Abstract
Heterogeneous catalysis, which has served well the petrochemical industry, may valuably contribute towards a bio-based economy by sustainably enabling selective reactions to renewable chemicals. Carbohydrate-containing matter may be obtained from various widespread sources and selectively converted to furanic platform chemicals: furfural (Fur) and 5-(hydroxymethyl)furfural (Hmf). Valuable bioproducts may be obtained from these aldehydes via catalytic transfer hydrogenation (CTH) using alcohols as H-donors under relatively moderate reaction conditions. Hafnium-containing TUD-1 type catalysts were the first of ordered mesoporous silicates explored for the conversion of Fur and Hmf via CTH/alcohol strategies. The materials promoted CTH and acid reactions leading to the furanic ethers. The bioproducts spectrum was broader for the reaction of Fur than of Hmf. A Fur reaction mechanism based on literature data was discussed and supported by kinetic modelling. The influence of the Hf loading and reaction conditions (catalyst load, type of alcohol H-donor, temperature, initial substrate concentration) on the reaction kinetics was studied. The reaction conditions were optimized to maximize the yields of 2-(alkoxymethyl)furan ethers formed from Fur; up to 63% yield was reached at 88% Fur conversion, 4 h/150 °C, using Hf-TUD-1(75), which was a stable catalyst. The Hf-TUD-1(x) catalysts promoted the selective conversion of Hmf to bis(2-alkoxymethyl)furan; e.g., 96% selectivity at 98% Hmf conversion, 3 h/170 °C for Hf-TUD-1(50).
Highlights
CHys may be selectively converted to the chemical platforms furfural (Fur) and 5-(hydroxymethyl)furfural (Hmf) via consecutive hydrolysis and dehydration reactions promoted by acid catalysts (Scheme 1) [3]
The conversion of furanic aldehydes—namely, furfural (Fur) and 5-(hydroxymethyl)furfural (Hmf)—to useful furanic ethers was effectively carried out using Hf-containing TUD-1 type mesoporous silicate catalysts (Hf-TUD-1(x), x = molar ratio Si/Hf) synthesized via a one-pot approach without using surfactants or expensive polymeric organic templates
Hf sites played determinant catalytic roles in the reduction and acid chemistry involved in the conversion of Fur and Hmf to 2-(alkoxymethyl)furan ethers (AMFs) and bis(2alkoxymethyl)furan (BAMFs), respectively
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The increasing greenhouse gas emissions and climate change are partly associated with the increasing energy demands and our dependency on fossil fuels [1,2]. Environmental policies have stimulated the use of renewable sources and the diversification of energy supplies. Non-edible vegetal biomass such as residues/surpluses of agriculture, forestry, and paper industries are renewable sources of organic carbon, possessing carbohydrates (CHys) such as hemicelluloses and cellulose. CHys may be selectively converted to the chemical platforms furfural (Fur) and 5-(hydroxymethyl)furfural (Hmf) via consecutive hydrolysis and dehydration reactions promoted by acid catalysts (Scheme 1) [3]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
