Directional and integrated conversion of whole components in biomass for levulinates and phenolics with biphasic system

Directional methanolysis of kitchen waste for the co-production of methyl levulinate and fatty acid methyl esters: Catalytic strategy and machine learning modeling

To add value to ordinary kitchen waste, heterogeneous acid-base catalytic methanolysis was conducted to produce high-value liquid biofuels, methyl levulinate (ML) and fatty acid methyl esters (FAMEs). Yields of 53.3 % ML and 98.5 % FAME were achieved by methanolysis of kitchen waste under the co-catalysis of carbon-silica composite (C/Si-SO₃H) and zirconium modified ultrastable Y zeolite (Zr/USY). These target products can be easily recovered from the methanolic phase and can be purified at the end of the reaction. The collaborative combination of C/Si-SO₃H and Zr/USY exhibited higher activity than their commercial counterpart. This strategy can be applied to differently composed kitchen waste and kitchen waste with different water content. Product yields were predicted using an artificial neural network method, and the relative importance of the influencing factors was investigated by the random forest method. The systematic insight gained from this work supports the value-added utilization of kitchen waste.

Depolymerization of Rice Straw Lignin into Value-Added Chemicals in Sub-Supercritical Ethanol

Depolymerization of lignin is an important step to obtain a lignin monomer for the synthesis of functional chemicals. In the context of more lignin produced from biomass and pulp industry, converting real lignin with low purity is still required more studies. In this study, the influence of solvent composition and reaction parameters such as binary solvents ratio, time, and temperature, the solvent-to-lignin ratio on the depolymerization of rice straw lignin was investigated carefully. Essential lignin-degraded products including liquid product (LP), char (solid), and gas were obtained, and their yields were directly influenced by reaction conditions. Results show that the maximum lignin conversion rate of 92% and LP yield of 66% was under the condition of 275°C, 30 min, 75 : 1 (mL solvent/1 g lignin), and ethanol 50%. Gas chromatography-mass spectroscopy (GC-MS) analysis was used for the analysis of the depolymerization products and identified 11 compounds which are mainly phenolic compounds such as 2-ethylphenol, 3-ethylphenol, phenol, methyl 2,4,6-trimethylbenzoate. The structure changes of LP and char in various conditions were analyzed using Fourier-transform infrared (FTIR).

A Review of Trends in the Energy Use of Biomass: The Case of the Dominican Republic

This review examines the use of residual biomass as a renewable resource for energy generation in the Dominican Republic. The odology includes a thorough examination of scientific publications in recent years about logistics operations. The use of mathematical models can be beneficial for the selection of areas with a high number of residual biomass and processing centers; for the design of feedstock allocation; for the planning and selection of the mode of transport; and for the optimization of the supply chain, logistics, cost estimation, availability of resources, energy efficiency, economic performance, and environmental impact assessment. It is also essential to consider the exhaustive analysis of the most viable technological solutions among the conversion processes, in order to guarantee the minimum emissions of polluting or greenhouse gases. In addition, this document provides a critical review of the most relevant challenges that are currently facing logistics linked to the assessment of biomass in the Dominican Republic, with a straightforward approach to the complementarity and integration of non-manageable renewable energy sources.

Production of methyl levulinate from cellulose over cobalt disulfide: The importance of the crystal facet (111)

The conversion of cellulose to platform chemicals has attracted much attention because of its renewability. This work proposed an earth-abundant cobalt disulfide as a heterogeneous catalyst for methyl levulinate production from cellulose. The highest yield of methyl levulinate reached 61 mol% under the tested conditions of 200 °C, 2 MPa initial pressure, 0.45 catalyst/cellulose mass ratio, and 3 h reaction time. The XRD and TEM analyses demonstrated the crystal facet (111) of cobalt disulfide as a robust active site, which was in good agreement with the highest acidity of the crystal facet (111) calculated by the work functions. The XPS characterization showed that the main chemical valence of cobalt disulfide responsible for the methyl levulinate production was the surface Co²⁺ species. This study is valuable for the development of a recoverable catalyst for the cellulose to methyl levulinate process.

Directional depolymerization of lignin into high added-value chemical with synergistic effect of binary solvents

This work exploits a one-pot method for directional depolymerizing organosolv lignin into high added-value phenolic monomers with synergistic reaction system consisted of methanol-dimethoxymethane binary solvents and acid catalyst. The influence of solvent composition and reaction parameters such as different catalyst, binary solvents ratio, time, and temperature on the conversion of lignin and yield of products were investigated carefully, the optimum yield of liquid products and phenolic monomers were achieved at 67.39% and 27.67% at 200 °C kept for 60 min with low amount of acid catalyst. The plausible mechanism on the depolymerization of lignin was proposed in view of product distributions. Moreover, the combination of co-solvents and acidic catalyst was also suitable for converting different types of lignin into phenolic monomers, and the recyclability of joint reaction system was satisfactory. These results can provide promising prospects on developing an effective method for achieving high added-value phenolic compounds from lignin.