Actually, the use of biomass as feedstock for the production of fuel, energy and chemicals represents one of the future technologies that can help reduce global warming and reduce dependence on fossil fuels. Specifically, cellulose is one of the most abundant components of biomass and, therefore, represents one of the promising materials in selective hydrolytic processes to generate fuels and chemicals of high added value [1].

Here, supercritical water (SWC) is recognized to possess good ability to depolymerize cellulose. Although more than 96% of the cellulose is solubilized, the presence of oligomers remains high (> 60% C) [2]. A possible mechanism to solve this problem is complete the hydrolysis of cellulose using heterogeneous acid catalysts (sulfonated mesoporous silica, sulfated zirconia, sulfonated activated carbon) [3]. Furthermore, Fukuoka and Dhepe [4] and Luo et al. [5] reported heterogeneous catalytic processes for the conversion of cellulose to sugars and microcrystalline alcohols, by combining hydrolysis hydrogenation over supported noble metal catalysts, such as Pt / Al2O3 and Ru/C [6]. Therefore, parameters such as porosity, specific area, active phase and the acidity of the catalysts are key factors in the development of these processes.

Microporous materials (pore diameter<2 nm) as zeolites offer high acidity, thermal and chemical stability at elevated temperature. On the other hand, mesoporous materials MCM and SBA type have larger pores with narrow size distribution which promotes steric selectivity for the conversion of bulky molecules such as sugar. However, the acidic properties are limited to the incorporation of another element such as Al for the synthesis of siliceous structure.

Therefore, the main objective of this work is the synthesis of an active for cellulose hydrolysis catalyst, the mordenite zeolite using as a source of Si and Al, and a structuring agent to expand the pore size. In addition, it is proposed to study the effect of adding Ag on the conversion of cellulose to glucose.

The synthesized mesoporous zeolitic support showed a significant increase in the pore volume and size thereof.

The incorporation of Ag does not significantly change the pore diameter, allowing oligomers bulky molecules reach the active sites. By XPS, the presence of Ag(I) ions interacting with the structure was observed. Through the adsorption and desorption of NH₃, it was determined that silver species favor the formation of strong acid sites.

The combination of a mesoporous zeolite with Ag(I) ions allowed the almost complete hydrolysis of cellulose (81.8%) with a yield of 43.5% glucose. This behavior is favored by the interaction between Ag(I) ions with the structure as well as by strong H⁺ sites.

 

1. O.Bobleter, Prog. Polym. Sc 19 (1994) 797.

2. D.Cantero, M.Bermejo, M.Cocero, Biores. Tech. 135 (2013) 697.

3. A. Chareonlimkun, V. Champreda, A. Shotipruk, N. Laosiripojana, Biores. Techn. 101 (2010) 4179-4186.

4. A. Fukuoka, P.L. Dhepe, Angew. Chem. Int. Ed. 45 (2006) 5161.

5. N. Yan, C. Zhao, C. Luo, P.J. Dyson, H. Liu, Y. Kou, J. Am. Chem. Soc. 128 (2006) 8714.

6. R.D. Cortright, R.R. Davda, J.A. Dumesic, Nature 418 (2002) 964.