燃料化学学报最新文献

A series of Cu/ZnO catalysts were prepared by the coprecipitation method and the effect of Cu/Zn ratio on the strong metal support interaction (SMSI) as well as its relation to the catalytic performance of Cu/ZnO in the gaseous hydrogenation of furfural to furfuryl alcohol was investigated. The H₂-TPR, XRD, SEM, TEM and XPS characterization results reveal that there exists the SMSI effect in the Cu/ZnO catalyst that influences the catalyst microstructure. ZnO support, acting as a geometric modifier on the active metal Cu particles, has a significant influence on the electronic state of the surface Cu species. The strength of SMSI is related to the Cu/Zn ratio and the SMSI strength of various Cu/ZnO catalysts follows the order of 20Cu/ZnO> 40Cu/ZnO> 60Cu/ZnO> 80Cu/ZnO. Under the same reaction conditions, the lifetime of the 20Cu/ZnO catalyst with a furfural conversion of above 80% is only 5 h, in comparison with the lifetime of 28 h for the 60Cu/ZnO catalyst. That is, appropriate SMSI can enhance the stability of the Cu/ZnO catalyst in the hydrogenation of furfural to furfuryl alcohol, whereas excessive SMSI is detrimental to the catalyst activity.

To address the issue of coking and deactivation of Zn/HZSM-5 catalysts used for lightolefins aromatization, a high-temperature hydrothermalmethod was employed for catalyst pretreatment. The catalysts were characterized using XRD, N₂ physical adsorption-desorption, NH₃-TPD, Py-FTIR, XPS, and TG techniques. The effect of high-temperaturehydrothermal pretreatment on the catalytic performance and stability of the catalyst was investigated using ethylene aromatization as a probe reaction. The results showed that the Zn/HZSM-5 catalyst exhibited excellent catalytic performance after48 h of high-temperature hydrothermal pretreatment. Although the conversion of ethylene slightly decreased, the catalyst lifetime was significantly extended, increasing from 72to 216 h, while the aromatics selectivity remained above 60%. It was suggested that the hydrothermal treatment enhanced the interaction between ZnO species and Brønsted acid sites, promoting the generation of ZnOH⁺ species. This not only suppressed the hydrogen transfer reaction but also significantly enhanced the dehydrogenation performance of the catalyst, improving the selectivity towards hydrogen. Additionally, the catalyst exhibited increased carbon capacity and reduced carbon deposition rate after hydrothermal treatment, demonstrating excellent anti-coking properties.

Deactivation of Cu/ZnO/Al₂O₃ catalysts in CO₂ hydrogenation to methanol reaction is one of the main reasons limiting their application. We synthesized a series of La modified Cu/ZnO/Al₂O₃ catalysts by adding different contents of La to improve the stability. In the 100 h short-term stability test at 200 °C under 3 MPa with a GHSV of 12000 mL/(g·h), the unmodified Cu/ZnO/Al₂O₃ catalysts degraded obviously over 100 h. In sharp contrast, the stability was significantly promoted by the addition of La. The best activity was achieved with 5% La added samples (4% CO₂ conversion and 85% methanol selectivity),which also showed impressive stability over 1000 h except about 17% deactivation during the initial 190−220 h. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results revealed that the addition of 5% La improved the dispersion of Cu and Zn, inhibited the sintering of Cu, stabilized the Cu^0/+ species and retarded oxidation of Cu in catalysts, which attributed to the high stability of the catalysts.

In this paper, the adsorption behavior of pyridine, a typical basic nitrogen compound in diesel oil, on Ti-doped, Zr-doped, N-doped and intrinsic graphene has been investigated by density functional methods. The corresponding adsorption energy, adsorption configurations, Mulliken charge transfer, differential charge density and density of states were discussed. The results show that doping graphene with metal atoms such as Ti or Zr can significantly obviously enhance the adsorption energy between pyridine and graphene surfaces, while non-metal N doping has a relatively minor effect. The magnitude of the adsorption energy of pyridine on the surfaces of graphene modified with different atoms follows the order: Ti-doped>Zr-doped>N-doped>intrinsic graphene. Pyridine interacts with Ti- or Zr-doped graphene through N−Ti, N−Zr and π−π interactions, while with N-doped and intrinsic graphene, it interacts via N−N, C−N and π−π interactions. There are significantelectron transfer and chemical bond formation between pyridine and metal-doped (Ti, Zr) graphene surfaces, indicating chemical adsorption. However, there is no chemical bond formation with non-metal N-doped graphene and intrinsic graphene, suggesting physical adsorption in these cases. Overall, pyridine exhibits more stable adsorption on the surfaces of Ti, Zr-doped graphene.

Co/SiC catalysts have exhibited excellent performance in Fischer-Tropsch synthesis reaction. However, few research focuses on investigating the effect of SiC supports surface properties of on catalyst performance. In this study, ZrO₂ was utilized to modify the SiC surface, leading to the preparation of a series of Co-ZrO₂/SiC catalysts. The physicochemical properties of the catalyst were comprehensively analyzed by using N₂ adsorption, XRD, H₂-TPR, XPS analyses. Catalytic performance was evaluated using a fixed bed reactor, shedding light on the effect of ZrO₂ modified SiC support on cobalt-based Fischer-Tropsch synthesis catalysts. The results indicated that ZrO₂ surface modification on SiC resulted in an enhanced reduction degree of Co/SiC catalysts. Additionally, ZrO₂ exhibited strong interaction with the amorphous phase on the SiC surface, thereby weakening the interaction between Co and the amorphous phase. This led to an increase in the electron density of cobalt species, consequently improving the selectivity of Co/SiC catalysts towards long-chain hydrocarbons.

