燃料化学学报最新文献

Pyridine and its derivatives, collectively referred to as pyridine bases, are widely used in industries such as pesticides and pharmaceuticals, serving as crucial intermediates in the chemical industry. In recent years, with the development of the pesticide and pharmaceutical industries, the demand for pyridine bases has rapidly increased. The Chichibabin condensation reaction is the most commonly route for industrial production of pyridine bases. Currently, the most used ZSM-5 zeolite catalyst is limited by the instability of its silicon-aluminum framework structure, resulting in a short active reaction cycle (5 h). To address this limitation, this study selected the thermally stable and hydrothermally stable Silicalite-1 zeolite. Polyvinylpyrrolidone (PVP) was employed as a colloidal dispersant and Fe was introduced into the MFI framework through in-situ modification during the hydrothermal synthesis of zeolite. The influence of PVP dosage, template agent dosage, and other crystallization conditions on the crystallinity, pore structure, and acidity of Silicalite-1 zeolite products was investigated using XRD, SEM, TG, and N₂ adsorption-desorption measurement. The acidity of Fe-modified Silicalite-1 zeolites was characterized using NH₃-TPD, Py-FTIR, FT-IR, and XPS. These results indicated that the introduction of seed crystals effectively reduced the particle size of the zeolite to about 200 nm. Fe-modified Silicalite-1 displayed a disk-like morphology with excellent crystal dispersion. The highest relative crystallinity of the zeolite reached 103% with 15% seed crystal input and 3.75% PVP addition. The Fe-modified Silicalite-1 possessed a significantly enhanced abundance of both Lewis (L) and Brønsted (B) acid sites, resulting in an increase in the initial activity from 66% to 85% for the pyridine bases synthesis through the Chichibabin condensation. Compared to ZSM-5, Fe-modified Silicalite-1 exhibited superior catalytic stability, maintaining the total carbon conversion and pyridine bases yield above 66% and 40%, respectively, over a 15 h reaction period. Furthermore, the strategy proposed in this study, employing polyvinylpyrrolidone as a colloidal stabilizer to modify Silicalite-1 zeolite, could significantly broadened the application prospects of weakly acidic pure silica zeolites in the field of acid catalysis. This approach has demonstrated significant scientific value and industrial potential.

Bio-oil has complex compositions and high oxygen content, which restricts its high-value utilization. Commercial activated carbon (AC) and HY zeolite were used as composite catalysts to study their effect on pyrolysis volatiles from rice straw and poplar sawdust by changing the mixing modes of two catalysts. The results showed that the loading modes of AC and HY zeolite obviously affected the products distribution and bio-oil components. The lowest yield of bio-oil was obtained when HY zeolite and AC were mechanically mixed at a mass ratio of 1:1 (YACM). But the loading mode of YACM was beneficial to the deoxidation and aromatic hydrocarbon generation. Under the mode of YACM, the aromatics content in rice straw and poplar sawdust bio-oil can be increased from 13.8% and 8.0% without catalyst to 56.4% and 53.1%, respectively. However, the layered loading with upper HY zeolite and lower AC (YTACL) was favorable for formation of phenolic compounds. The selectivity to monocyclic and bicyclic aromatic hydrocarbons followed the order of YTACL > ACTYL > YACM, and YACM > ACTYL > YTACL, respectively. Compared with HY zeolite, AC catalyst possessed smaller pore size and fewer acidity, and the active sites of AC were conducive to rearrangement of furan compounds to generate cyclopentanone, 2-cyclopentenone and methyl-cyclopentenone, and further rearrangement to form phenol. Therefore, the loading mode of YTACL exhibited a promotion effect on the formation of phenol, cresol, toluene, ethylbenzene and p-xylene. The strong acidic sites of HY zeolite were favorable for the aromatization, so the loading mode of ACTYL had good selectivity to the formation of naphthalene, methylnaphthalene, anthracene and pyrene. This work will provide a guide for products regulation from biomass pyrolysis and enrich aromatics and phenols in bio-oil.

