Bio-based Platform Molecules Research Articles

Acetalization strategy in biomass valorization: a review

Acetalization serves as both a synthesis tool for renewable cyclic acetal fuel additives and a protection strategy to improve selectivity in biomass conversion.

Heterogeneous catalytic oxidation of furfural with hydrogen peroxide over a niobia catalyst

Oxidation of furfural was conducted using niobia as a heterogeneous catalyst, which displayed an unconventional behavior, giving 2,3-dihydroxybutanedioic acid (tartaric acid) as the main oxidation product.

Polymers from Cellulosic Waste: Direct Polymerization of Levoglucosenone using DBU as a Catalyst.

The bio-based platform molecule levoglucosenone (LGO) is now produced at multi-ton scale by the pyrolysis of cellulosic waste. As such it has become an industrially viable, non-petroleum-derived chemical feedstock. Herein we report the direct (one-step) and operationally simple polymerization of LGO that provides a highly sustainable method for polymer synthesis. Specifically, the ability of LGO to act as an electrophile has been harnessed so as to deliver high molecular weight polymers (Mn=236,000 g/mol, Đ=2.4) possessing excellent thermal stabilities (TD5 %=249 °C). Furthermore, there is a significant capacity for the effective chemical manipulation of these polymers as exemplified by treatment of them under Baeyer-Villiger conditions and so creating a simple and green route to hydrophilic materials. These one- and two-step transformations provide the most direct route to new, LGO-derived polymer scaffolds yet reported. E-factors of ca. 0.012 and atom economies of up to 99 % have been realized.

Gold-Catalyzed Oxidative Transformation of Free Sugars into Biobased Platform Molecules

Gold-Catalyzed Oxidative Transformation of Free Sugars into Biobased Platform Molecules

Electrochemical Incorporation of Electrophiles into the Biomass-Derived Platform Molecule 5-(Chloromethyl)furfural.

The 5-(chloromethyl)furfural (CMF) derivative ethyl 5-(chloromethyl)furan-2-carboxylate undergoes two-electron electrochemical reduction in a simple, undivided cell to give the corresponding furylogous enolate anion, which can either be quenched with carbon dioxide to give a 5-(carboxymethyl)furan-2-carboxylate or with hydrogen ion to give a 5-methylfuran-2-carboxylate, thereby expanding the derivative scope of CMF as a biobased platform molecule.

Efficient synthesis of fully renewable, furfural-derived building blocks via formal Diels-Alder cycloaddition of atypical addends.

Diels-Alder (DA) cycloaddition of furanics is emerging as a key transformation in circular chemistry, providing access to highly versatile, biobased platform molecules. Further development of this technology into viable industrial applications faces major challenges, a notorious one being the lack of reactivity of the most readily available furans, i.e. the furfural derivatives. Herein we describe the remarkably-facile intramolecular DA reaction of allyl acetals of different furfurals to efficiently afford formal DA adducts with the atypical, unreactive dienophile allyl alcohol. Our methodology gives access to unprecedented oxanorbornene derivatives in high chemo-, regio- and stereoselectivity, which can be readily diversified into valuable products. This offers the potential of scalable production of renewable chemical building blocks from cheap, bioderived platform molecules.

Hydrogenation of levulinic acid to γ-valerolactone over hydrophobic Ru@HCP catalysts.

This study introduces an efficient strategy for promoting the synthesis of γ-valerolactone (GVL) via levulinic acid (LA) hydrogenation. A series of hyper-crosslinked porous polymer (HCP) supported Ru catalysts with different monomers were prepared. The wettabilities were controlled by the surface functional groups. The hydrophobic catalysts showed much higher activity than the hydrophilic ones in the hydrogenation of LA to GVL, highly possible due to the substrate enrichment. Further insight showed that the reaction proceeded through the 4-HVA route. These results illustrated the importance of surface wettability in bio-based molecule upgrading, which is beneficial for catalyst design.

A perspective on automated advanced continuous flow manufacturing units for the upgrading of biobased chemicals toward pharmaceuticals.

