Advancements in Wood Biomass Derived Bio-products

A-Z Knowledge on Wood-derived Chemicals

The main chemical components of wood are cellulose, hemicellulose, lignin and extractives.

Paper manufacturers, wood bio-refineries and extraction companies already isolate such wood constituents for the manufacture of a broad range of products. These products are successfully marketed in many applications today, such as:

Paper and paperboard
Cosmetics
Food supplements
Pharmaceuticals
Specialty chemicals
Detergence
Aroma
Construction materials
And more

However, wood chemicals continue to offer opportunities for new product developments. These products can meet the requirements of various industrial sectors in search for new effect and bio-based chemicals alternative to oil-based products.

R&D initiatives are currently very dynamic in this area. Let's take a look at the advances in wood biomass-derived chemicals...

R&D Projects for the Valorization of Wood Cellulose

Nanocellulose

Research initiatives focus on the use of nanocellulose as a strength enhancing additive for renewable and biodegradable matrix polymers such as PLA. Research also concentrates on the development of porous nanocellulosic materials for insulation & packaging.

New coatings are also being developed with outstanding barrier properties in food packaging and printing paper applications. New developments concentrate on the use of nanocellulose as a rheological modifier in cosmetics (thickener), pharma (tablet binder) and paint applications.

Levoglucosenone (LGO)

Levoglucosenone (LGO) is a biology derived chemical which can be produced from waste cellulose. Current developments focus on LGO conversion to new polar aprotic bio-solvents. These new solvents are alternatives to NMP, DMF and DMAc which are under significant regulatory pressure worldwide due to their toxicity.

R&D Projects for the Valorization of Lignin from Wood

Carbon Fiber

Lignin represents a potential low-cost source of carbon suitable for displacing synthetic polymers, such as: Polyacrylonitrile (PAN) in the production of carbon fiber. Using lignin in the carbon fiber manufacturing process improves:

Raw material availability
Decreases raw material sensitivity to petroleum cost, and
Decreases environmental impacts

The goal of replacing steel panels with lightweight, yet strong, carbon fiber-reinforced plastics is to significantly reduce vehicle weight and improve fuel economy.

Resins and Adhesives

Resins and adhesives offer a large opportunity, especially for formaldehyde-free applications. Formaldehyde is currently considered a carcinogen and its banishment from consumer and packaging goods and building products is highly likely in the near term.

Technical needs and challenges for lignin in this area center on:

Effective, practical means for molecular weight and viscosity control
Functional group enhancement to improve oxidative and thermal stability, for example:
- Carbonylation
- Carboxylation
- Amination
- Epoxidation, and
- De-etherification
Consistent mechanical processing properties
Control lignin color, and
Precise control of cure kinetics

Product consistency in these application targets will also be a technical challenge.

Polymer Modifiers

Polymer modifiers can be simple, low-cost fillers or may be high-value additives that improve various polymer physical or performance properties. Currently, lignin use concentrates on the former; Current research is concentrating on the latter by creating technologies that improve polymer:

Alloying
Mutual solubility
Cross-linking, and
Control of color

Relevant technologies include:

Predictable molecular weight control
Facile introduction of reactive functionality, and
Polyelectrolytic functionality

Monomeric Molecules

Very selective depolymerization, also invoking C-C and C-O bond rupture, could yield a plethora of complex aromatics that are difficult to make via conventional petrochemical routes. These complex aromatics include:

Propylphenol
Eugenol
Syringols
Aryl ethers
Alkylated methyl aryl ethers

Research is concentrating on developing technology that would allow highly selective bond-scission to capture the monomeric lignin building block structures. However, markets and applications for monomeric lignin building blocks would need to be developed.

This development is therefore longest-term and currently has unknown market pull for large-scale use. Since, most of the chemical industry is used to single, pure-molecule raw materials, using mixtures of products in a chemical raw material feed, as would arise from lignin processing, constitutes a challenge.

BTX Molecules (Benzene, Toluene, Xylene)

Developments concentrate on non-selective depolymerization technologies in the form of C-C and C-O bond rupture. This can lead to the production of aromatics in the form of BTX plus phenol and includes aliphatics in the form of C1 to C3 fractions.

