Fuel Processing Technology最新文献

The catalytic decomposition of methane (CDM) is a hydrogen and nanostructured carbon production process with minimal CO₂ emission. Among the transition metal-based catalysts (e.g. Ni, Fe, Co, etc.), Ni-based catalysts are most widely studied due to the higher catalytic activity in decomposing methane. However, the limited lifespan of the catalyst makes it unsuitable for practical applications. Effective methane decomposition catalysts should be designed to optimize both reaction efficiency and catalyst lifetime. A Ni/CeO₂ catalyst, developed in previous studies, Co was added to promote low-temperature (< 700 °C) activity manipulating the redox property of Co. Among the prepared catalysts with varying Ni:Co ratio, the methane conversion rate of the Ni₈Co₂/CeO₂ catalyst was approximately twice that of the Ni₁₀/CeO₂ catalyst, confirming its excellent low-temperature activity. The reaction rate of Ni₈Co₂/CeO₂ catalyst was 4.38 mmol/min∙g_cat at 600 °C with WHSV of 36 L/g_cat∙h. In terms of characteristics of carbon products, Raman spectroscopy analysis revealed that the carbon grown on the catalyst surface exhibited high crystallinity, with D-G band ratio (I_D/I_G) of 1.01. The fresh and used catalyst samples were characterized by TEM, XPS, XAS, and other methods to analyze the parameters affecting catalytic activity.

Economical production of lignin-based jet fuel (LJF) can improve the sustainability of sustainable aviation fuels (SAFs) as well as can reduce the overall greenhouse gas emissions. However, the challenge lies in converting technical lignin polymer from biorefinery directly to jet fuel in a continuous operation. In this work, we demonstrate a simultaneous depolymerization and hydrodeoxygenation (SDHDO) process to produce lignin-based jet fuel from the alkali corn stover lignin (ACSL) using engineered Ru-HY-60-MI catalyst in a continuous flow reactor, for the first time. The maximum carbon yield of LJF of 17.9 wt% was obtained, and it comprised of 60.2 wt% monocycloalkanes, and 21.6 wt% polycycloalkanes. Catalyst characterization of Ru-HY-60-MI suggested there was no significant change in HY zeolite structure and its crystallinity after catalyst engineering. Catalyst characterizations performed post the SDHDO experiments indicate presence of carbon and K content in the catalyst. K content presence in the spent catalyst was due to K⁺ ion was exchanged between lignin solution and HY-60 while carbon presence validated the SDHDO chemistry on the catalyst surface. Tier α fuel property testing indicates that LJF production using SDHDO chemistry can produce SAF with high compatibility, good sealing properties, low emissions, and high energy density for aircraft.

This work aims to investigate the structural behaviour of asphaltene under mechanical stress using ball milling. Asphaltene samples were collected and separated from Kuwait export crude using n-heptane and subsequently ball milled for up to 24 h. X-ray diffraction was used to provide an insight into asphaltene macrostructure properties, which subsequently utilised to determine crystallite parameters. The results showed that the mechanical stress has a great influence on these structural parameters, with an increase of the aromatic sheet's inter-layer distance from 3.6 $\AA$ to 3.9 $\AA$. While the height of stacked aromatic sheets per cluster and the number of stacked aromatic sheets per cluster decreased from 24.6 $\AA$ to 9.3 $\AA$ and 8 to 3.2, respectively. A significant increment in the aromaticity value was also observed after the ball milling experimentations, indicating mechanical stress induces cyclisation and aromatisation. The XRD profiles of the higher milling time samples reveals a high background intensity. This suggests a formation and/or increasing the proportion of highly disordered materials. In addition, the effects magnitude on asphaltene crystal parameters between the mechanical stress against heat stress was compared. The results showed core structural parameters are more sensitive to mechanical stress over heat stress.

A major challenge for upgrading hydrothermal liquefaction biocrude into sustainable aviation fuel is the presence of inorganic material. Unlike commercial crude oil or biofuel from energy crops, excessive amounts of contaminants such as salt, water, and ash in biocrude oil from hydrothermal liquefaction can cause catalyst deactivation during hydroprocessing, decreased distillation efficiency, and equipment fouling from alkali deposits. Therefore, efficient removal of these impurities in HTL biocrude oil is essential. This work investigated a novel 3-stage pretreatment process, removing water, salt, and ash without chemicals, to produce a HTL biocrude oil precursor suitable for hydroprocessing. The influence of water to oil (W:O) ratio, temperature, and time on desalting efficiency was determined. After pretreatment, 81% of salt was removed, reducing total salt content to <0.1%. Improvements in elemental composition and physicochemical fuel properties were observed in biocrude oils from two feedstocks, with up to 39.8% decrease in oxygen content, 55% decrease in sulfur content, 22.2% decrease in nitrogen content, 9.86% increase in higher heating value, 73.4% decrease in total acid number, 99.9% decrease in viscosity, and 17.0% decrease in density. Compared with a single-step distillation as pretreatment, 3-stage pretreatment resulted in increased salt and heteroatom removal, improved heating value, and lower acidity. The precursor quality was viable for subsequential hydrotreating and other downstream refinery processes.