Biomass is a renewable, almost infinite reservoir of a large diversity of highly functionalized chemicals. The conversion of biomass toward biobased platform molecules through biorefineries generally still lacks economic viability. Profitability could be enhanced through the development of new market opportunities for these biobased platform chemicals. The fine chemical industry, and more specifically the manufacturing of pharmaceuticals is one of the sectors bearing significant potential for these biobased building blocks to rapidly emerge and make a difference. There are, however, still many challenges to be dealt with before this market can thrive. Continuous flow technology and its integration for the upgrading of biobased platform molecules for the manufacturing of pharmaceuticals is foreseen as a game-changer. This perspective reflects on the main challenges relative to chemical, process, regulatory and supply chain-related burdens still to be addressed. The implementation of integrated continuous flow processes and their automation into modular units will help for tackling with these challenges.Graphical abstract

Selective conversion of 2-methylfuran to 3-acetyl-1-propanol in water over Pd@HZSM-5 catalyst with balanced metal-acid cooperation

Biomass is a promising renewable carbon resource, and bio-based platform molecules such as furan derivatives play an important role in the green manufacturing of high value-added chemicals. Of these, the conversion of 2-methylfuran (2-MF) to 3-acetyl-1-propanol (3-AP) over a bifunctional catalyst has attracted significant interest. However, bifunctional catalysts prepared by traditional method suffer from poor catalytic performance and limited stability due to the agglomeration of metal NPs. Here, Pd@HZSM-5, in which Pd NPs were encapsulated in HZSM-5 in situ showed improved stability and 3-AP yield. The highest yield of 3-AP (90.6%) to date was obtained with a nearly 100% conversion of 2-MF. The catalytic performance over a series of Pd@Zeolite confirms the superiority of the encapsulation effect, which is ascribed to the optimal adjustment of metal/acid balance. The Pd@HZSM-5 catalyst displayed excellent stability due to the encapsulation structure, which restricts the Pd NPs agglomeration. The highest yield of 3-AP was obtained at a high concentration of 2-MF (60%), which implies a promising strategy for the green industrial manufacture of 3-AP. This work reports a new bifunctional catalytic system for the green synthesis of 3-AP from 2-MF, thus stimulating the downstream biomass market.

Sustainable production of methanol from one-pot catalytic conversion of cellulose over non-precious copper-based catalysts

Methanol is an important bio-based platform molecule that can be used directly as a fuel or fuel additive, and can also be used to catalytically produce bulk chemicals and drop-in fuels. Currently, methanol is mainly produced from methane and coal via an indirect syngas route, which has the disadvantage of higher energy consumption. Here, we report a novel approach for the sustainable production of methanol from catalytic conversion of cellulose over a series of non-precious Cu-based catalysts, including Cu-TiO2-Al2O3 (Cu-TiAl), Cu-ZnO-Al2O3 (Cu-ZnAl), Cu-ZrO2-Al2O3 (Cu-ZrAl), and so on. The effects ofcatalyst supports, Culoading, and reaction conditions on the methanol yield from catalytic conversion of cellulose were systematically evaluated. It is demonstrated that 5%Cu-TiAl showed the highest methanol yield of 30.7 wt% during catalytic conversion of cellulose at 250 °C and 1Mpa H2 for 10 h. The catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunner − Emmett − Teller analysis (BET), high-resolution transmission electron microscope (HR-TEM), and temperature-programmed desorption of ammonia (TPD) to reveal the possible catalyst structure–reactivity relationship of these Cu-based catalysts. It is found that the unique xOTi–Cu–AlOx interfacial structure and high acidity of 5%Cu-TiAl are beneficial for the selective cleavage of the C–C and C–O bonds within cellulose to form methanol. This work provides a simple and efficient method to produce cellulosic methanol with relatively low energy consumption.

Perspectives for the Upgrading of Bio-Based Vicinal Diols within the Developing European Bioeconomy.

