Gas‐Phase Partial Oxidation of Lignin to Carboxylic Acids over Vanadium Pyrophosphate and Aluminum–Vanadium–Molybdenum

Lotfi, Samira; Boffito, Daria C.; Patience, Gregory S.

doi:10.1002/cssc.201501036

Cited by 32 publications

(32 citation statements)

References 43 publications

(89 reference statements)

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“…17 Overview of the oxidative lignin depolymerisation methods: alkaline oxidation to phenolics, 112,113,180,338, acidic/pH-neutral oxidation to phenolics, [474][475][476][477][478][479][480][481][482][483][484][485][486][487] and oxidation to non-phenolic carboxylic acids. 179,[488][489][490][491] The yield histograms indicate the relative distribution of maximum reported monomer yields for each depolymerisation study and for each lignin substrate (if multiple substrates were used). The process characteristics and monomer yields of each individual study can be found in the ESI † (Tables S6-S8).…”

Section: Depolymerisation Of Isolated Ligninmentioning

confidence: 99%

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

et al. 2018

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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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Section: Depolymerisation Of Isolated Ligninmentioning

confidence: 99%

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

et al. 2018

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“…Highly exothermic or endothermic processes, explosive reactions, and vapourizing/reacting liquid streams are more challenging in fixed beds compared to fluidized beds. Atomizing non‐volatile compounds—fructose, xylose, vegetable oil, lignin, glycerol, and bitumen—through spargers into micro‐fluidized beds requires high gas velocities (

5 normalm \cdot s^{- 1}

20 normalm \cdot s^{- 1}

), which attrit even supported catalysts. Heating the gas to reaction conditions is a limiting factor, and so solids backmixing and higher gas velocities heat the atomized droplets faster.…”

Section: Uncertaintymentioning

confidence: 99%

Experimental methods in chemical engineering: Reactors—fluidized beds

et al. 2019

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Industry relies on fluidized beds to synthesize chemicals (acrylonitrile, maleic anhydride, titanium dioxide, vinyl chloride), combust coal, dry powders, and treat waste. Fluidized bed folklore declares that they are hard to scale‐up and the gas phase is backmixed. Commercial failures that disregard standard design criteria around powder management, gas/solids injection, and mixing reinforce this belief. However, engineers select fluidized beds for processes that are impractical with conventional technologies to achieve economies of scale for highly exothermic, endothermic, or explosive reactions, for catalysts that deactivate in seconds (or minutes), and for chemistry that requires multiple dosing cycles. Failures are more frequent for these challenging applications. For this reason, researchers study reaction kinetics in fixed beds despite internal mass transfer limitations and axial and radial temperature and concentration gradients. Fluidized bed hydrodynamics vary with powder properties (particle diameter, size distribution, density, sphericity), operating conditions (gas density, viscosity, temperature, pressure), reactor geometry (diameter, height, mass, grid geometry). The minimum fluidization velocity (Umf) is a property that identifies the transition from the fixed bed regime to the fluidized bed regime and equals the gas velocity at which the upward drag force equals the weight of the powder. At the experimental scale, fluidized beds operate isothermally, solids are completely backmixed, and the gas phase is close to plug flow (Ug<-0.25em3Umf). Here, we describe the relationship between powder properties and fluidization quality, list experimental techniques, describe recent applications, and gas phase hydrodynamics and uncertainties.

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“…We present how to reduce uncertainty with methodical design algorithms and guidelines to select reactor types and geometry. Other articles as part of this special series on experimental methods in chemical engineering, discuss thermogravimetric analysis and small fixed and fluidized beds to estimate intrinsic fluid‐solid reaction kinetics …”

Section: Descriptionmentioning

confidence: 99%

Experimental methods in chemical engineering: Micro‐reactors

et al. 2019

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Whereas the bulk chemical industry has historically sought economic advantage through economies of scale, a paradigm shift has researchers developing systems on smaller scales. Nano-cages and nano-actuators increase selectivity and robustness at the molecular scale. In parallel, micro-contactors with sub-millimetre lateral dimensions are decreasing boundary layers that restrict heat and mass transfer and thus meet the objectives of process intensification with great increases in productivity with a smaller footprint. These contactors continue to serve chemical engineers and chemists to synthesize fine chemicals and characterize catalysts; however, they have now been adopted for sensors in biological and biochemical systems. A bibliometric analysis of articles indexed in the Web of Science in 2016 and 2017 identified five major clusters of research: catalysis and bulk chemicals; nanoparticles; organic synthesis and flow chemistry; systems and micro-fluidics applied to biochemistry; and micro-channel reactors and mass transfer. In the early 1990s, less than 100 articles a year mentioned micro-reactors, while over 943 articles mentioned it in 2017. Here, we introduce micro-reactors and their role in the continuous synthesis of fine chemicals across the various scales to commercialization.

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Gas‐Phase Partial Oxidation of Lignin to Carboxylic Acids over Vanadium Pyrophosphate and Aluminum–Vanadium–Molybdenum

Cited by 32 publications

References 43 publications

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

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

Experimental methods in chemical engineering: Reactors—fluidized beds

Experimental methods in chemical engineering: Micro‐reactors

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