Investigating the potential for a self-sustaining slow pyrolysis system under varying operating conditions

Biochar production from cellulose under reductant atmosphere: influence of the total pyrolysis time

Today's rising energy costs, coupled with increasing energy demand, make it necessary to search for more efficient energy processes. In recent years, there have been increasing efforts to develop efficient catalysts based on waste-derived char, by a single step where the carbon precursor and the metallic active phase one undergo a single common thermal process under a reductant atmosphere at high temperature. The use of a reductant atmosphere drives the formation of carbonaceous materials with different characteristics than those obtained under the standard nitrogen-inert one. Our work evaluates the influence of the residence time and the heating rate on the physicochemical properties of the biochar obtained. Relatively long residence times and slow heating rates, improve the yield to the resulting biochar, without increasing production cost, making the subsequent char-based metallic catalyst synthesis more efficient. The heating rate was shown to be key in improving the properties of the char in a smoother and more controlled way, unlocking a new working pathway for the efficient design and production of char-based catalysts in a one-pot synthesis.

Plastic waste as pyrolysis feedstock for plastic oil production: A review

Turning plastic waste into plastic oil by pyrolysis is one of the promising techniques to eradicate plastic waste pollution and accelerate the circular economy of plastic materials. Plastic waste is an attractive pyrolysis feedstock for plastic oil production owing to its favorable chemical properties of proximate analysis, ultimate analysis, and heating value other than its abundant availability. Despite the exponential growth of scientific output from 2015 to 2022, a vast majority of the current review articles cover the pyrolysis of plastic waste into a series of fuels and value-added products, and up-to-date reviews exclusively on plastic oil production from pyrolysis are relatively scarce. In light of this void in the current review articles, this review attempts to provide an up-to-date overview of plastic waste as pyrolysis feedstock for plastic oil production. A particular emphasis is placed on the common types of plastic as primary sources of plastic pollution, the characteristics (proximate analysis, ultimate analysis, hydrogen/carbon ratio, heating value, and degradation temperature) of various plastic wastes and their potential as pyrolysis feedstock, and the pyrolysis systems (reactor type and heating method) and conditions (temperature, heating rate, residence time, pressure, particle size, reaction atmosphere, catalyst and its operation modes, and single and mixed plastic wastes) used in plastic waste pyrolysis for plastic oil production. The characteristics of plastic oil from pyrolysis in terms of physical properties and chemical composition are also outlined and discussed. The major challenges and future prospects for the large-scale production of plastic oil from pyrolysis are also addressed.

Process Design for Value-Added Products in a Biorefinery Platform from Agro and Forest Industrial Byproducts

Agroforestry wastes are industrial byproducts available locally such as eucalyptus sawdust (EUC) and sugarcane bagasse (SCB). These byproducts can be used as lignocellulosic raw materials to produce high-value products. This study is a techno-economic analysis of four potential scenarios to produce polyhydroxybutyrate (PHB) and levulinic acid (LA) from hemicellulosic sugars by a fermentative pathway in a biomass waste biorefinery. Mass and energy balances were developed, and technical and economic assessments were carried out to obtain gas, char, and tar from residual solids from autohydrolysis treatment. It was determined that microbial culture could be an attractive option for added-value product production. More than 1500 t/year of PHB and 2600 t/year of LA could be obtained by the proposed pathways. Microbial and enzymatic conversion of LA from sugars could significantly improve energy consumption on the conversion strategy. The products from solid residual valorization (char and tar) are the most important for economic performance. Finally, a variation in specific variables could mean substantial improvements in the final indicators of the processes, reaching a higher NPV than USD 17 million.

