Fuel Processing Technology最新文献

In order to understand the effect of traditional solvents on lignin pyrolysis, the decarbonylation and decarboxylation reactions of various phenylic lignin model compounds were theoretically investigated using DFT methods at M06-2×/6–31++G(d,p) level. The calculation results show that activation energy of the decarbonylation and decarboxylation reactions of lignin model compounds can be reduced when H₂O/CH₃OH existed. There are two types of reaction for the H₂O/CH₃OH during the pyrolysis. For first type, the synergistic reaction of lignin with H₂O/CH₃OH as hydrogen transfer carrier. The energy barriers of the main elemental reaction steps during this type of pyrolysis are about 285.0–300.0 kJ/mol (H₂O) and 275.0–290.0 kJ/mol (CH₃OH) (decarbonylation), 170.0–210.0 kJ/mol and 155.0–200.0 kJ/mol (decarboxylation). For another type, the synergistic reaction of lignin with H₂O/CH₃OH as hydrogen source. The energy barriers of the main elemental reaction steps during this type of pyrolysis are about 260.0–278.0 kJ/mol and 240.0–260.0 kJ/mol, 303.0–312.0 kJ/mol and 291.0–297.0 kJ/mol. Furthermore, the reaction temperature has the most significant impact on decomposition reaction of lignin in a methanol medium, suggesting that the reaction in the methanol medium is better than that in the water environment.

This paper explores pyrolysis potential for effective modified biochar (MB) production, serving as a green and novel carbon-based catalyst support in Fischer-Tropsch to olefins synthesis. For this purpose, the MB produced from the pyrolysis of pre-treated Peanut shell (PS) and Cladophora glomerata algae (CG) was used as a high porosity support for cobalt catalyst synthesis. The impregnation technique was applied to prepare the cobalt catalysts, and the catalysts were promoted with potassium. Various methods examine catalysts physico-chemical properties. After 10  h of reduction at 400 °C, the catalysts' activity and selectivity were studied in a fixed-bed reactor. TEM images show that the metal particles are suitably distributed on the porous surface of the modified biochars. The majority of the particles were between 5 and 15 nm in size. Also, TPR results indicate a suitable metal dispersion of about 10% and good catalyst reducibility have been achieved. The cobalt catalysts produced on MBs of CG and PS exhibited FT rates of 0.245 and 0.223 (g HC/g cat.h), with CO conversion rates of 50.25% and 45.68% in each case. Finally, K-promoted cobalt catalysts supported on MBs of CG and PS showed the α-olefins selectivities of 38.67% and 35.49% for C2-C13 hydrocarbons, respectively.

Digestate is the secondary product of the fermentation process in biogas plants. The use of digestate as a fertilizer is very common. However, this is more and more limited nowadays and therefore alternative uses for digestate are sought. The research described in this article maps the possibilities of using digestate from the wet fermentation process for the syngas generation. This work is focuses on the gasification of the digestate with spruce chips mixtures. The mixtures were prepared with a proportion of 0, 25, 50, 75 and 100% of the digestate. The experiments were carried out on a semi-operational fluidized bed gasifier at atmospheric pressure. The working temperature of the fluidized bed was 810 °C; the gasification was autothermal. The gasification was carried out with three types of gasification agents, i.e. air, air-steam, and oxygen-steam for each fuel mixture. The aim of the research was to assess the effect of the digestate with wood chips on the qualitative and quantitative properties of the syngas. The digestate can be characterized as a secondary energy source reducing the consumption of primary energy sources. The produced syngas is of high quality and the digestate can become a very desirable fuel for the syngas production.

In this work pyrolysis of palm oil and lignin has been investigated using a two-stage process at 550 °C, with a first step configuration of continuous condensation for vapors and separation of gases, and a second step with distillation of vapors. Experiments were realized as pyrolysis of palm oil, palmitic acid, and Kraft lignin, as well as co-pyrolysis of palm oil/lignin, palmitic acid/lignin and palmitic acid/guaiacol. It has been shown that the addition of lignin improves the quality of palm oil pyrolysis bio-oil, thanks to the conversion of fatty acids coproduct to fatty acid methyl esters (FAME). The production of methyl esters in the reaction environment using palm oil and lignin was studied by conducting experiments with palmitic acid and lignin, as well as palmitic acid and guaiacol (the main product obtained from lignin pyrolysis). The results highlighted that during pyrolysis, the production of FAME is a consequence of a direct esterification reaction on palmitic acid. The formation of FAMEs during pyrolysis presents a promising avenue to optimize the utilization of palm oil by generating FAMEs as supplementary fuel products, Furthermore, it is possible to consider the application of the studied process for the conversion of free fatty acids into FAME.

