Abstract
Functionalization of silica surfaces using organo-silanes is highly sensitive to reaction conditions. Silica-coated nanoparticles were functionalized with propyl-sulfonic acid groups (PS) under different synthesis conditions including, various solvents (Ethanol, methanol, acetonitrile, and toluene), water content in the reaction media (0% to 50%), 3-mercaptopropyl-trimethoxysilane concentration (MPTMS) (0.5% to 10%), and reaction time (6 to 16 h). Size of the PS-nanoparticles was determined by TEM and varied from 3.5 to 20.3 nm with sulfur load. Elemental analysis revealed sulfur contents from 0.8% to 22%. FTIR analysis showed increased C-H band intensities with increasing sulfur content of PS-nanoparticles. Although PS-nanoparticles with sulfur loads under 3% did not improve the hydrolysis of cellobiose, PS acid-functionalized nanoparticles with about 6% S achieved 96.0% cellobiose conversion. The control experiment, without catalyst, converted 32.8% of the initial cellobiose. PS-nanoparticles with (6% - 8% S) were obtained using (0.5%) silane concentration and 15 - 16 h reaction time in ethanol.
Highlights
One of the challenges in the production of renewable fuels and chemicals from lignocellulosic biomass is*L
The range of the acid loading values from this research agrees with values previously reported for propyl-sulfonic acid-functionalized silicas [54]; the acid capacity of some of the nanoparticles was probably underestimated because the nanoparticles could not be dispersed in the NaCl solution
Nanoparticles that gained a high load of propyl groups floated on the top of the solution and were difficult to disperse in aqueous solutions, so not
Summary
One of the challenges in the production of renewable fuels and chemicals from lignocellulosic biomass is*L. The most accepted process for production of cellulosic ethanol uses an acid hydrolysis to pretreat lignocellulosic biomass and an enzymatic hydrolysis to break the cellulose chains into monomer sugars [6]. Cellulolytic enzymes are a big portion of the operational cost to produce cellulosic ethanol because they are expensive catalysts with limited reusability [7] [8]. These enzymes work optimally under a narrow set of conditions, plus reaction rates are slow [9] [10]. A number of articles have been published on the performance of heterogeneous catalysts on the hydrolysis of glycosidic bonds [15]-[18], research is in the early stage and more investigation is needed
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