Hydrothermal saline promoted grafting: A new route to sulfonic acid SBA-15 silica with ultra-high acid site loading for biodiesel synthesis

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Donna Robbins
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1 Eletroni Supplementry Mteril (ESI) for Green Chemistry. This journl is The Royl Soiety of Chemistry 2014 yrotherml sline promote grfting: A new route to sulfoni i SBA-15 sili with ultr-high i site loing for ioiesel synthesis 5 C. Pirez,*, A. F. Lee, J. C. Mnyil, C.M.A. Prlett, K. Wilson * Europen Bioenergy Reserh Institute, Shool of Engineering n Applie Sienes, Aston University, Birminghm, B4 7ET, UK Shool of Chemistry, Criff University, Prk Ple, Criff, CF10 3AT Present ress : UCCS, University of Lille I, Villeneuve Asq, Frne 10 * Corresponing uthor: E-mil: k.wilson@ston..uk S1 Experimentl 15 S1.1 Ctlyst synthesis SBA-15 synthesis: SBA-15 mteril ws prepre following Zho s protool 1. SBA-15 ws prepre from 1.0 g of Pluroni P123 trilok opolymer whih ws issolve in 7.5 ml of wter n 25 ml of 2M Cl solution (Fisher), stirre t 35 C. 2.3 ml of TES were e to the solution, whih ws mintine t 35 C for 24 h uner stirring. Then, the mixture ws then ge t 80 C for 24 h. Finlly, 20 the soli prout ws filtere, wshe 3 times with eionize wter n line sttilly in ir t 550 C for 6 h. ne-pot synthesis: PrS 3 -SBA-15 ws synthesize y o-onenstion metho, oring to the protool of Mrgolese 2. 4 g of Pluroni 123 ws first issolve with 125 m 3 of 2 M Cl t 40 C. Susequently, 8.2 ml of tetrethylorthosilite (TES) ws e, n fter 45 min retion, 0.76 ml 25 of 3-merptopropyl-trimethoxysilne (MPTMS) n 3.8 ml of 2 2 were e simultneously n the solution ws stirre for 24 h. The mixture ws then ge t 100 C for further 24 h, n the resulting soli filtere, wshe three times with wter n finlly rie overnight t room temperture (RT). Templte ws extrte y Me reflux metho. The i tlyst ws lle PrS 3 -SBA-15- P. 30 Grfting sulfoni groups in toluene: SBA-15 ws funtionlize with propylsulfoni i y stnr post-grfting metho. 1 g SBA-15 ws e to solution ontining 1 ml of merptopropyl trimethoxysilne (MPTMS 95%, Alf Aesr) in 30 ml of toluene (Fisher 99%). The suspension ws then refluxe t 130 C uner stirring for 24 h, fter whih the resulting thiol-funtionlize soli ws filtere, wshe three times with methnol (Fisher 99%) n rie t RT. Thiol groups were onverte

