Fossil Feedstocks Research Articles

Economic and environmental assessment of automotive plastic waste end‐of‐life options: Energy recovery versus chemical recycling

AbstractMost automotive plastic waste (APW) is landfilled or used in energy recovery as it is unsuitable for high‐quality product mechanical recycling. Chemical recycling via pyrolysis offers a pathway toward closing the material loop by handling this heterogeneous waste and providing feedstock for producing virgin plastics. This study compares chemical recycling and energy recovery scenarios for APW regarding climate change impact and cumulative energy demand (CED), assessing potential environmental advantages. In addition, an economic assessment is conducted. In contrast to other studies, the assessments are based on pyrolysis experiments conducted with an actual waste fraction. Mass balances and product composition are reported. The experimental data is combined with literature data for up‐ and downstream processes for the assessment. Chemical recycling shows a lower net climate change impact (0.57 to 0.64 kg CO2e/kg waste input) and CED (3.38 to 4.41 MJ/kg waste input) than energy recovery (climate change impact: 1.17 to 1.25 kg CO2e/kg waste input; CED: 6.94 to 7.97 MJ/kg waste input), while energy recovery performs better economically (net processing cost of −0.05 to −0.02€/kg waste input) compared to chemical recycling (0.05 to 0.08€/kg waste input). However, chemical recycling keeps carbon in the material cycle contributing to a circular economy and reducing the dependence on fossil feedstocks. Therefore, an increasing circularity of APW through chemical recycling shows a conflict between economic and environmental objectives.

Molecular Recycling for a Circular Economy

Abstract One company is moving the needle in the plastic waste crisis using a depolymerization process called methanolysis to create new high-performance materials. This article describes molecular recycling technologies that can process hard-to-recycle plastics otherwise destined for a landfill, incineration, or the environment. These technologies use waste as a feedstock to produce new materials with significantly fewer greenhouse gas emissions compared to traditional processes that use fossil feedstocks.

Photocatalytic Transformation of Biomass and Biomass Derived Compounds-Application to Organic Synthesis.

Biomass and biomass-derived compounds have become an important alternative feedstock for chemical industry. They may replace fossil feedstocks such as mineral oil and related platform chemicals. These compounds may also be transformed conveniently into new innovative products for the medicinal or the agrochemical domain. The production of cosmetics or surfactants as well as materials for different applications are examples for other domains where new platform chemicals obtained from biomass can be used. Photochemical and especially photocatalytic reactions have recently been recognized as being important tools of organic chemistry as they make compounds or compound families available that cannot be or are difficultly synthesized with conventional methods of organic synthesis. The present review gives a short overview with selected examples on photocatalytic reactions of biopolymers, carbohydrates, fatty acids and some biomass-derived platform chemicals such as furans or levoglucosenone. In this article, the focus is on application to organic synthesis.

Interactions between Iron and Nickel in Fe–Ni Nanoparticles on Y Zeolite for Co-Processing of Fossil Feedstock with Lignin-Derived Isoeugenol

Interactions between Iron and Nickel in Fe–Ni Nanoparticles on Y Zeolite for Co-Processing of Fossil Feedstock with Lignin-Derived Isoeugenol

Biobased Production of Succinic Acid and Its Derivatives Using Metabolically Engineered Microorganisms

As concerns over climate crisis and environmental issues continue to mount, there is an urgent need to transition towards a more sustainable society. One key aspect of this transition is establishing systems for production of industrially important chemicals from fossil feedstocks to renewable biomass. Succinic acid (SA) is recognized as one of the most important platform chemicals due to its potential in numerous industrial applications. Consequently, extensive efforts have been made to develop metabolically engineered microbial strains capable of producing SA with high efficiency. In this paper, the current status of microbial SA production is reviewed with an accompanying table summarizing the titer, yield, and productivity achieved by various metabolically engineered microorganisms. In addition, this paper discusses downstream processes for the purification of biobased SA and showcases microbial production of several SA derivatives of interest. Finally, future perspectives on the successful industrialization of biobased SA are discussed.