Biomass pyrolysis: A review on recent advancements and green hydrogen production

Biomass pyrolysis has recently gained increasing attention as a thermochemical conversion process for obtaining value-added products, thanks to the development of cutting-edge, innovative and cost-effective pyrolysis processes. Over time, new and novel pyrolysis techniques have emerged, and these processes can be tuned to maximize the production of high-quality hydrogen. This review examines recent advancements in biomass pyrolysis by classifying them into conventional, advanced and emerging approaches. A comprehensive overview on the recent advancements in biomass pyrolysis, highlighting the current status for industrial applications is presented. Further, the impact of each technique under different approaches on conversion of biomass for hydrogen production is evaluated. Techniques, such as inline catalytic pyrolysis, microwave pyrolysis, etc., can be employed for the sustainable production of hydrogen. Finally, the techno-economic analysis is presented to understand the viability of pyrolysis at large scale. The outlook highlights discernments into future directions, aimed to overcome the current shortcomings.

Intelligent Predictive Maintenance (IPdM) in Forestry: A Review of Challenges and Opportunities

The feasibility of reliably generating bioenergy from forest biomass waste is intimately linked to supply chain and production processing costs. These costs are, at least in part, directly related to assumptions about the reliability and cost-efficiency of the machinery used along the forestry bioenergy supply chain. Although mechanization in forestry operations has advanced in the last 20 years, it is evident that challenges remain in relation to production capability, standardization of wood quality, and supply guarantee from forestry resources because of the age and reliability of the machinery. An important component in sustainable bioenergy from biomass supply chains will be confidence in consistent production costs linked to guarantees about harvest and haulage machinery reliability. In this context, this paper examines the issue of machinery maintenance and advances in machine learning and big data analysis that are contributing to improved intelligent prediction that is aiding supply chain reliability in bioenergy from woody biomass. The concept of “Industry 4.0” refers to the integration of numerous technologies and business processes that are transforming many aspects of conventional industries. In the realm of machinery maintenance, the dramatic increase in the capacity to dynamically collect, collate, and analyze data inputs including maintenance archive data, sensor-based monitoring, and external environmental and contextual variables. Big data analytics offers the potential to enhance the identification and prediction of maintenance (PdM) requirements. Given that estimates of costs associated with machinery maintenance vary between 20% and 60% of the overall costs, the need to find ways to better mitigate these costs is important. While PdM has been shown to help, it is noticeable that to-date there has been limited assessment of the impacts of external factors such as weather condition, operator experiences and/or operator fatigue on maintenance costs, and in turn the accuracy of maintenance predictions. While some researchers argue these data are captured by sensors on machinery components, this remains to be proven and efforts to enhance weighted calibrations for these external factors may further contribute to improving the prediction accuracy of remaining useful life (RUL) of machinery. This paper reviews and analyzes underlying assumptions embedded in different types of data used in maintenance regimes and assesses their quality and their current utility for predictive maintenance in forestry. The paper also describes an approach to building ‘intelligent’ predictive maintenance for forestry by incorporating external variables data into the computational maintenance model. Based on these insights, the paper presents a model for an intelligent predictive maintenance system (IPdM) for forestry and a method for its implementation and evaluation in the field.

Progress of the Pyrolyzer Reactors and Advanced Technologies for Biomass Pyrolysis Processing

In the future, renewable energy technologies will have a significant role in catering to energy security concerns and a safe environment. Among the various renewable energy sources available, biomass has high accessibility and is considered a carbon-neutral source. Pyrolysis technology is a thermo-chemical route for converting biomass to many useful products (biochar, bio-oil, and combustible pyrolysis gases). The composition and relative product yield depend on the pyrolysis technology adopted. The present review paper evaluates various types of biomass pyrolysis. Fast pyrolysis, slow pyrolysis, and advanced pyrolysis techniques concerning different pyrolyzer reactors have been reviewed from the literature and are presented to broaden the scope of its selection and application for future studies and research. Slow pyrolysis can deliver superior ecological welfare because it provides additional bio-char yield using auger and rotary kiln reactors. Fast pyrolysis can produce bio-oil, primarily via bubbling and circulating fluidized bed reactors. Advanced pyrolysis processes have good potential to provide high prosperity for specific applications. The success of pyrolysis depends strongly on the selection of a specific reactor as a pyrolyzer based on the desired product and feedstock specifications.

