Fuel Processing Technology最新文献

The world's energy requirement is rising continuously due to an increase in the global population and demand for better quality of life. Fossil fuels are non-renewable, and their consumption poses global warming. Biomass-derived fuels are sustainable alternatives to fossil fuels as they are originated from renewable feedstocks. The present study investigates the production of biocrude from hydrothermal liquefaction of Canadian agricultural straws at identical conditions. Further, barley straw is found to be promising; therefore, hydrothermal liquefaction process parameters are varied for barley straw to maximize the biocrude yield with lower oxygen content. At optimum reaction conditions, the existence of carboxylic acids, phenols, aldehydes, and ketones is identified in the produced biocrude. Further, the recyclability study of the aqueous phase is attempted to explore the possibility of reusing this phase. The physicochemical characteristics of the biocrude (main product) and by-products (hydrochar, non-condensable gases, and aqueous phase) are also studied to identify the suitable areas of applications. The present experimental study demonstrates a detailed understanding of the liquefaction behavior of Canadian barley straw for biocrude production with an immense potential to co-refine in the existing petroleum refineries.

One-step transesterification between ethylene carbonate (EC) and ethanol (EtOH) can effectively prevent the formation of azeotropes in the synthesis of diethyl carbonate (DEC) / ethyl methyl carbonate (EMC). However, owing to the influence of volume and electronic effects of EtOH molecules, the catalytic activity is insufficient. In this study, we propose an on-line synthesis technique for catalysts and prepare a unique heterogeneous alkali catalyst, PS-(NR₃OH)EG. This technique simplifies the catalyst preparation process and protects it from exposure to water and carbon dioxide in the air. The active sites of PS-(NR₃OH)EG are derived from the product ethylene glycol (EG). PS-(NR₃OH)EG exhibits excellent catalytic performance in promoting EC and EtOH transesterification. The physicochemical properties of PS-(NR₃OH)EG are analysed, and the reaction conditions are optimized. The results indicate that PS-(NR₃OH)EG has superior catalytic activity and stability compared to the similar previously reported catalysts. Notably, after continuous reaction in a fixed-bed reactor for 500 h, PS-(NR₃OH)EG maintain its initial catalytic activity. This study provides theoretical and experimental guidance for catalyst preparation and transesterification reaction process design.

The limited solubility of lignin in commonly used solvents poses a challenge for its depolymerization into high-value monomers. This paper investigates the solubility of alkali lignin in water, methanol, ethanol, acetone, 1,4-dioxane, and their binary solution, and examines their impact on lignin depolymerization. The distribution of depolymerization products was correlated with the chemical structure changes in various solvent. Among the solvents tested, water-acetone mixtures demonstrated exceptional solubility for alkali lignin (95.24%) and provide the highest yield of bio-oil and phenolic monomers. The enhanced solubility of guaiacol units in acetone, combined with the addition of water in the co-solvent system dramatically improved the solubility of alkali lignin. Moreover, formic acid donated hydrogen protons to facilitate lignin depolymerization and prevented the repolymerization of unstable intermediates. Optimal reaction conditions were achieved at 300 °C for 120 mins using a mixed solvent composed of water, acetone, and formic acid in a ratio of 5:5:1 (v/v/v), corresponding to the highest yield of bio-oil with 81.45 wt%, the lowest yield of residue with 6.20 wt%, and a phenolic monomer content of 57.48%. Furthermore, this co-solvent system revealed satisfactory adaptability for converting various lignin into phenolic monomers.

The self-sintering of green petroleum coke (GPC) is an important method for the synthesis of high-strength graphite blocks owing to its relatively short production cycle. However, the volatilization of small molecular components in GPC inevitably results in the generation of pores and microcracks which seriously deteriorates the mechanical performance of carbon blocks. Herein, we report a facile quinoline-assisted composition regulation approach to prepare high mechanical strength carbon blocks using GPC as the starting material. Quinoline exhibits three major functions. Firstly, unideal organic volatiles can be effectively removed via quinoline extraction, thereby inhibiting the generation of pores and microcracks. Secondly, the presence of quinoline can promote the polymerization of aryl compounds due to its easy formation of free radicals. Thirdly, the interactions between the graphite layers are enhanced by the polarization of the aromatic rings, which clearly improves the mechanical performance of the carbon blocks. As a result, the obtained carbon block GPC/QI-17-C demonstrates an apparent density of 1.56 g·cm⁻³, flexural strength of 39.61 MPa and compressive strength of 136.98 MPa, which are 1.16, 3.39 and 4.53 times that of pristine GPC counterparts, respectively.

A series of highly ordered microporous Ce-based metal-organic frameworks (MOFs) were synthesized as the precursors for catalyst construction. The corresponding Ru catalysts were prepared by Ru impregnation on the derived CeO₂ by pyrolysis of Ce-MOF, and investigated for the CH₄ synthesis via CO₂ hydrogenation. Among the catalysts, Ru catalyst supported on the CeO₂-B derived from Ce-BDC exhibited a highly competitive efficiency for CO₂ methanation, giving a CH₄ selectivity of 100% with a CO₂ conversion of 62% at 275 °C and 0.1 MPa, and the CH₄ productivity reached 0.49 mol/(mol_Ru·h). Characterization results revealed that more oxygen vacancies and corresponding surface oxygen species formed on the surface of CeO₂-B derived from Ce-BDC caused to the stronger interaction between Ru and CeO₂-B, which promoted the CO₂ adsorption and hydrogenation capacity of the catalyst, resulting in its better catalytic property. In situ diffuse reflectance infrared Fourier transform (DRIFT) studies further revealed that the route of HCOO* into CH₄ is a more competitive way of CO₂ hydrogenation to CH₄.

Acidic promoters are significant in the hydrodeoxygenation (HDO) of bioderived furans into alkanes over metal-acid bifunctional catalysts. Here, a supported Pd/HPW-SiO₂ catalyst was prepared to investigate the promotion effect of phosphotungstic acid (HPW) on the HDO of HMF-acetone adduct (H-Ac). Characterizations suggested that an intimate contact between Pd and HPW was established in Pd/HPW-SiO₂. HPW promoters significantly reduced the reduction temperature of Pd oxides with enhanced hydrogenation and HDO capability. Particularly, in-situ DRIFTS confirmed that Pd-HPW sites significantly weakened the π_CO η₂ adsorption mode (ν₃(C=O)) of C=O group on Pd surfaces. Thereby, the HDO efficiency was synergistically improved through releasing more Pd metal sites to activate hydrogen for hydrogenation and HDO with HPW promoters. Eventually, >90% yield of nonane was efficiently achieved at 160 °C. This work is applicable to explore the structure-activity relationship of bifunctional catalysts in the efficient HDO of complicated oxygenated bioderived furans.

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.