Unlock the Compact Structure of Lignocellulosic Biomass by Mild Ball Milling for Ethylene Glycol Production

Abstract

Ball milling pretreatment was found to be an efficient method to promote the catalytic conversion of lignocellulosic biomass to ethylene glycol (EG). After 3–6 h ball milling of Miscanthus at 450 rpm, the EG yield reached about 52%, which is comparable to the result of pure cellulose conversion. The reasons of the promotion effect were investigated by characterizing the structure of biomass and the reaction residuals with X-ray diffraction, scanning electron microscopy, particle size distribution analyzer, contact angle measurement, thermogravimetric analysis-differential scanning calorimetry, and Fourier-transform infrared spectroscopy. The mild ball milling liberated (hemi)­cellulose from the compact plant tissues without affecting the crystallinity of cellulose. It reduced the size of biomass to 30 μm and improved the accessibility of (hemi)­cellulose, leading to a hydrophilic surface and high energy state of biomass for catalytic conversion. During the catalytic conversion, the mass transfer between sugar intermediates and heterogeneous hydrogenation catalysts were improved. Correspondingly, the self-reaction of sugar intermediates, and the reactions between sugar intermediates and lignin fractions were suppressed, resulting in the high EG yield.

Lignocellulosic Biomass: Understanding Recalcitrance and Predicting Hydrolysis

“…Particle size was identified as a key parameter affecting cellulose hydrolysis potential (Barakat et al, 2014;Vaidya et al, 2016). The reduction of particle size through milling, grinding, and extrusion could enhance the affinity between cellulose and enzymes, deconstruct lignocellulose compact structure and thus increase the rate of hydrolysis (Silva et al, 2012;Pang et al, 2018;Yu et al, 2019). Studies have demonstrated that mechanical deconstruction facilitates enzymatic hydrolysis of various feedstocks such as wood chips (Jiang et al, 2017), miscanthus and wheat straw (Kim et al, 2018) and corn stover (Yu et al, 2019).…”

Structure–property–degradability relationships of varisized lignocellulosic biomass induced by ball milling on enzymatic hydrolysis and alcoholysis

“…The morphology, particle size, and surface properties of biomass play a crucial role in its conversion [ 24 ], therefore such characteristics were investigated first. The SEM images in Fig.…”

Cellulose Conversion Into Hexitols and Glycols in Water: Recent Advances in Catalyst Development

“…Despite some unresolved issues, many reported catalysts possess excellent catalytic properties and stability in hydrothermal conditions, which allowed their successful testing not only in the conversion of pure microcrystalline cellulose, but also for cellulose containing materials such as cotton, cotton wool, paper (Ribeiro et al, 2017a,d, 2018b), wood lignocellulosic biomass (Yamaguchi et al, 2016; Ribeiro et al, 2018b; Xiao et al, 2018b; Pang et al, 2019), corn stalks, millet, sugarcane, etc. (Liu et al, 2017; Li et al, 2018a), which demonstrates a promising outlook for the future development of multi tonnage production of value-added chemicals and fuels from cellulose biomass.…”