal changes as the solid acid becomes progressively saturated - Signals for pulses 1, 6, 9, 11 and 13.

17 Solvent Gel Internal Solution (m)

18 a) eat Flow /mw 2 Aqueous Titration Microcalorimetry - ydrated Sulfonated Resins with 0.1 M Na solution Time/min b) Na / mmole Δ neut / kj -4-8 Δ o neut = kj mol -1-12

19 Liquid Titration Calorimetry Δ neut. (Na) aq - Sulfonated Polystyrene Resins - Dependence on Level of Sulfonation 62 Δ o neut Na(aq) / kj mol Cation Exchange Capacity / mmol g -1

20 Liquid Titration Calorimetry Sulfonated Resins Δ neut. (Na) aq - vs Concn Internal Solution 58 Gel resin Gel resins Δ neut /kj mol -1 Δ neut. (Na) aq /kj mol Solution Concentration /mol kg -1 (water) Concn Internal Solution /mol kg -1

21 Liquid Titration Calorimetry Sulfonated Resins Δ neut. (Na) aq - vs Concn Internal Solution 58 Gel resins Δ neut. (Na) aq /kj mol -1 Δ neut /kj mol Cl p-ts Solution Concentration /mol kg -1 (water) Concn Internal Solution /mol kg -1

22 FT-Raman Spectroscopy - ydrated Sulfonated Resins ( + Form) -S cm -1 Polystyrene 97% sulfonated -S cm -1 Polystyrene 70% sulfonated Polystyrene 43% sulfonated Polystyrene 24% sulfonated

23 Degree of Acid Dissociation vs Concn of Internal Solution - FT-Raman Data 100 Et-S 3 p-ts α /% % Dissociation 50 Gel resins Internal Solution Concentration /mol kg -1

24 Conclusions Sulfonated Polystyrene (ydrated) igh sulfonation = reduced acid dissocation = increased acid strength = higher catalytic activity Effective acid catalysts in water Enhanced acid strength/activity not seen in other supported sulfonic acids

25 Sulfonated polystyrene S 3 Sulfonated silica S 3 S 3 Et F F F F F F Si F F F F F F F F S 3 Si Si Si F F F F CF 3 Fluorinated polyethylene Nafion Si Si

26 Catalyst Acid Site o neut. Initial Rate (TN) Concentration (aq. Na) /mol (acid-mol) -1 min -1 /mmol g -1 /kj mol -1 Polystyrene-S 3 AMB AMB Silica-S 3 MCM MCM MCM SBA Aqueous Strong Acids 0.1 mol dm -3 Cl mol dm -3 p-ts

27 Physical characteristics of Amberlyst resin powders Sulfonated polystyrene resin ( 125 μm) Cation exchange capacity a /mmol g -1 Surface area b /m 2 g -1 Pore volume c /cm 3 g -1 Average pore size /nm Amberlyst Amberlyst Amberlyst a Rohm and aas data. 5 b BET adsorption isotherm using N 2. c Total volume of pores with diameters nm (BJ).

28 Physical characteristics of Amberlyst resin powders Sulfonated polystyrene resin ( 125 μm) Cation exchange capacity a /mmol g -1 Surface area b /m 2 g -1 Pore volume c /cm 3 g -1 Average pore size /nm Amberlyst Amberlyst Amberlyst a Rohm and aas data. 5 b BET adsorption isotherm using N 2. c Total volume of pores with diameters nm (BJ).

29 Physical characteristics of Amberlyst resin powders Sulfonated polystyrene resin ( 125 μm) Cation exchange capacity a /mmol g -1 Surface area b /m 2 g -1 Pore volume c /cm 3 g -1 Average pore size /nm Amberlyst Amberlyst Amberlyst a Rohm and aas data. 5 b BET adsorption isotherm using N 2. c Total volume of pores with diameters nm (BJ).

30 -Δ 0 ads /adsorbed N 3 for Amberlyst resins at 100 o Cby adsorption calorimetry, sample size 5 mg

31 -Δ 0 ads /adsorbed N 3 for Amberlyst resins at 100 o Cby adsorption calorimetry, sample size 20 mg

32 Acidity data by N 3 adsorption calorimetry at 100 o C. Sulfonated resin Average -Δ 0 ads a /kj mol -1 Total N 3 adsorbed b /mmol g -1 Cation exchange capacity c /mmol g -1 Amberlyst ± ± Amberlyst ± ± Amberlyst ± ± Nafion NR ± ± a Average up to coverage where Δ 0 ads falls below -80 kj mol-1. b coverage where Δ 0 ads falls numerically below -80 kj mol -1. c Rohm and aas data. 5

33 Acidity data by N 3 adsorption calorimetry at 100 o C. Sulfonated resin Average -Δ 0 ads a /kj mol -1 Total N 3 adsorbed b /mmol g -1 Cation exchange capacity c /mmol g -1 Amberlyst ± ± Amberlyst ± ± Amberlyst ± ± Nafion NR ± ± a Average up to coverage where Δ 0 ads falls below -80 kj mol-1. b coverage where Δ 0 ads falls numerically below -80 kj mol -1. c Rohm and aas data. 5

