A surface science perspective on TiO2 photocatalysis

Recent developments of zinc oxide based photocatalyst in water treatment technology: A review

Lignocellulosic biomass pyrolysis mechanism: A state-of-the-art review

In pursuit of more sustainable and competitive biorefineries, the effective valorisation of lignin is key. An alluring opportunity is the exploitation of lignin as a resource for chemicals. Three technological biorefinery aspects will determine the realisation of a successful lignin-to-chemicals valorisation chain, namely (i) lignocellulose fractionation, (ii) lignin depolymerisation, and (iii) upgrading towards targeted chemicals. This review provides a summary and perspective of the extensive research that has been devoted to each of these three interconnected biorefinery aspects, ranging from industrially well-established techniques to the latest cutting edge innovations. To navigate the reader through the overwhelming collection of literature on each topic, distinct strategies/topics were delineated and summarised in comprehensive overview figures. Upon closer inspection, conceptual principles arise that rationalise the success of certain methodologies, and more importantly, can guide future research to further expand the portfolio of promising technologies. When targeting chemicals, a key objective during the fractionation and depolymerisation stage is to minimise lignin condensation (i.e. formation of resistive carbon–carbon linkages). During fractionation, this can be achieved by either (i) preserving the (native) lignin structure or (ii) by tolerating depolymerisation of the lignin polymer but preventing condensation through chemical quenching or physical removal of reactive intermediates. The latter strategy is also commonly applied in the lignin depolymerisation stage, while an alternative approach is to augment the relative rate of depolymerisation vs. condensation by enhancing the reactivity of the lignin structure towards depolymerisation. Finally, because depolymerised lignins often consist of a complex mixture of various compounds, upgrading of the raw product mixture through convergent transformations embodies a promising approach to decrease the complexity. This particular upgrading approach is termed funneling, and includes both chemocatalytic and biological strategies.

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Chemicals from lignin: an interplay of lignocellulose fractionation, depolymerisation, and upgrading

https://cyberleninka.org/article/n/638974.pdf

Characteristics and adsorption capacities of low-cost sorbents for wastewater treatment: A review

Microwave-assisted rapid pyrolysis of woodblock without adding susceptor and detailed product analysis

The corrosive sulfur compounds present in the mineral oil causes the formation of dibenzyl disulfide (DBDS) complex and it can also erode the on-load tap changing selector contacts leading to generation of silver sulfide (AgS2).The present work reports the effect of DBDS and Ag2S concentrations in mineral oil on thermally aged pressboard material. The results demonstrate that surface discharge inception voltage (SDIV) is higher for the aged pressboard specimen. The higher concentrations of DBDS showed a reduction of more than 50% in the magnitude of SDIV compared to its effect with the addition of Ag2S. The surface potential analysis indicates a higher initial potential for the aged specimens with an increased half lifetime. In addition, only deep traps observed on the aged specimens with a slight right shift in its trap energy level. The mechanical strength of aged pressboard specimens with DBDS and Ag2S is understood using tensile testing and simultaneous analysis is captured using Digital Image Correlation (DIC) technique to understand its strain percentage at different areas on the pressboard material during its elongation. The laser induced breakdown spectroscopy (LIBS) analysis is performed to identify the elements responsible for thermal ageing such as carbon, copper and sulfur on the surface of pressboard material. The plasma temperature calculated from sulfur peaks is higher for DBDS aged specimen compared to AgS2 and a linear correlation is observed on the LIBS intensity with ageing duration. Further, the Principal Component Analysis (PCA) is used for its classification on the degradation of pressboard due to the diffusion of both copper and silver sulfide from the mineral oil. The two principal components (PC1 and PC2) provided a higher variance of 99.8% with a clear classification observed between the unaged and aged pressboard specimens due to the addition of both DBDS and Ag2S in mineral oil. INDEX TERMS thermal ageing, sulfur, surface discharge, fluorescence, trap density, DIC, strain, elongation, LIBS, plasma temperature, PCA

Date of publication xxxx 00, 0000, date of current version xxxx 00, 0000

Catalytic Hydropyrolysis and Hydrodeoxygenation of Biomass and Model Compounds for Fuels and Chemicals

Characterization and Evaluation of Resource Recovery Potential of Beach Plastic Wastes using Analytical Py-GC/MS

Vanillin is a major fine chemical in the flavoring industry and one of the pyrolysates from lignin. In order to understand the primary decomposition pathways of vanillin, analytical fast pyrolysis experiments were performed in the temperature range of 500°C–650°C, and the primary pyrolysates were quantified. The proposed pyrolysis chemistry involves 31 elementary reactions of 23 species. Thermodynamic and kinetic analyses were performed using quantum chemical density functional theory calculations. Reaction pathways for the formation of three major phenolics, viz., guaiacol, 5-formylsalicyaldehyde and 4-hydroxybenzaldehyde, that accounted for ∼80 wt% yield at 650°C, were proposed. Based on the bond dissociation energies (BDEs) of homolytic cleavage of the various bonds in vanillin, the primary reaction is shown to involve the cleavage of O–CH3 bond whose BDE is 61.4 kcal mol−1. New bimolecular reactions such as ipso-addition involving the reaction of vanillin with hydrogen and methyl radicals were proposed. The generation of 4-hydroxy methoxybenzyl radical was found to be vital for the formation of guaiacol, while 4-hydroxy-3-(λ3-methoxyl) benzaldehyde radical was the key intermediate for the formation of 5-formylsalicyaldehyde. Multiple pathways for the formation of guaiacol, 5-formylsalicyaldehyde, catechol and 4-hydroxybenzaldehyde were evaluated. In order to track the time evolution of vanillin and its major pyrolysates, a detailed kinetic model was developed using the elementary reactions and their Arrhenius rate parameters. Based on the kinetic model, it is inferred that the timescale of fast pyrolysis is captured well by the model.

Ravikrishnan Vinu

Papers

Microwave-assisted rapid pyrolysis of woodblock without adding susceptor and detailed product analysis

Date of publication xxxx 00, 0000, date of current version xxxx 00, 0000

Catalytic Hydropyrolysis and Hydrodeoxygenation of Biomass and Model Compounds for Fuels and Chemicals

Characterization and Evaluation of Resource Recovery Potential of Beach Plastic Wastes using Analytical Py-GC/MS

Mechanistic Kinetic Analysis of Fast Pyrolysis of Vanillin to Primary Phenols