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Leveraging high entropy alloy catalysis for lignin valorization OBJECTIVES INTRODUCTION RESULTS METHODOLOGY 1. Synthesis of various HEA/HEO catalysts. 2. Assessing catalytic activity in batch on the MRCD of Soda miscanthus lignin with respect to reduction temperature. 3. Performing characterization techniques like TPR, XPS etc. RESULTS + Model β-O-4 compound - H2O (Dehydration) - γ-OH (Hydrodeoxygenation) + H2 (Hydrogenolysis) Model β-O-4 compound + C-O cleavage Varying atomic radii leads to severe lattice distortion ΔEads Pd0 Ni0 eNi Pd Different d-band centers correspond to different adsorption energy levels Electron transfer according to electronegativities Multiple active sites for catalysis Strong metal support interaction evidenced r2 r3 r1 Pd0 Support Lignin is the largest renewable source of aromatic building blocks in nature and has the potential to become an ideal feedstock for functionalized aromatics. Recently, mild reductive catalytic depolymerization (MRCD) of the lignin macromolecule into lower molecular weight fragments has gained attention, as a way to convert waste lignin streams from industry into highvalue chemicals. The lignin structure consists of phenylpropane units randomly linked with C-C or C-O-C bonds, out of which the β-O-4 ether bond is most prevalent. In literature, a novel class of catalysts called the high entropy alloys (HEA) have shown to be active in breaking the C-O bond, and therefore in this work, high entropy alloys supported on high entropy oxide (HEA/HEO) catalysts have been developed. The activity of various HEA/HEO formulations on the MRCD of Soda miscanthus lignin is investigated herein. The depolymerization of lignin entails two different phenomena – solvolysis and catalysis, the former generates unstable intermediates allowing for their repolymerization. Therefore, suppressing solvolysis by limiting batch time and exploring an active catalyst for the reductive cleavage of ethereal bonds is of essence. HEAs are entropydriven alloys consisting of 5 or more metal components in almost equimolar ratios, leading to unexpected synergistic effects for catalysis due to their unique properties! M(NO3)x.yH2O Citric acid Evaporation 110°C Calcination 500°C Catalyst screening Depolymerization performance as a function of molecular weight Reduction 5% H2/Ar , , , , , , , , , , , , , , CONCLUSIONS •Contact •<name>.<surname>@ugent.be •www.ugent.be/<...> • Universiteit Gent • @ugent • Ghent University Fig 1. TPR profile of HEO - noble (Pd0.17Cu0.23Ni0.23Co0.21Al0.16 - left) and non-noble (Fe0.23Cu0.17Ni0.22Co0.22Al0.16 - right) •Upon reduction at 600°C, both the catalyst formulations yielded activity gain of 12.1% over the benchmark. •XPS done on HEA/HEO catalysts reduced at 600°C showed a significant increase in Cu0 on the surface of the catalysts. Param Naik, Jeriffa De Clercq, Jeroen Lauwaert, An Verberckmoes Industrial Catalysis and Adsorption Technology, Department of Materials, Textiles and Chemistry, Ghent University, Valentin Vaerwyckweg 1, 9000 Ghent, Belgium Temperature (°C) Temperature (°C) TCD signal (a.u.) Temperature (° C) H 2 uptake (μ mol/g) 335.8 1018.3 659.4 62.38 783.8 78.55 Temperature (° C) H 2 uptake (μ mol/g) 237.4 70.9 375.5 429.5 800.7 323.0 Fig 3. XPS profile of non-noble Cu 2p (Fe0.23Cu0.17Ni0.22Co0.22Al0.16) showing increasing Cu0species from HEO (left) to HEA/HEO (right) reduced at 600°C 54 56 58 60 62 64 66 68 70 72 Mw reduction (%) Fig 2. Column chart showing the activity of novel HEA/HEO catalysts in MRCD in % reduction in molecular weight (g/mol) Reduced 400°C (HEA/HEO) Reduced 600°C (HEA/HEO) Calcined (HEO) Mw lignin feed = 16954 g/mol, Feed concentration = 25 mg/mL, 10 mL 70% aq. EtOH, 200°C, 10 bar H2, 3h PdCu/Al2O3FeCuNiCoAlPdCuNiCoAl Binding energy (eV) Binding energy (eV) Cu 2p1/2 Cu 2p1/2 Cu 2p3/2 Cu 2p3/2 Both Cu 2p peaks are sharper and more intense after reductive treatment at 600°C