Development of the required non-selective chemistries is part of the long-term opportunity. But, it is likely to be achievable sooner than highly selective depolymerizations. In fact, some of the past hydro-liquefaction work with lignin suggests that, with further development, this concept is a good possibility.

R&D Projects for the Valorization of Sugars from Wood

Single Cell Protein (SCP)

SCP consists of microorganisms such as filamentous fungi, yeast, algae, and bacteria that are rich in protein. R&D projects are ongoing to use sugar streams generated by wood biorefineries for the production of single cell protein.

SCP can be used as a protein source in fish feed. SCP can be more a nutritional alternative to the current products used in the aquaculture such as soybean meal in particular. SCP has a high B vitamin content and a tunable amino-acid profile. This GMO-free product is safe, nontoxic and contains no fatty acids.

Bio-surfactants

Potential R&D on Sugars Derived from Wood

Industrial research focuses on the development of new bio-based surfactants, thickeners, emulsifiers, texturing agents from C5 and C6 pure sugars derived from wood hemicelluloses.

These research initiatives are market pull projects to meet the requirements of the cosmetics industry in a continuous search for new bio-based products and effects.

Bio-based Polymers

There are R&D initiatives which focus on the conversion of C6 sugars (glucose, mannose) derived from wood hemicelluloses to diacid and diamines monomers. They are then used for the development of bio-based polyamides.

Bio-fuels

R&D initiatives are focused on the development of new biomass fractionation technologies, like:

Acid-based
Enzyme-based
Solvent-based, or combinations of these chemistries
Supercritical water hydrolysis
Steam explosion…

All these technologies can economically fractionate the wood biomass to sugar and lignin streams which all need to be valorized.

Research concentrates on developing the most efficient process (biomass treatment, enzymes production, fermentation and distillation) to produce a cost competitive 2G ethanol equivalent to 1G bioethanol.

Bioethanol Production from Biomass

R&D Projects for the Valorization of Extractives from Wood

Tannins

Research initiatives focus on the development of bio-based adhesives in particle board applications. R&D programs are also ongoing to use tannins as an alternative to bisphenol A for the manufacture of bio-based epoxy resins in food packaging, floor coatings and paint applications.

New developments concentrate on the hydrophobization of catechic tannins towards innovative insulating foams.

The bio-based tannin foams exhibit a thermal insulation capacity comparable to totally synthetic, oil-derived foams, such as polyurethanes. Their advantage is that they do not burn and thus, do not emit toxic gases on burning.

Lignans

Lignans are wood extractives, the content of which is particularly high in wood knots. Current R&D initiatives focus on the characterization and the bio-activity of lignans present in various softwood and hardwood tree species. This development can potentially lead to new applications for lignans in the pharma, nutraceuticals and cosmetics industry.

Terpenes

R&D projects focus on the use of phenolic terpene resins for the development of bio-based binder as an alternative to the bitumen mix in waterproofing membranes applications.

Stilbenoids

Indirect effects of current plant protection products are pointed at the environment and human health. There are R&D initiatives focused on the development of new biocontrol fungicide produced from extracts of co-products from the forest industry. Wood co-products contain active polyphenols (e.g, stibenoids in particular) which are effective molecules which can be included in a biocontrol agent formula and used in organic agriculture.

Having learnt about the research areas; let's turn our attention towards some innovative, novel biomaterials derived from wood biomass...

Wood Chemistry Reinventing Polymers for a Greener Future

Wood Chemistry Reinvents Polymers for a Greener Future

Environmentally friendly materials have become more widely used as consumers became aware of the consequences associated with the use of petrochemical-derived products. By using renewable resources, the industry reduces the use of fossil resources and the amount of carbon dioxide that is present in the atmosphere.

The development of novel biomaterials derived from wood biomass and produced with a reduced carbon footprint contributes to this sustainable approach. These materials improve resource management and the overall performance and efficiency of our environment. Wood chemistry can contribute to reinvent plastics for a greener future.

Let's take a look at the wood-biomass derived materials...

Biopolymers Derived from Wood Extractives

Tannins-based Foams

Tannins are present in many plants and trees such as:

Oak
Pine
Chestnut
Quebracho, and
Many others

Tannins are polymers consisting mainly of glycosides, belonging to the polyphenol family, and are able to precipitate proteins. Historically, tannins, both hydrolyzable and condensed, have been associated with the preservation of hides for leather.