Simultaneous production of biogas and volatile fatty acids through anaerobic digestion using cereal straw as substrate

Cereal straw is one of the most abundant wastes worldwide, with 30.000 million tons produced per year. Bioconversion of this residual material into carboxylates by anaerobic digestion could potentially replace conventional production based on fossil feedstocks (oil). In this work, fundamental issues of this bioconversion have been explored, including: different kinds of straw (wheat, barley and rye), biomass size reduction, mass balances and modeling of the different steps of the digestion. Under optimum conditions, 44% of the raw material was effectively converted into VFAs (mainly acetate) when barley was used as substrate. Wheat and rye straw presented lower conversion rates due to the higher lignin content compared to barley straw. According to the modeling proposed, methanogenesis and hydrolysis presented very similar reaction rates, which resulted in a simultaneous production of VFAs and biogas. In view of these results, a process integration is proposed where biogas covers the thermal needs of the biotransformation of barley biomass into VFAs.

Durable flame-retardant, smoke-suppressant, and thermal-insulating biomass polyurethane foam enabled by a green bio-based system

Bio-based polyurethane foam has attracted increasing attentions due to eco-friendliness and fossil feedstock issues. However, the inherent flammability limits its application in different fields. Herein, we demonstrate a green bio-based flame-retardant system to fabricate polyurethane foam composite with durable flame retardancy, smoke suppression, and thermal insulation property. In this system, the green bio-based polyol (VED) with good reactivity and compatibility plays a role of flame retardant and EG acts as a synergistic filler. As a result, the LOI value of foam composite increased to 30.5 vol.% and it achieved a V-0 rating in the UL-94 vertical burning test. Additionally, the peak heat release rate (pHRR) and the total smoke production (TSP) decreased by 66.1% and 63.4%, respectively. Furthermore, the foam composite maintained durable flame retardancy after accelerated thermal aging test, whose thermal-insulating property was maintained even after being treated in high-humidity environment with 85% R.H. for a week. This work provides a facile strategy for durable flame retardancy and long-term thermal insulation performance, and creates opportunities for the practical applications of bio-based foam composites.

Use of Single-cell Oils in the Production of Bio-based Epoxy: An Overview of the Most Suitable Microorganisms and Oil Properties

Epoxy resins are widely used polymers that are mainly synthesized from fossil feedstocks. In order to reduce the use of fossil-derived epoxies, various solutions are widely studied, such as replacing conventional raw materials with more environmentally friendly, non-toxic solutions, such as vegetable oil. One of the less studied but potentially highly competitive feedstock for the synthesis of bio-based epoxies is single-cell oils (SCO). Single-cell oils have a number of advantages over vegetable oils, such as the fatty acid profiles of SCO are more suitable for the polymerization of epoxides, the production of SCOs is faster and more environmentally friendly. Thanks to the wide range of SCO-producing microorganisms, it is possible to find the exact SCO that is suitable for the specific application of the produced epoxy. Despite the potential advantages, SCO derived from microorganisms such as yeasts, fungi and bacteria, have received very limited coverage in the scientific literature. Therefore, this review summarizes the available information on single-cell oils and evaluates their suitability for use as feedstock in epoxide synthesis. The following aspects are reviewed in this paper: microorganism strains that can be used in the production of SCO; fermentation rates and SCO yields; applicable low-cost raw materials used for the cultivation of microorganisms; the fatty acid profile of the relevant SCO and other factors that are significant for suitability evaluation of the relevant SCO. To the best of authors knowledge this is the first review paper to summarize potential SCOs for their application in synthesis of bio-based epoxides and first paper to give an overview of fungal and bacterial oils for such application.

L-Lysine Stabilized FeNi Nanoparticles for the Catalytic Reduction of Biomass-Derived Substrates in Water Using Magnetic Induction.