Assessing the Carbon Footprint of Biochar from Willow Grown on Marginal Lands in Finland

Willow biochar can help to sequestrate carbon. However, biomasses should not be grown on arable lands, as it would increase competition with food production and lead to sustainability issues such as increased food prices and decreased food security. The purpose of this study is to calculate the carbon footprint (CF) of willow biochar in Finland and assess the greenhouse gas compensation potential of marginal lands if they are utilized for willow biochar production. The CF of willow biochar is inadequately assessed together with marginal lands in the literature. A cradle-to-grave Life Cycle Assessment (LCA) of willow biochar was conducted. The results were then applied to assess the total CF of marginal lands. It was found that the CF of willow biochar is −1875 kgCO2eq t−1 of dry biochar. Grown on marginal lands in Finland, willow biochar could compensate 7.7% of yearly agricultural greenhouse gas emissions. On buffer zones, willow biochar could also compensate some of the emissions depending on the zone size. The results of the study support current findings of biochar as a carbon negative product. The study also indicates that willow biochar produced in marginal lands can be used to compensate agricultural greenhouse gas emissions to some extent.

Inhibition of ammonia and hydrogen sulphide as faecal sludge odour control in dry sanitation toilet facilities using plant waste materials

On-site dry sanitation facilities, although cheaper than wet sanitation systems, suffer from high malodour and insect nuisance as well as poor aesthetics. The high odour deters users from utilizing dry sanitation toilets as an improved facility leading to over 20% open defecation in Sub-Saharan Africa. To address this malodour concern, this study first assessed odour levels, using hydrogen sulphide (H₂S) and ammonia (NH₃) as indicators, on two dry sanitation facilities named T1 and T2. The potential of using biomass (sawdust, rice husk, moringa leaves, neem seeds), ash (coconut husk, cocoa husk) or biochar (sawdust, rice husk, bamboo) as biocovers to remove or suppress odour from fresh faecal sludge (FS) over a 12-day period was investigated. Results showed that the odour levels for H₂S in both T1 (3.17 ppm) and T2 (0.22 ppm) were above the threshold limit of 0.05 ppm, for unpleasantness in humans and vice versa for NH₃ odour levels (T1 = 6.88 ppm; T2 = 3.16 ppm; threshold limit = 30 ppm limit). The biomasses exhibited low pH (acidic = 5–7) whereas the biochars and ashes had higher pHs (basic = 8–13). Basic biocovers were more effective at H₂S emission reduction (80.9% to 96.2%) than acidic biocovers. The effect of pH on suppression of NH₃ was determined to be statistically insignificant at 95% confidence limit. In terms of H₂S and NH₃ removal, sawdust biochar was the most effective biocover with odour abatement values of 96.2% and 74.7%, respectively. The results suggest that biochar produced from locally available waste plant-based materials, like sawdust, can serve as a cost-effective and sustainable way to effectively combat odour-related issues associated with dry sanitation facilities to help stop open defecation.

Universal Model for the Cogeneration of Heat, Power and Char in a Decoupled Pyrolysis and Gasification Process for Techno-Economic Assessment

Present work aims to present a complete and detailed heat-mass balance data, streams elemental and species composition as crucial input data for Techno-Economic Assessment (TEA). Combined heat, power and char (CHPC) generation in decoupled pyrolysis and gasification processes ensures a highly efficient, reliable and sustainable economic use of biomass. Innovative process model based on simultaneous heat-mass balance with the elemental (C, H, O) and species (CO, H2, CO2, CH4 and H2O) composition of each stream provides reliable data with a general/average variability in a range of ±10% and ±5% for the main outputs. Thermodynamic calculations verified not only the concept but also a numerical range of the results. Comparisons with recently published, scientific and data from technology providers, prove their general applicability and consistency. TEA cases, presented in a complete and detailed table, allow selection of the relevant calculation basis providing reliable data for doubtless evaluation at investors/entrepreneurs striving for a successful business model.

