Solvothermal conversion of lignosulfonate assisted by ni catalyst - Investigation of the role of ethanol and ethylene glycol as solvents

In this study, reductive solvolysis of lignosulfonate using Ni-based catalysts in ethylene glycol (EG) and ethanol (EtOH) at 250 °C was investigated. The liquefied fractions, regarded as oil, were carefully analyzed using size-exclusion chromatography (SEC) and gas chromatography⁻mass spectrometry with flame ionization detection (GC-MS-FID). The oil yields from catalytic conversion in EtOH and EG were similar, being 31 and 32 wt.%, respectively. The oil fractions from depolymerization in EtOH had lower molecular weight compared to the oil products in EG, indicating a higher degree of degradation of liquefied products in EtOH. On the other hand, EG showed superior activity in inhibiting condensation reactions; 16 and 46 wt.% tetrahydrofuran (THF) soluble and THF insoluble solid fractions were obtained from conversion in EtOH, while those numbers in EG were 45 and 23 wt.%, respectively. The Ni-based catalyst was introduced to provide active sites for hydrogenation of lignosulfonate fragments released into the solvent. The presence of NiS in the spent catalyst, formed from reaction between Ni and sulfur in the lignosulfonate, was confirmed. The sulfur content in the oil obtained in EtOH was 0.38 wt.%, which in comparison to lignosulfonate with 3.1 wt.% sulfur, indicated a high level of desulfurization

Liquefaction of Lignosulfonate in Supercritical Ethanol Using Alumina-Supported NiMo Catalyst

Lignosulfonate was subjected to a reductive catalytic degradation in ethanol medium at 310 °C in the presence of alumina supported NiMo catalysts and H2. The liquid and solid products were analyzed with size exclusion chromatography (SEC), gas chromatography mass spectrometry (GC–MS), two-dimensional gas chromatography (GC × GC), heteronuclear single quantum coherence nuclear magnetic resonance (HSQC NMR) and elemental analysis. The highest oil yield and the lowest char yield obtained was 88 and 15 wt %, respectively. The liquefied species were mainly dimers and oligomers with minor yields of monomers. The catalyst was important for stabilization of reactive intermediates either by hydrogenation or coupling with ethanol. Simultaneous deoxygenation and desulfurization reactions took place in the presence of the catalyst; the oxygen and sulfur content in the oil fraction obtained after 4 h reaction time were 11.2 and 0.1 wt %, indicating considerable deoxygenation and desulfurization compared to the lignosulfonate feedstock (O, 30.8 wt %; S, 3.1 wt %). The effect of the reaction parameters such as temperature, reaction time and catalyst mass was studied. It was observed that by increasing the temperature from 260 to 310 °C the degradation increased, however, the SEC analysis showed that the degradation progressed only to a certain size range dimers to oligomers in the reaction temperatures studied. Investigating the effect of reaction time of 1, 2, 3, and 4 h indicated that degradation, deoxygenation, desulfurization and alkylation reactions progressed over time. The reusability of the catalyst without any pretreatment was confirmed by an almost constant oil yield in three repeated experiments with the same catalyst batch. The results show that alumina supported NiMo catalysts are very promising catalysts for conversion of lignosulfonate to liquid products

A simple synthetic route to methyl 3-fluoropyridine-4-carboxylate by nucleophilic aromatic substitution

The nitro group of methyl 3-nitropyridine-4-carboxylate (1) has successfully been replaced by fluoride anion via nucleophilic aromatic substitution to give the 3-fluoropyridine- 4-carboxylate 2

Rational and evolutionary engineering of <i>Saccharomyces cerevisiae</i> for production of dicarboxylic acids from lignocellulosic biomass and exploring genetic mechanisms of the yeast tolerance to the biomass hydrolysate

BACKGROUND: Lignosulfonates are significant wood chemicals with a $700 million market, produced by sulfite pulping of wood. During the pulping process, spent sulfite liquor (SSL) is generated, which in addition to lignosulfonates contains hemicellulose-derived sugars—in case of hardwoods primarily the pentose sugar xylose. The pentoses are currently underutilized. If they could be converted into value-added chemicals, overall economic profitability of the process would increase. SSLs are typically very inhibitory to microorganisms, which presents a challenge for a biotechnological process. The aim of the present work was to develop a robust yeast strain able to convert xylose in SSL to carboxylic acids. RESULTS: The industrial strain Ethanol Red of the yeast Saccharomyces cerevisiae was engineered for efficient utilization of xylose in a Eucalyptus globulus lignosulfonate stream at low pH using CRISPR/Cas genome editing and adaptive laboratory evolution. The engineered strain grew in synthetic medium with xylose as sole carbon source with maximum specific growth rate (µ(max)) of 0.28 1/h. Selected evolved strains utilized all carbon sources in the SSL at pH 3.5 and grew with µ(max) between 0.05 and 0.1 1/h depending on a nitrogen source supplement. Putative genetic determinants of the increased tolerance to the SSL were revealed by whole genome sequencing of the evolved strains. In particular, four top-candidate genes (SNG1, FIT3, FZF1 and CBP3) were identified along with other gene candidates with predicted important roles, based on the type and distribution of the mutations across different strains and especially the best performing ones. The developed strains were further engineered for production of dicarboxylic acids (succinic and malic acid) via overexpression of the reductive branch of the tricarboxylic acid cycle (TCA). The production strain produced 0.2 mol and 0.12 mol of malic acid and succinic acid, respectively, per mol of xylose present in the SSL. CONCLUSIONS: The combined metabolic engineering and adaptive evolution approach provided a robust SSL-tolerant industrial strain that converts fermentable carbon content of the SSL feedstock into malic and succinic acids at low pH.in production yields reaching 0.1 mol and 0.065 mol per mol of total consumed carbon sources.. Moreover, our work suggests potential genetic background of the tolerance to the SSL stream pointing out potential gene targets for improving the tolerance to inhibitory industrial feedstocks. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13068-022-02121-1