Authors: Yue Qin | Ke Tang | Han Wang | Xin Fang | Shuling Shen | Xin Hong
Source: Journal of Fuel Chemistry and Technology (article, 2025-04-29)
Field: Chemistry — Inorganic Chemistry

Preparation and adsorption denitrification performance of MOFs material MIL-101(Cr) Diesel, being the most widely consumed fuel oil, has garnered increasing global attention for the production of clean diesel. The NO<sub><italic>x</italic></sub> produced upon the combustion of nitrogen compounds in diesel constitutes one of the primary sources of atmospheric pollutants, whereas adsorption denitrification technology enables the removal of nitrogen compounds from diesel under relatively mild conditions. Adsorption technology revolves around adsorbents, and metal-organic frameworks (MOFs), emerging as a novel porous adsorbent material, exhibit unparalleled superior adsorption and separation capabilities compared to conventional porous materials. Currently, there exist up to seventy thousand types of MOFs materials, among which MIL-101(Cr) stands out due to its excellent thermal and chemical stability, high specific surface area, large pore volume and pore size, and relatively superior adsorption performance among all easily prepared MOFs materials. Presently, the majority of MIL-101(Cr) syntheses utilize hydrofluoric acid as a mineralizer, a toxic and highly corrosive substance. Furthermore, it necessitates intricate activation processes for its removal during the later stages of synthesis, thereby impeding its industrial application and promotion. MIL-101(Cr), being a carboxylic acid-based MOFs, allows for particle size control through the use of monocarboxylic acids. The four metal organic framework materials (MOFs) (MIL-101(Cr)-0, MIL-101(Cr)-0.5, MIL-101(Cr)-1.0 and MIL-101(Cr)-1.5) with different amounts of acetic acid 0, 0.5, 1.0 and 1.5 mL as acid mineralizers replacing hydrofluoric were prepared by using the hydrothermal synthesis method. The MIL-101(Cr)-<italic>x</italic> samples, characteried by XRD, SEM, FT-IR and N<sub>2</sub> adsorption-desorption, were used for adsorption denitrification of pyridine or quinoline from model fuels with initial alkaline nitrogen content of 1732 μg/g. The effects of adsorption time and temperature on the adsorption denitrification performance were investigated. The experimental results indicate that MIL-101(Cr)-0.5 has a larger specific surface area and pore volume. When the adsorbent dosage is 0.05 g, the model fuel dosage is 10 mL, the adsorption temperature is 40 ℃, and the adsorption time is 40 min, MIL-101(Cr)-0.5 has the better adsorption denitrification effect. The alkaline nitrogen content in the model fuel containing pyridine is reduced to 253.8 μg/g and the denitrification rate 85.35%, 343.86 μg/g and 80.15% for quinoline. However, relying solely on experimental chemistry methods poses significant time and cost constraints on the development of MOFs materials. In contrast, computational chemistry offers not only efficient simulation of the adsorption and separation behaviors of existing MOFs, allowing for a deeper analysis of their mechanisms, but also the ability to predict the performance of MOFs that have yet to be synthesized. In light of this, this article employs Materials Studio software to simulate and calculate the adsorption energy of pyridine and quinoline molecules on MIL-101(Cr) metal cluster ligands, as well as the distance between the basic lone pair electrons of nitrogen in pyridine and quinoline molecules and the unsaturated metal site Cr<sup>3+</sup> in MIL-101(Cr). The results showed that the absolute value of pyridine adsorption energy was significantly greater than that of quinoline, and the distance between the basic lone pair electrons of pyridine and the unsaturated metal site Cr<sup>3+</sup> of MIL-101(Cr) was smaller than that of quinoline. Therefore, the adsorption ability of pyridine was stronger than quinoline. Chemistry ; Adsorption ; Denitrification ; Metal-organic framework ; Chemical engineering ; Inorganic chemistry ; Environmental chemistry ; Organic chemistry ; Nitrogen Metal-Organic Frameworks: Synthesis and Applications ; Industrial Gas Emission Control ; Catalytic Processes in Materials Science