•The pyrolysis peat char as a new carrier to prepare composite catalyst.•The porosity of char was significantly enhanced by KOH and CO2 activation.•A high syngas yield of 88.1% was obtained over the ...Fe/CPC catalyst.•The presence of FeC and FeSiO3 can ensure the activity and stability of catalyst.•The mol% of syngas decreased from 88.1% to 64.2% after 8 h.
The pyrolysis char derived from solid waste peat was used in the removal of biomass tar. A laboratory dual-stage reactor was designed to obtain a cost-effective and eco-friendly tar removal approach using peat pyrolysis char-based catalyst. Rich pore structure of pyrolysis char can enhance the adsorption and removal performance of tar, the KOH and CO2 activation method were used to increase the pore structure of pyrolysis char. Toluene was chosen as the model compound of biomass tar for basic research. The effects of pyrolysis char and transition metal Fe on toluene removal were studied. The investigated reforming parameters were reaction temperature (700–900 °C), residence time (0.3–0.8 s) and steam-to-carbon ratio (1.5:1–4:1). The results indicated that the peat pyrolysis char-based Fe catalysts showed excellent catalytic performance (toluene conversion >89%) and gas selectivity, especially the catalyst that activated by CO2 had the best selectivity for syngas (88.1 mol%), and the waste peat catalyst was compared with other waste pyrolysis char-based catalysts. Textural characterization showed that the excellent catalytic activity and stability of the catalysts are due to the presence of FeC and FeSiO3 structures. Such the peat pyrolysis char can as a carrier be used to remove tar and produce high content syngas in pyrolysis process.
•Sludge activated carbon was produced from sludge pyrolysis char.•Thermogravimetric, kinetic studies for sludge pyrolysis char were evaluated.•The DMP adsorption effect of SAC were studied.•Compared ...the adsorption efficiency of SAC and commercial activated carbon.
Although sludge pyrolysis has been extensively studied in sludge disposal, it is challenging to utilize sludge pyrolysis products. Here, we report a method for preparing sludge activated carbon (SAC) by activating sludge pyrolysis carbon by zinc chloride. The effect of ZnCl2 concentration, activation temperature and activation time on the activated carbon were investigated. The prepared activated carbons were characterized by thermogravimetric analysis, thermal kinetics analysis, Fourier transform infrared spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and N2 adsorption-desorption. The results show that when the ZnCl2 concentration was 8 mol/L with an activation time of 1 h at an activation temperature of 800 °C, the SAC iodine adsorption value and methylene blue adsorption value were 816.27 mg/g and 95.25 mg/g, respectively. The SAC exhibited a high BET surface area (up to 765.88 m2/g). The experimental results for simulated wastewater adsorption by SAC prepared under the above preparation conditions show that at an initial concentration of dimethyl phthalate (DMP) of 30 mg/L, addition amount of SAC of 20 mg, adsorption time of 30 min and temperature of 25 °C, the removal ratio of DMP can reach 87%. According to the data obtained, sludge pyrolysis char is a suitable precursor for activated carbon preparation. The obtained SAC could be used as a low-cost adsorbent with favorable surface properties.
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•Pyrolysis oil of side wall rubber was investigated to produce H2-rich syngas.•Proving the activity and process optimization of the two-layer catalysts.•In-situ activation of the char ...catalysts to produce H2-rich syngas.•Combustion bottom ash as the second catalyst for further increasing H2 content.
Pyrolysis oil and pyrolysis char from waste tires have been reported with poor quality but could be a source and catalyst for generating hydrogen-rich syngas, respectively. In this study, the influence of two-layer catalysts on the catalytic reforming syngas distribution derived from side wall rubber pyrolysis oil (SWRPO) was explored. The side wall rubber pyrolysis char (SWRC), as a catalyst and carrier support of nickel, was used as the first-layer catalyst, and the calcined bottom ash (CBA) from oil sludge combustion was used as the secondary catalyst. Steam was used as an activator to activate SWRC and improve the concentration of CO and H2 in catalytic reforming syngas. Different analysis methods (BET, XRD, SEM, and Raman) were employed to characterize the properties of catalysts. Consequently, the yield and LHV of syngas increased from 0.05 g·goil−1 and 2.03 kJ·g−1 to 0.42 g·goil−1 and 11.32 kJ·g−1, respectively. The H2 concentration increased from 20.38 vol% to 44.68 vol% in syngas with two-layer catalysts, and the H2 selectivity reached 0.16. The yield of carbon deposit increased to 0.57 g·goil−1 with the SWRPO total conversion of 95.55 %. The lifetime of two-layer catalysts reached 17 h with a stability conversion process of SWRPO.
•Effect of wheat straw on structure and reactivity of co-pyrolysis char was investigated.•Wheat straw inhibited the ordering of microstructure and promoted the reactivity.•Positive synergy was ...observed on gasification activation energy of co-pyrolysis char.•Gasification reactivity index is exponential with microcrystalline structure parameter.
