Towards efficient and greener processes for furfural production from biomass: A review of the recent trends

As mentioned in several recent reviews, biomass-based furfural is attracting increasing interest as a feasible alternative for the synthesis of a wide range of non-petroleum-derived compounds. However, the lack of environmentally friendly, cost-effective, and sustainable industrial procedures is still evident. This review describes the chemical and biological routes for furfural production. The mechanisms proposed for the chemical transformation of xylose to furfural are detailed, as are the current advances in the manufacture of furfural from biomass. The main goal is to overview the different ways of improving the furfural synthesis process. A pretreatment process, particularly chemical and physico-chemical, enhances the digestibility of biomass, leading to the production of >70 % of available sugars for the production of valuable products. The combination of heterogeneous (zeolite and polymeric solid) catalyst and biphasic solvent system (water/GVL and water/CPME) is regarded as an attractive approach, affording >75 % furfural yield for over 80 % of selectivity with the possibility of catalyst reuse. Microwave heating as an activation technique reduces reaction time at least tenfold, making the process more sustainable. The state of the art in industrial processes is also discussed. It shows that, when sulfuric acid is used, the furfural yields do not exceed 55 % for temperatures close to 180 °C. However, the MTC process recently achieved an 83 % yield by continuously removing furfural from the liquid phase. Finally, the CIMV process, using a formic acid/acetic acid mixture, has been developed. The economic aspects of furfural production are then addressed. Future research will be needed to investigate scaling-up and biological techniques that produce acceptable yields and productivities to become commercially viable and competitive in furfural production from biomass.

Preparation of 5-hydroxymethylfurfural using magnetic Fe3O4@SiO2@mSiO2-TaOPO4 catalyst in 2-pentanol

5-Hydroxymethylfurfural (HMF) is one of the most important platform molecules and could be transformed into a variety of fuel additives and high value-added chemicals. Multiple catalyst systems have been developed for the conversion of carbohydrates to HMF, but there are still unavoidable problems, including high temperature and pressure, difficult recovery of solvent, corrosion of equipment, poor catalyst circulation, etc. Herein, a new magnetic Fe3O4@SiO2@mSiO2-TaOPO4 catalyst for the preparation of HMF from fructose in 2-pentanol was developed. The structures of the catalysts were characterized by FT-IR, TSM, EDS, SEM, XRD and VSM. The 2-pentanol solvent is not only conducive to the production of HMF, but also enables the reaction to be carried out at a lower pressure. The highest yield of HMF (85.4%) was obtained using 20 wt% catalyst under 10% substrate concentration (0.5 g of fructose) at 120 °C for 3 h. The catalysts can be easily separated by magnetism. The slight decrease in catalyst activity after 7 cycles was mainly due to the loss of catalyst during the cycle operation. Simultaneously, the total yield of HMF was 51.3% after scale-up to 15 g of fructose, showing the possible industrial application potential of this catalyst system.

Valorization of Waste Lignocellulose to Furfural by Sulfonated Biobased Heterogeneous Catalyst Using Ultrasonic-Treated Chestnut Shell Waste as Carrier

Recently, the highly efficient production of value-added biobased chemicals from available, inexpensive, and renewable biomass has gained more and more attention in a sustainable catalytic process. Furfural is a versatile biobased chemical, which has been widely used for making solvents, lubricants, inks, adhesives, antacids, polymers, plastics, fuels, fragrances, flavors, fungicides, fertilizers, nematicides, agrochemicals, and pharmaceuticals. In this work, ultrasonic-treated chestnut shell waste (UTS-CSW) was utilized as biobased support to prepare biomass-based heterogeneous catalyst (CSUTS-CSW) for transforming waste lignocellulosic materials into furfural. The pore and surface properties of CSUTS-CSW were characterized with BET, SEM, XRD, and FT-IR. In toluene–water (2:1, v:v; pH 1.0), CSUTS-CSW (3.6 wt%) converted corncob into furfural yield in the yield of 68.7% at 180 °C in 15 min. CSUTS-CSW had high activity and thermostability, which could be recycled and reused for seven batches. From first to seventh, the yields were obtained from 68.7 to 47.5%. Clearly, this biobased solid acid CSUTS-CSW could be used for the sustainable conversion of waste biomasses into furfural, which had potential application in future.

Sequential dehydration of sorbitol to isosorbide over acidified niobium oxides

The synergy of Brønsted and Lewis acid sites facilitated the sequential dehydration of sorbitol to isosorbide under solvent-free conditions.

Hydrolysis of Hemicellulose and Derivatives-A Review of Recent Advances in the Production of Furfural

Biobased production of furfural has been known for decades. Nevertheless, bioeconomy and circular economy concepts is much more recent and has motivated a regain of interest of dedicated research to improve production modes and expand potential uses. Accordingly, this review paper aims essentially at outlining recent breakthroughs obtained in the field of furfural production from sugars and polysaccharides feedstocks. The review discusses advances obtained in major production pathways recently explored splitting in the following categories: (i) non-catalytic routes like use of critical solvents or hot water pretreatment, (ii) use of various homogeneous catalysts like mineral or organic acids, metal salts or ionic liquids, (iii) feedstock dehydration making use of various solid acid catalysts; (iv) feedstock dehydration making use of supported catalysts, (v) other heterogeneous catalytic routes. The paper also briefly overviews current understanding of furfural chemical synthesis and its underpinning mechanism as well as safety issues pertaining to the substance. Eventually, some remaining research topics are put in perspective for further optimization of biobased furfural production.

Effective conversion of biomass into bromomethylfurfural, furfural, and depolymerized lignin in lithium bromide molten salt hydrate of a biphasic system

A biphasic system including acidic lithium bromide trihydrate effectively converted lignocellulosic biomass into bromomethylfurfural (BMF), furfural (FF) and depolymerized lignin.

Transfer hydrogenation of cinnamaldehyde with 2-propanol on Al2O3 and SiO2–Al2O3 catalysts: role of Lewis and Brønsted acidic sites

Neither surface Brønsted acidic nor basic sites are involved in the catalytic transfer hydrogenation reaction of cinnamaldehyde with 2-propanol.