2 into -S 3 y mil oxition with 30 ml of 30 % hyrogen peroxie (gm-alrih) y ontinuous stirring t room temperture for 24 h. The sulfonte soli prout ws susequently filtere, wshe three times with methnol n rie t RT. The i tlyst ws lle PrS 3 /SBA-15-Tol. 5 Grfting sulfoni groups in 2 /NCl solution: 1 g SBA-15 ws mixe in 30ml 2 with (or without) NCl for 15min. Then, 1ml of MPTMS is e. The suspension ws then refluxe t 100 C uner stirring for 24 h, fter whih the resulting thiol-funtionlize soli ws filtere, wshe three times with 2 n rie t RT. Thiol groups were onverte into -S 3 y mil oxition with 30 ml of 30 % hyrogen peroxie (gm-alrih) y ontinuous stirring t room temperture for 24 h. The 10 sulfonte soli prout ws susequently filtere, wshe three times with methnol n rie t RT. The i tlyst ws lle PrS 3 /SBA X (where X orrespon to the mount of NCl mg use for the grfting proess) S1.2 Chrteriztion 15 All the i tlysts were fully hrterize. Nitrogen sorption-esorption ws mesure using Qunthrome Nov 2000e porosimeter using NVAWin softwre. Smples were egsse t 120 C for 2 h efore nlysis y N 2 -sorption t 196 C. BET surfe res were lulte over the reltive pressure rnge Pore imeters n volumes were lulte pplying the BJ metho to the esorption isotherm for reltive pressures >0.35. Low-ngle power XRD ptterns were 20 reore on PANlytil X pertpro iffrtometer fitte with n X elertor etetor n Cu Kα (1.54 A ) soure lirte ginst stnr (PANlytil). Low ngle ptterns were reore for 2θ = with step size of TEM pitures were otine with JEL 2100 trnsmission eletron mirosope operte t 200 kv, with imges reore y Gtn Ultrsn 1000XP igitl mer. Imge nlysis ws unertken 25 using ImgeJ softwre. XPS ws performe using Krtos Axis X-ry photoeletron spetrometer fitte with hrge neutrliser n mgneti fousing lens employing Al Kα monohromte rition ( ev). Surfe elementl nlysis ws unertken on Shirley kgroun-sutrte spetr pplying the pproprite instrument n element-speifi response ftors. Spetrl fitting ws onute using CsXPS version , with ining energies orrete to the C 1s pek t ev 30 n high-resolution C 1s, 1s, S 2p n 2p XP spetr fitte using ommon Gussin/Lorentzin pek shpe. Errors were estimte y vrying the Shirley kgroun sutrtion proeure ross resonle limits n re-lulting fits. Thermogrvimetri nlysis (TGA) ws performe using Stnton Reroft STA780 therml nlyzer on mg smples uner helium (20 m 3.min 1 totl

3 flow) uring heting t 10 C. min 1 etween 20 C n 800 C. Ai site titrtion were me vi N 3 pulse hemisorption using Qunthrome ChemBET 3000 instrument t 100 C on smples egsse t 150 C. After N 3 sturtion into the tlysts, TPD-N 3 ws performe t 100 o C up to 800 o C, followe y Mss spetrometer (m/z=16). DRIFT spetr were otine using Niolet Avtr MCT with Smrt Colletor essory, mi/ ner infrre soure n merury mium tellurie (MCT-A) photon etetor t 196 C (liqui N 2 ). Smples were ilute with KBr power (5 wt% in KBr) for nlysis n then loe into n environmentl ell n sujete to itionl rying uner vuum t 200 C for 2 h prior to mesurements to remove moisture physisore uring ir exposure. All spetr were normlize from pek oserve t 1850m-1 for etter visuliztion of hnging in 10 silnol region. 1, 13 C, n 29 MAS-NMR ws onute t the EPSRC UK Ntionl Soli-stte NMR Servie t Durhm using Vrin VNMRS 400 instrument. Spetr were quire uner Cross polristion (CP) & iret exittion (DE) using tetrmethylsilne s referene. S1.3 Esterifition n trnsesterifition retion 15 Esterifition retions were performe uner stirre th onitions t tmospheri pressure in Rley s rousel retion sttion using 25 mm imeter glss retor vessel. 10 mmol of plmiti i ws rete t 60 C in 12.5 ml methnol (molr rtio Me:i = 30) with 50 mg tlyst n 0.6 ml (2.5mmol) of ihexylether e s n internl stnr. Retion profiles were otine vi perioi smpling n off-line GC nlysis, with prout lirtion urves use to verify mss 20 lnes (ll >98 %). All tlyti profiles re n verge of two seprte runs with 3 injetions per smple. Esterifition ws monitore using Vrin 450-GC equippe with CP-l 5 CB 15 m 0.25 mm 0.25 μm pillry olumn. Dihloromethne ws use to ilute smples for GC nlysis. Turnover frequenies (TF) were etermine from the liner portion of the initil retion rte profile for onversions elow 25%, normlize to the i site onentrtion etermine from N 3 titrtions. 25 Glyeryl plmitte trnsesterifition ws me in 50ml ACE glss pressure flsk uner stirring t 80 o C. 10 mmol of Triplmitte (C16) ws issolve in mixture of 12.5 ml methnol with 12.5ml utnol e to i soluilty. Then, 50 mg of tlyst n 0.3 ml of ihexylether ws e s n internl stnr. Smpling ws me fter 24h of retion. Triplmitte trnsesterifition ws monitore using Vrin 450-GC equippe with 1079 progrmmle iret oole on-olumn injetor 30 n Phenomenex pillry olumn ZB-1T Inferno 15m x 0.53mm x 0.15µm. The proportion of methyl n utyl ester proue were the sme for the ifferent tlysts teste (75% methyl ester n 25% utyl ester).

