Kegnæs, Søren

Melián Rodríguez, Mayra

Riisager, Anders

Shunmugavel, Saravanamurugan

Online Research Database In Technology

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Downloaded from orbit.dtu.dk on: Dec 21, 2017Lignin valorization using heterogeneous catalytic oxidationMelián Rodríguez, Mayra; Shunmugavel, Saravanamurugan; Kegnæs, Søren; Riisager, AndersPublication date:2014Document VersionPeer reviewed versionLink back to DTU OrbitCitation (APA):Melián Rodríguez, M., Shunmugavel, S., Kegnæs, S., & Riisager, A. (2014). Lignin valorization usingheterogeneous catalytic oxidation. Poster session presented at Summer School on Catalysis of Biomass, Liblice,Czech Republic.Introduction The research interest in biomass conversion to fuels and chemicals has increased significantly in the last decade in view of current problems such as global warming, high oil prices, food crisis and other geopolitical scenarios.        Many different reactions and processes to convert biomass into high-value products and fuels have been proposed in the literature, giving special attention to the conversion of lignocellulosic biomass, which does not compete with food resources and is widely available as a low cost feedstock.                      Figure 1. View of the role of lignin, cellulose and hemicellulose in a typical plant.               Lignin constitutes up to 40% of the heating value of lignocellulosic biomass. It is the most complex fraction and is harder to process compared to the sugar fractions.                  Figure 2. Type of  bonds in lignin.  The complexity has led lignin to be treated as a waste stream, and typically burned to produce energy. However, lignin is a significant portion of the total carbon in biomass, and better use of this fraction is a requirement to improve the economic balance of any bio-refinery.  For this reason, research on upgrading lignin has become of recent interest, as many interesting products, mainly aromatics, can potentially be produced from lignin. Here we therefore present an overview conversion of lignin into chemicals using heterogeneous catalysis.             Lignin valorization using heterogeneous catalytic oxidation  M. Melián-Rodríguez1, S. Saravanamurugan1, S. Kegnæs1 and A. Riisager 1* Address: Centre for Catalysis and Sustainable Chemistry, Technical University of Denmark,    Kemitorvet Byg 207, 2800 Kgs. Lyngby, Denmark  E-mail: mayro@kemi.dtu.dk Phone: +45 4525 2432 Results                    Table 1. Data for Veratryl alcohol oxidation with different catalyst.                              Experimental  Catalyst preparation An appropriate amount of aqueous solution of ruthenium or manganese precursors was mixed with support (alumina or silica), dried and calcined at 450oC to get metal the corresponding supported metal oxide catalysts.  Catalytic reactions A 50 ml autoclave (Microclave reactor from Autoclave Engineers) was charged with an appropriate amount of veratryl alcohol, catalyst (150 mg) and water as solvent (10 ml) and then pressurized with Air (5 bar). The autoclave was heated to 160oC and the stirring started once the temperature reached 140oC (300 rpm). After 5 h of stirring, the autoclave was quenched with cold water and analyzed by GC and GC-MS. Conclusion Time-course study revealed that 8 hours of reaction time required to get an optimum yield towards veratraldehyde. Among the catalyst employed, Ru/Al2O3 gave a highest yield to veratraldehyde ( 67 %) along with 93 % conversion of veratryl alcohol. However, Ru/SiO2  also gave a comparable yield of veratraldehyde. Temperature study shows that 160oC gives the highest conversion of veratraldehyde over Ru/Al2O3. Linkage type Softwood lignin Total linkages (%) Hardwood lignin Total linkages (%) β-O-4 45-50 60 5-5 19-22 9 β-5 9-12 6 β-1 7-9 7 α-O-4 6-8 - 4-O-5 4-7 6,5 β-β 2-4 3 References  Acknowledgement   The authors appreciate financial support granted to the International Network Programme (12-132649) from The Danish Agency for Science, Technology and Innovation, Haldor Topsøe A/S and DTU Chem. Soc. Rev., 41 (2012) 8075 Energy Fuels, 25 (2011) 4713 J. Polym. Environ., 10 (2002) 39  Chem. Rev., 110 (2010) 3552 J. Catal. 285 (2012) 315 Chem. Eng. Technol., 34 (2011) 29  Fuel Process. Technol.45 (1995) 161  Energy Fuels, 7 (1993) 426 Chem. Eur. J., 34 (2011) 29 Eur. Polymer J., 49 (2013) 1151   CATALYST BET surface AREA (m2/g) Veratryl alcohol CONVERSION (%) Veratraldehyde YIELD (%)   Ru/Al2O3 166 93 67   Ru/SiO2 422 96 46   Mn/Al2O3 152 69 17   Al2O3 204 46 3   SiO2 472 59 3   Blank -  34 2         Cellulose (40-50%)        Hemicellulose (25-35%)         Lignin (20-30%)  HOORRRORβ4HOβ-O-4OOHRORα-O-4OHRR4αOR4-O-5ORR5 45-5OO55β−βROOORORRβββ-1ROROHHOORR1ββ-5ROR OHO R5βHO OOOOOCatalystveratryl alcohol veratraldehydeO2Figure 4. Time-course study on the conversion of  veratryl alcohol over Ru/Al2O3.  0204060801000 2 4 6 8veratraldehydeveratryl alcoholt Yield (%)  020406080100160 C 140 C 120 Cveratraldehyde YIELDVeratryl alcohol CONVERSION (%)  Figure 3. Temperature study on the conversion of  veratryl alcohol using Ru/Al2O3 as catalyst. 

Lignin valorization using heterogeneous catalytic oxidation

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Lignin valorization using heterogeneous catalytic oxidation

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