Design of Nickel Supported on Water-Tolerant Nb2O5 Catalysts for the Hydrotreating of Lignin Streams Obtained from Lignin-First Biorefining

Glauco F Leal; Sérgio Lima; Inês Graça; Heloise Carrer; Dean H Barrett; Erico Teixeira-Neto; Antonio Aprigio S Curvelo; Cristiane B Rodella; Roberto Rinaldi

doi:10.1016/j.isci.2019.05.007

Design of Nickel Supported on Water-Tolerant Nb₂O₅ Catalysts for the Hydrotreating of Lignin Streams Obtained from Lignin-First Biorefining

iScience. 2019 May 31:15:467-488. doi: 10.1016/j.isci.2019.05.007. Epub 2019 May 9.

Authors

Glauco F Leal¹, Sérgio Lima², Inês Graça², Heloise Carrer³, Dean H Barrett⁴, Erico Teixeira-Neto⁵, Antonio Aprigio S Curvelo⁶, Cristiane B Rodella³, Roberto Rinaldi⁷

Affiliations

¹ Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK; Department of Physical Chemistry, Institute of Chemistry of São Carlos, University of São Paulo, Av. Trabalhador São Carlense, 400, São Carlos, São Paulo 13566-590, Brazil; Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, São Paulo 13083-970, Brazil.
² Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
³ Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, São Paulo 13083-970, Brazil.
⁴ Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, São Paulo 13083-970, Brazil; School of Chemistry, University of the Witwatersrand, Johannesburg, South Africa.
⁵ Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, São Paulo 13083-970, Brazil.
⁶ Department of Physical Chemistry, Institute of Chemistry of São Carlos, University of São Paulo, Av. Trabalhador São Carlense, 400, São Carlos, São Paulo 13566-590, Brazil.
⁷ Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK. Electronic address: rrinaldi@ic.ac.uk.

Abstract

In biomass conversion, Nb₂O₅ has attracted increasing attention as a catalyst support presenting water-tolerant Lewis acid sites. Herein, we address the design of Ni/Nb₂O₅ catalysts for hydrotreating of lignin to hydrocarbons. To optimize the balance between acidic and hydrogenating properties, the catalysts were first evaluated in the hydrotreating of diphenyl ether. The best catalyst candidate was further explored in the conversion of lignin oil obtained by catalytic upstream biorefining of poplar. As primary products, cycloalkanes were obtained, demonstrating the potential of Ni/Nb₂O₅ catalysts for the lignin-to-fuels route. However, the Lewis acidity of Nb₂O₅ also catalyzes coke formation via lignin species condensation. Thereby, an acidity threshold should be found so that dehydration reactions essential to the hydrotreatment are not affected, but the condensation of lignin species prevented. This article provides a critical "beginning-to-end" analysis of aspects crucial to the catalyst design to produce lignin biofuels.

Keywords: Biofuel; Catalysis; Energy Materials.