Journal of Analytical and Applied Pyrolysis最新文献

As a widely used organic solvent, N-methylpyrrolidone (NMP) may suffer thermal decomposition during large-scale industrial usage. The complex potential energy surface and corresponding pressure-dependent rate coefficients of NMP and NMP radicals were obtained at a high level of theory. The intermediates and products of NMP pyrolysis within 900–1200 K were identified and measured by synchrotron vacuum ultraviolet photoionization mass spectrometry. Theoretical calculations show that the Keto-enol tautomerization and direct ring-opening channel yielding C₂H₄, CO, and CH₃NCH₂ exhibit the highest rate coefficient among NMP unimolecular reactions at low and high temperatures, respectively. However, the fuel decomposition process cannot be exclusively dominated by single low-barrier channel. The ring-opening reaction forming imino aldehyde radical and following decarbonylation reactions are favored channels during the NMP radical decomposition, while the formation of the dihydropyrrolidone via H or CH₃ loss competes with them at higher temperatures. Various smaller heterocycle radicals can be produced and act as intermediates for the multi-step isomerization of the ring-opening products with a relatively low energy barrier, changing the position of the functional group and radical site. A variety of nitrogenous and oxygenated species were observed in the experiment, such as ketene, methyl isocyanate, pyrrole, benzene, and different kinds of imines. Among them, C₂H₄, HCN, and CO are the major products for NMP decomposition. Potential reaction pathways from NMP to the major experimentally observed products were inferred based on the calculated results and existing knowledge on the pyrolysis of nitrogenous and oxygenated compounds. These results shed light on the complex C/H/O/N reaction system. The calculated rate coefficients and extensive mole fractions data could provide good support for the modeling of a detailed reaction mechanism in the future.

Microalgae, while promising biofuel production, pose challenges in pyrolysis due to elevated moisture and protein levels, resulting in suboptimal fuel properties. Catalytic co-pyrolysis offers promising possibilities for sustainable resource utilization and waste management, generating bio-oil. This review explores biofuel production from co-pyrolysis of microalgae biomass, and waste feedstock, investigating reactor design, catalyst impact, and reaction mechanisms. Also, the investigation encompasses both thermodynamic and kinetic aspects, aiming to unravel the underlying reaction mechanisms and rate laws governing these processes. The kinetic studies provided vital information, laying the groundwork for optimizing reactor design and improving process conditions. Reactor selection is crucial for efficient processes, optimizing heat and mass transfer. Catalysts, especially Cu/HZSM-5, Ni–Mg/ZSM-5, CaO and Ce, enhances bio-oil quality and yield by reducing nitrogenous and oxygenated compounds and promoting high-value aromatics hydrocarbons. In co-pyrolysis, synergistic effects enhance bio-oil quality through interactions between acid and base catalysts. HCl presence during PVC co-pyrolysis with microalgae alters chemical profiles, influencing chlorine distribution in biochar and bio-oil. This research emphasizes comprehending optimal reactor design, catalyst dynamics, and reaction pathways for achieving efficiency, yield enhancements, and reduced environmental impacts. These advancements open doors towards producing valuable biofuels and chemicals from various microalgae biomass and plastic waste sources thereby contributing towards sustainability & circular economy practices in waste management.

The progress of textile recycling is significantly impeded by the absence of adequate methodologies for determining the composition of fibres in textile blends. The examination of textile mixtures poses considerable difficulties, particularly due to the presence of elastane fibres, which in their limited quantities cannot be easily detected using conventional analytical techniques. Further, the undetected elastane fibres pose difficulty in separation during recycling of the textiles as they end up as impurities in cases where dissolution of the fibres is employed. Consequently, it is of utmost importance to explore new analytical tools that possess the capability to identify the primary fibres in post-consumer waste. In the current investigation, we conducted a study to assess the capabilities of Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Pyrolysis coupled with Gas Chromatography and Mass Spectrometry (Py-GC/MS) for the characterization of postconsumer textile fabrics. A comprehensive pyrolysis database was established encompassing prevalent pure fibres commonly employed in textile production. In addition, an examination was conducted on three textile blends with predetermined compositions, and the findings were subsequently compared with data obtained through the utilization of ATR-FTIR. The data derived from the original fibres was ultimately utilized for the examination of post-consumer fabric samples acquired from a waste landfill. The utilization of Py-GC/MS, scanning electron microscopy (SEM) and ATR-FTIR enabled to discern fibre compositions of mixtures even those that contained relatively low fibre content.

