Propyl-sulfonic (PS) acid-functionalized nanoparticles were synthesized, characterized and evaluated as catalysts for pretreatment of corn stover. Silica coated nanoparticles were functionalized with 0.5% mercaptopropyltrimethoxysilane (MPTMS) at neutral pH in a mixture of water and ethanol. Sulfur contents of the acid functionalized nanoparticles, measured in a CHNS analyzer, varied from 6%-10%, and the acid load ranged from 0.040 to 0.066 mmol H+/g. A Box-Behnken design was employed to calculate the minimum number experiments required to obtain an estimate of the surface response for temperature, catalyst load, and %S content of the catalyst. Pretreatment of corn stover was carried out at three temperature levels 160, 180, and 200°C for 1 h. Three levels of catalyst load were used 0.1, 0.2, and 0.3 g of catalyst per gram of biomass. Hydro-thermolysis controls were carried at each temperature level. The catalyst load did not have an effect on the glucose yield at 160°C, and the average glucose yield obtained at this temperature was 59.0%. The glucose yield was linearly correlated to the catalyst load during pretreatment at 180°C, and a maximum glucose yield of 90% was reached when using 0.2 g of PS nanoparticles that had a total sulfur content of 6.1%. Complete hydrolysis of glucose was reached at 200°C but the average xylose yield was 4.6%, and about 20.2% of the combined glucose and xylose were lost as hydroxymethylfurfural and furfural. Results showed that acid-functionalized nanoparticles can be potential catalysts for the pretreatment of biomass for its later conversion to ethanol.
 G. Gonzalez, J. LopezSantin, G. Caminal and C. Sola, “Dilute Acid-Hydrolysis of Wheat Straw Hemicellulose at Moderate Temperature—A Simplified Kinetic-Model,” Biotechnology and Bioengineering, Vol. 28, No. 2, 1986, pp. 288-293. http://dx.doi.org/10.1002/bit.260280219
 A. Herrera, S. J. Tellez-Luis, J. J. Gonzalez-Cabriales, J. A. Ramirez and M. Vazquez, “Effect of the Hydrochloric Acid Concentration on the Hydrolysis of Sorghum Straw at Atmospheric Pressure,” Journal of Food Engineering, Vol. 63, No. 1, 2004, p. 103.
 Y. Lee and S. Kim, “Diffusion of Sulfuric Acid within Lignocellulosic Biomass Particles and Its Impact on Dilute-Acid Pretreatment,” Bioresource Technology, Vol. 83, No. 2, 2002, pp. 165-171.
 E. Viola, F. Nanna, E. Larocca, M. Cardinale, D. Barisano and F. Zimbardi, “Acid Impregnation and Steam Explosion of Corn Stover in Batch Processes,” Industrial Crops and Products, Vol. 26, No. 2, 2007, p. 195.
 C. E. Wyman, B. E. Dale, R. T. Elander, M. Holtzapple, M. R. Ladisch and Y. Y. Lee, “Coordinated Development of Leading Biomass Pretreatment Technologies,” Bioresource Technology, Vol. 96, No. 18, 2005, pp. 1959-1966. http://dx.doi.org/10.1016/j.biortech.2005.01.010
 J. Delgenes, “Effects of Lignocellulose Degradation Products on Ethanol Fermentations of Glucose and Xylose by Saccharomyces Cerevisiae, Zymomonas Mobilis, Pichia Stipitis, and Candida Shehatae,” Enzyme and Microbial Technology, Vol. 19, No. 3, 1996, pp. 220-225.
 G. D. Yadav, “Synergism of Clay and Heteropoly Acids as Nano-Catalysts for the Development of Green Processes with Potential Industrial Applications,” Catalysis Surveys from Asia, Vol. 9, No. 2, 2005, pp. 117-137.
 S. Chafin, K. Pennybaker, D. Fahey, B. Subramaniam and K. Gong, “Economic and Environmental Impact Analyses of Solid Acid Catalyzed Isoparaffin/Olefin Alkylation in Supercritical Carbon Dioxide,” Industrial Engineering Chemistry Research, Vol. 47, No. 23, 2008, p. 9072.
 M. A. Harmer, C. Junk, V. Rostovtsev, L. G. Carcani, J. Vickery and Z. Schnepp, “Synthesis and Applications of Superacids. 1,1,2,2-Tetrafluoroethanesulfonic Acid, Supported on Silica,” Green Chemistry, Vol. 9, No. 1, 2007, pp. 30. http://dx.doi.org/10.1039/b607428f
 M. A. Harmer, W. E. Farneth and Q. Sun, “Towards the Sulfuric Acid of Solids,” Advanced Materials, Vol. 10, No. 15, 1998, p. 1255.
