Davide di Marino

  • RWTH Aachen
  • Templergraben 55 52056
  • Aachen
  • Germany

 

My SuBiCat publications:

 

2017  Liquid/Liquid extraction of biomass derived lignin from lignocellulosic pretreatments

Stiefel, Di Marino, Eggert, Künrich, Schmidt, Grande, Leitner, Jupke, Wessling, Green Chem., 2017,19, 93-97

Despite the rapid progress in the field of biomass fractionation and lignin valorization, no industrial process for chemical utilization of lignin has yet been established. One major step in that direction has been made with the advent of biorefineries and new biomass fractionation methods that deliver a relatively clean lignin stream, allowing a more efficient recovery and utilization of this fraction. However, the transfer of lignin from the fractionation solvent to a different medium for subsequent valorization has been largely disregarded so far. In this work, we demonstrate the use of a green liquid/liquid-extraction to transfer lignin from the organic phase of the OrganoCat process into differently concentrated alkaline solutions for further utilization. We show that alkaline solutions of pH 13 and 14 are able to almost completely extract the OrganoCat lignin from the organic phase but that this extraction might be accompanied by changes in the molecular structure of lignin, here shown by a change in the apparent molecular weight distribution.

 

2017  Emulsion electro oxidation of kraft lignin

Di Marino, Aniko, Stocco, Kriescher, Wessling, Green Chem., 2017,19, 4778-4784

Lignin is one of the most abundant bio-polymers present in nature and its valorization is still a challenge to an economically feasible biorefinery concept. The heterogeneity and scarce reactivity of lignin are significant hurdles to the development of new valorization processes. We propose an in situ extraction electrochemical depolymerization system. Kraft lignin dissolved in a deep eutectic solvent together with an extractant phase is able to form a stable emulsion. Electro-oxidation of the emulsion using a nickel or graphite electrode results in successful depolymerization and simultaneous fractionation of the products. Over-oxidation of the depolymerization products is anticipated to be suppressed upon swift extraction from the lignin phase into the extraction phase.

 

2016  Electrochemical depolymerisation of lignin in a deep eutectic solvent

Davide Di Marino,a David Stöckmann, Stefanie Kriescher, Serafin Stiefela, and Matthias Wessling, Green Chem., 2016,18, 6021-6028

Lignocellulosic biomass is an important renewable resource that could substitute fossil feedstocks as a raw material for high value chemicals production. While the cellulosic fraction of biomass gives access to saccharides only, lignin could possibly give access to low molecular weight aromatic compounds. Electrochemical processes represent a green and cheap alternative to homogenous and heterogeneous catalysis as well as to valorization processes that need high temperatures and high pressures. Electrochemical processes involving lignin need strong alkalinity of the reaction medium in order to dissolve lignin and to obtain an electrically conducting solution. However, strong alkalinity is supposed to be one of the reasons for consecutive oxidations to undesired organic acids and carbon dioxide. The high pH also limits the use of only a few metals as electrode materials, due to corrosion. We report the use of pure deep eutectic solvents (DES) in order to dissolve lignin in combination with an electrochemical oxidative depolymerisation. DESs are cheap, biodegradable and easy to handle and interest in using these solvents for biomass fractionation is growing in the last years. The development of processes for the valorization of lignin in the fractionation solvent is crucial and at the moment just very few example of valorization of lignin in DES are known. DES systems are proposed as an alternative to NaOH and ILs as electrolyte for the lignin electrochemical depolymerisation processes and a proof of principle for lignin electrochemical depolymerisation is showed. The process can be performed in pure or diluted DES and a subsequent liquid-liquid extraction of the products can be successfully performed. Molecular weight of lignin decreases due to the electrochemical process producing low molecular weight products, as shown in the size exclusion chromatography (SEC) measurement. We present successful extraction of the products and their characterization by SEC and GC-MS, proving that a successful depolymerisation of lignin was achieved. GC-MS identified vanillin and guaiacol as the most abundant produced phenolic compounds, with relative yields up to 38 % for guaiacol and 37 % for vanillin. Optimization of the process parameters, such as electrode material and stability, applied potentials and DES recycling are the next important steps that need to be taken into account for the electrochemical depolymerisation of lignin in this new class of solvents.

 

2016  An integrated electrochemical process to convert lignin to value added products under mild conditions

Stiefel, Schmitz, Peters, Di Marino, Wessling, Green Chem., 2016,18, 4999-5007

The controlled depolymerization of lignin is a promising approach for the generation of value-added compounds from biomass. And even though many different technologies to this end have been developed in the past, most of them require elevated temperatures and pressures to realize the depolymerization. In contrast, the electrochemical depolymerization of lignin can be achieved at ambient pressure and room temperature. However, as electrochemical processes are predominantly surface-catalyzed, the influence of the electrode structure plays a major role with regard to the process effectivity. In addition, the unselective mechanism of the electrochemical process reduces product yield by overoxidizing products. We report the use of 3D-structured electrode materials for the electrochemical depolymerization of lignin with a subsequent membrane filtration in order to increase product yield. The complete depolymerization of lignin at room temperature and ambient pressure to monomeric products could be achieved in less than four hours, with the successful continuous separation of monomers and residual lignin.

 

My SuBiCat poster presentations:

 

Improving deep eutectic solvents wood pre-treatment through liquid hot water

Tailor-Made Fuels from Biomass conference, Aachen, Germany, June 2017

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Electrochemical depolymerisation of lignin in a deep eutectic solvent and in situ product recovery

6th Nordic Wood Biorefinery conference (NWBC), Helsinki, Finland, October 2015

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E-mail: Davide.diMarino@avt.rwth-aachen.de

Direct phone: +49 (0) 241 80 29941

Website link: http://www.avt.rwth-aachen.de