4 S2 Results n Disussion Tle S1 shows how the physil prmeters of grfte sulfoni i tlysts vries s funtion of [NCl] from x= mg. Aition of up to 200mg of NCl results in erese in surfe re 5 ttriute to n inrese of grfting effiieny s eviene y the S ontent n i site loing. Further inreses in [NCl] inhiit silne grfting with oth erese in S n i site loing oserve long with onomitnt inrese in surfe re. The N 2 -isotherms lso hnge s funtion of [NCl] with the BJ plot showing imol istriution (Fig S1), exept for the tlyst PrS 3 /SBA , where NCl onentrtion is optiml. NCl lerly influenes the grfting on 10 the sili surfe n it ppers we nee n optiml onentrtion of NCl to hieve monolyer overge of -PrS 3 on the surfe. Tle S1. Texturl properties of PrS 3 /SBA-15 with ifferent NCl onentrtion in the solution NCl (mg) NCl/ surfe molr rtio BET /m².g -1 Vp /m 3.g -1 BJ pore imeter Plne sping Unit ell prmeter e Wll thikness f Surf. S ontent g /wt% Ai pity h /mmol +.g -1 Sulfur ensity -2 Ai ensity , , , , , in SBA-15 lulte from TGA nlysis, From BET eqution. Anlyze from the esorption rnh. From Brggs lw using 15 (100) plne, e 0 = (2100)/ 3, f 0 - pore imeter, g Surfe S ontent from XPS. h Bse on N 3 pulse titrtion Tle S2. Summry of eonvolute Qn n Tm speies in 29 MAS-NMR for SBA-15 n Pr-S 3 /SBA-15 tlysts prepre vi, one-pot, toluene, n 2 /NCl grfting routes. Smples Q4 /% Q3 /% Q2 /% T3 /% T2 /% Tm/(Tm+Qn) /% SBA PrS 3 -SBA-15-P PrS 3 /SBA-15-TL PrS 3 /SBA PrS 3 /SBA

NCl onentrtion; -x=0, -x=100, -x=200, -x=500 n e-x=1000 mg. g -1 2 5 Fig. S2.

5 ) ) e e ) e SBA-15 Fig. S1. ) N 2 isotherms ) BJ pore size istriution n ) low ngle XRD of PrS 3 /SBA-15 prepre with ifferent NCl onentrtion; -x=0, -x=100, -x=200, -x=500 n e-x=1000 mg. g Fig. S2. Vrition in i site loing of PrS 3 /SBA-15 prepre with ifferent NCl onentrtion showing orreltion with NCl: surfe rtio. [] etermine to e 3 mmol.g -1 s lulte from TGA on the prent SBA-15