The reduction of biomass-derived compounds gives access to valuable chemicals from renewable sources, circumventing the use of fossil feedstocks. Herein, we describe the use of iron-nickel magnetic nanoparticles for the reduction of biomass model compounds in aqueous media under magnetic induction. Nanoparticles with a hydrophobic ligand (FeNi3 -PA, PA=palmitic acid) have been employed successfully, and their catalytic performance is intended to improve by ligand exchange with lysine (FeNi3 -Lys and FeNi3 @Ni-Lys NPs) to enhance water dispersibility. All three catalysts have been used to hydrogenate 5-hydroxymethylfurfural into 2,5-bis(hydroxymethyl)furan with complete selectivity and almost quantitative yields, using 3 bar of H2 and a magnetic field of 65 mT in water. These catalysts have been recycled up to 10 times maintaining high conversions. Under the same conditions, levulinic acid has been hydrogenated to γ-valerolactone, and 4'-hydroxyacetophenone hydrodeoxygenated to 4-ethylphenol, with conversions up to 70 % using FeNi3 -Lys, and selectivities above 85 % in both cases. This promising catalytic system improves biomass reduction sustainability by avoiding noble metals and expensive ligands, increasing energy efficiency via magnetic induction heating, using low H2 pressure, and proving good reusability while working in an aqueous medium.

Strategic selection tool for thermoplastic materials in a renewable circular economy: Identifying future circular polymers

To progress towards a renewable circular economy for thermoplastic materials it is imperative to decouple from fossil feedstocks, to maximise looping strategies and to manufacture occasionally littered articles from readily biodegradable materials. This transition is complex due to the combination of stringent technical specifications that are required for ordinary plastic products and the demands that all end-of-life scenarios foist on these products. The presented strategic material selection tool for fast moving consumer goods in a renewable circular economy prioritises their suitability for the expected end-of-life fates and the contrived technical performance. This framework is tested for 17 common consumer articles and 21 biobased plastics. The strategic selection tool shows that consumer articles that are made from foamed and fibrous plastics, such as matrasses and textiles, can potentially be produced from biobased alternatives, such as biobased poly(ethylene terephthalate) (PET), poly(trimethylene terephthalate) (PTT), poly(butylene succinate) (PBS), poly(butylene succinate-co-adipate) (PBSA) and poly(butylene adipate-co-terephthalate) (PBAT). On the other hand, the tool also reveals that there are currently no adequate alternatives in barrier (food) packages and in elastomeric products such as tyres, soles of footwear and gloves. Biobased PET is a good polymer for beverage bottles provided that the leakage to the natural environment is minimised with an effective collection, reuse and recycling system. Although there are no viable single-biobased-polymeric alternatives for flexible packages to pack for instance dried foods, solutions could be developed in the form of multi-layered films of various biobased and biodegradable materials. But it would also imply that a dedicated new recycling technology needs to be developed for such multilayer films. The presented tool demonstrates that the technology is ready to start the transition towards a renewable circular economy for consumer articles such as matrasses, cushions, beverage bottles. Simultaneously, new biobased polymeric solutions need to be developed for multiple other applications such as tyres, footwear, gloves and flexible barrier packaging.

Assessment of electrified ethylene production via biomass gasification and electrochemical CO reduction

