Use of Plasticized Biochar Intermediate for Producing Biocarbons with Improved Mechanical Properties

Slow pyrolysis of woody materials under elevated pressure was previously shown to result in macroscopic morphology changes, appearing as a solid that had experienced a molten phase, described as "transient plastic phase biochar" (TPPB). Experiments have been conducted to study the influence of process variables on the formation of TPPB. Results suggest TPPB formation is mediated through hydrolysis that allow for a molten phase to occur. Elevated pressure plays a key role by keeping water in the condensed phase. Despite drastic changes in material morphology, notable differences between TPPB and standard biochar (not TPPB or "NTPPB") were not detected using proximate analysis, solid state 13C NMR, and helium pycnometry, indicating the material chemistry was minimally affected. Clear differences between the mechanical properties of the TPPB and NTPPB powders and pellets were shown using tabletability experiments. The utility of TPPB was then demonstrated by comparison of tensile and compression strengths of materials calcined (N2) at (900 degrees C) to form transient plastic phase biocarbon (TPPC). The TPPB precursor resulted in a TPPC pellet with 10 times greater tensile (4.4 MPa) and compressive strength (17.6 MPa) and nearly two times greater density than carbon pellets produced from NTPPB.acceptedVersio

Use of plasticized biochar intermediate for producing biocarbons with improved mechanical properties

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Investigation of the properties and reactivity of biocarbons at high temperature in mixture of CO/CO2

The CO2 gasification reactivity of biocarbons produced from birch wood chips under different atmospheric and pressurised conditions was investigated in this work. The reactivity tests were conducted by using a Macro-TGA at 1100°C in a gas mixture of 50% CO2 and 50% CO to simulate the conditions in an industrial ferromagnese furnace. The results showed that biocarbons produced under different conditions have different CO2 gasification reactivities. The biocarbon produced in an atmospheric fixed bed reactor has the highest reactivity. This biocarbon has a high surface area and content of catalytic inorganic elements, which favour the Boudouard reaction and consumes fixed carbon. Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) showed that migration and transformation behaviours of inorganic elements in the studied biocarbons are different at the same gasification condition. Together with inductively coupled plasma atomic emission spectroscopy (ICP-OES) analysis, SEM-EDS analysis revealed that the most intensive transformation of inorganic elements occurred during gasification of the biocarbon sample produced at atmospheric conditions with slow heating rate and purging of N2. Such pyrolysis condition promotes presence of catalytic inorganic elements on the biocarbon surface, which promotes the Boudouard reaction.publishedVersio

Investigation of gasification reactivity and properties of biocarbon at high temperature in a mixture of CO/CO2

Understanding the conversion behaviors of biocarbon under conditions relevant to industrial conditions is important to ensure proper and efficient utilization of the biocarbon for a dedicated metallurgical process. The present work studied the reactivity of biocarbon by using a Macro-TGA at 1100 °C in a gas mixture of CO2 and CO to simulate the conditions in an industrial closed submerged arc manganese alloy furnace. The conversion residues from the Macro-TGA tests were collected for detailed characterization through a combination of different analytical techniques. Results showed that biocarbons produced under various conditions have different reactivities under the studied conditions. The biocarbon produced in an atmospheric fixed bed reactor with continuous purging of N2 has the highest reactivity. Its fixed carbon loss started as the gas atmosphere shifted from the inert Ar to a mixture of CO and CO2 at 1100 °C. And only 450 s was needed to reach a desired fixed-carbon loss of 20%. The high reactivity of the biocarbon is mainly related to its porous structure and high content of catalytic inorganic elements, which favor gasification reactions of the carbon matrix towards the surrounding gas atmosphere and consumption of carbon consequently. In contrast, biocarbon produced under constrained conditions and from wood pellets and steam exploded pellets have more compact appearance and dense structures. Significant fixed carbon loss for these biocarbons started 80–200 s later than that of the biocarbon produced at atmospheric conditions with purging of N2. Additionally, it took longer time, 557–1167 s, for these biocarbons to realize the desired fixed-carbon loss. SEM-EDX analyses results revealed clear accumulation and aggregation of inorganic elements, mainly Ca, on the external surface of the residues from gasification of biocarbon produced in the fixed bed reactor with purging of N2. It indicates more intensive migration and transformation of inorganic elements during gasification at this condition. This resulted in formation of a carbon matrix with more porous structure and active sites on the carbon surface, promoting the Boudouard reaction and conversion of carbon.publishedVersio

Biocarbon Production via Plasticized Biochar: Role of Feedstock, Water Content, Catalysts, and Reaction Time

