Supplementary information

Transcription

1 Supplementary information Heteropoly acids as efficient acid catalysts in the one-step conversion cellulose to sugar alcohols Regina Palkovits *[a],[b], Kameh Tajvidi [b], Agnieszka Ruppert [c], Joanna Procelewska [b],[d] Reaction scheme Scheme 1. Reaction scheme of the hydrogenolysis of cellulose including hydrolysis to glucose and further hydrogenation, hydrogenolysis and dehydration reactions to sorbitol, sorbitan and isosorbide together with erythritol, xylitol, glycerol, propylene and ethylene glycol and methanol (n = 1-3). Chemicals The catalyst material (5 wt% Ru/C) was provided from Johnson Matthey and used as delivered. α-cellulose (fibres from spruce), para-toluenesulfonic acid, silicotungstic (H 4 [Si(W 3 O 10 ) 4 ]) acid, H 2 SO 4 and H 3 PO 4 were purchased from Aldrich, phosphotungstic (H 3 [P(Mo 3 O 10 ) 4 ) and from Fluka, and they were used without any pre-treatment or purification. Further characterization of the utilized α-cellulose can be found in ref. 7. The polymeric resins Amberlyst 70 (Aldrich) and Dowex 50wx2-10 (Rohm and Haas) were used as delivered. Catalytic experiments In a typical experiment, α-cellulose (500 mg, 3.1 mmol by glycosidic unit), 5%Ru/C catalyst (100 mg), and water (10 ml) together with the required amount of acid were added in a 36 ml stainless steel autoclave equipped with Teflon inserts. The reactor was flushed several times with hydrogen and pressurized to 50 bar hydrogen pressure. Heating of the autoclave to 160 C took about 15 min. After reaction, the autoclave was cooled down, remaining pressure was released, and the reaction mixture was centrifuged to separate remaining solid and the product solution.

2 Analysis Product quantification was carried out using HPLC measurements in 2 mm TFA on a Shimadzu LC-10A based on calibration curves of the pure compounds. The setup was equipped with a column switch, combining a 100 and a 300 mm organic acid resin column of 8 mm i.d. Therein, sugars and sugar alcohols were analyzed using a RI detector. Further by-prducts were measured using a UV-detector. The conversion of cellulose X Cellulose was determined based on the weight of cellulose used in the reaction m Cellulose,0 and the solid recovered after reaction considering the amount of the solid catalyst in the remaining solid with m Cellulose =m recovered solid - m Catalyst. X Cellulose m = Cellulose,0 m m Cellulose,0 Cellulose The yields of the different products Y Product were calculated assuming that the stoechiometric coefficient of the substrate υ Substrate is equal to one for a (C 6 H 10 O 5 ) n cellulose unit as starting material: Υ Pr oduct n = Pr oduct n n Substrate,0 Pr oduct,0 υ υ Substrate Pr oduct Therein, n Substrate is equal to the molar amount of (C 6 H 10 O 5 ) in the starting substrate, n Product,0 is equal zero and n product corresponds to the molar amount of the product as determined by HPLC. For spruce, conversion and yield were calculated assuming 45% cellulose and 30% hemicellulose in the feedstock, treated as 75% cellulose in the calculation. Consequently, spruce is assumed to contain 6.17mmol g -1 * 75% = 4.63 mmol g -1 glycosidic units. Zinc dodecatungstophosphate and supported heteropoly acid Zinc dodecatungstophosphate was prepared following ref. 21. Therein, H 3 PW 12 O H 2 O was dissolved in water (8g in 20mL). The clear solution was added dropwise to an ethanolic zinc acetate solution (1.07g in 20mL). After stirring for 30min, filter paper is dipped into the solution for 15min, washed with water and ethanol and dried. The procedure was repeated 20times followed by calcination in air at 673K till complete removal of the filter paper.

3 Supported HPW were prepared following ref. 20 by incipient wetness impregnation of the desired amount of an alcoholic solution (methanol) containing 12-tungstophosphoric acid (H3PW12O40 x nh2o) on silica (Merck). Remaining solvent was removed under vacuum at 323 K, the catalyst was dried under air at 363 K overnight and finally calcined under air (473 K, 2 h, 10 Kmin -1 ) prior to catalytic tests.