The chemical industry needs new methods for sourcing carbon-containing feedstocks from renewable sources to decrease CO2 emissions and reduce reliance on fossil fuels. Ethylene, a crucial base chemical used for making polymers and ethylene oxide, is primarily produced through steam cracking of fossil feedstocks. However, an evolving technology is the electrochemical reduction of CO2 or CO to produce ethylene. The study assesses the environmental, economic and energetic performance of a new biomass-based process that produces ethylene based on the electrochemical reduction of CO. The results are based on mass and energy balances from process simulation. The CO is produced by either gasification of biomass or combustion of biomass with CO2 capture and CO2 electrolysis. Besides ethylene, the process produces acetic acid, ethanol, oxygen and hydrogen as by-products which are purified and sold. The annual output varies between 36 and 68 kt ethylene with a biomass input of 157 kt. The levelized cost of ethylene ranges from 3,920 to 7,163 €/t with the gasification routes being the most cost-effective. The ethylene price is heavily dependent on electricity price, current density, operating voltage, and by-product prices. The carbon efficiency of the gasification-based routes is lower (64%) than the combustion-based routes (85%–86%). However, the energy efficiency is higher for the gasification-based routes (42%) compared to the combustion-based routes (28%). Conversion of ethanol to ethylene increases the ethylene yield with minimal impacts on the ethylene price. In terms of CO2 emissions, the gasification-based routes show lower emissions. Scenarios using wind power show a significant emission reduction potential compared to fossil products.

Biomass Photoreforming for Hydrogen and Value‐Added Chemicals Co‐Production on Hierarchically Porous Photocatalysts

AbstractBiomass, a naturally abundant, sustainable and clean resource has great potential as an alternative to replace the limited fossil feedstock for value‐added chemicals and fuels. Biomass with abundant reductive functional groups could theoretically act as electron donor to consume photogenerated holes and/or active free radicals. Biomass photoreforming over semiconductor photocatalysts using solar light as energy input attracts much attention in this context. However, biomass photoreforming still suffers low conversion efficiency and product selectivity due to its structural complexity, poor solubility and unclear reaction mechanism. Owing to the advanced features of mass diffusion of biomass derivatives and adjustable surface properties, hierarchically porous photocatalysts with desired active sites at each length scale of porosity have shown their superiority in boosting the conversion efficiency and selectivity of biomass photoreforming. Herein, a critical review is presented on selective biomass photoreforming for simultaneous H2 and value‐added chemicals co‐production on hierarchically porous photocatalysts. The fundamentals of biomass photoreforming and current bottleneck of biomass valorization by photocatalytic process are presented and analyzed. The rational photocatalyst design with hierarchically porous structure to improve the biomass conversion and product selectivity by boosting mass transfer is highlighted. Finally the challenges and opportunities for photocatalytic biomass valorization are presented in the perspective ssection.

Comparison of co-refining of fast pyrolysis oil from Salix via catalytic cracking and hydroprocessing

Lignocellulosic biomass from energy crops, i.e., short rotation coppice willows such as Salix spp., can be used as feedstock for production of transportation biofuels. Biomass conversion via fast pyrolysis followed by co-refining with fossil oil in existing refinery infrastructure could enable a fast introduction of large-scale production of biofuels. In this study, Salix was first liquefied using ablative fast pyrolysis in a pilot scale unit. The resulting pyrolysis oil, rich in oxygenates, was thereafter co-refined in 20 wt% ratio with fossil feedstock using two separate technologies, a fluidized catalytic cracking (FCC) laboratory unit and a continuous slurry hydroprocessing pilot plant.In the FCC route, the pyrolysis oil was cracked at 798 K using a commercial FCC catalyst at atmospheric pressure, while in the hydroprocessing route, the oil was processed at 693 K and a hydrogen pressure of 15 MPa in the presence of an unsupported molybdenum sulfide catalyst. Both routes resulted in significant deoxygenation (97 wt% versus 93 wt%). It is feasible to co-refine pyrolysis oil using both methods, the main difference being that the hydroprocessing results in a significantly higher biogenic carbon yield from the pyrolysis oil to liquid and gaseous hydrocarbon products (92 wt%) but would in turn require input of H2. In the cracking route, besides the liquid product, a significant part of the biogenic carbon ends up as gas and as coke on the catalyst. The choice of route depends, among other factors, on the available amount of bio-oil and refining infrastructures.

