Catalysis Communications最新文献

Developing sulfur-tolerant catalysts for industrial application is crucial but yet challenging. Herein, carbon shells are introduced to Pt/CeO₂ to inhibit the deactivation caused by SO₂ for CO oxidation. The chemical properties and catalytic activity indicate that Pt/CeO₂@C effectively sustains the valence state of Pt species and exhibits T₁₀₀ of 180 °C for CO oxidation in the presence of SO₂ and H₂O. This approach provides a new perspective for enhancing the SO₂ tolerance of catalysts for exhaust treatment.

H₂O_2, a powerful oxidant with a vast number of industrial applications, is being synthesized by the energy intensive anthraquinone process. Recently, H₂O₂ has been synthesized using H₂O and O₂ by photocatalysis. Graphitic carbon nitride (g-C₃N₄) is a popular low-cost photocatalyst that is known to produce H₂O₂. However, the properties g-C₃N₄ needs to be tailored to improve the yield of H₂O₂. We discuss such a modification of g-C₃N₄ by alkali metal cation doping. Among the Li⁺, Na⁺ and K⁺ ions, doping of 10 wt% of K⁺ in g-C₃N₄ increase the yield of H₂O₂ (200 μmol g⁻¹ h⁻¹) by 2.5 times as compared un-doped g-C₃N₄ under natural sunlight.

For the first time, the successful synthesis of 4,4-bis(5-methylthiophen-2-yl)pentanoic acid (bisthiophenic acid-methyl; BTA-M) and its alkyl esters (BTAE-M) from levulinic acid (LA) and its esters with 2-Methylthiophene (2-Met) has been achieved, utilizing solid acid catalysts (Amberlyst-15 and Indion-190). Notably, Indion-190, a cost-effective catalyst, demonstrated the formation of BTA-M and bisthiophenic methyl ester-methyl (BTME-M) with 96–98% selectivities and 99% conversion of LA and methyl levulinate under optimized, solvent-free reaction conditions. The recyclability of Indion-190 has been showcased, maintaining good recyclability for the preparation of BTA-M and BTME-M over three reaction cycles, with a slight decrease in the conversion of reactants.

Reed flower-like SmMnO_x and cauliflower-like SmMnO_x-rGO catalysts were successfully synthesized by a coprecipitation-coupled solvothermal method for selective catalytic reduction (SCR) of NO_x. The NO_x conversion of the two catalysts is more than 90% in the temperature range of 75–200 °C, and the N₂ selectivity of SmMnO_x-rGO is above 90%. Moreover, both of them exhibit more than 62% of resistance to H₂O and SO₂ at a very low temperature of 100 °C, much superior than the fluffy spherical SmMnO_x prepared by coprecipitation method. The strong synergy between Mn and Sm endowed by the flower-like structure contributes to a low degree of crystallization, a high ratio of (Mn³⁺+Mn⁴⁺)/Mn, more chemisorbed oxygen species, strong redox ability, and more Lewis acid sites, hence effectively enhancing low-temperature SCR activity and resistance to H₂O and SO_2. In addition, the decreased ratio of Mn⁴⁺/Mn after rGO doping hinders the side reaction of NH₃ oxidation, thus enhancing the N₂ selectivity of rGO-doped SmMnO_x catalyst.

Catalytic valorization of biomass into high energy density fuels plays a vital role in order to achieve future carbon neutrality. Herein, a class of H-MZ-5 catalysts with different mesoporous pore structures and acid site properties were synthesized. Among them, HMZ-5 prepared with tetrapropylammonium bromide (TPABr) and hexadecyltrimethylammonium bromide (CTAB) as templating agents showed the most excellent catalytic activity and selectivity of α-pinene dimerization. Under optimal catalytic conditions, 100% α-pinene was converted with 89.6% selectivity to dimers. The efficient catalytic activity and affordability of the catalysts in this system make it promising for industrial applications.