A Comparative Study of Pyrolysis Liquids by Slow Pyrolysis of Industrial Hemp Leaves, Hurds and Roots

This study assessed the pyrolysis liquids obtained by slow pyrolysis of industrial hemp leaves, hurds, and roots. The liquids recovered between a pyrolysis temperature of 275-350 °C, at two condensation temperatures 130 °C and 70 °C, were analyzed. Aqueous and bio-oil pyrolysis liquids were produced and analyzed by proton nuclear magnetic resonance (NMR), gas chromatography-mass spectrometry (GC-MS), and atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry (APPI FT-ICR MS). NMR revealed quantitative concentrations of the most abundant compounds in the aqueous fractions and compound groups in the oily fractions. In the aqueous fractions, the concentration range of acetic acid was 50-241 gL^-1, methanol 2-30 gL^-1, propanoic acid 5-20 gL^-1, and 1-hydroxybutan-2-one 2 gL^-1. GC-MS was used to compare the compositions of the volatile compounds and APPI FT-ICR MS was utilized to determine the most abundant higher molecular weight compounds. The different obtained pyrolysis liquids (aqueous and oily) had various volatile and nonvolatile compounds such as acetic acid, 2,6-dimethoxyphenol, 2-methoxyphenol, and cannabidiol. This study provides a detailed understanding of the chemical composition of pyrolysis liquids from different parts of the industrial hemp plant and assesses their possible economic potential.

Prospective contributions of biomass pyrolysis to China's 2050 carbon reduction and renewable energy goals

Recognizing that bioenergy with carbon capture and storage (BECCS) may still take years to mature, this study focuses on another photosynthesis-based, negative-carbon technology that is readier to implement in China: biomass intermediate pyrolysis poly-generation (BIPP). Here we find that a BIPP system can be profitable without subsidies, while its national deployment could contribute to a 61% reduction of carbon emissions per unit of gross domestic product in 2030 compared to 2005 and result additionally in a reduction in air pollutant emissions. With 73% of national crop residues used between 2020 and 2030, the cumulative greenhouse gas (GHG) reduction could reach up to 8620 Mt CO₂-eq by 2050, contributing 13–31% of the global GHG emission reduction goal for BECCS, and nearly 4555 Mt more than that projected for BECCS alone in China. Thus, China’s BIPP deployment could have an important influence on achieving both national and global GHG emissions reduction targets.

BIPP with biochar sequestration is a ready-to-implement negative emission technology in China. Here, the authors show that its national deployment could contribute to a 61% reduction of carbon emissions per GDP in 2030 compared to 2005, and contribute 13–31% of the global biomass-based negative emission goal by 2050.

Feedstock doping using iron rich waste increases the pyrolysis gas yield and adsorption performance of magnetic biochar for emerging contaminants

Magnetic carbons can significantly lower the costs of wastewater treatment due to easy separation of the adsorbent. However, current production techniques often involve the use of chlorinated or sulfonated Fe precursors with an inherent potential for secondary pollution. In this study, ochre, an iron-rich waste stream was investigated as a sustainable Fe source to produce magnetic activated biochar from two agricultural feedstocks, softwood and wheat straw. Fe doping resulted in significant shifts in pyrolysis yield distribution with increased gas yields (+50%) and gas energy content (+40%) lowering the energy costs for production. Physical activation transformed ochre to magnetite/maghemite resulting in activated magnetic biochars and led to a 4-fold increase in the adsorption capacities for two common micropollutants - caffeine and fluconazole. The results show that Fe doping not only benefits the adsorbent properties but also the production process, leading the way to sustainable carbon adsorbents.