6 The orreltion etween i site n sulfur loing shown in Figure S3 lso suggests omplete oxition of thiol groups n goo essiility of sulfoni i groups in ll the tlysts synthetize to N 3. The sene of isulfie groups (-Pr-S-S-Pr-) fter oxition in 2 2 ws verifie y 13 C 5 MASNMR, thermogrvimetri nlysis n XPS. The sene of ny fetures t 41 n 23 ppm in the 13 C MASNMR (Figure S4) inites tht isulfie re not forme in this synthesis. Figure S5 shows the TGA, from whih the sene of ny weight loss <350 C whih woul e ttriute to thiol ( S) or isulfie ( S-S-) eomposition 3,4 lso supports this oservtion. The weight loss oserve C orrespons to eomposition of propyl sulfoni i groups. 5 -Pr S n -Pr S-S-Pr- groups 10 on the surfe re not oserve y XPS nlysis s well (Fig.S5B). S loing mmolg Tol ne pot x=100 x=500 x=0 x=1000 x= Ai site loing / mmolg -1 Fig. S3: Correltion etween sulfur ensity n i site ensity for ll sulfoni i tlyst prepre s funtion of [NCl] shown s x= mg.g -1 ( 2 ), long with onventionl toluene grfting n one-pot o-onenstion methos. 15

7 S 2P Intensity /.u e. C 2 C 2 C 2 S (54) 2 (18) 3 (12).... Fig.S4. 13 C MAS NMR spetr of SBA-15 funtionlize with propylsulfoni i ; -SBA-15, -PrS 3 -SBA-15-P, - PrS 3 /SBA-15-Tol, -PrS 3 /SBA-15-0, e-prs 3 /SBA Bining energy / ev 5 Fig. S5. S2p spetr of mesoporous i tlysts prepre (Bkgroun-sutrte n fitte); - PrS 3 /SBA-15-Tol, - PrS 3 /SBA-15-P, - PrS 3 /SBA

8 1 Chemil shift / ppm Weight loss / % Temperture / C Fig. S6. TGA. - SBA-15, -PrS 3 /SBA-15-Tol, -PrS 3 -SBA-15-P, -PrS 3 /SBA e Ai loing / mmolg Chemil shift / ppm -5 5 Fig. S7 1 MAS NMR spetr of SBA-15 funtionlize with propylsulfoni i -SBA-15, -PrS 3 /SBA-15-Tol, - PrS 3 -SBA-15-P, -PrS 3 /SBA-15-0, e-prs 3 /SBA The ii properties of ll mterils ws etermine N 3 pulse titrtion (mmol +.g -1 ) with i site loings for PrS 3 /SBA foun to e 5 n 2.4 times higher ompre to PrS 3 /SBA-15- Tol n PrS 3 /SBA-15-P. N 3 temperture progrm esorption of the three tlysts show shift 10 to higher temperture (etween C) when the funtionliztion metho is hnge, initing

9 N 3 esorption / m/z=16 i strength inreses in the orer: PrS 3 /SBA > PrS 3 -SBA-15-P > PrS 3 /SBA-15- Tol (Fig S8), n is in goo greement with 1 MAS-NMR. An inrese in i strength n rise ue to the oopertive effets of i sites through formtion of hyrogen oning etween pir of jent sites, whih stilizes nion forme fter eprotontion of i group. 5 Desorption oserve 5 ove this temperture is ttriute to sulfoni i eomposition. 6 igher i strength ( ) PrS 3 /SBA-15-Tol (. ) PrS 3 /SBA-15-P ( ) PrS 3 /SBA Temperture / o C Fig. S8. Temperture progrmm esorption of N 3 (m/z=16) over PrS 3 /SBA-15-Tol, PrS 3 /SBA n PrS 3 /SBA-15-P. Pek res re normlise per grm of soli i tlyst. 10

10 T3 Pr-S T2 Pr-S Q4 Q3 Q2 e Chemil shift (ppm) Fig S9 19 MAS NMR spetr showing evolution Tm n Qn speies for (i) SBA-15, (ii) PrS 3 -SBA-15-P, (iii)tol- PrS 3 /SBA-15, (iv) PrS 3 /SBA-15-0 n (v) PrS 3 /SBA Inset shows strutures for Tm n Qn surfe speies. gnls t -91, -101, n -110 ppm, orrespon to Q2, Q3 n Q4 speies for the support respetively, while those 5 t -66 n -58 ppm, re ttriute to T3 n T2 oorinte orgnosilnes.