The development of highly efficient hydrodeoxidation (HDO) catalyst is the key to upgrade the quality of bio-oil. Co_xP-Ni₂P/SiO₂-y catalysts (y is the initial P/(Ni+Co) molar ratio) comprised of Co_xP-Ni₂P bimetallic sites and acidic site were prepared by doping Co into Ni₂P active phase using mesoporous SiO₂ as the support. The structure and chemical properties of the catalyst were characterized by XRD, BET, XPS, H₂-TPR, NH₃-TPD, Py-FTIR and TEM methods. The effects of Co doping and P/M molar ratio on the HDO performance of Ni₂P/SiO₂ catalyst were investigated taking m-cresol as the model compound. The results show that Co doping not only creates new Co_xP active sites, but also optimizes the electronic structure of Ni₂P, thus improving the HDO activity of the catalyst. Among the Co_xP-Ni₂P/SiO₂-y catalysts, Co_xP-Ni₂P/SiO₂-0.5 with P/M molar ratio of 0.5 exhibits the best catalytic performance, with the m-cresol conversion of 98.7% and selectivity to the deoxidized product methylcyclohexane (MCH) of 95.6% at 275 °C, 2 MPa and 1 h. The HDO of m-cresol over the Co_xP-Ni₂P/SiO₂-y catalyst mainly proceeded through hydrogenation-deoxygenation (HYD) pathway.

Bicyclohexane is a hydrogen storage reagent with high hydrogen density and low boiling point. Compared with the hydrogenation of biphenyl, the alkylation of benzene and cyclohexene to cyclohexylbenzene and hydrogenation is a promising way to prepare cyclohexane on a large scale. The research and development of high-efficiency cyclohexyl benzene hydrogenation catalyst should be further developed based on mature alkylation technology. This paper used an acidified USY molecular sieve to catalyze the alkylation of benzene and cyclohexene to cyclohexylbenzene, which achieved 100% conversion and selectivity. Furthermore, Pt/TiO₂/γ-Al₂O₃ catalyst is prepared by pre-deposition TiO₂ film of different thicknesses on γ-Al₂O₃ surface and then supported with platinum particles by Atomic layer deposition (ALD). The role of TiO₂ film in improving the cyclohexylbenzene hydrogenation performance of the catalyst is studied. TEM, CO pulse chemisorption, CO-DRIFTs, quasi-in situ XPS, H-D exchange, and H₂-TPR characterization show that compared with Pt/γ-Al₂O₃, TiO₂ thin films on Pt/TiO₂/γ-Al₂O₃ do not change the dispersion of Pt particles, but can form new Pt-TiO₂ interactions. The hydrogenation performance of cyclohexylbenzene was improved by increasing the electron density and the proportion of planar active sites on the surface of platinum and reducing the energy barrier of hydrogen spillover. The research provides theoretical support for further bicyclohexane organic liquid hydrogen storage reagent development. The relevant metal-support interaction regulation strategy can be applied to the development of efficient catalysts for other aromatic molecules hydrogenation.

The capture and hydrogenation of CO₂ into high-value chemicals such as alcohols is one of the important ways to reduce CO₂ emission and achieve carbon resource recycling. In this work, the catalytic performance of Rh/CeO₂ catalyst in the CO₂ hydrogenation was investigated; with the help of various characterization methods including XRD, Raman, H₂-TPR, CO₂-TPD, CO-DRIFTS and XPS, the influence of Rh loading (0.1%–2.0%) on the catalytic activity of Rh/CeO₂ and product selectivity in the CO₂ hydrogenation was revealed. The results indicate that for the hydrogenation of CO₂ at 250 °C and 3.0 MPa over the Rh/CeO₂ catalysts, ethanol is the major product at a low Rh loading of 0.1%. With the increase of Rh loading, the conversion of CO₂ increases, but accompanied by a decrease in the selectivity to ethanol; when the Rh loading reaches 2.0%, the main product turns to be methanol. It seems that the difference of various Rh/CeO₂ catalysts with different Rh loadings in the product selectivity for the CO₂ hydrogenation is ascribed to their difference in the structural and electronic properties of Rh; atomically dispersed Rh⁺ species favor the stabilization of CO* and its subsequent C–C coupling with CH₃* to form ethanol, whereas metallic Rh clusters facilitate the hydrogenation of CO* to produce methanol.

A series of silicon foam supported CoMn catalysts were prepared using impregnation, precipitation, and hydrothermal methods. Combining the characterization techniques such as XRD, H₂-TPR, N₂ physical adsorption, TEM, and XPS, the effect of different catalyst preparation methods on the catalytic performance in the synthesis of higher alcohols from syngas was investigated. It is shown that there are Co²⁺(Co₂C) and Co⁰ species on the surface of the catalyst. The active sites of Co₂C-Co⁰ on the surface of the catalyst prepared by hydrothermal method have a good synergistic effect, which is conducive to the generation of alcohols. A higher proportion of Co₂C also promotes the associative adsorption and insertion of CO, resulting in the highest alcohol selectivity. Under the reaction conditions of t=260 °C, p=5.0 MPa, GHSV=4500 h^–1 and H₂/CO(volume ratio)=2:1, the catalyst exhibited the best reaction performances with CO conversion of 11.1%, total alcohol selectivity of 34.7%, and C₂₊OH selectivity of 34.5%.

