Sulfation of wheat straw soda lignin: Role of solvents and catalysts

Malyar, Yuriy N.; Kazachenko, Аleksandr S.; Vasilyeva, Natalya Yu.; Fetisova, Olga Yu.; Borovkova, Valentina S.; Miroshnikova, Angelina V.; Levdansky, Alexander V.; Skripnikov, Andrey M.

doi:10.1016/j.cattod.2021.07.033

Cited by 11 publications

(12 citation statements)

References 34 publications

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“…In addition, as reported in [ 24 ], the Lewis acids used as the catalysts for WSSL sulfation lead to the production of WSSL sulfates with a sulfur content similar to that of the products of sulfation with sulfamic acid in the presence of some organic bases (e.g., thiourea, DMF, and pyridine).…”

Section: Resultsmentioning

confidence: 77%

“…It is noteworthy that the maximum sulfur content (16.5 wt%) in the synthesized WSSL derivatives noticeably exceeds the values reported earlier for the sulfation of lignins over base catalysts. In particular, when sulfating WSSL with sulfamic acid in the presence of urea in 1,4-dioxane, lignin sulfates with a maximum sulfur content of 10.1 wt% were obtained [ 24 ].…”

Section: Resultsmentioning

confidence: 99%

“…As the acidity decreases, the number of base centers on the catalyst surface obviously increases; this, in turn, leads to an increase in its activity in the sulfation process. According to the correlated dependences of the degree of lignin sulfation on the acid nature of the catalysts, the mechanism of their catalytic action is similar to the catalytic effect of some organic bases on the sulfation of natural compounds with sulfamic acid [ 24 , 26 , 28 , 48 , 49 , 50 , 51 ].…”

Section: Resultsmentioning

confidence: 99%

“…In [ 21 , 22 , 23 ], the catalytic effect of some organic bases on the sulfation of natural compounds with sulfamic acid was studied. Urea was shown to have the highest activity among the investigated bases [ 24 , 25 , 26 , 27 , 28 ].…”

Section: Introductionmentioning

confidence: 99%

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Sulfation of Wheat Straw Soda Lignin with Sulfamic Acid over Solid Catalysts

et al. 2022

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Soda lignin is a by-product of the soda process for producing cellulose from grassy raw materials. Since a method for the industrial processing of lignin of this type is still lacking, several research teams have been working on solving this problem. We first propose a modification of soda lignin with sulfamic acid over solid catalysts. As solid catalysts for lignin sulfation, modified carbon catalysts (with acid sites) and titanium and aluminum oxides have been used. In the elemental analysis, it is shown that the maximum sulfur content (16.5 wt%) was obtained with the Sibunit-4® catalyst oxidized at 400 °C. The incorporation of a sulfate group has been proven by the elemental analysis and Fourier-transform infrared spectroscopy. The molecular weight distribution has been examined by gel permeation chromatography. It has been demonstrated that the solid catalysts used in the sulfation process causes hydrolysis reactions and reduces the molecular weight and polydispersity index. It has been established by the thermal analysis that sulfated lignin is thermally stabile at temperatures of up to 200 °C. According to the atomic force microscopy data, the surface of the investigated film consists of particles with an average size of 50 nm. The characteristics of the initial and sulfated β-O-4 lignin model compounds have been calculated and recorded using the density functional theory.

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Section: Resultsmentioning

confidence: 77%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sulfation of Wheat Straw Soda Lignin with Sulfamic Acid over Solid Catalysts

et al. 2022

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“…The result of the sulfation process was characterized by the output parameter: Y 1 -sulfur content in xanthan sulfate (wt%). The choice of factors and ranges of their variation is based on [26][27][28][29][30][31].…”

Section: Statistical Analysis Of the Sulfation Xanthan Processmentioning

confidence: 99%

Food Xanthan Polysaccharide Sulfation Process with Sulfamic Acid

Kazachenko

Vasilieva

Borovkova

et al. 2021

Foods

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Xanthan is an important polysaccharide with many beneficial properties. Sulfated xanthan derivatives have anticoagulant and antithrombotic activity. This work proposes a new method for the synthesis of xanthan sulfates using sulfamic acid. Various N-substituted ureas have been investigated as process activators. It was found that urea has the greatest activating ability. BBD of xanthan sulfation process with sulfamic acid in 1,4-dioxane has been carried out. It was shown that the optimal conditions for the sulfation of xanthan (13.1 wt% sulfur content) are: the amount of sulfating complex per 1 g of xanthan is 3.5 mmol, temperature 90 °C, duration 2.3 h. Sulfated xanthan with the maximum sulfur content was analyzed by physicochemical methods. Thus, in the FTIR spectrum of xanthan sulfate, in comparison with the initial xanthanum, absorption bands appear at 1247 cm−1, which corresponds to the vibrations of the sulfate group. It was shown by GPC chromatography that the starting xanthan gum has a bimodal molecular weight distribution of particles, including a high molecular weight fraction with Mw > 1000 kDa and an LMW fraction with Mw < 600 kDa. It was found that the Mw of sulfated xanthan gum has a lower value (~612 kDa) in comparison with the original xanthan gum, and a narrower molecular weight distribution and is characterized by lower PD values. It was shown by thermal analysis that the main decomposition of xanthan sulfate, in contrast to the initial xanthan, occurs in two stages. The DTG curve has two pronounced peaks, with maxima at 226 and 286 °C.

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