Co-firing NH₃ with conventional hydrocarbon fuels is an important approach for reducing CO₂ emissions in existing combustion systems. Besides CO₂, the blending of NH₃ would also notably affect soot formation and its oxidation behaviors. In the present study, we focus on the effects of NH₃ on the nanostructure and oxidation characteristics of soot produced in diffusion flames of n-heptane/toluene mixtures. Two configurations of laminar co-flow diffusion flame, including both normal and inverse diffusion flames (NDF and IDFs), were used for investigation. High-resolution transmission electron microscopy (HRTEM), Raman spectroscopy (Raman), and Thermogravimetric analysis (TGA) were employed for soot characterization. The HRTEM and Raman spectra showed that with the increase of NH₃ blending ratio, the fringe length (L_a) and the degree of graphitization decreased while the microcrystal tortuosity (T_f) increased. The results are in consistent with TGA analysis which suggests the promoting effects of NH₃ on the soot oxidation reactivity. Difference between NDF and IDF with respect to the soot nanostructure and oxidation activity were discussed. It is our hope that the present results could deepen our understanding on the effects of NH₃ on soot nanostructure and oxidation behavior and benefit the design of particulate filters for combustion devices fueled with hydrocarbon/NH₃ mixtures.

In the current study, we examined the impact of spark duration strategy on a large bore compression ignition engine fueled with propane direct injection. An artificial neural network also was used to forecast engine in-cylinder performance characteristics. A rapid compression and expansion machine (RCEM) with a spark plug was tested with a high-pressure direct injection propane of 200 bar. While the timing of the injection was set to 20 °CA bTDC, the spark duration can range from 0.7 to 5.0 milliseconds. Crank angle degree, pressure, ignition coil number and spark duration were used as input parameters in the ANN model to predict in-cylinder performance, while engine performance parameters such as heat release rate (HRR), turbulent kinetic energy (TKE), tumble ratio, indicated power, and combustion efficiency (${\eta }_c$) were used as output parameters. The ANN model was created using the neural network toolbox and standard backpropagation with the Levenberg-Marquardt training algorithm was used with the learning rate and training epochs of the ANN model set to 0.001 and 1000, respectively. The accuracy of the model was validated by comparing the predicted datasets with the experimental data. The five projected parameters of heat release rate (HRR), turbulent kinetic energy (TKE), tumble ratio, indicated power, and combustion efficiency (${\eta }_c$) showed $R^2$ values of 0.9833, 0.9860, 0.9728, 0.9807, 0.9052, and 0.9999, respectively, and $\mathrm{MSE}$ values of 0.1419, 0.0023, 0.6428, 0.0106, 0.0050, and 0.0134. The $R^2$ of the validation dataset was nearly 0.98, which is close to that of the training dataset. The coefficients of determination ($R^2$) were greater than 0.9 in the projected results, and the $\mathrm{MSE}$ was reasonably low, indicating that a predictive model based on ANN model could predict in-cylinder performance of a large bore compression ignition engine.

In this study, Co-based catalysts supported over Ti-Al oxide and promoted with La, Ce, Mg, and K metals were assessed for CO₂ reforming of methane reaction to produce syngas. Titania-alumina mixed oxide supports were prepared using the template-assisted-solvothermal method, and then Co and promotors were co-impregnated over the as-prepared support. Different characterizations of catalysts showed that variation in promotor metal impacts these catalysts' physical and chemical properties. The Ti-Al oxide support possessed the perfect hexagonal morphology. Potassium-promoted catalysts possessed the highest number of basic sites, whereas the La-promoted catalyst possessed the highest number of acidic sites. La promotion improved the Co dispersion, while Mg promotion enhanced the metal support integration. La-promoted catalysts are deactivated because of active metal oxidation and the generation of hard carbon. The carbon was deposited in all catalysts; however, the activity of the Mg-promoted catalyst was unaffected. The intermediate surface basicity and strong metal support interaction improved the Mg-promoted catalyst's stability. The La and Mg-promoted catalysts possessed lower apparent activation energies.