The previous decade has witnessed a drastic increase of European incentives aimed at pushing forward the transition from an exclusively petro-based economy toward a strong and homogeneous bio-based economy. Since 2012, numerous programs have been developed to stimulate and promote research and innovation relying on sustainable and renewable resources. Terrestrial biomass is a virtually infinite reservoir of biomacromolecules, the biorefining of which provides platform molecules of low complexity yet with tremendous industrial potential. Among such bio-based platform molecules, polyols and, more specifically, molecules featuring vicinal diols have gained tremendous interest and have stimulated an increasing research effort from the chemistry and chemical engineering communities. This Review revolves around the most promising process conditions and technologies reported since 2012 that specifically target bio-based vicinal diols and promote their transformation into value-added molecules of wide industrial interest, such as olefins, epoxides, cyclic carbonates, and ketals.

Lignin‐First Monomers to Catechol: Rational Cleavage of C−O and C−C Bonds over Zeolites

A catalytic route is developed to synthesize bio-renewable catechol from softwood-derived lignin-first monomers. This process concept consists of two steps: 1) O-demethylation of 4-n-propylguaiacol (4-PG) over acidic beta zeolites in hot pressurized liquid water delivering 4-n-propylcatechol (4-PC); 2) gas-phase C-dealkylation of 4-PC providing catechol and propylene over acidic ZSM-5 zeolites in the presence of water. With large pore sized beta-19 zeolite as catalyst, 4-PC is formed with more than 93 % selectivity at nearly full conversion of 4-PG. The acid-catalyzed C-dealkylation over ZSM-5 zeolite with medium pore size gives a catechol yield of 75 %. Overall, around 70 % catechol yield is obtained from pure 4-PG, or 56 % when starting from crude 4-PG monomers obtained from softwood by lignin-first RCF biorefinery. The selective cleavage of functional groups from biobased platform molecules through a green and sustainable process highlights the potential to shift feedstock from fossil oil to biomass, providing drop ins for the chemicals industry.

Arylboronic acids catalyzed upgrade of glucosamines for deoxyfructosazine and insights on reaction mechanism

Chitin is the most abundant N-containing polysaccharide in nature and d-glucosamine is one of the most successful commercial monomer products in the current market. Here we reported an arylboronic acids catalyzed upgrade of glucosamines in aqueous solution for deoxyfructosazine which is an important high-value compound in pharmaceutical and food industries, as well as a promising bio-based platform molecule for speciality chemicals and sustainable functional materials. Such direct integration of deoxyfructosazine into development of renewable chemicals/functional materials might be a practical way for utilization of chitin as a renewable nitrogen source. A mechanism focusing on a catalytic cycle of arylboronic acid via a boron transfer was also proposed.

Catalytic Biomass Upgrading Exploiting Liquid Organic Hydrogen Carriers (LOHCs)

The use of hydrogen at high-pressure is associated with major safety concerns, storage, and high cost. Therefore, the development of reductive chemical processes based on the use of low-pressure hydrogen is very attractive in view of an industrial-scale application. This perspective focuses on the most representative studies reported until 2021 dealing with the reductive manipulation processes of diverse biomass-based feedstock utilizing alternative liquid organic hydrogen carriers (LOHCs). In this context, the research has been dedicated mainly to formic acid and small molecular alcohols, specifically isopropanol. The perspective illustrates the transformations of biobased platform molecules, such as levulinic acid, furfural, and 5-hydroxymethylfurfural, into valuable products, including biofuels. In addition, the lignin upgrading mediated by these H2 sources is discussed.

Selective oxidation of bio-based platform molecules and their conversion products over metal nanoparticle catalysts: a review

The conversion of bio-renewable raw materials into valuable products (biofuels, bifunctional carbonyls/carboxyls) that serve as the basis for biopolymers, has become one of the most important areas in the development of novel hybrid catalysts.

Chemoselective formation of cyclo-aliphatic and cyclo-olefinic 1,3-diols via pressure hydrogenation of potentially biobased platform molecules using Knölker-type catalysts.

