Engineering surface framework TiO6 single sites for unprecedented deep oxidative desulfurization.

Catalytic oxidative desulfurization (ODS) using titanium silicate catalysts has emerged as an efficient technique for the complete removal of organosulfur compounds from automotive fuels. However, the precise control of highly accessible and stable-framework Ti active sites remains highly challenging. Here we reveal for the first time by using density functional theory calculations that framework hexa-coordinated Ti (TiO6) species of mesoporous titanium silicates are the most active sites for ODS and lead to a lower-energy pathway of ODS. A novel method to achieve highly accessible and homogeneously distributed framework TiO6 active single sites at the mesoporous surface has been developed. Such surface framework TiO6 species exhibit an exceptional ODS performance. A removal of 920 ppm of benzothiophene is achieved at 60°C in 60 min, which is 1.67 times that of the best catalyst reported so far. For bulky molecules such as 4,6-dimethyldibenzothiophene (DMDBT), it takes only 3 min to remove 500 ppm of DMDBT at 60°C with our catalyst, which is five times faster than that with the current best catalyst. Such a catalyst can be easily upscaled and could be used for concrete industrial application in the ODS of bulky organosulfur compounds with minimized energy consumption and high reaction efficiency.

Synergistic effect of K and Zn on Fe-based catalysts for efficient CO2 hydrogenation.

Excessive emission of CO2 into the atmosphere has severely impacted the global ecological environment. Converting CO2 into valuable chemicals and fuels is of great significance for sustainable development. However, low activity and undesirable selectivity often result from the inherent inertness of CO2. Herein, K- or/and Zn-modified Fe-based catalysts were prepared by an incipient-wetness impregnation method for CO2 hydrogenation via a cascade reaction. The results indicate that K species exist as K2O while Zn species exist as ZnFe2O4. In the CO2 hydrogenation pathway, K2O facilitates the adsorption of CO2 and restrains the adsorption of H2, accelerating the transformation of CO2 into C2-C4 olefins rather than paraffins while Zn species promote the dispersion of Fe species, leading to improved activity. Synergistically, a K- and Zn-modified Fe-based catalyst (2Zn-10K-Fe/Al) shows excellent catalytic CO2 hydrogenation activity, achieving a CO2 conversion of 77% which is 1.8 times that (42%) of the unmodified Fe-based catalyst (Fe/Al). Our catalyst also shows a significantly promoted selectivity to C2-C4 olefins of 17% in comparison with the Fe/Al catalyst (0%). It is envisioned that such a binary effect of elements might contribute to the low-cost and industrial production of Fe-based catalysts for selective CO2 conversion.

Intraparticle ripening to create hierarchically porous Ti-MOF single crystals for deep oxidative desulfurization.

The catalytic oxidative desulfurization (ODS) technique is able to remove sulfur compounds from fuels, conducive to achieving deep desulfurization for the good of the ecological environment. Ti-based metal-organic frameworks (Ti-MOFs) possessing good affinity to organic reactants and considerable numbers of Ti active sites are promising catalysts for ODS. However, current Ti-MOFs suffer from severe diffusion limitations caused by the size mismatch between sole micropores and bulky sulfur compounds, leading to poor ODS performance. Here, a facile method of intraparticle ripening without any additive is developed to obtain hierarchically meso-microporous Ti-MIL-125 single crystals (Meso-Ti-MIL-125) for the first time. Such Meso-Ti-MIL-125 shows a BET surface area of 1401 m2 g-1 and a mesoporous volume that is 1.7 times as high as that of the conventional Ti-MIL-125. Our novel Meso-Ti-MIL-125 exhibits excellent catalytic performance in the ODS of a series of bulky thiophenic sulfur compounds, completely removing benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (DMDBT) from model fuels, which is, respectively, 2.4 times, 1.5 times, and 6.7 times higher than the removal achieved with conventional Ti-MIL-125. Such a facile synthetic strategy is envisioned to be applied in many kinds of crystalline materials, such as zeolites, for industrial production.

Ti-MOF single-crystals featuring an intracrystal macro-microporous hierarchy for catalytic oxidative desulfurization.