Ammonia borane (NH₃BH₃, AB) is an ideal feedstock with high hydrogen storage capacity. In this paper, nitrogen-containing carbon material (Ni_0.6Cu_0.4O/NC) catalyst was prepared by high-temperature carbonization of Ni/Cu-ZIF precursor under nitrogen atmosphere. The microstructure as well as the composition of the as-prepared catalyst were characterized. In addition, the catalytic performance of the catalyst was tested under reaction conditions. The results showed that the activation energy (E_a) for hydrolysis of AB over Ni_0.6Cu_0.4O/NC catalyst was 56.8 kJ/mol with TOF value as high as 1572.2 h^–1. The hydrogen production could be approximated as a zero-order reaction with respect to the concentration of AB, and a one-order reaction with respect to the amount of catalyst. The catalyst still maintained good activity after ten cycles, indicating the good stability.

It is essential to investigate the influence of alkaline earth metals on the pyrolysis mechanism and resulting products of lignin to enhance the efficient thermochemical conversion and utilization of lignin or biomass. In this study, the density functional theory method was used to simulate the pyrolytic reaction pathways of a β-O-4 type lignin dimer model compound (1-methoxy-2-(4-methoxyphenethoxy)benzene, mc) affected by alkaline earth metal ions Ca²⁺ and Mg²⁺. The computational findings suggest that Ca²⁺ and Mg²⁺ tend to combine with the oxygen atom at the C_β position and the oxygen atom on the methoxy group of the lignin dimer model compound, forming stable complexes that modify the bond lengths of the C_α–C_β and C_β–O bonds and affect their pyrolysis energy barriers. During the catalytic pyrolysis process, the presence of Ca²⁺ and Mg²⁺ can promote the concerted decomposition reaction, leading to increased production of products like 1-methoxy-4-vinylbenzene, 2-methoxyphenol and catechol. Meanwhile, they can suppress homolytic cleavage reactions of the C_β–O and C_α–C_β bonds, thereby hindering the formation of other products such as 1-ethyl-4-methoxybenzene and 2-hydroxybenzaldehyde.

Chemical looping oxidative dehydrogenation (CL-ODH) provides a multifunctional conversion platform that can take advantage of the selective oxidation of lattice oxygen in oxygen carrier to achieve high-valued ethane to ethylene conversion. In this study, we explored the effect of B-site element in MgX₂O₄ (X=Cr, Fe, or Mn) spinel-type oxygen carriers on the performance of ethane CL-ODH. The properties test and characterization of MgX₂O₄ spinel were tested by fixed bed and H₂-TPR, O₂-TPD, TG, in-situ Raman, SEM, and TEM. The results showed that because MgCr₂O₄ only released a small amount of adsorbed surface oxygen, it tended to catalyze the conversion of ethane to coke and hydrogen. MgFe₂O₄ facilitated the deep oxidation of ethane into CO₂ by providing more surface lattice oxygen. Meanwhile, since a significant amount of bulk lattice oxygen was released by the MgMn₂O₄ oxygen carrier, it could burn hydrogen in a targeted manner to advance the reaction and increased ethylene’s selectivity. Thereby, MgMn₂O₄ achieved an ethane conversion of 73.72% with an ethylene selectivity of 81.46%. Furthermore, the MgMn₂O₄ catalyst demonstrated stable reactivity and an ethylene yield of about 62.00% in ethane CL-ODH over the 30 redox cycles. The screening tests indicated that the B-site elements in MgX₂O₄ spinel oxides could significantly influence their ability to supply lattice oxygen, thereby affecting their performance in ethane CL-ODH reaction.

Pyrolysis, an economically viable method, thermochemically converts solid fuel into transportation fuels and value-added chemicals, such as clean gas, liquid fuels, and chemicals, alongside undesirable by-products. Photoionization mass spectrometry (PIMS) is a versatile technique for real-time process analysis, offering ‘soft’ ionization for complex analytes, detecting and analyzing ions during in-situ pyrolysis. This review focuses on recent applications of PIMS during pyrolysis of solid fuels (i.e. coal, biomass and energetic materials). It summarizes studies on mass spectrometric analysis combined with different reactors and highlights the benefits through online PIMS as a diagnostic tool for in-situ analysis. It provides an overview of interplay between experimental advancements and models and discusses future perspectives, potential applications in support of mechanistic studies.

Formic acid (FA) is a sustainable liquid organic hydrogen carrier and the catalyst for hydrogen production from FA has received significant attention. However, the development of efficient non-noble metal catalysts still remains challenges. In this work, we provide a technologically rather simple and environmental-friendly strategy to synthesize Co₂P catalyst for dehydrogenation of FA by pyrolyzing soybean powder and cobalt salt. The K-containing solid bases in catalyst could act as Lewis acid sites for the HCOO⁻ intermediate adsorption while the self-doped N could act as Lewis base sites to enhance the H⁺ adsorption. The P contained in soybean could combine with Co to form Co₂P for H−C bond cleavage of HCOO⁻. At a Co(NO₃)₂·6H₂O/soybean mass ratio of 1:15, the as prepared Co₂P catalyst demonstrated a gas production rate of 237.47 mL/(g·h) and a good stability. This study provides a novel strategy to develop non-noble metal heterogeneous catalysts for FA dehydrogenation.