 R. Raja and J. M. Thomas, “The Expanding World of Nanoparticle and Nanoporous Catalysts,” In: P. Yang, Ed., The Chemistry of Nanostructured Materials, World Scientific Publishing Co. Pte. Ltd., Singapore City, 2003, pp. 329-357. http://dx.doi.org/10.1142/9789812560049_0012
 C. S. Gill, B. A. Price and C. W. Jones, “Sulfonic Acid-Functionalized Silica-Coated Magnetic Nanoparticle Catalysts,” Journal of Catalysis, Vol. 251, No. 1, 2007, pp. 145-152. http://dx.doi.org/10.1016/j.jcat.2007.07.007
 P. F. Siril, A. D. Davison, J. K. Randhawa and D. R. Brown, “Acid Strengths and Catalytic Activities of Sulfonic Acid on Polymeric and Silica Supports,” Journal of Molecular Catalysis A: Chemical, Vol. 267, No. 1-2, 2007, p. 72.
 P. L. Dhepe, M. Ohashi, S. Inagaki, M. Ichikawa and A. Fukuoka, “Hydrolysis of Sugars Catalyzed by Water-Tolerant Sulfonated Mesoporous Silicas,” Catalysis Letters, Vol. 102, No. 3-4, 2005, p. 163.
 J. A. Bootsma and B. H. Shanks, “Cellobiose Hydrolysis Using Organic-Inorganic Hybrid Mesoporous Silica Catalysts,” Applied Catalysis A-General, Vol. 327, No. 1, 2007, pp. 44-51.
 L. Peña, M. Ikenberry, B. Ware, K. L. Hohn, D. Boyle and D. Wang, “Cellobiose Hydrolysis Using Acid-Functionalized Nanoparticles,” Biotechnology and Bioprocess Engineering, Vol. 16, No. 6, 2011, pp. 1214-1222.
 L. Peña, M. Ikenberry, K. L. Hohn and D. Wang, “AcidFunctionalized Nanoparticles for Pretreatment of Wheat Straw,” Journal of Biomaterials and Nanobiotechnology, Vol. 3, No. 3, 2012, pp. 342-352.
 A. J. Rondinone, A. C. S. Samia and Z. J. Zhang, “Superparamagnetic Relaxation and Magnetic Anisotropy Energy Distribution in CoFe2O4 Spinel Ferrite Nanocrystallites,” Journal of Physical Chemistry B, Vol. 103, No. 33, 1999, pp. 6876-6880.
 N. Moumen, P. Bonville and M. Pileni, “Control of the Size of Cobalt Ferrite Magnetic Fluids: Mossbauer Spectroscopy,” Journal of Physical Chemistry, Vol. 100, No. 34, 1996, pp. 14410-14416.
 X. Shen, X. Fang, Y. Zhou and H. Liang, “Synthesis and Characterization of 3-Aminopropyltriethoxysilane-Modified Superparamagnetic Magnetite Nanoparticles,” Chemistry Letters, Vol. 33, No. 11, 2004, pp. 1468-1469.
 G. Morales, G. Athens, B. Chmelka, R. van Grieken and J. Melero, “Aqueous-Sensitive Reaction Sites in Sulfonic Acid-Functionalized Mesoporous Silicas,” Journal of Catalysis, Vol. 254, No. 2, 2008, pp. 205-217.
 S. Hamoudi, S. Royer and S. Kaliaguine, “Propyl- and Arene-Sulfonic Acid Functionalized Periodic Mesoporous Organosilicas,” Microporous and Mesoporous Materials, Vol. 71, No. 1-3, 2004, pp. 17-25.
 E. Cano Serrano, J. Campos Martin and J. Fierro, “Sulfonic Acid-Functionalized Silica through Quantitative Oxidation of Thiol Groups,” Chemical Communications (London, 1996), Vol. 39, No. 2, 2003, pp. 246-247.
 R. Badley and W. Ford, “Silica-Bound Sulfonic-Acid Catalysts,” Journal of Organic Chemistry, Vol. 54, No. 23, 1989, pp. 5437-5443.
 A. Sluiter, B. Hames, R. Ruiz, C. Scarlata, J. Sluiter and D. Templeton, “Determination of Sugars, Byproducts, and Degradation Products in Liquid Fraction Process Samples,” NREL/ TP-510-42618, National Renewable Energy Laboratory, Golden, 2008.
 D. Brunel, A. Cauvel, F. Di Renzo, F. Fajula and B. Fubini, “Preferential Grafting of Alkoxysilane Coupling Agents on the Hydrophobic Portion of the Surface of Micelle-Templated Silica,” New Journal of Chemistry, Vol. 24, No. 10, 2000, pp. 807-813.