In addition to the tanning industry, tannins can also be efficiently used in the oenological sector as clarifying agents for the production of wine and beer. Tannins are also used in:

Cosmetics and the pharmaceutical industry for their antioxidant and anticancer properties
Textile industry as efficient natural dyes, and
Animal nutrition to integrate naturally into animal diets

There are promising new developments ongoing to synthesize Tannin-based rigid foams which confer outstanding thermal insulating properties.

Tannin-based rigid foams are 95% of natural origin obtained by polycondensations of polyflavonoid tannins and furfuryl alcohol.
Their thermal insulation capacity is comparable to that of totally synthetic, oil-derived foams, such as polyurethanes, but with the advantage that they do not burn.
Tannin-based rigid foams can be proposed as insulation material, heavy metal adsorbent, floral foam or shock absorber.

Tannins-based Adhesives

There is also a growing demand for increasing the use of naturally derived materials in many of today’s products within the wood products industries. One area suited to this is the development of natural tannin adhesive in composite manufacture.

A considerable benefit of tannin adhesive is the much higher moisture content of the wood chips which can be tolerated with these adhesives than with any of the synthetic phenolic and amino resin adhesives. Interior and water resistant-type adhesives presenting no formaldehyde emission can be obtained either by special hardeners or by tannin auto-condensation without any hardener.

Polyterpene Resins

Turpentine is oil obtained from pine trees. It is a very important substance with many applications as a solvent, in the pharmaceutical industry and in the production of oils, resins, and varnishes.

Turpentine is initially separated from wood chips after they have been "cooked" in the Kraft paper-making process. It is separated off as a mixture of water and turpentine vapors, which separate out when left to separate in a tank, as turpentine is much lighter than water. This crude sulfate turpentine is a complex mixture of C10 monoterpene hydrocarbons and is distilled to collect alpha pinene, beta pinene, and other monocyclic terpenes.

Alpha-pinene, beta-pinene, and d-limonene are natural and renewable feedstocks for the manufacture of polyterpene resins. Polyterpene resins are light colored products with excellent stability and unique properties to make them effective for diverse applications such as:

Agricultural retention

Waterproofing Membranes Based on Polyterpene Resins

Chewing gum
Tapes, and
A Broad range of adhesives

These are excellent tackifiers in pressure sensitive and hot melt adhesive systems using styrene-butadiene rubber (SBR) and styrene block copolymers, particularly S-B-S. Other applications include:

Paints
Coatings
Caulks and sealants
Investment castings, and
Waterproofing agents

Polyterpene oligomers are used in the agricultural industry as a retention aid and sticker for herbicide and pesticide application.

There are also new developments which focus on the use of phenolic terpene resins for the development of bio-based binder as an alternative to the bitumen mix in waterproofing membranes applications.

Bio-based Polymers Derived from Wood-based Lignin

Paper-making and other wood-pulping processes produce 70 million tons of lignin byproduct each year, 98% of which is incinerated to generate energy. Lignin can also be an important source of synthetic materials because of its:

Abundance in nature
Low cost
Stable supply, and
No competition to the human food supply

Lignin, a cross-linked phenolic polymer, contains a large number of aromatic groups that can be used as a substitute for petroleum‐based aromatic fine chemicals.

Explore the following bio-material advances from wood-based lignin.

Lignin-based Composites

Mixing lignin with natural fibers such as flax, hemp or other fiber plants and some natural additive produces lignin-based fiber composites. These can be processed on conventional plastics processing machines. Lignin-based composites can be used for the manufacture of various products such as computer, television or mobile phone casings.

Wood-based lignin can also be used as a copolymer in Bio-composites. Poly-lactide (PLA) is a biodegradable polymer formed from the polymerization of microbially produced lactic acid.

However, PLA confers low physical properties such as impact strength, small elongation at break, suboptimal thermal properties. The development of lignin/PLA composites can contribute to boosting the thermal and mechanical properties of PLA.

