Effective Depolymerization of Sodium Lignosulfonate over SO42−/TiO2 Catalyst

Abstract

In this paper, liquefaction of sodium lignosulfonate (SL) over SO42−/TiO2 catalyst in methanol/glycerol was investigated. Effects of temperature, time, the ratio of methanol to glycerol and catalyst dosage were also studied. It was indicated that optimal reaction condition (the temperature of 160 °C, the time of 1 h, solvent ratio (methanol/glycerol) of 2:1, catalyst dosage of 5 wt % (based on lignin input)) was obtained after sets of experiments. The maximum yields of liquefaction (89.8%) and bio-oil (86.8%) were gained under the optimal reaction conditions. Bio-oil was analyzed by elemental analysis, FT-IR and gas chromatogram and mass spectrometry (GC/MS). It was shown that the functional groups of bio-oil were enriched and calorific value of bio-oil was increased. Finally, it can be seen from GC/MS analysis that the type of products included alcohols, ethers, phenols, ketones, esters and acids. Phenolic compounds mainly consisted of G (guaiacyl)-type phenols.

Chemical and Thermal Characteristics of Ion-Exchanged Lignosulfonate

“…Na-LS appears to be a better candidate for energy generation than H-LS. This is due to the fact that the high carbon and low oxygen content (low O/C ratio) are favorable for energy-oriented application, since the lower O/C ratio results in a higher calorific value [ 28 ]. In general, H-LS has a greater elemental percentage than Na-LS due to the high ash content in Na-LS, which reduces the proportion of its chemical element.…”

Deriving high value products from depolymerized lignin oil, aided by (bio)catalytic funneling strategies

“…2A). [33][34][35][36] Depolymerization of softwood lignosulphonates has been achieved with heterogeneous catalysts in the presence of oxygen and yields vanillin as the major product. Typical yields of vanillin from softwood sources are on the order of 5-7 wt% on lignin basis, leaving much room for improvement.…”

“…With oxidative depolymerization of lignocelluloses yielding complex mixtures of monophenolic aldehydes, ketones and acids, [33][34][35][36][52][53][54][55][56][57][58][59][60][61] purification of these into single pure compounds is commonly perceived as uneconomical. To circumvent this problem, some strategies have been devised that can valorize such unrefined complex lignin-oils in a more direct manner.…”

“…[3][4][5][6][7][8][9][10][11][12][13][14]31,32 Over the past few decades, much progress has been achieved regarding the alkaline and oxidative depolymerization of lignin, process being related to pulping industry. [33][34][35][36] More recently, reductive catalytic fractionation (RCF) of lignin have surfaced as elegant and promising techniques to turn lignin into valuable monomers. [37][38][39][40][41] Concurrently, also thermal lignin depolymerization processes (e.g., pyrolysis) have been a focus point of development.…”

Catalytic reductive depolymerization of corncob lignin to produce bio-oil via formic acid/ethanol system

“…The wide band around 3406 cm -1 represents the stretching vibration of -O-H bond. Two weak peaks at 2937 and 2842 cm -1 are attributed to stretchings of C-H in methyl, methylene, and methine groups (Mei et al 2020). The bands found at 2800 to 3000 cm -1 in all bio-oils were stronger than those in lignin.…”