4 Complete Product Distributions: Table 1. Properties and catalytic activity of several acidic catalysts combined with Ru/C in the hydrogenolysis of cellulose a Entry Catalyst Conv. b Yield c [%] [%] Sorbitol Sorbitan Isosorbide Xylose Xylitol m-erythritol Glycerol Propandiol Ethandiol MeOH 1 HCl d H 2SO H 3PO p-tsa H 4 [Si(W 3 O 10 ) 4 ] H 3 [P(W 3 O 10 ) 4 ] Amberlyst Dowex50wx S.1 SiMo e S.2 VMo e, h < S.3 H2SO4 + W f S.4 H2SO4 + W-Ru/C d, g a Reaction conditions: cellulose (500 mg, 3.1 mmol by glycosidic unit), water (10 ml), Ru/C (100 mg), solid acid (100mg), 433 K, 50 bar H2 (298 K), 7 h. b Determined by weight difference of cellulose before and after reaction. c Based on theoretical stoichiometric coefficients corresponding to the carbon content of the reaction product. d 3 h. e 7 h. f 1 h, 50 mg Ru/C + 50 mg W metal. g 100 mg (2.5%-Ru+0.25%-W)/C; for preparation of bimetallic catalysts, a solution of ruthenium(iii) acetylacetonate and tungsten hexacarbonyl with the corresponding amount was impregnated in activated carbon (Norit ROX 0.8), the material was dried under vacuum and reduced at 250 C in hydrogen for 4h. h H 4 [PMo 10 V 2 O 40 ] has been prepared according to a publication by Tsigdinos et al. [G. A. Tsigdinoa, C. J. Hallada; Inorg. Chem., 1968, 7 (3), ].

5 Table 3. Properties and catalytic activity of several acidic catalysts combined with Ru/C in the hydrogenolysis of cellulose a Entry Catalyst Conv. b Yield c [%] [%] Sorbitol Sorbitan Isosorbide Xylose Xylitol m-erythritol Glycerol Propandiol Ethandiol MeOH 12 40% HPA/SiO2 d % HPA/SiO2 d % HPA/SiO2 d Zn-HPA Hydroxymethylfurfural 2-Furoic acid Furfural Levulinic acid % HPA/SiO2 d % HPA/SiO2 d % HPA/SiO2 d a Reaction conditions: cellulose (500 mg, 3.1 mmol by glycosidic unit), water (10 ml), Ru/C (100mg), solid acid (100 mg), 433 K, 50 bar H2 (298 K), 7 h. b Determined by weight difference of cellulose before and after reaction. c Based on theoretical stoichiometric coefficients corresponding to the carbon content of the reaction product. d tested without Ru/C catalyst.

6 Table 2. Properties and catalytic activity of HPA in combination with Ru/C in the hydrogenolysis of spruce [a] Entry Catalyst Conv. b,d Yield c,d [%] [%] Sorbitol Sorbitan Isosorbide Xylose Xylitol m-erythritol Glycerol Propandiol Ethandiol MeOH 10 H4[Si(W 3 O 10 ) 4 ] H3[P(Mo 3 O 10 ) 4 ] a Reaction conditions: spruce (500 mg, 3.1 mmol by glycosidic unit), water (10 ml), Ru/C (100 mg), 433 K, 50 bar H2 (298 K), 7 h. b Determined by weight difference of cellulose before and after reaction. c Based on theoretical stoichiometric coefficients corresponding to the carbon content of the reaction product. d Conversion and yield were calculated assuming 45% cellulose and 30% hemicellulose, calculated as 75% cellulose.

7 Additional experiments Reference experiments with glucose (1, 3) and cellobiose (5, 6) as substrate together with recycling of the heteropoly acids (2, 4) Yield sorbitol sorbitan Yield [%] xylitol 20 0 PW + Ru/C 1 PW Recycle 2 SiW + Ru/C 3 SiW Recycle 4 PW + Ru/C Cellobiose 5 SiW + Ru/C Cellobiose 6 Figure S.1. Reference experiments with glucose and cellobiose as substrate together with recycling experiments. (SiW - H 4 [Si(W 3 O 10 ) 4 ]; PW - H 3 [P(Mo 3 O 10 ) 4 ]) Reaction conditions: Experiments with glucose and cellobiose (1,3,5,6) were carried out in a stainless steel autoclave using 500 mg glucose or cellobiose, respectively, together with 100 mg 5%-Ru/C and 500 mg HPA (~17.4mmol L -1 ) in 10 ml water (1h, 160 C, 50 bar H 2 (25 C)). For recycling experiments, 5 ml of the reaction mixture from a precious experiment were transferred into an autoclave, another 250 mg glucose and 50 mg Ru/C catalyst were added and the reactions (2, 4) were carried out under identical reaction conditions (1h, 160 C, 50 bar H 2 (25 C)). Note that the presented yields in the case of recycling experiments are based on the freshly added substrate to allow comparability with reference experiments.