Comparison of Pyrolysis Liquids from Continuous and Batch Biochar Production—Influence of Feedstock Evidenced by FTICR MS

Bio-oils from biomass pyrolysis can be a resource for upgrading to chemicals or fuels. Here, for the first time, we compare the composition of bio-oils produced from two feedstocks (wheat straw, softwood) in pyrolysis units of different mode of operation (continuous—rotary kiln vs. batch) using Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) in different ionization modes (APPI (+), ESI (+/−)). Our results demonstrate that the pyrolysis unit design had only a minor influence on the composition of bio-oils produced from low-mineral containing wood biomass. Yet, the wheat straw-derived bio-oil produced in the continuous unit comprised lower molecular weight compounds with fewer oxygen-containing functional groups and lower O/C and H/C ratios, compared to bio-oils from batch pyrolysis. Longer residence time of vapours in the heated zone in the rotary kiln and a higher mineral content in wheat straw resulted in increased catalytically-mediated secondary reactions that favoured further bio-oil decomposition. This work shows for the first time that it is possible to produce distinct bio-oils without the need for external catalyst addition, by matching reactor type/design and feedstock.

Charcoal as an Alternative Reductant in Ferroalloy Production: A Review

This paper provides a fundamental and critical review of biomass application as renewable reductant in integrated ferroalloy reduction process. The basis for the review is based on the current process and product quality requirement that bio-based reductants must fulfill. The characteristics of different feedstocks and suitable pre-treatment and post-treatment technologies for their upgrading are evaluated. The existing literature concerning biomass application in ferroalloy industries is reviewed to fill out the research gaps related to charcoal properties provided by current production technologies and the integration of renewable reductants in the existing industrial infrastructure. This review also provides insights and recommendations to the unresolved challenges related to the charcoal process economics. Several possibilities to integrate the production of bio-based reductants with bio-refineries to lower the cost and increase the total efficiency are given. A comparison of challenges related to energy efficient charcoal production and formation of emissions in classical kiln technologies are discussed to underline the potential of bio-based reductant usage in ferroalloy reduction process.

Potentials, Limitations, Co-Benefits, and Trade-Offs of Biochar Applications to Soils for Climate Change Mitigation

Biochar is one of the most affordable negative emission technologies (NET) at hand for future large-scale deployment of carbon dioxide removal (CDR), which is typically found essential to stabilizing global temperature rise at relatively low levels. Biochar has also attracted attention as a soil amendment capable of improving yield and soil quality and of reducing soil greenhouse gas (GHG) emissions. In this work, we review the literature on biochar production potential and its effects on climate, food security, ecosystems, and toxicity. We identify three key factors that are largely affecting the environmental performance of biochar application to agricultural soils: (1) production condition during pyrolysis, (2) soil conditions and background climate, and (3) field management of biochar. Biochar production using only forest or crop residues can achieve up to 10% of the required CDR for 1.5 ∘ C pathways and about 25% for 2 ∘ C pathways; the consideration of dedicated crops as biochar feedstocks increases the CDR potential up to 15–35% and 35–50%, respectively. A quantitative review of life-cycle assessment (LCA) studies of biochar systems shows that the total climate change assessment of biochar ranges between a net emission of 0.04 tCO 2 eq and a net reduction of 1.67 tCO 2 eq per tonnes feedstock. The wide range of values is due to different assumptions in the LCA studies, such as type of feedstock, biochar stability in soils, soil emissions, substitution effects, and methodological issues. Potential trade-offs between climate mitigation and other environmental impact categories include particulate matter, acidification, and eutrophication and mostly depend on the background energy system considered and on whether residues or dedicated feedstocks are used for biochar production. Overall, our review finds that biochar in soils presents relatively low risks in terms of negative environmental impacts and can improve soil quality and that decisions regarding feedstock mix and pyrolysis conditions can be optimized to maximize climate benefits and to reduce trade-offs under different soil conditions. However, more knowledge on the fate of biochar in freshwater systems and as black carbon emissions is required, as they represent potential negative consequences for climate and toxicity. Biochar systems also interact with the climate through many complex mechanisms (i.e., surface albedo, black carbon emissions from soils, etc.) or with water bodies through leaching of nutrients. These effects are complex and the lack of simplified metrics and approaches prevents their routine inclusion in environmental assessment studies. Specific emission factors produced from more sophisticated climate and ecosystem models are instrumental to increasing the resolution and accuracy of environmental sustainability analysis of biochar systems and can ultimately improve the characterization of the heterogeneities of varying local conditions and combinations of type feedstock, conversion process, soil conditions, and application practice.