For the first time, we demonstrate a Ti-MOF (Ti-metal organic framework) single-crystal featuring an intracrystal macro-microporous hierarchy (Hier-NTU-9) by a vapor-assisted polymer-templated method. This Hier-NTU-9 possesses macropores (100-1000 nm) derived from polymer templates and enhanced transport ability of bulky molecules, exhibiting almost double the desulfurization activity compared to the conventional NTU-9.

[Mechanism of total flavonoid extract from Dracocephalum moldavica on bleomycin-induced pulmonary fibrosis in mice based on pyroptosis pathway].

This study investigated the mechanism of total flavonoid extract from Dracocephalum moldavica(TFDM) in mice with bleomycin(BLM)-induced pulmonary fibrosis(PF) and explored its mechanism against the pyroptosis pathway. A mouse model of PF was established by intratracheal infusion of bleomycin(4 mg·kg~(-1)), and the normal group was treated with the same dose of saline under the same conditions. After the second day of modeling, the distilled water was given to the normal and model groups by gavage, and the corresponding drug were given to the TFDM and the dexamethasone groups for 28 consecutive days. After 28 days, lung tissues of mice with PF were taken to determine the content of hydroxyproline(HYP). The degree of lung inflammation and fibrosis was observed by hematoxylin-eosin(HE) and Masson stainings, and the content of interleukin-18(IL-18) and interleukin-1ß(IL-1ß) in the serum of mice with PF were measured by enzyme-linked immunosorbent assay(ELISA). Western blot was used to determine the expression levels of proteins in the lung tissues of mice with PF. HE staining showed that the BLM group had abnormal lung tissue structures and showed more inflammatory cell infiltration. Masson staining showed plenty of collagenous fibrotic tissues that were stained blue in the lung tissues. As compared with the normal group, the content of HYP and levels of IL-18 and IL-1ß in the serum of rats in the BLM group were up-regulated(P<0.01). The protein expressions of type Ⅰ collagen(Col-1), fibronectin 1(FN1), α-smooth muscle actin(α-SMA), cysteinyl aspartate specific proteinase-1(caspase-1), gasdermin D(GSDMD), NOD-like receptor thermal protein domain associated protein 3(NLRP3), p62, and apoptosis-associated speck-like protein containing a CARD(ASC) in the lung tissues of mice with PF in the BLM group were increased(P<0.01), whereas the protein expressions of autophagy-related 5(ATG5) and Beclin1 were decreased(P<0.01). Compared with the BLM group, the TFDM groups and dexamethasone group showed normal lung tissue structures and reduced inflammatory cell infiltration. Less collagenous fibrous tissues in blue color were seen and the fibrosis in the lung tissue was alleviated in the TFDM groups and dexamethasone group, with the down-regulation of the content of HYP and the levels of IL-18 and IL-1ß(P<0.05, P<0.01). In the TFDM groups and dexamethasone group, the protein expression levels of Col-1, FN1, α-SMA, caspase-1, GSDMD, NLRP3, p62, and ASC were decreased(P<0.01), and the protein expressions of ATG5 and Beclin1 were increased(P<0.01) in the lung tissues of mice with PF. From the above results, it is known that TFDM down-regulates the levels of inflammatory factors and related proteins, and effectively mitigates the process of BLM-induced PF by regulating the pyroptosis pathways and potentially affecting the autophagy.

Boosting molecular diffusion following the generalized Murray's Law by constructing hierarchical zeolites for maximized catalytic activity.

Diffusion is an extremely critical step in zeolite catalysis that determines the catalytic performance, in particular for the conversion of bulky molecules. Introducing interconnected mesopores and macropores into a single microporous zeolite with the rationalized pore size at each level is an effective strategy to suppress the diffusion limitations, but remains highly challenging due to the lack of rational design principles. Herein, we demonstrate the first example of boosting molecular diffusion by constructing hierarchical Murray zeolites with a highly ordered and fully interconnected macro-meso-microporous structure on the basis of the generalized Murray's Law. Such a hierarchical Murray zeolite with a refined quantitative relationship between the pore size at each length scale exhibited 9 and 5 times higher effective diffusion rates, leading to 2.5 and 1.5 times higher catalytic performance in the bulky 1,3,5-triisopropylbenzene cracking reaction than those of microporous ZSM-5 and ZSM-5 nanocrystals, respectively. The concept of hierarchical Murray zeolites with optimized structural features and their design principles could be applied to other catalytic reactions for maximized performance.