 M. Hair, “Hydroxyl-Groups on Silica Surface,” Journal of Non-Crystalline Solids, Vol. 19, 1975, pp. 299-309.
 U. H. Goerl, A. Mueller and H. G. Arndt Koban, “Investigations into the Silica/Silane Reaction System,” Rubber Chemistry and Technology, Vol. 70, No. 4, 1997, pp. 608-623. http://dx.doi.org/10.5254/1.3538447
 M. Colilla, I. Izquierdo-Barba, S. Sanchez-Salcedo, J. Fierro, J. Hueso and M. Vallet-Regi, “Synthesis and Characterization of Zwitterionic SBA-15 Nanostructured Materials,” Chemistry of Materials, Vol. 22, No. 23, 2010, pp. 6459-6466. http://dx.doi.org/10.1021/cm102827y
 L. Dubois and B. Zegarski, “Bonding of Alkoxysilanes to Dehydroxylated Silica Surfaces—A New Adhesion Mechanism,” Journal of Physical Chemistry, Vol. 97, No. 8, 1993, pp. 1665-1670.
 B. Rac, A. Molnar, P. Forgo, M. Mohai and I. Bertoti, “A Comparative Study of Solid Sulfonic Acid Catalysts Bas ed on various Ordered Mesoporous Silica Materials,” Jour nal of Molecular Catalysis. A, Chemical, Vol. 244, No. 1-2, 2006, p. 46.
 X. S. Zhao, G. Q. Lu and X. Hu, “Characterization of the Structural and Surface Properties of Chemically Modified MCM-41 Material,” Microporous and Mesoporous Materials, Vol. 41, No. 1-3, 2000, pp. 37-47.
 C. Tripp and M. Hair, “Reaction of Methylsilanols with Hydrated Silica Surfaces—The Hydrolysis of Trichloromethylsilanes, Dichloromethylsilanes, and Monochloromethylsilanes and the Effects of Curing,” Langmuir, Vol. 11, No. 1, 1995, pp. 149-155.
 A. L. Smith, “Infrared Spectra-Structure Correlations for Organosilicon Compounds,” Spectrochimica Acta, Vol. 16, No. 1-2, 1960, pp. 87-105.
 M. Alvaro, A. Corma, D. Das, V. Fornes and H. Garcia, “‘Nafion’-Functionalized Mesoporous MCM-41 Silica Shows High Activity and Selectivity for Carboxylic Acid Esterification and Friedel-Crafts Acylation Reactions,” Journal of Catalysis, Vol. 231, No. 1, 2005, p. 48.
 R. Buzzoni, S. Bordiga, G. Ricchiardi, G. Spoto and A. Zecchina, “Interaction of H2O, CH3OH, (CH3)2O, CH3CN, and Pyridine with the Superacid Perfluorosulfonic Membrane Nafion: An IR and Raman Study,” Journal of Physical Chemistry, Vol. 99, No. 31, 1995, pp. 11937-11951.
 I. Diaz, C. Marquez-Alvarez, F. Mohino, J. Perez-Pariente and E. Sastre, “Combined Alkyl and Sulfonic Acid Functionalization of MCM-41-Type Silica Part 1. Synthesis and Characterization,” Journal of Catalysis, Vol. 193, No. 2, 2000, pp. 283-294.
 J. Melero, L. Fernando Bautista, G. Morales, J. Iglesias and R. Sanchez Vazquez, “Biodiesel Production from Crude Palm Oil Using Sulfonic Acid-Modified Mesostructured Catalysts,” Chemical Engineering Journal, Vol. 161, No. 3, 2010, pp. 323-331.
 M. Lim, C. Blanford and A. Stein, “Synthesis of Ordered Microporous Silicates with Organosulfur Surface Groups and Their Applications as Solid Acid Catalysts,” Chemistry of Materials, Vol. 10, No. 2, 1998, p. 467.
 O. Bobleter, “Hydrothermal Degradation of Polymers Derived from Plants,” Progress in Polymer Science, Vol. 19, No. 5, 1994, pp. 797-841.
 V. V. Ordomsky, J. van der Schaaf, J. C. Schouten, T. A. Nijhuis, “Fructose Dehydration to 5-Hydroxymethylfurfural over Solid Acid Catalysts in a Biphasic System,” ChemSusChem, Vol. 5, No. 9, 2012, pp. 1812-1819.
 C. Moreau, R. Durand, D. Peyron, J. Duhamet, P. Rivalier, “Selective Preparation of Furfural from Xylose over Microporous Solid Acid Catalysts,” Industrial Crops and Products, Vol. 7, No. 2-3, 1998, pp. 95-99.
 K. Shimizu, H. Furukawa, N. Kobayashi, Y. Itaya and A. Satsuma, “Effects of Bronsted and Lewis Acidities on Activity and Selectivity of Heteropolyacid-Based Catalysts for Hydrolysis of Cellobiose and Cellulose,” Green Chemistry, Vol. 11, No. 10, 2009, pp. 1627-1632.
 R. Gosselink, J. van Dam, C. Boeriu and D. Bravo, “Characterisation of Structure-Dependent Functional Properties of Lignin with Infrared Spectroscopy,” Industrial Crops and Products, Vol. 20, No. 2, 2004, pp. 205-218. http://dx.doi.org/10.1016/j.indcrop.2004.04.022