Energy & Fuels最新文献

Aiming to valorize waste plastics in industrial hydrocracking units, this study has focused on the synthesis of catalysts for valorizing a mixture of plastic pyrolysis oil (PPO) and vacuum gas oil (VGO). Pt–Pd catalysts supported on composites made of USY zeolite, amorphous silica-alumina (ASA), and Al₂O₃ were used. Three different supports were prepared, in which the amount of USY zeolite was maintained constant at 25 wt % and the contents of ASA and Al₂O₃ were varied. The catalytic tests were carried out in a batch reactor under the following conditions: 420 and 440 °C, 80 bar contact time of 120 min, and a stirring rate of 1300 rpm. The results (conversion, yields, and composition of product fractions) are related to the properties of the catalysts, by taking into account the effects of the accessibility of the reactants, metal dispersion, and acidity. The catalyst with the support composed of 25 wt % USY zeolite, 50 wt % ASA, and 25 wt % Al₂O₃ offered the best results at both temperatures. In particular, at 440 °C, the yields obtained for the naphtha and light cycle oil fractions were 33.2 and 35.3 wt %, respectively, with an appropriate composition for use in blending the pools of gasoline and diesel in refineries. In addition, the coke formed in the process was also analyzed using temperature-programmed oxidation (TPO), focusing on analyzing the role of ASA in the acidic support, minimizing the deposition on the inner channels of the zeolite, and hence slowing down the clogging of its structure and catalyst deactivation.

The pores of continental shale reservoirs contain a large amount of complex shale oil fluid. Shale pore spaces are extremely small, primarily at the nanometer scale, and exhibit intense fluid–rock interactions, making it challenging to provide detailed fluid composition and distribution within the micronano pores of continental shale. Hence, this study uses lacustrine shale oil from the Jiufotang Formation and Shahai Formation in the Ludong Sag, Kailu Basin. The pore size distribution was measured by low-temperature nitrogen adsorption with the different grain-sized rock samples after extraction to compare the fluid presence within different shale pores. The results show that as the shale grain size decreases, the relative content of small-molecule hydrocarbon-like saturates of rock extracts decreases, while the resin and asphaltene content increases. Strong positive correlations exist between total organic carbon and free hydrocarbon (pyrolysis parameter, S₁), as well as between EOM (extracted organic matter) and S₁. With the free hydrocarbon (S₁) increasing, the EOM contents also increase, indicating that shale oil in the pores becomes more mobile. Changes in specific surface area (SSA) and micropore volume have a strong correlation with EOM content, whereas the relationship between changes in mesopore and macropore volumes and EOM content is very weak. The SSA and micropore volume of the extracted residue increase compared to those of the original sample, while the macropore volume decreases. Shale pores are predominantly composed of medium to small pores with higher saturated hydrocarbon contents. Conversely, changes in macropore volume have the strongest correlation with the content among the hydrocarbon components, indicating higher resin proportions in the macropores. Shale pores are primarily occupied by mobile hydrocarbons, with smaller molecules like saturated hydrocarbons mainly found in medium to small pores, while larger polar molecules like resins are more abundant in larger pores. This study offers a new method for characterizing shale oil fluids within various micronano pore structures in shale.

Premixed flames of ammonia/hydrogen/air mixtures were investigated in a combustor capable of creating an isotropic and homogeneous turbulent field. Based on the propagation characteristics under different hydrogen ratios, turbulence intensities, and pressures with Lewis numbers of about 1, the effects of flame chemistry, turbulent stretch, and pressure on the turbulent burning velocity were analyzed. The results show that turbulence intensity can significantly enhance the flame propagation, while the effect of pressure varies under different turbulence conditions and the hydrogen ratio corresponds to the enhancement of the flame chemistry, which has a great influence on the flame propagation. The increase of pressure and turbulence intensity makes the flame have a larger Karlovitz number and thus susceptible to turbulent stretching. In addition, the turbulent flame shows obvious self-similar accelerated propagation, but there is a deviation in the fitting index when the hydrogen ratio is larger. In addition, considering the effect of pressure on the combustion process, this paper studies the applicability of several correlations for turbulent burning velocity under high pressure and introduces the normalized pressure and turbulence integral length scales into these correlations for in-depth analysis and then further discusses the limitations of the existing correlations.

Given the variety of novel amines as potential next-generation solvents for CO₂ capture, knowledge of their thermodynamic properties is imperative to guiding their selection. In this work, 37 alternative amines belonging to different molecular families are investigated using the soft-statistical associating fluid theory (soft-SAFT) molecular equation of state (EoS). Limited experimental data of density, vapor pressure, and viscosity were used in parametrizing the molecular models, relying on the transferability of parameters related to their functional groups, yielding a modeling accuracy of within 10% of available data. The physical basis of soft-SAFT allowed determining the role of carbon chain length, molecular geometry, and degree of functionalization on key properties for CO₂ capture including density, vapor pressure, heat capacity, heat of vaporization, and viscosity, identifying short-chain molecules with cyclic/branched structures and secondary or tertiary amine functional groups as more preferred. pK_a values were obtained from COSMO-RS as a measure of the affinity for CO₂, establishing the imperative role of functionalization with primary and secondary amine groups. The cost and flammability of the alternative solvents were also included as additional criteria for their final selection. In addition to quantifying the role of the molecular structure on the performance of the solvents, the methodology of this work allowed us to identify morpholine (Morph) and ethylenediamine (EDA) as potential next-generation CO₂ capture solvents, with superior performance to the current ones, to be further investigated for large-scale validation. This work showcases the relevance of using molecular modeling for systematic screening of novel solvents for CO₂ capture, even in the absence of experimental data.

Two-dimensional materials are a class of materials consisting of nanosized dimensions resembling thin sheetlike structures. Some trending 2D materials include metal–organic frameworks (MOF), MXenes, and hexagonal boron nitride (h-BN). MOFs belong to a new class of materials with numerous merits, such as uniform distribution of tunable pore size, ultrahigh porosity, accessibility of production, and structural alteration ability. Nevertheless, the insulating nature of MOFs is regularly recognized as a bottleneck factor in the expansion of their applications, specifically in the field of electronics. MXenes have been a recent boom in material science research. These sheetlike structures are produced by customizable etching of Al from Ti₃AlC₂. These new classes of materials have tremendous applications in energy storage, and hexagonal boron nitride is another emerging class of 2D materials. The utilization of 2D materials in supercapacitor electrodes has demonstrated enhanced electrochemical characteristics, including higher energy density, prolonged charging–discharging cycles, exceptional capacitive properties, and increased specific capacitance. This Review details the utilization of 2D MOFs, h-BN, and MXenes in supercapacitors. 2D MOFs and MXenes offer significant surface areas and a high proportion of surface atoms rich in redox activities, facilitating improved pseudocapacitive performance by enabling interactions with electrolyte ions. Additionally, the intercalation of 2D structures such as MXene, h-BN, and MOFs with other compounds, hybrid designs for additional electrochemical active sites, and suggestions for overcoming limitations are discussed in detail.