Propyl-Sulfonic Acid Functionalized Nanoparticles as Catalyst for Pretreatment of Corn Stover

Abstract

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.

Pre-treatment of biomasses using magnetised sulfonic acid catalysts

“…Several physical and chemical pre-treatments using heat, acids, bases, organic solvents and ionic liquids have been developed and studied extensively. Although, chemical pre-treatment techniques are attractive due to the higher reaction efficiency and excellent mass transfer capabilities (Guo et al, 2012), use of chemical agents leads to various environmental issues and also requires expensive unit operations on the downstream side of the process (Peña et al, 2014). Therefore, reusable pre-treatment agents that also minimise environmental impacts are required.…”

“…In addition, solid acid catalysts allow for simple separation from products by vacuum filtration or magnetic separation (Lai et al, 2011;Guo et al, 2013;Peña et al, 2014). Further, the catalysts may be used repeatedly for the reaction without neutralisation, therefore decreasing energy consumption and waste (Zhou et al, 2011).…”

“…Researchers have been exploring solid acid catalysts for pre-treatment of biomass streams. For example, Peña et al (2014) reported glucose yield of 59% achieved from corn stover treated used propyl-sulfonic acid-functionalised nanoparticle catalyst at 160°C for 60 min followed by the addition of 2 mL of accelerase enzyme along with 2.5 g wet corn stover for 24 h hydrolysis. The study also reported that as pre-treatment temperature increased to 180°C, the yield of glucose increased reached the maximum of 90%.…”

New trends in application of nanotechnology for the pretreatment of lignocellulosic biomass

“…Similarly, in another study, Pena et al . demonstrated the catalytic efficiency of a nanocatalysts, i.e.…”

“…Acid‐functionalized nanoparticles are also referred to as solid acid nanocatalysts; these catalysts have a strong ability to catalyze hydrolysis reactions. It has been demonstrated that acid‐functionalized magnetic nanoparticles could have a similar catalytic effect to mineral acids (used in chemical pretreatment methods) during biomass pretreatment, with the added advantage that these nanoparticles are recoverable and reusable due to their strong magnetic nature . Recycling and reuse of the pretreatment nanocatalysts will be helpful in minimizing the process cost due to minimum downstream processing requirements.…”