11 Intensity Wvenumer (m -1 ) Fig. S10. DRIFTS spetr; -SBA-15, -PrS 3 /SBA-15-Tol n -PrS 3 /SBA A Isolte (3739m -1 ) Geminl (3735m -1 ) Viinl hin (3200m -1 ) -one prtner (3536m -1 ) Viinl Terminl (3710m -1 ) 5 B 2 /NCl reflux N + N + N + Cl - Cl - Cl - (Et) 3 -PrS Pr-S Pr-S 10 Sheme S1. A) Assignment of DRIFTS moe of hyroxyl groups; B) Possile role of 2 0/NCl in tivting siloxne riges for grfting.

12 I /.u Fig. S11A shows N 2 isotherms of SBA-15, PrS 3 /SBA-15 fter grfting (in toluene n 2 /NCl mixture) n y one pot synthesis. Both the prent support n erivtise tlysts exhiit Type IV isotherms with 1 hysteresis loops, hrteristi of open ylinril pores. BJ pore size istriutions (Fig. S11B) show fter grfting in toluene the pore istriution is similr to SBA owever, fter grfting in 2 /NCl, the isotherms shift to lower prtil pressure initing nrrower pore imeter. The oserve wiening of the hysteresis loop suggests there my e some nrrowing of the pore openings following grfting in 2 /NCl. 30 A) B) C) (100) (210) (110) (200) FigS11. A) N 2 sorption isotherms; B) BJ pore size istriution; n C) low ngle XRD for ) line SBA-15; ) PrS 3 /SBA-15-Tol; ) PrS 3 /SBA n )-PrS 3 -SBA-15-P. 2θ / 10 Low ngle XRD ptterns (Fig. S11C) onfirm retention of the p6mm hexgonl strutures for SBA- 15, PrS 3 /SBA-15-Tol, PrS 3 -SBA-15-P with typil 100, 110, n 200 plnes oserve. The presene of the extr 210 plne in PrS 3 /SBA is similr to reports for SBA-15 following tretment in oiling 2, N 3 or F solution. 7 Aoring to Zho et l, this 210 is expete

13 for mterils with p6mm hexgonl symmetry, 1 n is often oserve in XRD ptterns of MCM-41, 8 whih is more struture mteril thn SBA-15. Thus we n infer tht the oservtion of the 210 iffrtion line for PrS 3 /SBA is refletion of improve struturl orer following sulfontion. Loss of the 110 refletion is however intriguing, ut hs een reporte to e very 5 sensitive to the hnges in pore with:unit ell rtio; 9 thikening of the wlls on high ensity grfting oul ount for this oservtion. Tle S3 summrises physil n hemils properties of SBA-15 n PrS 3 /SBA-15 tlysts whih shows the surfe re of PrS 3 /SBA-15-Tol n PrS 3 -SBA-15-P ereses y ~30% 10 ue to nhoring or inorportion of PrS 3 groups. The surfe re of PrS 3 /SBA ereses y ~71%, whih we ttriute to the high sulfoni i overge n loss of miroporosity upon tretment in oiling wter s reporte y Glrneu n l. who emonstrte 50% of surfe re in SBA-15 mteril. 10 This erese in surfe re is ttriute re-eposition of soluilize sili into stle revies of miropores leing to restruturing of the SBA-15 wlls in wter n loss of 15 miroporosity. verll the use of 2 /NCl s grfting mei result in n inrese in sulfur y ~3.5 times ompre to onventionl grfting in toluene. Tle S3. Summry of physil properties of SBA-15 n Pr-S 3 /SBA-15 tlysts prepre vi one-pot, toluene, n optimum 2 /NCl grfting routes. Mterils BET /m².g - 1 Vp /m 3.g - 1 BJ pore imeter Plne sping Unit ell prmeter Wll thikness e Surf. S ontent f /% Ai pity g /mmol +.g -1 Sulfur ensity -2 Ai ensity -2 SBA Pr-S 3/SBA-15-Tol Pr-S 3/SBA , Pr-S 3-SBA-15-P 797 1, From BET eqution. Anlyze from the esorption rnh. From Brggs lw ssuming tht the pek orrespons to the (100) plne, 0 = (2100)/ 3, e 0 - pore imeter, f Surfe S ontent from XPS. g Bse on N 3 pulse titrtion 20