Coal gasification slag (CGS) presents significant challenge to the green and low-carbon development of the coal gasification industry due to its limited utilization restriction. In this study, cationic surfactant DTAB was used with kerosene to formulate an emulsion collector. The flotation results showed that, the increase in collector dosage could significantly improve the combustible recovery. At an optimal collector dosage of 10 kg/t, an increased DTAB ratio could significantly diminish the ash content of flotation concentrates and improve flotation precision. Through flotation dynamics experiments and fitting of the Fuerstenau upgrading curve, it confirmed that the entrainment of fine-grained particles with high ash content is the primary contributor to high ash content in flotation concentrates. Combined with FTIR spectroscopy, XPS and other analysis method, it validated that the surfactant effectively reduced the dispersed particle size of the agent, the increased contact angle of RC surface also improved hydrophobicity and improved particles hydrophobic agglomeration strength. Molecular dynamics simulation further illuminated that the surfactant covered part of the hydrophilic sites on the residue carbon (RC) surface and influenced the electrostatic interaction. The research results have important theoretical significance for perfecting the flotation theory of CGFS.

The development of highly effective bifunctional catalysts for n-hexadecane hydroisomerization is still essential to produce second-generation biodiesel. Herein, a Pt-Pd/ZSM-22-G (abbreviated as Pt-Pd/Z22-G) bimetallic catalyst was prepared by employing a room temperature electron reduction (RTER) method with glow discharge as the electron source. As a contrast, a series of Pt/Z22-H, Pd/Z22-H and Pt-Pd/Z22-H catalysts were prepared by the conventional hydrogen reduction method. The Pt-Pd/Z22-G catalyst reveals more exposed metal sites, larger C_Me/C_H+ values and an enhanced distribution of Pt-Pd(111) facets compared with the Pt/Z22-H, Pd/Z22-H and Pt-Pd/Z22-H catalysts. These modifications are originated from the stronger electron interactions and the smaller metal nanoparticles because of the effects of highly energetic reducing electrons. The n-hexadecane hydroisomerization results show that the iso-hexadecane yield over the Pt-Pd/Z22-G catalyst is 82.9%, which is the highest among four investigated catalysts in this work. This phenomenon occurs because more exposed Pt-Pd(111) facets and larger C_Me/C_H+ ratios are beneficial for the adsorption and hydrogenation of iso-alkene intermediates at metal sites to increase the iso-alkanes yield based on density functional theory (DFT) calculations. Furthermore, the iso-alkanes yield over the Pt-Pd/Z22-G catalyst also keeps steady after long-term tests for 120 h because of the limited metal aggregation and carbon deposition.

This paper proposes a new method of pulverized coal gasification using high-temperature tertiary air in a cement precalciner, in which an external hanging gasifier is added nearby. A full-scale model is established and simulated for the entrained flow gasifier. During the gasification process, the global reaction mechanism is used to model the release and reactions of volatiles from pulverized coal, and a particle surface reaction model is employed to calculate the fixed carbon content. The mechanism by which reducing gas reacts with NO is also considered. The results of the velocity, temperature, gas composition, NO_x emissions, calorific value, volatile conversion ratio and char burnout ratio, are achieved in the simulation. The results show that the volatile conversion ratios were close to 100%, and the carbon conversion ratios ranged from 27.97% to 62.76% among all the tested conditions. The concentrations of NO at the outlet of the gasifier were 109, 98, 75, 91, 87, 76, and 90 mg/m³ separately in 7 conditions. These values are significantly lower than those of complete combustion. However, the addition of raw meal had the best temperature control effect, leading to a significant decrease in thermal NO_x production and no side effects on the stability of the production line.

The additivation of solid biofuels has proven to be an effective method for reducing total particulate matter (TPM) and carbon monoxide (CO) emissions, as well as for reducing ash-related problems related to, e.g., fouling and slagging. During the combustion with additives, potassium (K) released from the solid biofuels is bound into temperature-stable compounds, thus preventing the formation of inorganic (i.e., K-based) TPM. Simultaneously by reducing K in the gas phase, the inhibition of gas-phase oxidation (e.g., CO oxidation) due to interference of K within the existing radical pool is hindered. Particularly kaolin, an aluminum-silicate-based additive has proven effective in reducing not only TPM but also CO emissions. The mitigation effects on CO emissions have previously been reported mostly in a subordinate role and explanations are given in the form of hypotheses. In this study, seven additives (i.e., kaolin, kaolinite, meta-kaolinite, aluminum hydroxide, muscovite, muscovite coated with titanium dioxide and kalsilite, each at 0.3 wt%_a.r.) were investigated during wood pellet combustion in a small-scale furnace (7.8 kW). For both CO and TPM emissions, kaolin proved to be most effective (i.e., −52% CO, −49% TPM), followed by muscovite, kaolinite, TiO₂ coated muscovite, aluminum hydroxide, and meta-kaolinite.