The hydrogenative conversions of the biobased platform molecules 4-hydroxycyclopent-2-enone and cyclopentane-1,3-dione to their corresponding 1,3-diols are established using a pre-activated Knölker-type iron catalyst. The catalyst exhibits a high selectivity for ketone reduction, and does not induce dehydration. Moreover, by using different substituents of the ligand, the cis-trans ratio of the products can be affected substantially. A decent compatibility of this catalytic system with various structurally related substrates is demonstrated.

Selective catalytic oxidation of diglycerol

The selective catalytic oxidation of diglycerol using oxygen gives new biobased platform molecules named “diglycerose”.

Aldol Reactions of Biorenewable Triacetic Acid Lactone Precursor Evaluated Using Desorption Electrospray Ionization Mass Spectrometry High-Throughput Experimentation and Validated by Continuous Flow Synthesis.

Desorption electrospray ionization-mass spectrometry (DESI-MS) was used as a high-throughput experimentation (HTE) tool to rapidly identify derivatives of the biobased platform molecule triacetic acid lactone (TAL). TAL is a platform molecule capable of conversion to a wide range of useful commodity chemicals, agrochemicals, and advanced pharmaceutical intermediates. In the present study, a diverse family of aldol reaction mixtures were prepared in high-density microtiter plates with a liquid handling robot, then printed with a pin tool onto a PTFE surface for analysis by DESI-MS. Our DESI-MS results indicate that aldol products of TAL were obtained for each substrate tested, in good agreement with previously reported TAL reactivity. These HTE experiments also revealed solvent-dependent reactivity trends that facilitated reaction scale up. Our findings suggest that DESI-MS analysis can rapidly inform the selection of optimal reaction conditions from a wide variety of conditions for scale up using continuous synthesis conditions.

Molecular Oxygen-Promoted Synthesis of Methyl Levulinate from 5-Hydroxymethylfurfural

Methyl levulinate (ML) is a biobased platform molecule, which has versatile applications in fine chemical synthesis and food additives. However, during the ML production, one of the main barriers is that humins are usually cogenerated, which leads to poor reaction efficiency and catalyst deactivation. The following findings are herein reported for the first time: in a catalytic system with H-beta25, molecular oxygen could act as both a humins cleaner and a reaction accelerator for the synthesis of value-added ML from 5-hydroxymethylfurfural (HMF) or furfuryl alcohol (FA). The reaction efficiency and the catalyst reusability were significantly improved in the presence of oxygen. Besides, the effects of different reaction parameters as well as catalysts have been investigated. The mechanism of ML formation from HMF in the presence of O2 and the role of O2 in humins removal were also proposed.

Continuous Flow Upgrading of Selected C2–C6Platform Chemicals Derived from Biomass

The ever increasing industrial production of commodity and specialty chemicals inexorably depletes the finite primary fossil resources available on Earth. The forecast of population growth over the next 3 decades is a very strong incentive for the identification of alternative primary resources other than petro-based ones. In contrast with fossil resources, renewable biomass is a virtually inexhaustible reservoir of chemical building blocks. Shifting the current industrial paradigm from almost exclusively petro-based resources to alternative bio-based raw materials requires more than vibrant political messages; it requires a profound revision of the concepts and technologies on which industrial chemical processes rely. Only a small fraction of molecules extracted from biomass bears significant chemical and commercial potentials to be considered as ubiquitous chemical platforms upon which a new, bio-based industry can thrive. Owing to its inherent assets in terms of unique process experience, scalability, and reduced environmental footprint, flow chemistry arguably has a major role to play in this context. This review covers a selection of C2 to C6 bio-based chemical platforms with existing commercial markets including polyols (ethylene glycol, 1,2-propanediol, 1,3-propanediol, glycerol, 1,4-butanediol, xylitol, and sorbitol), furanoids (furfural and 5-hydroxymethylfurfural) and carboxylic acids (lactic acid, succinic acid, fumaric acid, malic acid, itaconic acid, and levulinic acid). The aim of this review is to illustrate the various aspects of upgrading bio-based platform molecules toward commodity or specialty chemicals using new process concepts that fall under the umbrella of continuous flow technology and that could change the future perspectives of biorefineries.