Wood-based Lignin alternative to Bisphenol A

Wood-based lignin a highly available renewable resource, can also be a safer, greener alternative to bisphenol A (BPA) in various applications:

Adhesives
Coatings
Electronic equipment
Food packaging, and
Containers

Approximately 3.5 million tons of BPA are produced annually worldwide. The downside is that bisphenol A can mimic the hormone estrogen, potentially affecting the body and brain.

Researchers have found that lignin fragments can be converted into a compound called bis-guaiacol-F (BGF), which has a similar shape to BPA. R&D developments are ongoing to design BGF which cannot interfere with hormones but can keep the desirable thermal and mechanical properties of BPA.

Lignin-based Adhesives

Due to its abundant presence of phenolic groups, wood-based lignin can potentially replace phenol in phenol–formaldehyde (PF) resins in wood composite adhesives. Such adhesives can be used in the production of plywood, particle board and other kinds of wood composites. PF is highly toxic chemical and an irritant to the eyes and respiratory tract. Moreover, PF resins can be very expensive, because of the fluctuating price of phenol. Therefore, replacing current synthetic PF resins based on petrochemicals offers great economic and health benefits.

Lignin-based Adsorbents

Lignin-derived products can be used as adsorbents of selected heavy metals and toxic organic compounds. Black liquor lignin from the pulp and paper industry can be used as a precursor for activated carbon. The lignin is carbonized in an oxygen-free atmosphere and the resulting carbon is then activated with steam. The resulting lignin-based activated carbon is considered to have the potential for use in dye wastewater treatment.

Lignin-acrylamide-based Flocculant

Chemically modified lignin can be used as a flocculant. Flocculants, often positively charged molecules, are used to remove suspended solids from liquids by forming aggregates of colloids and other suspended particles that precipitate and play an important role in wastewater treatment and the removal of contaminants to prepare potable water.

Environmentally friendly flocculants that are nontoxic and biodegradable are highly desirable. Acrylamide grafted onto a lignin backbone has flocculant properties. The positively charged lignin-acrylamide has the ability to coagulate aluminum and enhance the removal efficiency of dissolved organic carbon.

Lignin-based Carbon Materials

Lignin can be used as a precursor for carbon fibers as an alternative to high-cost precursors such as polyacrylonitrile (PAN). Moreover, the impact on the environment caused by toxic by-products such as hydrogen cyanide (during PAN processing) has raised serious concerns. Renewable, bio-based alternatives for carbon precursors are being developed, and the carbonized structure of lignin allows it to be used as renewable, low-cost graphitic carbon materials.

Lignin-based carbon materials such as fibers, mats, nanofibers, and mesoporous carbon have been successfully developed by a number of research groups.

Bio-based Polymers from Wood Sugars

The major component of wood biomass is cellulose. Since about half of the organic carbon in the biosphere is present in the form of cellulose, the conversion of cellulose into valuable chemicals has a paramount importance. The depolymerization of cellulose results in the formation of glucose.

Hemicellulose is the second most abundant polymer. Unlike cellulose, hemicellulose has a random and amorphous structure, which is composed of several heteropolymers including:

Xylan
Galactomannan
Glucuronoxylan
Arabinoxylan
Glucomannan, and
Xyloglucan

Wood Sugars - Extraction and Value

Hemicellulose Extraction from Wood Chips

Hardwood hemicelluloses contain mostly xylans, whereas softwood hemicelluloses contain mostly glucomannan. The depolymerization of hemicellulose results in the formation of glucose as well as the other C5 sugars (xylose, arabinose) and C6 sugars (mannose, galactose, rhamnose).

There are different techniques to extract wood sugars using a variety of wood fractionation technologies such as:

Dilute acid
The steam explosion followed by enzymatic hydrolysis
Supercritical fluid
Concentrated acid, and
Organosolv processes

Once isolated, cellulose, hemicellulose, and lignin can be converted and/or incorporated into a wide range of materials.

The polysaccharides are deconstructed into monomeric hexose C6 and pentose C5 sugars which are then converted into a wide range of value-added building-block chemicals and bio-based polymers:

C5 and C6 sugar derived building-block chemicals include 1,4-diacids (succinic acid, fumaric acid, malic acid), 2,5-furan dicarboxylic acid (2,5-FDCA), 3-hydroxy propionic acid (3-HPA), aspartic acid, glucaric acid, glutamic acid, itaconic acid, levulinic acid, 3-hydroxybutyrolactone (3-HBL), glycerol, sorbitol and xylitol/arabinitol.