Furfural is a versatile platform molecule and a model compound to explore the key factors influencing activity and selectivity in heterogeneous catalysis. In this study, Pd and AuPd nanoparticles (average size 3.5–4 nm) were deposited on TiO₂ by sol immobilization method and were evaluated for liquid-phase furfural hydrogenation. Alloying Au and Pd caused a decrease in activity, an enhancement in stability, and a change in selectivity, favouring the complete hydrogenation of furfural over the decarbonylation reaction. These variations in catalytic performance were elucidated by combining in situ attenuated total reflectance infrared spectroscopy and density functional theory studies.

Lignin is an aromatic polymer with prospects for producing high value-added chemicals. In this study, hydrogenolysis of alkaline lignin was carried out at 240 °C for 8 h in a hydrothermal kettle using Ni/xCeO₂-yAl₂O₃ as catalyst and formic acid as hydrogen source. Compared with Ni catalysts supported by single oxides, the results showed that Ni/xCeO₂-yAl₂O₃ composite-supported catalysts exhibited better catalytic depolymerization performance with higher bio-oil yields. Among them, Ni/1CeO₂–3Al₂O₃ exhibited the most outstanding catalytic activity, with a bio-oil yield of 52.77 wt% and a phenolic compound yield of 7.21 wt%.

This study's objective is to examine the potential of the chitosan-supported Ag and Ag₂O nanoparticles on the reduction of CO₂. The transition state of the reduction reaction was systematically calculated using the nudged elastic band and the semi-empirical tight-binding calculations. It is found that the large charge polarization on the Ag and Ag₂O nanoclusters can modulate chitosan's surface reactivity. The formation of the metal hydrates is the rate-determining step for reducing CO₂. The calculated activation energy of the order of 1.5 eV demonstrates that Ag and Ag₂O /chitosan could be used as catalysts for converting to CO₂ formic acid_.

Molybdenum disulfide /reduced Graphene Oxide /Polyaniline nanocomposites (NCs) was prepared via a two-step synthesis procedures involving hydrothermal and in-situ chemical polymerization techniques. The morphological analysis revealed a well-interconnected structure. X-ray diffraction and Raman spectroscopy revealed the effective formation of the nanocomposites, while Ultraviolet-diffuse reflectance spectroscopy demonstrated enhanced visible light absorption. The degradation rates were up to 96.59% for Methylene Blue, 70.24% for Rhodamine Blue, and 46.03% for Methyl Orange under sunlight light irradiation. The antimicrobial activity of the NCs against various strains, including Escherichia coli, Candida Albicans, and Staphylococcus aureus showed that the prepared nanocomposite possesses better effectiveness against Candida Albicans.

Due to the uncontrolled discharge of textile effluents, the extent of reactive dyes in wastewater is rising. Due to their toxicity, efficient removal becomes quite essential. In this report, NiAl layered double hydroxide (LDH) has been prepared using the coprecipitation methodology for the photocatalytic degradation of reactive dyes. The as-prepared materials were characterized by different techniques, such as DRS, XRD, FESEM, HRTEM, and XPS etc. The XRD pattern of the LDH confirms the formation of the rhombohedral (R3m) phase. The FESEM analysis reveals the irregular hexagon-like shape of the prepared LDH. The NiAl LDH has 98(1) and 87(1)% photodegradation efficiencies towards the removal of reactive blue 19 and reactive Red 120, respectively. The control experiments in the presence of different scavengers confirm that hydroxyl radicals and superoxide anions participate in photocatalytic degradation. The HRMS studies confirm the formation of different smaller fragments, thereby providing a deeper insight into the photodegradation mechanism. Moreover, the demineralization efficiency (88.9%) is quite close to the degradation efficiency for reactive blue 19, signifying practically complete demineralization of the pollutants. The recyclability studies ascertain the high stability of the photocatalyst. Therefore, the as-prepared NiAl LDHs can be considered a promising photocatalyst for the removal of reactive dyes from wastewater.