Effect of Ni(NO3)2 Pretreatment on the Pyrolysis of Organsolv Lignin Derived from Corncob Residue

Wenli Wang,Longfei Liu,Changwei Hu,Yichen Liu,Yue Wang

doi:10.3390/pr9010023

Abstract

The thermal degradation of lignin for value-added fuels and chemicals is important for environment improvement and sustainable development. The impact of pretreatment and catalysis of Ni(NO3)2 on the pyrolysis behavior of organsolv lignin were studied in the present work. Samples were pyrolyzed at 500 ∘C with an upward fixed bed, and the characteristics of bio-oil were determined. After pretreatment by Ni(NO3)2, the yield of monophenols increased from 23.3 wt.% to 30.2 wt.% in “Ni-washed” and decreased slightly from 23.3 wt.% to 20.3 wt.% in “Ni-unwashed”. Meanwhile, the selective formation of vinyl-monophenols was promoted in “Ni-unwashed”, which indicated that the existence of nickel species promoted the dehydration of C-OH and breakage of C-C in pyrolysis. In comparison with “Water”, HHV of bio-oil derived from “Ni-unwashed” slightly increased from 27.94 mJ/kg to 28.46 mJ/kg, suggesting that the lowering of oxygen content in bio-oil is associated with improved quality. Furthermore, the content of H2 in gas products dramatically increased from 2.0% to 7.6% and 17.1%, respectively.

Highlights

As environmental pollution and the depletion of fossil resources have become more serious, people have paid more attention to lignocellulosic biomass, which is an environmentally-friendly and renewable resource [1,2,3]
The results revealed that Ni(NO3 )2 pretreatment efficiently influenced the pyrolysis performance of organsolv lignin, showing differences in char, gas, and bio-oil products
Corncob residue was an industrial waste left from the catalytic hydrolysis of hemicellulose to produce xylose, which meant cellulose and lignin were the major components of corncob residue [28]

Summary

Introduction

As environmental pollution and the depletion of fossil resources have become more serious, people have paid more attention to lignocellulosic biomass, which is an environmentally-friendly and renewable resource [1,2,3]. Cellulose, and hemicellulose are the three major components of lignocellulosic biomass. The conversion of carbohydrates in biomass (cellulose and hemicellulose) to cellulosic ethanol and biogas has been well developed [1,4,5]. Lignin left by these utilizations of lignocellulosic biomass were considered as an undesired by-product. Lignin had the highest H/Ceff ratio among the three main components of biomass, implying that lignin had more potential in conversion into fuels with high energy density [7,8]. The development of sustainable and efficient ways to convert lignin into chemicals or fuels is much needed

Methods

Results

Conclusion