La-modified sba-15/h2o2 systems for the microwave assisted oxidation of organosolv beech wood lignin

Abstract

In this manuscript, the in uence of organosolv beech wood lignin (LOB) on its oxidative conversion to high added-value phenolic aldehydes is discussed. Environmental friendly and low-cost H 2 O 2 was used as the oxygen atom donor. e catalyst was prepared by immobilizing Lanthanum compounds onto the periodic mesoporous channels of siliceous SBA-15. e activity of the La/SBA-15 was investigated towards oxidation of LOB in the presence of hydrogen peroxide as oxidant with microwave irradiation. Considering the characteristics of LOB, an unexpected low syringaldehyde concentration at 10min of reaction time (1.47 g/L, corresponding to 15.66% yield) was obtained; the other major product was vanillin at 25min (0.78 g/L, i.e., 9.94% yield). e high reactivity of syringyl nuclei may be pointed out as the main reason for the faster production and degradation of syringaldehyde in oxidation. Other low molecular weight phenolic products were found: vanillic acid, syringic acid and minor quantities of aceto-derivatives. e pro le of products concentration with the reaction time of catalytic oxidation with microwave irradiation are shown and discussed with reference to the investigated lignin features. e mechanism of the microwave catalytic oxidation for LOB under alkaline conditions was proposed.

Microwave-Assisted Catalytic Solvolysis of Lignin to Phenols: Kinetics and Product Characterization

“…In microwave-assisted reactions, the yield of vanillin was ca. 10 wt % in alkaline media using organosolv lignin and La/SBA-15 as a catalyst . In addition to vanillin, in this study, reasonable yield of vanillic acid (15 mg g –1 ) at 120 min was observed with LaFeO 3 as a catalyst.…”

“…10 wt % in alkaline media using organosolv lignin and La/SBA-15 as a catalyst. 21 In addition to vanillin, in this study, reasonable yield of vanillic acid (15 mg g −1 ) at 120 min was observed with LaFeO 3 as a catalyst. The yield of vanillic acid reported in the literature is low, in alkaline or aqueous media using La/SBA-15 or Co 3 O 4 as catalysts.…”

Microwave-Assisted Catalytic Solvolysis of Lignin to Phenols: Kinetics and Product Characterization

“…In microwave-assisted reactions, the yield of vanillin was ca. 10 wt % in alkaline media using organosolv lignin and La/SBA-15 as a catalyst . In addition to vanillin, in this study, reasonable yield of vanillic acid (15 mg g –1 ) at 120 min was observed with LaFeO 3 as a catalyst.…”

“…10 wt % in alkaline media using organosolv lignin and La/SBA-15 as a catalyst. 21 In addition to vanillin, in this study, reasonable yield of vanillic acid (15 mg g −1 ) at 120 min was observed with LaFeO 3 as a catalyst. The yield of vanillic acid reported in the literature is low, in alkaline or aqueous media using La/SBA-15 or Co 3 O 4 as catalysts.…”

Direct Oxidation of Hibiscus cannabinus Stalks to Vanillin Using CeO2 Nanostructure Catalysts

“…According to Zhao et al [ 32 ], there is an increase in vanillin yield when the power irradiation ranges from 50 W to 250 W. This is due to the fact that the intensity of the electromagnetic radiation increases at the same time, resulting in a large amount of heat energy being generated by rapidly alternating electricity compared to conventional heating. A study by Gu et al [ 47 ] proves that the production yield of vanillin improves using the microwave. They reported a 9.94% yield of vanillin was achieved from organosolv lignin in 25 min of reaction time under 200 W of microwave irradiation with the use of mesoporous La/SBA–15 catalyst, which is thirty times greater than under conventional heating.…”

Characterization and analysis of toughened bio‐oil‐based phenolic foam prepared from poplar

“…The content of phenols reached 30.03% of the aromatic compounds. The reason for the different components of bio‐oil under different catalytic conditions is that H 2 O 2 has a positive effect on the structural depolymerization of part of lignin, and an appropriate amount of H 2 O 2 can split various bonds in lignin, such as ether bonds, carbonyl, and hemicellulose ester bonds, to form more aromatic compounds 20 . Base catalysis can effectively promote the formation of acids and alcohols, 9 in addition, the synergistic catalysis of NaOH/H 2 O 2 can increase the content of phenols 21 …”