Examples of important commercial polymers derived from the 1,4-diacid platform are PBS and its copolymers, PBT resins and yarns, PTMEG, P4HB, Polyamides PA-4,6, PA-4,10. Polymers derived from the 2,5-furan dicarboxylic acid platform (2,5-FDCA) can be the 100% bio-based polyethylene-furanoate polymer (PEF) used in bottles, fibers, and films applications.

Polyhydroxyalkanoates (PHAs) are bio-polyesters which can be produced by levulinic acid. Polylactic acid (PLA) is derived from lactic acid (LA) which is mainly produced via the fermentation of glucose and sucrose by lactic acid bacteria. PLA is mostly used in food, beverage, and pharmaceutical and personal care applications.

Therefore, there is a strong potential for the valorization of sugars streams from wood. Indeed, wood biomass presents a growing interest because it does not compete with food or feed production. It can increase sustainability by providing a new source of industrial sugars which are important building blocks for various basic chemicals and intermediates. Wood sugars could, therefore, be a future alternative to sugars currently generated by agro-refineries for the manufacture of biopolymers.

However, the techno-economic viability of efficient and sustainable processes for fractionation of wood into sugars and lignin and to further conversion of both fractions into high added value products still need to be demonstrated. New wood-based value chains need to be achieved for the production of chemical building blocks, materials and biofuels (other than ethanol) in a cascading approach, by a combination of biotechnology and chemical processes.

Bio-based Polymers from Wood Cellulose

Softwood is the dominant raw material used in the production of cellulose plastics. To isolate cellulose fiber from the biomass:

The wood is cooked or heated in a digester resulting to the production of pulp
(Pulp chemical composition consists of hemicelluloses and alpha cellulose)
↓
Residues of resins and lignin are removed by treating the pulp with bleaching agents
(This bleaching step also contributes to the reduction of hemicelluloses content of the pulp)
↓
Water is then taken out of the pulp before processing the pulp with high alpha cellulose content
↓
The pulp is reacted with certain acids and anhydride to produce cellulose esters used in the production of cellulose plastics

Cellulose esters are available in various:

Types
Viscosities
Butyryl and acetyl ratios, and
Hydroxyl contents

Cellulose acetate is one of the most important esters of cellulose. Depending on the way it has been processed, cellulose acetate can be used for great varies of applications such as films, membranes or fibers. Cellulose acetate butyrate can be used as binders and additives in coatings applications for a variety of substrates, including:

Plastics
Textiles
Metal, and
Wood

Cellulose acetate propionate is used in various applications such as printing inks, varnishes, nail polish, lacquers, and many more which require:

Low odor
Clarity
Fast solvent release
Anti-blocking, and
Good adhesion to a variety of substrates

Barriers to the Development of Wood Biomass-derived Bio-products

The most important barriers towards the development of wood bio-based products market are their high pricing in terms of purchase and the technological barriers that still face many of the related processes.

Bio-based products are more expensive than their fossil-fuel derived equivalents. This is because of:

High feedstock prices, and
High capital and operating costs of related production processes

Many of which are still at an R&D, or demonstration level. The low prices of fossil fuels in the last years worsen the situation as they make the use of wood biomass feedstock economically unattractive.

Let's take a look at the major barriers for a sustainable production and market development of bio-based products derived from wood biomass.

Feedstock Related Barriers

High feedstock prices, and
High capital and operating costs of related production processes

Technology Related Barriers

The conversion of wood biomass to chemicals is a promising alternative to replace petroleum as a renewable source of carbon. However, most of the proposed processes are still currently unable to compete economically with petroleum refineries due, in part, to the incomplete utilization of the streams (lignin, hemicelluloses, cellulose).

As of a matter of fact, several obstacles must be overcome to make sugars, cellulose, and lignin available.

Initially, the cellulose is surrounded by hemicellulose, another polysaccharide, which due to its heterogeneric nature, contains a variety of sugars connected by a variety of glycosidic linkages that cannot be hydrolyzed by the cellulolytic enzymes.