To onfirm struture of PrS 3 /SBA-15-2 -200, TEM

support n the others sulfonte tlysts (Fig. S12).

show orere mterils with long hnnels, in or with

S12. TEM pitures of prepre PrS 3 /SBA-15; -

14 To onfirm struture of PrS 3 /SBA , TEM nlysis hs een performe n ompre with SBA-15 sili support n the others sulfonte tlysts (Fig. S12). SBA-15, PrS 3 /SBA-15- Tol n PrS 3 -SBA-15-P ll show orere mterils with long hnnels, in or with XRD nlysis. A B 100nm 100nm C ED 200nm 200nm 5 Fig. S12. TEM pitures of prepre PrS 3 /SBA-15; - SBA-15, -PrS 3 /SBA-15-Tol, -PrS 3 /SBA , - PrS 3 /SBA-15-P

15 Plmiti Ai Conv. /% Time /h Fig. S13. Plmiti i onversion versus time; ( ) PrS 3 /SBA-15-Tol, ( ) PrS 3 -SBA-15-P, ( ) PrS 3 /SBA , ( ) Amerlyst-15 Tle S4. Detils of tivities in esterifition n trnsesterifition using the ifferent sulfoni tlysts prepre Funtionliztion metho TN Toluene 67 TG4 (60 C)* X= TG16 (80 C)* ne Pot 56 Toluene 8 X= ne Pot 12 *Triglyerie retion ws performe in pressure flsk/smpling fter 24h. 1. D. Zho, J. Feng, Q. uo, N. Melosh, G.. Frerikson, B. F. Chmelk n G. D. Stuky, Siene, 1998, 279, D. Mrgolese, J. A. Melero, S. C. Christinsen, B. F. Chmelk n G. D. Stuky, Chemistry of Mterils, 2000, 12, J. Aguo, J. M. Arsug n A. Arenii, Miroporous n Mesoporous Mterils, 2008, 109, P.-J. Chiu, S. Vetrivel, A. S. T. Ching n.-m. Ko, New Journl of Chemistry, 2011, 35, I. K. Mrk n B.. Shnks, Journl of Ctlysis, 2006, 244, S. Sreevrhn Rey, B. Dvi Rju, V. v Kumr, A.. Pmsri, S. Nrynn n K. S. Rm Ro, Ctlysis Communitions, 2007, 8, S. A. Kozlov n S. D. Kirik, Miroporous n Mesoporous Mterils, 2010, 133, J. S. Bek, J. C. Vrtuli, W. J. Roth, M. E. Leonowiz, C. T. Kresge, K. D. Shmitt, C. T. W. Chu, D.. lson n E. W. Sheppr, Journl of the Amerin Chemil Soiety, 1992, 114, S. Pikus, L. A. Solovyov, M. Kozk n M. Jronie, Applie Surfe Siene, 2007, 253, A. Glrneu, M. Ner, F. Guenneu, F. Di Renzo n A. Geeon, The Journl of Physil Chemistry C, 2007, 111, S15

Supporting Information

Supporting Information Supporting Informtion Control Synthesis of Tuulr Hyperrosslinke Polymers for Highly Porous Cron Nnotues Xioyn Wng, Pn Mu, Chong Zhng, Yu Chen, Jinghui Zeng, Feng Wng n Ji-Xing Jing *, Shnxi Key Lortory