Studies into transient plastic phase biochar (TPPB) were conducted to compare how feedstock, moisture, acetic acid addition, and reaction time impacted the formation of TPPB and mechanical properties. Our results show that pyrolysis conditions sufficient for TPPB formation from birch wood do not lead to TPPB formation from spruce, cellulose (paper plates), or rice straw. However, TPPB formation was possible with spruce and rice straw with the addition of water to the initial material. Plasticized biochar and non-plasticized biochar (NTPPB) produced from spruce and rice straw were compared in terms of the charcoal yield, proximate analysis (fixed carbon content), and mechanical properties of pelletized particles. Despite observing only minimal differences in the charcoal yields and fixed carbon contents between TPPB and NTPPB, the tensile strengths of biochar and biocarbon pellets [calcined at 900 °C (N2)] were substantially improved with TPPB. Biocarbon pellets produced from spruce TPPB and rice straw TPPB were 5× and 1.5× stronger than the NTPPB counterparts. Adding 75 wt % H2O to birch (nominal 8% moisture content) resulted in biocarbon with nearly 10 times higher tensile strength, despite both biocarbon materials being produced from a birch TPPB precursor. Birch biochars produced with shorter reaction times produced biocarbon pellets with nearly 3× higher tensile strength. Lastly, measured tensile (39 MPa) and compressive (188 MPa) strength values obtained from finely ground birch TPPB samples constitute one of the strongest biocarbon materials reported to date and would have sufficient mechanical strength to serve as a direct substitute for petroleum carbon anodes without any binder. These results demonstrate that plasticized biochar can be produced from a variety of different feedstocks and increasing their water content along with reducing the reaction time improves the mechanical properties of the biocarbon formed from the plasticized biochar intermediate.Biocarbon Production via Plasticized Biochar: Role of Feedstock, Water Content, Catalysts, and Reaction TimeacceptedVersio

Volatile matter characterization of birch biochar produced under pressurized conditions

The volatile matter (VM) content and composition of birch biochars produced at 320 °C under elevated pressure (0.1–11 MPa) and constant pressure or constant volume reactor conditions were characterized by thermogravimetry/mass spectrometry (TG/MS) and pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS). Some of the thermal properties of the biochars and the composition of the VMs varied as a function of the maximal pressure applied during carbonization. The samples prepared at higher pressures released more volatiles up to 320 °C, while the maximal rate of thermal decomposition at around 440 °C showed decreasing tendency with the carbonization pressure. In terms of VM composition, the most apparent effect was the significant increase of the amounts of apoallobetulins from biochars prepared at elevated pressures, which were formed by dehydration, ring closure and rearrangement from the betulin content of birch. The change in the ratio of the evolved guaiacol and 4-methylguaiacol as well as that of syringol and 4-methylsyringol as a function of the maximal pressure of carbonization indicated a modification of the lignin decomposition mechanism. © The Author(s) 2024.publishedVersio

Comprehensive Characterization of Kukui Nuts as Feedstock for Energy Production in Hawaii

13-C-AJFE-UH-This is an open access article under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) license https://creativecommons.org/licenses/by/4.0/. Please cite this article as: Jinxia Fu, Seren Weber, and Scott Q. Turn ACS Omega 2023 8 (25), 22567-22574. https://doi.org/10.1021/acsomega.3c00860Fuel properties of oil-bearing kukui (Aleurites moluccana) nuts, a commonly found crop in Hawaii and tropical Pacific regions, were comprehensively studied to evaluate their potential for bioenergy production. Proximate and ultimate analyses, heating value, and elemental composition of the seed, shell, and de-oiled seed cake were determined across five sampling locations in Hawaii. The aged and freshly harvested kukui seeds were found to have similar oil contents, ranging from 61 to 64%wt. Aged seeds, however, have 2 orders of magnitude greater free fatty acids than those freshly harvested (50% vs 0.4%). The nitrogen content of the de-oiled kukui seed cake was found to be comparable to that of the soybean cake. Aging of kukui seeds can decrease the flashpoint temperature and increase the liquid 12solid phase transition temperatures of kukui oil obtained. Mg and Ca are the major ash-forming elements present in the kukui shells, >80%wt of all metal elements detected, which may reduce deposition problems for thermochemical conversion in comparison with hazelnut, walnut, and almond shells. The study also revealed that kukui oil has similar characteristics to canola, indicating that it is well-suited for biofuel production

Construction and Demolition Waste-Derived Feedstock: Fuel Characterization of a Potential Resource for Sustainable Aviation Fuels Production

13-C-AJFF-UH-11, 13This is an open access article under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) license https://creativecommons.org/licenses/by/4.0/. Please cite this article as: Bach Q-V, Fu J and Turn S (2021) Construction and Demolition WasteDerived Feedstock: Fuel Characterization of a Potential Resource for Sustainable Aviation Fuels Production. Front. Energy Res. 9:711808. doi: 10.3389/fenrg.2021.711808Detailed characterization of physical and fuel properties of construction and demolition waste (CDW) can support research and commercial efforts to develop sustainable aviation fuels. The current study reports time-series data for bulk density, mineral composition, reactivity, and fuel properties (proximate analysis, ultimate analysis, heating value and ash fusibility) of the combustible material fraction of samples mined from an active CDW landfill on the island of O\u2bbahu, Hawai\u2bbi. The fuel properties are in ranges comparable to other reference solid wastes such as demolition wood, municipal solid wastes, and landfilled materials. Ash fusion temperatures (from initial deformation to fluid deformation) among the samples were found to lie in a narrow range from 1,117 to 1,247\ub0C. Despite higher ash contents, the CDW derived feedstock samples had comparable heating values to reference biomass and construction wood samples, indicating the presence of higher energy content materials (e.g., plastics, roofing material, etc.) in addition to wood. The waste samples show lower reactivity peaks in the devolatilization stage, but higher reactivity peaks (located at lower temperatures) in the gasification and combustion stage, compared with those of reference biomass and construction woods. Mineral elemental analysis revealed that materials from various sources (gypsum, plastic, rust, paint, paint additives, and soils) were present in the samples. Soil recovered from the landfill contained higher Ca, Cu, Fe, K, Mn, Pb, and Zn levels than soil samples from elsewhere on the island. Results from this study can provide insight on variations in the physical and fuel properties of the CDW derived feedstocks, and support the design of conversion systems