The synthesis of high-value γ-valerolactone (GVL) from biomass-derived methyl levulinate (ML) conventionally requires a high-pressure hydrogen, which incurs significant costs and safety concerns. This study proposes an innovative approach to produce GVL by integrating ML hydrogenation with aqueous phase reforming of methanol (APRM) using Pt/Co_xAl catalysts, thereby eliminating the need for an external hydrogen source. The influence of catalyst composition, methanol concentration, and reaction temperature on catalytic performance has been carefully examined. The results suggest that Pt/Co₁Al demonstrated exceptional activity, yielding up to 98.2% GVL, and maintaining stable performance over multiple cycles. Characterization results revealed that Pt⁰ facilitates both APRM and ML hydrogenation, while Brønsted acid sites catalyze the hydrolysis of ML and lactonization of intermediates. The synergy between Pt⁰ and Brønsted acid sites is essential for GVL formation. The appropriate amount of Co not only enhances Pt dispersion but also increases Brønsted acid sites, thereby boosting catalytic efficiency. This work offers a sustainable and economically feasible strategy for transforming biomass derivatives into valuable fuels and chemicals.

Cobalt nitrate and copper nitrate was mixed to prepare solution A. Phenyldicarboxylic acid and N,N-dimethylformamide was mixed to prepare solution B. Co/Cu Lavashield skeleton series materials (Co/Cu-MIL precursors) was then synthesized by mixing the above two solution via solvothermal method. The precursor was further carbonized to produce the MOFs derivatives, i.e. bimetallic carbon nanorods (Co_xCu_1–x/CNR) catalysts. The morphology and composition of the catalysts were explored by SEM, TEM, XRD, XPS and other characterization means. The results showed that Co_xCu_1–x/CNR was successfully obtained after calcination of Co/Cu-MIL at high temperature. The activity of the catalyst was optimal when x=0.5, the solvothermal temperature of 120 °C and the calcination temperature of 650 °C. The TOF value of the Co_0.5Cu_0.5/CNR catalyst for the hydrolysis of ammonia borane for the production of hydrogen was 2718.21 h^–1 with activation energy of 51.64 kJ/mol. The catalyst had good cyclic stability. Although the activity decreased, the conversion of AB still maintained 100% after 10 cycles.

Developing low cost and high-performance oxygen evolution electrocatalysts is significant to improve the efficiency of water electrolysis for large-scale hydrogen production. Cobalt hydroxide is a promising electrocatalyst for oxygen evolution reaction (OER), but its poor conductivity and activity seriously restrict the practical application. A simple one-step low temperature molten salt method was applied to successfully synthesize the Ce-doped cobalt hydroxide nitrate (Ce-CoNH/CF), which exhibits outstanding OER performance with a low overpotential of 448 mV at the current density of 1000 mA/cm² in 1 mol/L KOH. The remarkable performance of Ce-CoNH/CF electrode in OER may be the comprehensive result of fast reaction kinetics, large electrochemical active specific surface area (ECSA) and small charge transfer resistance (R_ct) as revealed by the Tafel, cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) analysis. Under the simulated industrial test conditions (6 mol/L KOH, 70 °C), the Ce-CoNH/CF electrode still displays excellent OER performance.

Ni, Co-induced highly distributed NiCoP nanoparticles embedded nitrogen-doped carbon nanotubes (NCNTs) (NiCo/NiCoP-NCNTs) were directly synthesized by a one-step phosphorization and carbonization process. As a bifunctional electrocatalyst for water splitting, NiCo/NiCoP NCNTs show impressive catalytic performance with an overpotential of only 206 mV for the hydrogen evolution reaction and 360 mV for the oxygen evolution reaction in 0.5 mol/L H₂SO₄ and 1 mol/L KOH solutions, respectively. In addition, NiCo/NiCoP NCNTs maintain a stable cell voltage of 1.68 V at 10 mA/cm² with only a 10% decrease in current density over 48 h, showing remarkable stability. The improved catalytic activity can be attributed to the integration of NiCoP nanoparticles and the synergies between NCNTs and NiCo alloy. Additionally, the improved electrocatalytic performance can be attributed to the increased electrochemically active surface area and the reduced electron transfer resistance of the NiCo/NiCoP-NCNTs. Overall, the NiCo/NiCoP-NCNTs demonstrated significant performance for advanced water electrolysis applications.