The acetalization of acetone with glycerol to yield 2,2-dimethyl-1,3-dioxolane-4-methanol (solketal) was successfully catalyzed by mesoporous substituted silicates including the novel Hf-TUD-1 material. This reaction offers an attractive path for the conversion of glycerol, which is the main side-product in the synthesis of biodiesel, to a valuable compound with potential for industrial applications. The most promising among the heterogeneous catalysts employed in this work, Zr-and Hf-TUD-1 and Sn-MCM-41, display mainly Lewis acid properties as demonstrated by characterization with FT-IR analysis of pyridine adsorption, and achieve superior results compared to a reference solid acid catalyst such as Ultrastable zeolite Y. Especially the newly synthesized Hf-TUD-1, showing the highest conversion and turnover among the screened materials, is a promising catalyst for the acetalization of acetone with glycerol in a sustainable process. The excellent performance of these mesoporous catalysts is ascribed to their combination of acidity, wide pores, large specific surface area and relatively hydrophobic surface.Scheme 1 Solketal prepared from the acetalization of acetone with glycerol. † Electronic supplementary information (ESI) available: Comparison between heterogeneous catalysts for the conversion of glycerol to solketal. See

DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

Currently, valorization of lignocellulosic biomass almost exclusively focuses on the production of pulp, paper, and bioethanol from its holocellulose constituent, while the remaining lignin part that comprises the highest carbon content, is burned and treated as waste. Lignin has a complex structure built up from propylphenolic subunits; therefore, its valorization to value-added products (aromatics, phenolics, biogasoline, etc.) is highly desirable. However, during the pulping processes, the original structure of native lignin changes to technical lignin. Due to this extensive structural modification, involving the cleavage of the β-O-4 moieties and the formation of recalcitrant C-C bonds, its catalytic depolymerization requires harsh reaction conditions. In order to apply mild conditions and to gain fewer and uniform products, a new strategy has emerged in the past few years, named ‘lignin-first’ or ‘reductive catalytic fractionation’ (RCF). This signifies lignin disassembly prior to carbohydrate valorization. The aim of the present work is to follow historically, year-by-year, the development of ‘lignin-first’ approach. A compact summary of reached achievements, future perspectives and remaining challenges is also given at the end of the review.

No abstract

No abstract