Process optimization of lignin conversion into value added chemicals by thermochemical pretreatment and electrooxidation on a stainless steel anode

Abstract

Wheat straw soda lignin was subjected to thermochemical (TC) pretreatment at low to moderate temperatures followed by electrooxidation (EO) on an SS-304 anode to produce some value-added organic chemicals. The influence of independent process variables on the product yield of major organic chemical groups, namely, aromatic carbonyl compounds (COarom), aromatic hydrocarbons (HCarom), and aliphatic hydrocarbons (HCaliph), was studied. Response surface methodology (RSM) was used to optimize the process conditions for maximizing the amount of chemical production according to the Box-Behnken experimental design (BBD). For COarom, the optimal conditions were 2 h TC pretreatment at 200°C followed by 12 h of EO at 2.24 mA cm−2current density to yield 24.7% of desired products. The optimized synthesis conditions for HCaromare 2 h TC treatment at 200°C yielding 16.1% desired products. As individual compounds, vanillin, acetosyringone, syringaldehyde, acetovanillone,o-xylene and toluene were significantly produced in different product groups. A small amount of organosilicon compounds (ORGSi) and HCaliphwas also produced.

Techno-economic feasibility of bioethanol production via biorefinery of olive tree prunings (OTP): optimization of the pretreatment stage

“…Results from the technoeconomic and energy assessment were analyzed by the statistical software Design-Expert 8.0.7.1 (Stat-Ease Inc., Minneapolis, MN, USA). The response surface methodology (RSM) was applied, which is a collection of statistical and mathematical techniques needed for developing, improving and optimizing processes (Singh and Ghatak 2017). This methodology was extensively applied at industrial levels, particularly in situations, where several input variables influence the process performance (Myers et al 2016).…”

Electro-oxidative depolymerisation of technical lignin in water using platinum, nickel oxide hydroxide and graphite electrodes

“…11 Among electrochemical approaches, the electro-oxidation of lignin at the anode is the most common one studied. 12 Even if electrocatalytic approaches similar to that adopted in the present study were reported in the literature for other combinations of lignins and working electrodes, [13][14][15] investigations regarding the electrochemical conversion of P1000 lignin, up to now, are absent. Only a few studies are available concerning its chemical valorisation through inorganic catalysts, such as CuMgAlO x or NiMo sulphide, in organic solvents under harsh reaction conditions.…”

Greener Routes to Biomass Waste Valorization: Lignin Transformation Through Electrocatalysis for Renewable Chemicals and Fuels Production

“…Syringaldehyde and acetovanillone were formeda th igher current densities of 6.71 mA cm À2 and 4.47 mA cm À2 respectively. [121] 7.2. Integrated electrocatalysis:I onic-liquid and deep-eutectic-solvent electrolytes Ionic liquids are popular substitutes for aqueous electrolytes in biomass electrocatalysis due to their enhanced conductivity, non-volatility,g reater solubilizing capacity for lignin, thermal and chemical stability, and aw ider electrochemical window compared to water.…”

“…Optimized current density (2.24 mA cm −2 ) and reaction time (12 h) favored the formation of 24.7 % aromatic carbonyl compounds (e.g., 6.7 % vanillin and 11.4 % acetosyringone), while a different optimized current density (2.24–2.28 mA cm −2 ) with a shorter reaction time (0–0.85 h) was optimal for the formation of 16.1 % aromatic hydrocarbons (12 % o ‐xylene and 3 % toluene). Syringaldehyde and acetovanillone were formed at higher current densities of 6.71 mA cm −2 and 4.47 mA cm −2 respectively …”