Co-processing of fossil feedstock with lignin-derived model compound isoeugenol over Fe-Ni/H-Y-5.1 catalysts

Co-processing of n-hexadecane with lignin derived isoeugenol as a model compound was investigated in this work using low-cost mono- and bimetallic iron and nickel supported on H-Y-5.1 zeolite. Different Fe-Ni metal ratios in the catalyst led to different reaction rates of processes and product distribution. The presence of just 0.26 wt% isoeugenol in the mixture with n-hexadecane made hydroisomerization-hydrocracking of the latter two-fold less active. Catalysts with smaller metal particle sizes, lower than 6 nm were more efficient pointing out on structure sensitivity. Extremely high activity in co-processing was obtained over 2 wt% Fe – 8 wt% Ni/H-Y-5.1 catalysts with the median metal particle size of 4.6 nm and metals-to-acid site ratio of 8.6. Fe catalyst were much less active in isoeugenol hydrodeoxygenation, while high cracking activity of hexadecane was observed in the presence of Ni. Alkylation of n-hexadecane was a feature of 8 wt% Fe – 2 wt% Ni/H-Y-5.1, whereas, over the 5 wt% Fe – 5 wt% Ni/H-Y-5.1 bifunctional catalyst no undesired oxygen-containing cyclic products were detected. This catalyst exhibited the highest hydrogen consumption according to temperature programmed desorption, which can serve as a marker for efficient hydrodeoxygenation. The spent catalysts contained ca 40 wt% of coke with predominantly aliphatic species.

A Review of Coal and Biomass Hydrogasification: Process Layouts, Hydrogasifiers, and Catalysts

Despite the increasing need for chemicals and energy, the scenario in which fossil feedstocks can be completely replaced by renewables is currently unrealistic. Thus, the combination of biomass and non-renewable matrix-based (i.e., coal) technologies could provide a greener way toward the partial substitution of traditional fuels. The hydrogasification of carbonaceous feedstocks (coal and biomass) for the main production of CH4 offers a promising alternative to this end. However, hydrogasification has received very little attention, and the present review seeks to shed light on the process, reactor, and catalytic advances in the field. Independent of the selected matrices, various efforts have been devoted to the identification of efficient methods for the production of hydrogen feed to the gasifier and energy as well as the reduction in pollutant emissions from the plants. Moreover, the reactor configurations proposed are focused on the intensification of gas-solid contact to reduce by-product formation. The co-hydrogasification of both renewable and non-renewable feedstock is also reviewed, paying attention to the synergistic effect between the two matrices. In addition, due to the slow rates of hydrogasification reaction, the key role of catalysts and feedstock impurities on the reaction kinetics is discussed.

Planet-compatible pathways for transitioning the chemical industry.

Chemical products, such as plastics, solvents, and fertilizers, are essential for supporting modern lifestyles. Yet, producing, using, and disposing of chemicals creates adverse environmental impacts which threaten the industry's license to operate. This study presents seven planet-compatible pathways toward 2050 employing demand-side and supply-side interventions with cumulative total investment costs of US$1.2-3.7 trillion. Resource efficiency and circularity interventions reduce global chemicals demand by 23 to 33% and are critical for mitigating risks associated with using fossil feedstocks and carbon capture and sequestration, and constraints on available biogenic and recyclate feedstocks. Replacing fossil feedstocks with biogenic/air-capture sources, shifting carbon destinations from the atmosphere to ground, and electrifying/decarbonizing energy supply for production technologies could enable net negative emissions of 0.5 GtCO2eq y-1 across non-ammonia chemicals, while still delivering essential chemical-based services to society.

TM2 -B2 Quadruple Active Sites Supported on a Defective C3 N Monolayer as Catalyst for the Electrochemical CO2 Reduction: A Theoretical Perspective.