Numerous innovative low-carbon ironmaking technologies rely on the use of a high-temperature, highly reducing gas, with examples including the gas-based direct reduction approach, hydrogen-enriched blast furnace fuel injection, and hydrogen-rich carbon circulation oxygen blast furnaces. However, the process of obtaining high-temperature and highly reducing gases inevitably leads to carbon deposition, and effective methods for controlling carbon deposition have yet to be developed for practical applications. Thus, within the context of metallurgical process conditions, this article provides a comprehensive review of the advancements in carbon deposition research by integrating findings from the fields of fuel chemistry and carbon material synthesis. Initially, the thermodynamic fundamentals of the carbon deposition reactions are examined, and subsequently, the influences of temperature, H₂, and catalysis on the carbon deposition reactions are discussed. In addition, the growth and erosion mechanisms of carbon on the surface of the medium are analyzed. Finally, this review consolidates the methods available for controlling carbon deposition, encompassing changes in the process conditions, the development of anti-carbon materials, and research into special processes. This article also identifies gaps in the literature and outlines future directions in related fields, notably proposing the application prospects of the sulfur passivation and thermal plasma reforming technologies in the reforming and heating of highly reducing gases.

The high-value recycling of discarded phenol-formaldehyde resins (PF) remains an unresolved challenge. Herein, we propose a novel approach leveraging γ-Al₂O₃ to convert PF into high-value hexamethylbenzene at a low temperature using a one-pot method. This study explores the degradation capability of PF, methylation reaction efficiency, and hydrodeoxygenation capacity among various cost-effective commercial catalysts: γ-Al₂O₃, ZrO₂, and TiO₂. It reveals the influence of different reaction times on PF pyrolysis and product distribution, and it was found that high value-added hexamethylbenzene exhibited the highest yield (73.33 wt%) with selectivity (75.83%) using γ-Al₂O₃ at 350 °C and 2 h of reaction. Experiments using PF models demonstrate the crucial synergy between γ-Al₂O₃ and C(aryl)-OH in the cleavage of C(aryl)-C(alkyl) bonds and methylation reactions. A pathway for PF C-C/C-O bonds cleavage-methylation tandem reaction is proposed, based on ¹³C methanol isotope experiments. PF undergoes C(aryl)-C(alkyl) bond cleavage to produce phenolic intermediates, which were then methylated; this is accompanied by the cleavage of C(aryl)-OH and C(aryl)-OCH₃, culminating in C-alkylation to form hexamethylbenzene. This research provides new insights into the high-value recycling of PF.

The hydroisomerization of long-chain n-alkanes proves to be an effective approach for the production of renewable second-generation biodiesel, and the development of bifunctional catalysts with synergistic effect between metal and acidic sites was the key to increase the yield of iso‐alkanes. Herein, novel hierarchical SAPO-31 nanoparticles (S31-Hi) were synthesized with varied amounts of the growth inhibitor 1-octyl-3-methylimidazolium chloride ionic liquid (OMIMCl IL) in a one-stage crystallization, and a proposed formation process was discussed. The 0.1Pd/S31-Hi bifunctional catalysts were prepared by loading only 0.1 wt% Pd based on the S31-Hi by wetness impregnation method and their catalytic performances were evaluated for the hydroisomerization of n-hexadecane. The catalytic performance of 0.1Pd/S31-H based on the S31-H synthesized by adding an appropriate amount of OMIMCl ILs was significantly improved, which can be attributed to the enhanced diffusion originating from its smaller crystal size, higher Pd dispersion, and larger C_Pd/C_H+ value, which was beneficial for achieving synergistic catalysis. The iso‐hexadecane yield of 77.8% and proportion of multi-branched isomers of 51.5%, and catalytic stability within 100 h time on stream was obtained over the 0.1Pd/S31-H at n-hexadecane conversion of 89.3%. These catalysts have application potential for the production of second-generation clean biodiesel with excellent low temperature fluidity.