Microwave-Assisted One-Step Conversion of Wood Wastes into Levulinic Acid

Abstract

This study aimed to evaluate the use of softwood and hardwood waste for the production of levulinic acid by one-stage conversion using microwave radiation combined with acid catalysis. The analysis demonstrated that the type and concentration of the acid used, the concentration of biomass in the reaction mixture and pressure value had the greatest impact on the yield of levulinic acid. The highest efficiency of carbohydrate conversion to levulinic acid, regardless of the type of raw material, was achieved using a pressure of 225 PSI and sulfuric acid as a catalyst. Maximum yield from biomass, ca. 16.5% for cherry wood chips and ca. 25% for pine chips, was obtained using sulfuric acid at a concentration of 1% v/v and 2% v/v, respectively, for the following process parameters: Exposure time 20 min, biomass concentration 3.3%, and the pressure of 225 PSI. The ratio of actual yield to theoretical yield was high: 64.7% ± 4.5% for pine chips and 43.4% ± 1.0% for cherry wood chips. High efficiency of the presented method of biomass conversion to levulinic acid indicates the possibility of its use for waste management in the wood processing industry. High concentration of levulinic acid in the post-reaction mixture allows for cost-effective extraction and purification of the compound.

Solid residue and by-product yields from acid-catalysed conversion of poplar wood to levulinic acid

“…The highest observed theoretical levulinic acid was 59.5% for poplar wood at 180 °C, 150 min and 2 M sulphuric acid (Run 1) that corresponds to a levulinic acid yield of 20.1 wt % of the initial biomass. The yields are in line with those from other lignocellulosic feedstocks such as wheat straw, pine chips and miscanthus that have been reported to be between 50 and 70% (Kang et al 2018;Kłosowski et al 2019). While the theoretical yield is more appropriate for discussing the catalysis process effect on the maximum stoichiometric yields achievable, the absolute weight yield evaluates the economic implications of both the technology and feedstocks, therefore both solid and theoretical yields will be discussed.…”

“…Catalytic processes, including acid hydrolysis, partially decompose the lignocellulose into individual sugars before conversion into a range of platform chemicals. The conversion of lignocellulosic biomass with the use of acid catalysts has been investigated for the production of levulinic acid and furfural, from cellulose and hemicellulose fractions of biomass, respectively (Shen and Wyman 2011;Galletti et al 2012;Dussan et al 2013;Yu and Tsang 2017;Chen et al 2018;Kłosowski et al 2019). Both levulinic acid and furfural have been recognised among the top 30 platform chemicals by the United States Department of Energy (Moriarty et al 2016).…”

Recent advances, perspectives and challenges on levulinic acid production from residual biomass

“…Microwave radiation can also be used for hydrothermal fructose degradation to HMF and LA. Microwave heating results in better energy balance, lower heat losses, more efficient temperature control, reduced process costs and decreased catalytic reaction time 46,47 . Microwave irradiation associated with the catalytic activity of ZnBr has been successfully used for LA production in high yields (up to 53% by weight) 48 .…”

“…Microwave heating results in better energy balance, lower heat losses, more efficient temperature control, reduced process costs and decreased catalytic reaction time. 46,47 Microwave irradiation associated with the catalytic activity of ZnBr has been successfully used for LA production in high yields (up to 53% by weight). 48 The presence of catalytic compounds, for instance, the addition of sodium chloride in the reaction, increased the ion concentration, which interrupted the network of hydrogen bonds in the cellulose, leading to a more significant dissolution of the cellulose in the solvent.…”

A Review of Microwave Synthesis of Zinc Oxide Nanomaterials: Reactants, Process Parameters and Morphologies

“…medical waste, garbage, sludge) [ 447 ]; medical applications (np. sterilisation, drying, diagnosis, novel methods for treating inoperable tumours) [ 447 , 484 ]; analytical chemistry (laboratory sample processing, ashing, digestion, extraction, moisture analysis) [ 432 , 485 ]; chemical reactions: organic and inorganic synthesis (microwave assisted synthesis of e.g., medications, polymers and nanomaterials) [ 406 , 407 , 429 , 430 , 431 , 432 , 433 , 434 , 435 , 436 , 437 , 438 , 439 , 440 , 441 , 442 , 443 , 444 , 447 , 455 , 475 , 476 , 477 , 478 , 479 , 480 , 486 , 487 , 488 , 489 , 490 , 491 , 492 , 493 , 494 , 495 ]. …”