Prospective Life Cycle Assessment of Large-Scale Biochar Production and Use for Negative Emissions in Stockholm

Several cities in Sweden are aiming for climate neutrality within a few decades and for negative emissions thereafter. Combined biochar, heat, and power production is an option to achieve carbon sequestration for cities relying on biomass-fuelled district heating, while biochar use could mitigate environmental pollution and greenhouse gas emissions from the agricultural sector. By using prospective life cycle assessment, the climate impact of the pyrolysis of woodchips in Stockholm is compared with two reference scenarios based on woodchip combustion. The pyrolysis of woodchips produces heat and power for the city of Stockholm, and biochar whose potential use as a feed and manure additive on Swedish dairy farms is explored. The climate change mitigation trade-off between bioenergy production and biochar carbon sequestration in Stockholm's context is dominated by the fate of marginal power. If decarbonisation of power is achieved, building a new pyrolysis plant becomes a better climate option than conventional combustion. Effects of cascading biochar use in animal husbandry are uncertain but could provide 10-20% more mitigation than direct biochar soil incorporation. These results help design regional biochar systems that combine negative carbon dioxide emissions with increased methane and nitrous oxide mitigation efforts and can also guide the development of minimum performance criteria for biochar products.

Potassium doping increases biochar carbon sequestration potential by 45%, facilitating decoupling of carbon sequestration from soil improvement

Negative emissions technologies offer an important tool to limit the global warming to <2 °C. Biochar is one of only a few such technologies, and the one at highest technology readiness level. Here we show that potassium as a low-concentration additive in biochar production can increase biochar’s carbon sequestration potential; by up to 45% in this study. This translates to an increase in the estimated global biochar carbon sequestration potential to over 2.6 Gt CO₂-C(eq) yr⁻¹, thus boosting the efficiency of utilisation of limited biomass and land resources, and considerably improving the economics of biochar production and atmospheric carbon sequestration. In addition, potassium doping also increases plant nutrient content of resulting biochar, making it better suited for agricultural applications. Yet, more importantly, due to its much higher carbon sequestration potential, AM-enriched biochar facilitates viable biochar deployment for carbon sequestration purposes with reduced need to rely on biochar’s abilities to improve soil properties and crop yields, hence opening new potential areas and scenarios for biochar applications.

A pilot-scale biomass pyrolytic poly-generation plant performance study and self-sufficiency assessment

This work studied the influence of pyrolysis temperature on the energy and mass balance of pyrolysis of rice husk (RH), cotton stalk (CS) and fruit branch (FB) in a pilot-scale biomass pyrolytic poly-generation plant. The paper presents energy balance and self-sufficiency assessment of pilot-scale pyrolysis plant processing different types of biomass. The results also include characterization of the pyrolysis products. The volatile matter varied from 6.5 to 25.8% at different temperatures for the three feed stocks, which can be used as indexes for the degree of carbonization of biochar. The yield of pyrolysis gases enriched with H₂, CH₄ and other alkanes, and olefins increased significantly with increasing pyrolysis temperature from 550 to 650 °C. With a lower heating value >17.1 MJ/m³, an energy self-sufficient system is possible using only the pyrolysis gas. Biomass pyrolytic poly-generation technology offers a promising means of converting abundant agricultural residues into energy and added-value products.