Microwave-Assisted Catalytic Solvolysis of Lignin to Phenols: Kinetics and Product Characterization

“…In microwave-assisted reactions, the yield of vanillin was ca. 10 wt % in alkaline media using organosolv lignin and La/SBA-15 as a catalyst . In addition to vanillin, in this study, reasonable yield of vanillic acid (15 mg g –1 ) at 120 min was observed with LaFeO 3 as a catalyst.…”

“…10 wt % in alkaline media using organosolv lignin and La/SBA-15 as a catalyst. 21 In addition to vanillin, in this study, reasonable yield of vanillic acid (15 mg g −1 ) at 120 min was observed with LaFeO 3 as a catalyst. The yield of vanillic acid reported in the literature is low, in alkaline or aqueous media using La/SBA-15 or Co 3 O 4 as catalysts.…”

Direct Oxidation of Hibiscus cannabinus Stalks to Vanillin Using CeO2 Nanostructure Catalysts

“…According to Zhao et al [ 32 ], there is an increase in vanillin yield when the power irradiation ranges from 50 W to 250 W. This is due to the fact that the intensity of the electromagnetic radiation increases at the same time, resulting in a large amount of heat energy being generated by rapidly alternating electricity compared to conventional heating. A study by Gu et al [ 47 ] proves that the production yield of vanillin improves using the microwave. They reported a 9.94% yield of vanillin was achieved from organosolv lignin in 25 min of reaction time under 200 W of microwave irradiation with the use of mesoporous La/SBA–15 catalyst, which is thirty times greater than under conventional heating.…”

Characterization and analysis of toughened bio‐oil‐based phenolic foam prepared from poplar

“…The content of phenols reached 30.03% of the aromatic compounds. The reason for the different components of bio‐oil under different catalytic conditions is that H 2 O 2 has a positive effect on the structural depolymerization of part of lignin, and an appropriate amount of H 2 O 2 can split various bonds in lignin, such as ether bonds, carbonyl, and hemicellulose ester bonds, to form more aromatic compounds 20 . Base catalysis can effectively promote the formation of acids and alcohols, 9 in addition, the synergistic catalysis of NaOH/H 2 O 2 can increase the content of phenols 21 …”

Microwave-Assisted Catalytic Solvolysis of Lignin to Phenols: Kinetics and Product Characterization

“…In microwave-assisted reactions, the yield of vanillin was ca. 10 wt % in alkaline media using organosolv lignin and La/SBA-15 as a catalyst . In addition to vanillin, in this study, reasonable yield of vanillic acid (15 mg g –1 ) at 120 min was observed with LaFeO 3 as a catalyst.…”

“…10 wt % in alkaline media using organosolv lignin and La/SBA-15 as a catalyst. 21 In addition to vanillin, in this study, reasonable yield of vanillic acid (15 mg g −1 ) at 120 min was observed with LaFeO 3 as a catalyst. The yield of vanillic acid reported in the literature is low, in alkaline or aqueous media using La/SBA-15 or Co 3 O 4 as catalysts.…”

Direct Oxidation of Hibiscus cannabinus Stalks to Vanillin Using CeO2 Nanostructure Catalysts

“…According to Zhao et al [ 32 ], there is an increase in vanillin yield when the power irradiation ranges from 50 W to 250 W. This is due to the fact that the intensity of the electromagnetic radiation increases at the same time, resulting in a large amount of heat energy being generated by rapidly alternating electricity compared to conventional heating. A study by Gu et al [ 47 ] proves that the production yield of vanillin improves using the microwave. They reported a 9.94% yield of vanillin was achieved from organosolv lignin in 25 min of reaction time under 200 W of microwave irradiation with the use of mesoporous La/SBA–15 catalyst, which is thirty times greater than under conventional heating.…”

Characterization and analysis of toughened bio‐oil‐based phenolic foam prepared from poplar

“…The content of phenols reached 30.03% of the aromatic compounds. The reason for the different components of bio‐oil under different catalytic conditions is that H 2 O 2 has a positive effect on the structural depolymerization of part of lignin, and an appropriate amount of H 2 O 2 can split various bonds in lignin, such as ether bonds, carbonyl, and hemicellulose ester bonds, to form more aromatic compounds 20 . Base catalysis can effectively promote the formation of acids and alcohols, 9 in addition, the synergistic catalysis of NaOH/H 2 O 2 can increase the content of phenols 21 …”