Blended textiles are favoured for their enhanced properties, combining the strengths of constituent fibres (typically synthetic fibres integrated with natural cellulosic fibres). However, the presence of aromatic components in blended textile waste (BTW) complicates its disposal and raises environmental concerns due to the release of toxic chemicals. To resolve this issue, this study suggests a pyrolysis system as a strategy to neutralise toxic aromatic compounds derived from BTW. Carbon dioxide (CO₂) was used as the partial oxidative reagent. The characterisation of BTW revealed its composition, containing rayon and polyester. The complex composition of BTW, particularly the recalcitrant nature of polyester, leads to the massive generation of toxic aromatic chemicals, such as terephthalic acid and its analogues, during thermolysis. However, introducing CO₂ to pyrolysis facilitates interacting with these toxic compounds, converting them into carbon monoxide (CO). The effectiveness of CO₂ for the suppression of toxic aromatic formations was further enhanced when adopting a nickel-based catalyst. CO₂-assisted catalytic pyrolysis achieved a 64.87 % reduction in toxic aromatic chemicals and an 11.36-fold increase in CO production compared with conventional pyrolysis. This study presents a promising approach for the sustainable disposal of BTW, emphasising the oxidative functionality of CO₂ in neutralising toxic aromatic chemicals into detoxified products, especially CO.

Solar methane pyrolysis in different molten media and reactor configurations was experimented to improve hydrogen production. Pure Sn, Ni_0.18Sn_0.82, Cu_0.45Bi_0.55, and KCl melts were compared at three different temperatures (1030–1130–1230 °C), and no significant difference was observed except for KCl and only at 1230 °C (X_CH4 = 72 % vs. 57 % for pure Sn). This enhanced performance was attributed to possible carbon dispersion in the salt, which probably modified the physical properties and enhanced hydrodynamics. A porous quartz sparger (downward injection) did not significantly enhance the bubbles hydrodynamics, mainly because bubbles were trapped and coalesced below the sintered disc. A custom-made sparger (lateral bubbling) did not either improve conversion due to non-uniform pores. A sparger with an upward injection should be preferred to generate small bubbles with longer residence time. When a solid bed of tungsten carbide particles was placed around the injector, overlaid by molten tin, the conversion was improved even at a relatively low temperature (X_CH4 = 17 % at 1030 °C). The immersed bed likely behaved as a porous device and increased the gas-solid surface contact. Combining particle bed and liquid bubbling system is very promising for further optimization of methane pyrolysis in molten media. The carbon collected above molten metals showed mostly a sheet-like structure with significant metal contamination. In case of KCl, most carbon was entrained with the gas, while the remaining was mixed with KCl in the reactor. The density of KCl is close to that of carbon, which prevented a good separation.

Catalytic ketonization of biomass is an effective approach for the deoxygenation of bio-oil and the enrichment of high-purity ketone products. However, the bio-oil contains a large amount of furanic components with oxygenated side groups (e.g., furfural, furfuralcohol, etc.), which severely hinders the efficiency of the ketonization reaction. In response to this challenge, this study employed Pd-based catalysts for selective conversion of furfural into "keto-friendly" components, thereby mitigating their inhibitory effects. Initially, three morphologies of CeO₂ (the main catalyst for ketonization) were selected to investigate their influence on furfural conversion. It was found that the products were mainly furfural (exceeding 86 %), with only up to approximately 13 % of "keto-friendly" products (mainly furans) detected, indicating that pure CeO₂ exhibits a weak catalytic effect on the effective conversion of furfural. Compared with pure CeO₂, the yield of "keto-friendly" products increased significantly when 1 wt% Pd was loaded, demonstrating the excellent catalytic performance of Pd in the effective conversion of furfural. Co-doping of Pd and Zr (5 wt%) on CeO₂ further increased the "keto-friendly" products to 66 %, suggesting a synergistic effect of Pd and Zr. Mechanism analysis revealed that Pd promotes the formation of furans and benzenes by enhancing the decarbonylation of furfural and subsequent furan ring opening reactions, while the competing carbonyl hydrogenation pathway is weakened. The findings of this study will be beneficial for enhancing the biomass ketonization conversion, thereby providing valuable references for the high-value utilization of biomass.

Lignin is one of the major components of organic macromolecules in peatland. Analysis of lignin in sediments is considered as a valuable tool for understanding peat vegetation as well as carbon cycle. It provides valuable perspectives on different sides such as occurrence of various vegetation types and the extent of decay in terrestrial organic material. Thermochemolysis technique using tetramethyl ammonium hydroxide (TMAH) was used for lignin analysis, in an ombrotrophic peatland. It specifically breaks of O-aryl bonds followed by methylation of the lignin components yielding phenolic subunits. Several discrepancies exist between TMAH thermochemolysis findings and those obtained from previous investigations with CuO oxidation. This could be explained by the specific pool of aryl ether, specifically targeted by the thermochemolysis, with discarding of C-C bonds. Hence, this would show the capacity of TMAH thermochemolysis to cleave oxidised lignin leaving lignin of fresh and preserved organic matter intact. The TMAH thermochemolysis method's efficiency in molecular characterization and lignin degradation was evaluated using principal component analysis (PCA). PCA reduced dimensionality and redundancy of component contributions, with the first two principal components accounting for 70.33 % of the total variance. PCA has reinforced the selectively of the thermochemolytic approach in targeting O-aryl bonds while maintaining C-C bonding of polyphenolic sub-units. Hence, two distinct oxidation phases: recent (acrotelm and mesotelm) and older (catotelm) have been revealed. PCA was applied to diagenetic and source vegetation proxies, revealing strong agreement among variables which is supported by the use of molecular ratios as indicators of organic matter source and dynamics in a peat core.