Modeling, experimental validation and optimization of Prosopis juliflora fuelwood pyrolysis in fixed-bed tubular reactor

This work studied the optimal conditions for pyrolysis of Prosopis juliflora wood in fixed-bed tubular reactor. The optimal conditions are measured by performing pyrolysis experiment with respect to wood properties such as particle size, moisture and pyrolysis condition such as, temperatures, heating rates. Higher solid yield (36.8%) was recorded for a slower heating rate of larger particle size at lower temperatures. Further, higher liquid yield (38.3%) was observed while maintaining high heating rate and temperature. It is observed that with increase in particle size, the yield of char and gas decreases and bio-oil increases. The literature reported biomass pyrolysis kinetic model is validated for Prosopis juliflora wood. The kinetic models are able to predict the performance of fixed-bed tubular reactor in terms of pyrolysis product properties. The validated kinetic model may be used for the design of commercial fixed bed pyrolysis reactor to process Prosopis juliflora wood.

Theoretical Study on Elementary Reaction Steps in Thermal Decomposition Processes of Syringol-Type Monolignol Compounds

This paper theoretically investigated a large number of reaction pathways and kinetics to describe the vapor-phase pyrolytic behavior of several syringol-type monolignol compounds that are derived from the primary pyrolysis of lignin: 1-(4-hydroxy-3,5-dimethoxyphenyl)prop-2-en-1-one (HDPP), sinapyl alcohol, 3-hydroxy-1-(4-hydroxy-3,5-dimethoxyphenyl)propan-1-one (HHDPP), 1-(4-hydroxy-3,5-dimethoxyphenyl)propane-1,3-diol (HDPPD), and syringol. The possible pyrolytic pathways involving unimolecular decomposition, addition, and abstraction reactions were investigated by comparing the energy barriers calculated at the B3LYP/6-311++G(d,p) level. In the proposed pathways, all syringol-type monolignols containing a side chain undergo its cleavage to form syringol through the formation of syringaldehyde or 4-vinylsyringol. Syringol is then converted into two products: (a) pyrogallol via the homolysis of the O-CH₃ bond and hydrogenation or (b) guaiacol via addition of an H atom with a carbon bearing methoxyl group in syrignol and the subsequent demethoxylation. The pyrolytic pathways of pyrogallol are classified into two processes: (a) the concerted dehydrogenation of the two hydroxyl H atoms and the unimolecular decomposition to produce acetylene (C₂H₂), ethynol (C₂HOH), and CO or (b) the displacement of an OH with H to produce catechol and resorcinol. Additionally, HDPP undergoes O-CH₃ bond cleavage to form but-1-en-3-yne. The high-pressure limit rate constants for all the proposed elementary reaction steps were evaluated on the basis of transition state theory.

Co-production of biochar, bio-oil and syngas from halophyte grass (Achnatherum splendens L.) under three different pyrolysis temperatures

In the present study, pyrolysis of Achnatherum splendens L. was performed under three different pyrolysis temperature (300, 500, and 700°C) to investigate the characteristics of biochar, bio-oil, and syngas. Biochar yield decreased from 48% to 24%, whereas syngas yield increased from 34% to 54% when pyrolysis temperature was increased from 300 to 700°C. Maximum bio-oil yield (27%) was obtained at 500°C. The biochar were characterized for elemental composition, surface, and adsorption properties. The results showed that obtained biochar could be used as a potential soil amendment. The bio-oil and syngas co-products will be evaluated in the future as bioenergy sources. Overall, our results suggests that A. splendens L. could be utilized as a potential feedstock for biochar and bioenergy production through pyrolytic route.

Universal model of slow pyrolysis technology producing biochar and heat from standard biomass needed for the techno-economic assessment

Biochar as a soil amendment and carbon sink becomes in last period one of the vast, interesting product of slow pyrolysis. Simplest and most used industrial process arrangement is a production of biochar and heat at the same time. Proposed mass and heat balance model consist of heat consumers (heat demand side) and heat generation-supply side. Direct burning of all generated uncondensed volatiles from biomass provides heat. Calculation of the mass and heat balance of both sides reveals the internal distribution of masses and energy inside process streams and units. Thermodynamic calculations verified not only the concept but also numerical range of the results. The comparisons with recent published scientific and vendors data prove its general applicability and reliability. The model opens the possibility for process efficiency innovations. Finally, the model was adapted to give more investors favorable results and support techno-economic assessments entirely.