Furthermore, these carbohydrates are surrounded by lignin, a polymer of substituted phenylpropane units that acts as a further barrier for the cellulolytic enzymes. The enzymatic hydrolysis step remains one of the main obstacles due to the high prices required to produce enzymatic cocktails needed to cope with the recalcitrance of the biomass to extensive enzymatic hydrolysis of cellulose.

Upscaling of Technology for Developing Wood Biomass-derived Products

Consequently, the ideal wood fractionation technology would consist of a process which makes all components (cellulose, lignin, hemicellulose) available at a high yield. The ideal process would contributing to produce hemimono sugars at high yield without enzymes. The ideal process would allow a low charge of cellulose hydrolysis enzymes and would facilitate a full and simple recovery of spent chemicals.

However, the wood fractionation processes which have been developed still face key challenges to be overcome:

The explosion pulping process is energy intensive
The alkaline treatment process degrades hemicelluloses
The acid treatment process leads to the formation of sticky lignin and requires acid recovery
The sulfite process can lead to the oxidation of hemicelluloses and requires sulfur recovery
The ORGANOSOLV process needs improvement with respect to the recovery and reuse of the involved solvents in order to allow a better cost reduction and energy balance of the process. More efﬁcient isolation and puriﬁcation of the various fractions down-stream is also essential

Successful commercialization of wood fractionation technology will greatly depend on the development of a continuous process. Such that, the process is able to efﬁciently fractionate the lignocellulosic components in rates adequate to meet the needs of the industry. New technologies utilizing the sugar and lignin streams as a feedstock for the production of novel chemicals need to mature in order to provide the economic impetus to the wood biomass-based reﬁnery.

Market Related Barriers

Barriers to Develop Building-blocks for the Manufacture of Bioplastics and specialty chemicals

The global production of bio-based building blocks (mono-ethylene glycol, mono-propylene glycol, lactic acid, succinic acid …) is expected to grow from 2.6 MMT in 2013 to 5.6 MMT in 2030.

Building blocks are used to produce bio-polymers (polyesters, PLA, polyurethanes, polyamides) and specialty chemicals (biocidal products, bio-lubricants). Bio-based building blocks are currently produced from sugars generated by agricultural feedstock based biorefineries.

The disintegrating wood process to sugars is complex. The cost competitiveness of the resulting wood sugars depends on a successful valorization of all streams (lignin in particular) generated by the sugar pulping process.

Consequently, production costs of bio-based building blocks derived from wood biomass are likely to be higher than their agricultural derived equivalents, because of the high capital and operating costs of wood biomass fractionation processes, many of which are still at an R&D or demonstration level.

Moreover, the low prices of fossil fuels in the last years worsen the situation as they hit the competitiveness of biochemicals products.

Barrier to Develop Bio-based Food and Feed Ingredients

The use of herbal medicines and phytonutrients or nutraceuticals continues to expand rapidly across the world. Many people now resorting to these products for the treatment of various health challenges in different national healthcare settings.

There is a tremendous surge in acceptance and public interest in natural therapies both in developing and developed countries, with plant extracts being available not only in drugstores, but now also in food stores and supermarkets.

However, EU registration of new bio-products, including wood extracts, can be time consuming and expensive. There are important legal restrictions for possible wood feedstock to enter in the bio-based food and feed ingredients value chain. There are wood extracts which need to be granted novel food approval in EU. For example, the magnolia book extract had to be granted novel food approval in EU for use in chewing gum and mints that will allow it to introduce new products with perceived breath-freshening benefits.

Strict Regulations on Food and Feed Items

Moreover, the relevant market is characterized by great heterogeneity. The different legislative requirements in different countries or economic spaces cause practical obstacles in imports/ exports of bio-based food and feed ingredients.

Though the new novel food regulation has recently introduced a faster-centralized authorization procedure where all applications will be submitted directly to the EU Commission instead of to the individual Member States. Applicants are to be aware that in most cases it will still take 2-3 years to access the European market due to supplementary information requests and other regulatory hurdles.

Coatings Ingredients Derived from Natural & Renewable Sources

View a wide range of biobased ingredients available today for paints, coatings and inks, analyze technical data of each product, get technical assistance or request samples.