This study employed a one-step synthesis method to prepare Beta zeolites (BZs) with various SiO₂/Al₂O₃ ratios and applied them as catalysts in the process of producing bio-oil from Kraft lignin (KL). The research investigated the changes in acidity and pore size of BZs under different SiO₂/Al₂O₃ ratios and their impact on the catalytic pyrolysis products of KL. Characterization and a series of physicochemical analyses of BZ with different SiO₂/Al₂O₃ ratios as well as catalytic pyrolysis products were carried out. The Pearson correlation coefficient was also used to correlate BZ SiO₂/Al₂O₃ ratios and the acidity/pore size of BZ as well as the distribution of the products and the deoxygenation effect. The results indicate that BZs with different SiO₂/Al₂O₃ ratios can effectively catalyze the upgrading of KL during pyrolysis. BZ with SiO₂/Al₂O₃ ratios of 45 exhibited stronger acidity, a more prominent layered porous structure, and a more orderly distribution of mesopores. It showed the best catalytic upgrading effect on KL, achieving a product yield of 58.4 %. More prominently, the oxygen content is reduced to 14.19 % and the deoxygenation extent of the heavy oil reached 37.1 %.

The goal of this project is to investigate the potential of fuel production directly from slow pyrolysis of straw pellets without further refining. A two-step condensation was used to separate liquids from the volatiles. The thermal process chosen is slow pyrolysis at 500°C to couple the fuel production with carbon capture by maximizing the char production alongside bio-oils collection. Condensation parameters were tuned to improve the pyrolysis oil quality. To assess the oil quality some requirements on marine fuels, bio-oils and boiler fuels were taken as reference. Three condensation conditions were inspected: the best pyrolysis overall process was repeated three times for a total of five pyrolysis processes (lately referred to as runs). As expected, the bio-oil characteristic changed with the condensation temperature. As a result of lowering the bio-oil condensation temperature, the bio-oil results less viscous, less dense, with lower heating value and with higher water content. The final bio-oil produced was almost compliant to ISO 8217:2017 for residual marine fuels K 380, apart from water content and acid number, while it was almost compliant for the standard EN 16900:2017 for industrial boilers fuels, apart for the kinematic viscosity. It was assessed that the char is produced with an average yield of 27 w% on dry basis, while bio-oil has a yield between 5 and 10 w%. It is possible to recover an average of 72 % of the total energy contained in the straw in the valuable products, gas, char and bio-oil. The carbon captured with charcoal was around 49 w% of the total present in straw. The pyrolysis experiments were performed using an innovative semi-batch, packed-bed reactor with gas re-circulation and a new two-fraction condensation appliance that is DTU patented. The innovation is both in the reactor, where the gas is directly heated and flushed back into the pyrolyser, and in the condensation section, where the bio-oil is separated from the water fraction during the pyrolysis. The company Stiesdal SkyClean A/S showed interest in further development and scale up of this pyrolysis and condensation system.

The urgent need for sustainable energy solutions and environmental monitoring necessitates innovative approaches to biomass utilization. This study explores unlocking the potential of rice husk pyrolysis oil for dual applications: producing high-energy solid fuel and environmentally sensitive carbon nanodots (B-CDs). Slow pyrolysis of rice husk oil, followed by atmospheric distillation, transforms the oil into bio-coal with a high calorific value of 29.85 MJ/kg, significant aliphatic and aromatic carbon content, lowest ash content, and abundant oxygen functional groups, making it a viable fossil fuel alternative. Further, oxidative crystalline cutting and surface modification of this bio-coal yield B-CDs that exhibit blue fluorescence with a quantum yield of 41 %, an average size of 3.4 nm, and excellent photostability and hydrophilicity. Notably, these B-CDs are self-doped with nitrogen on their surface, enhancing their functionality. They demonstrate high sensitivity for Fe²⁺ detection, with a limit of detection (LOD) of 0.34 μM over a linear range of 0–100 μM, and a strong response to alkaline conditions. Validation experiments in tap and seawater samples confirmed the practical environmental applications of B-CDs. This study not only contributes to the advancement of pyrolysis oil as a source of fuel energy but also emphasizes the production of valuable carbon nanomaterials for environmental application.