Evolution of co-pyrolysis char structure significantly influences its reaction reactivity. To explore the effect of structure on gasification characteristics of char, two ranks of coal, including anthracite coal (AC) and bituminous coal (BC) were introduced to the pyrolysis of wheat straw (WS). Microlithic and pore textures of char were examined by X-ray diffraction and specific surface area analyzer. Based on fractal theory and deconvolution method, quantitatively analysis from the effect of WS on co-pyrolysis char structure was obtained. Kinetic parameters of gasification were solved via the non-isothermal method and thermogravimetric analysis under CO2 atmosphere. The results showed that WS promoted the specific surface area of both BCWS char and ACWS char, but the promotion on the pore structure, including average pore size, was different. WS inhibited the ordering and uniformity of micro-scale structure of BCWS and ACWS char. Positive synergy from kinetic parameters during gasification of co-pyrolysis char was observed. Exponential relationship from microcrystalline structure parameter and gasification reactivity was found.
Digestate solid is a waste produced by biogas plants. It has a promising potential for the application of direct capture of CO2 from the air. In this study, digestate soild was carbonised under ...different temperatures to obtain digestate char. The carbon capture performance using the produced digestate char was further explored. Firstly, the structural properties of the prepared digestate char were characterised by N2-adsorption/desorption, X-ray diffractometry (XRD), Raman, X-ray photoelectron spectroscopy (XPS) and ultimate analysis. It was revealed that the addition of the carbonisation temperature from 400 to 800 °C led to the increase of specific surface area and total pore volume. When the carbonisation temperature increased, the degree of the molecular cleavage increased, and the content of graphite-C (C–C) increased, while the digestate char formed more carbonyl (CO), phenol, alcohol, or ether group (C–O). Furthermore, the effects of carbonisation temperature, gas flow rate and the adsorption temperature on the carbon capture performance of the digestate char were evaluated. The results showed that the carbon capture ability increased with the increase of carbonisation temperature, and with the increase of gas flow rate, the capacity of CO2 capture first increased and then decreased. In addition, when the adsorption temperature increased, the capacity of CO2 capture further decreased.
•The structural changes of digestate char with pyrolysis temperatures were systematically studied.•Digestate char shows good CO2 capture performance during direct air capture.•CO2 capture ability of digestate char is affected by carbonisation temperature, adsorption temperature and gas flow rate.
Biogas generation through anaerobic digestion provides an interesting opportunity to valorize some types of animal waste materials whose management is increasingly complicated by legal and ...environmental restrictions. To successfully expand anaerobic digestion in livestock areas, operational issues such as digestate management must be addressed in an economical and environmentally sustainable way. Biogas upgrading is another necessary stage before intending it to add-value applications. The high concentration of CO2 in biogas results in a reduced caloric value, so the removal of CO2 would be beneficial for most end-users. The current work evaluates the CO2 uptake properties (thermogravimetry study) of low-cost adsorbent materials produced from the animal wastes generated in the livestock area itself, specifically via pyrolysis of poorly biodegradable materials, such as meat and bone meal, and the digestate from manure anaerobic digestion. Therefore, the new element in this study with respect to other studies found in the literature related to biochar-based CO2 adsorption performance is the presence of high content of pyrolyzed proteins in the adsorbent material. In this work, pyrolyzed chars from both meat and bone meal and co-digested manure have been proven to adsorb CO2 reversibly, and also the chars produced from their representative pure proteins (collagen and soybean protein), which were evaluated as model compounds for a better understanding of the individual performance of proteins. The ultra-microporosity developed in the protein chars during pyrolysis seems to be the main explanation for such CO2 uptake capacities, while neither the BET surface area nor N-functionalities on the char surface can properly explain the observed results. Although the CO2 adsorption capacities of these pristine chars (6–41.0 mg CO2/g char) are far away from data of commercially activated carbons (~80 mg CO2/g char), this application opens a new via to integrate and valorize these wastes in the circular economy of the primary sector.
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•Chars from proteins and livestock waste adsorb CO2 reversibly.•Good fitting of micropore volume filling theory for CO2 adsorption•N-functionalities on pyrolysis chars surfaces do not benefit CO2 uptake.•Higher pyrolysis temperatures results in higher adsorption capacities of chars.•The potential contribution of inorganics to CO2 uptake should be further studied.
•Pellet and pellet char showed changes in porosity.•The pellet char yield with a small particle size was higher.•The pellet char having particle size of 150–250 μm had the largest specific surface ...area.•The effects of pelletizing pressure on the char yield, porosity and carbon structure were insignificant.