34 Acidity data by N 3 adsorption calorimetry at 100 o C. Sulfonated resin Average -Δ 0 ads a /kj mol -1 Total N 3 adsorbed b /mmol g -1 Cation exchange capacity c /mmol g -1 Amberlyst ± ± Amberlyst ± ± Amberlyst ± ± Nafion NR ± ± a Average up to coverage where Δ 0 ads falls below -80 kj mol-1. b coverage where Δ 0 ads falls numerically below -80 kj mol -1. c Rohm and aas data. 5

35 Acidity data by N 3 adsorption calorimetry at 100 o C. Sulfonated resin Average -Δ 0 ads a /kj mol -1 Total N 3 adsorbed b /mmol g -1 Cation exchange capacity c /mmol g -1 Amberlyst ± ± Amberlyst ± ± Amberlyst ± ± Nafion NR ± ± a Average up to coverage where Δ 0 ads falls below -80 kj mol-1. b coverage where Δ 0 ads falls numerically below -80 kj mol -1. c Rohm and aas data. 5

36 C 3 C C 2 3 C 3 C 3 + Limonenes C 3 C 2 C 3 + C 2 C Reaction rate data Catalyst Amberlyst 70 Amberlyst 15 Amberlyst 35 Nafion NR Isomerisation of α-pinene (conversion at 100 o C) Initial turnover frequency per acid site /h Benzylation of toluene (conversion of benzyl alcohol at 80 o C) Initial turnover frequency per acid site /h

37 C 3 C C 2 3 C 3 C 3 + Limonenes C 3 C 2 C 3 + C 2 C Reaction rate data Catalyst Amberlyst 70 Amberlyst 15 Amberlyst 35 Nafion NR Isomerisation of α-pinene (conversion at 100 o C) Initial turnover frequency per acid site /h Benzylation of toluene (conversion of benzyl alcohol at 80 o C) Initial turnover frequency per acid site /h

38 C 3 C C 2 3 C 3 C 3 + Limonenes C 3 C 2 C 3 + C 2 C Reaction rate data Catalyst Amberlyst 70 Amberlyst 15 Amberlyst 35 Nafion NR Isomerisation of α-pinene (conversion at 100 o C) Initial turnover frequency per acid site /h Benzylation of toluene (conversion of benzyl alcohol at 80 o C) Initial turnover frequency per acid site /h

39 C 3 C C 2 3 C 3 C 3 + Limonenes C 3 C 2 C 3 + C 2 C Reaction rate data Catalyst Amberlyst 70 Amberlyst 15 Amberlyst 35 Nafion NR Isomerisation of α-pinene (conversion at 100 o C) Initial turnover frequency per acid site /h Benzylation of toluene (conversion of benzyl alcohol at 80 o C) Initial turnover frequency per acid site /h

40 ydrothermal stability of Amberlyst 70 compared to Amberlysts 15, 35 and 36 Acid Sites (meq/g) Acid Site concentration after 6 h hydrothermal Amberlyst 35 Amberlyst 15 Amberlyst Temperature ( o C)

41 T o ta l a c id s ite c o n c e n tra tio n a fte r th e rm a l tre a tm e n t (2 0 0 C ) % of original total acid concn A 3 5 R E D A 7 0 B L U E A 1 5 B L A C K lo g [t]

42 S u l f u r c o n t e n t b y X R F C h y d r o t h e r m a l Sulfur content (% of original) A 3 5 R E D A 7 0 B L U E A 1 5 B L A C K lo g [t]

43 Acknowledgements EPSRC DTI Royal Society Purolite International Ltd BP University of uddersfield owell Edwards, University of Bradford Graham Fuller Colin Park Prem Siril Said Koujout annah Cross

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45 Flow adsorption calorimeter Automated gas sampling valve 1% N 3 in e Differential Scanning Calorimeter (flow-through cell) e carrier Mass spec

46 α-pinene conversion to camphene at 100 o C C 3 C C 2 3 C 3 C 3 + Limonenes C 3 % conversion Nafion powder 155 kj/mol 1.0 mmol/g Amberlyst 35 powder 125 kj/mol 5.0 mmol/g Silica-S kj/mol Amberlyst 1.0 mmol/g 15 powder Time / min

47 o ads (N 3 ) at 100 o C for supported sulfonic acids 160 Nafion 140 Amberlyst / kj mol-1 Δ 0 ads MCM-41-S 3 Amberlyst 15 (Silica S 3 ) Surface coverage / mmol g -1

48 Calorimeter signal Time /s Mass spec signal (m/e 15)

49 eat Flow / mw utput sensitive to the RATE of adsorption Increased probe gas flow rate over sample (reduced contact time) 0.2 Typical data for higher N 3 flow rate heat Intensity of m/z - 15 / arbitary units x x x Time / s Time / s Falling STICKING Factor MS signal

50 Acknowledgements Prem Siril Said Koujout Mark art Graham Fuller owell Edwards (Bradford)

51 Adsorption Calorimetry Gas/Vapour on Solid Capacities of adsorbent/catalysts Adsorption enthalpies Adsorption rates Desorption

52 Adsorption Calorimetry Gas/Vapour on Solid Capacities of adsorbent/catalysts Adsorption enthalpies Strength/abundance of catalytic sites Adsorption rates Desorption

53 Calorimeter signal Time /s Mass spec signal (m/e 15)