@inproceedings{01HAAQEM4S86D9TP17NVDH5H9F,
  abstract     = {{As much as 40% of all chemicals contain an aromatic moiety[1]. Currently, the main supplier of these compounds is the petrochemical industry, still one of the main sources of environmental pollution[2]. With the worsening climate change crisis and the depletion of fossil feedstocks, finding alternative sources for aromatics becomes imperative. The indigestible aromatic biopolymer lignin is the most promising candidate as it is the largest renewable source of aromatic compounds in nature[3]. Furthermore, lignin allows the straightforward derivation of functionalized aromatics, which can be used directly for multiple industrial applications; e.g., polymers, resins, foams, and dyes, thereby also replacing toxic components such as bisphenol A and phenol[4].

Mild reductive depolymerization is a highly favoured valorisation strategy due to its sustainable nature and superior selectivity to functionalized aromatics; however, the efficiency of this method is hindered by slow depolymerization rates in addition to limited insights in the depolymerization mechanism[5]. To overcome the latter, highly performant redox catalysts are needed for the selective cleavage of lignin’s beta-O-4 linkages [5], [6]. By studying the complex product pool after reaction, the depolymerization process can also be elucidated. 

In this work, both monometallic 5 w% Pd and 5 w% Pd-Cu nanoparticles are extensively studied on three different supports: γ-Al2O3, SiO2, and active carbon (AC). Both in-depth catalyst characterization (ICP, NH3-TPD, TEM-EDX, CO-chemisorption) and product pool analysis are performed (GPC, GC-MS, GPC-HPLC-UV/VIS, Py-GCxGC-MS and 2D-NMR). 

Results show that Pd-AC exhibits unique selectivity as well as the highest catalytic activity with a reduction in molecular weight of more than 80% after 6h, compared to 70% for Pd/γ-Al2O3 and Pd/SiO2. Moreover, the effect of Cu on Pd is found to be dependent on the support: the presence of Cu improves the activity of Pd on γ-Al2O3 and SiO2 and it also alters their selectivity. In contrast, the effect of Cu on the activity Pd/AC is negligible; however, it further boosts the catalyst’s selectivity towards a more deoxygenated and less hydrogenated product pool. Additionally, a two-step beta-O-4 cleavage mechanism is proposed, further substantiated by the use of model compounds.

Bibliography
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  author       = {{Atanasova, Boyana and De Saegher, Tibo and Vercammen, Joeri and Verberckmoes, An and De Clercq, Jeriffa and Lauwaert, Jeroen}},
  booktitle    = {{RRB23, the 19th International Conference on Renewable Resources & Biorefineries, Abstracts}},
  keywords     = {{lignin,biomass valorisation,heterogeneous catalysis}},
  language     = {{eng}},
  location     = {{Riga, Latvia}},
  pages        = {{2}},
  title        = {{Effects of the support and Cu as second metal on the performance of Pd catalysts in the mild reductive depolymerisation of Soda lignin}},
  year         = {{2023}},
}