The pyrolysis char structure affects gasification reactivity. In this study, the effects of pelletizing conditions on the structural characteristics of straw-biomass-pellet fast pyrolysis char were investigated. Agricultural rice straw was used to prepare cylindrical pellets having a diameter of 8 mm. Pyrolysis at 600 °C was carried out in a fixed-bed reactor. The porosity, pore structure, and carbon crystalline structure of the pyrolysis char were analyzed using the Brunauer-Emmett-Teller (BET) method and Raman spectroscopy. The results demonstrated yield of pellet pyrolysis char is significantly greater than that of raw biomass, with more mesopores and fewer macropores present in the pellet pyrolysis char. Additionally, the char yield of the pellets made of <88 μm straw particles was higher than that of the pellets with other particle size ranges. The pellet char had the largest specific surface area and showed greater carbon disorder when the biomass particle size was 150–250 μm. Moreover, the effects of pelletizing pressure on char yield, porosity, and carbon structure were insignificant.
Health-care waste management is a challenge for the health sector. Currently, pyrolysis technologies are being used to treat medical waste that can convert it to a hydrocarbon fuel. In the present ...study, hazardous health-care waste was pyrolyzed using a continuous tubular fast pyrolysis reactor. Mass balance analysis and formation of the 16 polycyclic aromatic hydrocarbons (PAHs), characterized by USEPA as priority pollutants, and was studied during the pyrolysis process in a wide range of operation conditions, i.e., reaction temperature (300–700 °C), residence time (100–190 s) and waste particle size (1–3 cm). Response surface methodology (RSM) and central composite design (CCD) were applied to optimize the operating variables. Cracking and decomposition of feedstock occurred almost optimally in 700 °C resulting in the generation of 73.4% liquid and 24.1% char. The PAHs were characterized in significant concentrations in pyrolytic oil (121–29440 mg/lit) and char (223–1610 mg/kg) products. The formation of total USEPA listed PAH components varied by the operating ranges of temperature, residence time and waste size. In the pyrolytic oil phase, the formation of total PAHs was drastically increased by increasing the waste particle size. It is also found that increasing the temperature and having longer residence times have a high influence on the total 16 USEPA PAHs formation rate in the char phase. It is concluded that fast pyrolysis of hazardous health-care waste, as thermal treatment method, would influence the formation and destruction of PAHs and their fraction to a different extent depending on the role of operating variables.
•Fast pyrolysis of hospital waste.•Polycyclic aromatic hydrocarbons (PAHs) in char and oil derived hospital waste pyrolysis.•Influence of pyrolysis operation variables on the generation of polycyclic aromatic hydrocarbons (PAHs).•Mass balance of hospital waste fast pyrolysis.
Pyrolytic char as a catalyst carrier has been widely used in tar removal. This paper aimed to develop a cost-effective and eco-friendly tar steam reforming approach by using waste peat char supported ...Ca catalysts in a laboratory dual-stage reactor. Tar model compound toluene was used in steam reforming experiment for facilitate fundamental research. The reaction temperature, residence time, steam-to-carbon ratio and the molar ratios of H2, CO, CO2 and CH4 in the generated gas were investigated. Experimental results show that the peat char supported Ca catalysts had good selectivity for H2, especially the catalyst which activated by KOH and CO2. The catalyst demonstrated better catalytic activity with a higher residence time (0.6 s–0.7 s) and S/C ratio (S/C > 2.5). Under the optimized conditions, the toluene conversion and the mol% of H2 can reached 94.4% and 68.5%, respectively. Meanwhile, the activity of the catalyst was proved by a variety of performance tests, and the deactivation and mechanism of catalysts were investigated. Finally, these cost-effective and green peat char-supported Ca catalysts could be used for tar removal.
•The as-synthesized catalysts show excellent selectivity for H2 (60.5%–68.5%).•The activated catalyst has better hydrogen selectivity.•A high toluene conversion of 94.4% was obtained.•The catalyst still had good activity after 8 h of experiment.•The CaO and Ca2SiO4 structures play the major catalytic role.
Co-pyrolysis of two different types of biomass among apple tree branch (ATB), knotweed stem (KWS), seaweed (SW) and rice straw (RSt) was conducted to obtain co-pyrolysis char (co-char), and then the ...steam gasification of those co-chars was compared with the steam co-gasification of the physically mixed individual biochars to investigate the synergetic effect resulted from alkali and alkali earth metal (AAEM) in each biomass involved. It is found that the silica species in the RSt had negative effect on the activity of co-char due to the formation of alkali silicate compounds. However, combination of RSt with some non-woody biomass such as SW also showed promoting effect. In particular, the gasification of the co-char from the combination of various biomass with low or no silica content showed improved gasification efficiencies due to the synergetic effect AAEM species in the co-char from the different biomass. Therefore, the biomass selection should play a significant role in the co-pyrolysis of different biomass in the two-stage gasification system.
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•Co-pyrolysis of various biomass could result in co-chars with different activities.•Less reactive co-char was obtained from biomass with high silica species.•The positive or negative impacts could be generated during biomass co-pyrolysis.•Biomass selection is important for highly efficient two-stage gasification.