Developing high-performance electrocatalysts for the CO2 reduction reaction (CO2 RR) holds great potential to mitigate the depletion of fossil feedstocks and abate the emission of CO2 . In this contribution, using density functional theory calculations, we systematically investigated the CO2 RR performance catalyzed by TM2 -B2 (TM=Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu) supported on a defective C3 N monolayer (V-C3 N). Through the screening in terms of stability of catalyst, activity towards CO2 adsorption, and selectivity against hydrogen evolution reaction, Mn2 -, Fe2 -, Co2 -, and Ni2 -B2 @V-C3 N were demonstrated to be a highly promising CO2 RR electrocatalyst. Due to quadruple active sites, these candidates can adsorb two or three CO2 molecules. Strikingly, different products, distributing from C1 to C2+ , can be generated. The high activity originates from the synergistic effect of TM and B atoms, in which they serve as adsorption sites for the C- and O-species, respectively. The high selectivity towards C2+ products at the Fe2 -, and Ni2 -B2 sites stems from moderate C adsorption strength but relatively weak O adsorption strength, in which a universal descriptor, that is, 0.6 ΔEC -0.4 ΔEO =-1.77 eV (ΔEC /ΔEO is the adsorption energy of C/O), was proposed. This work would offer a novel perspective for the design of high active electrocatalysts towards CO2 RR and for the synthesis of C2+ compounds.

Metabolic Engineering of Microorganisms to Produce Pyruvate and Derived Compounds.

Pyruvate is a hub of various endogenous metabolic pathways, including glycolysis, TCA cycle, amino acid, and fatty acid biosynthesis. It has also been used as a precursor for pyruvate-derived compounds such as acetoin, 2,3-butanediol (2,3-BD), butanol, butyrate, and L-alanine biosynthesis. Pyruvate and derivatives are widely utilized in food, pharmaceuticals, pesticides, feed additives, and bioenergy industries. However, compounds such as pyruvate, acetoin, and butanol are often chemically synthesized from fossil feedstocks, resulting in declining fossil fuels and increasing environmental pollution. Metabolic engineering is a powerful tool for producing eco-friendly chemicals from renewable biomass resources through microbial fermentation. Here, we review and systematically summarize recent advances in the biosynthesis pathways, regulatory mechanisms, and metabolic engineering strategies for pyruvate and derivatives. Furthermore, the establishment of sustainable industrial synthesis platforms based on alternative substrates and new tools to produce these compounds is elaborated. Finally, we discuss the potential difficulties in the current metabolic engineering of pyruvate and derivatives and promising strategies for constructing efficient producers.

Autocatalytic O-Formylation of Alcohols Using CO2

Global drive away from fossil feedstock requires the development of synthetic procedures to enhance the efficiency of CO2 capture and utilization processes using renewable starting materials and catalysts. Here, we report an alternative reaction pathway for the O-formylation of alcohols and bio-alcohols, which affords industrially relevant formate esters. Most products, reported herein, derive their carbon atoms exclusively from renewable sources. The reaction is catalyzed by formic acid, which can also be produced directly from CO2 captured in the reaction. The resulting in situ produced formic acid improves the reaction rate, with each catalyst recycling by simple filtration, product distillation, and reuse of the residual reaction mixture. Hence, CO2 is used as a C1 building block and simultaneously reduced to formic acid, which in turn autocatalytically promotes the reaction.

Sulfuric acid-catalyzed pyrolysis of iota-carrageenan in polyethylene glycol

The use of seaweed polysaccharides for fine chemical synthesis is a promising approach to replace fossil fuel-based feedstocks. In this work, acid-catalyzed pyrolysis of the polysaccharide iota-carrageenan from red seaweed has been studied using differential scanning calorimetry (DSC). DSC shows that sulfuric acid in a polyethylene glycol (PEG) solvent lowers the temperature of the exothermic decomposition peak by ca. 63 °C when compared with the pyrolysis of pure polysaccharide. Evolved products from the pyrolysis in a purpose-built glass tube vacuum reactor were analyzed using gas chromatography/mass spectrometry, and showed that levoglucosenone (LGO) and furfural were dominant. Yield of LGO was 12 mg/gIC or 9.0 mol% and of furfural was 2.8 mg/gIC or 2.8 mol% when 2% w/w H2SO4 was used as catalyst.