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Additive introduction based on porous amine-silica hybrid materials is one of the key technologies to enhance the ability of CO2capture. Hence, we first developed a one-step strategy of directly introducing brush-like cetyltrimethylammonium chloride (CTAC) and bis-(γ-triethoxysilylpropyl)-tetrasulfide (BTES) additives into the silica support to prepare micro-mesoporous organosilica nanoparticles with double brush-like additives modified (MMON-D). Then, the amine-functionalized CO2adsorbent (MMON-D-50) was obtained via tetraethylenepentamine impregnation. The adsorbent with double additives exhibited a higher CO2adsorption performance (4.04 mmol/gadsorbentand 0.33 mmol CO2/mmol N under pure CO2and 25 °C conditions) than that of the adsorbents with none or a single additive. Furthermore, spectra analysis, kinetics, and adsorption heats were performed to clarify the adsorption mechanism of the synergistic action of CTAC and BTES. The results revealed that CTAC as a quaternary ammonium formed on the adsorbent surface can facilitate the formation of carbamic acid. Meanwhile, BTES as a swelling agent endows silica support with a large pore size and inhibits the formation of silylpropyl carbamate to enhance CO2adsorption performance. This work supplies a novel surface-modified strategy for developing adsorbents with excellent CO2capture performance, which is of prime importance for both academic interests and practical applications.

As appropriate alternatives to precious metals in volatile organic compound (VOC) combustion, La-based perovskites have attracted increasing attention due to their tunable structure and sintering-resistance capacity. Herein, chemically tailored surface Co-enriched LaCoO3perovskite oxides (LCO) with abundant surface defects were successfully constructed via a facile selective acid-etching method, in which lanthanum located at the A-site was preferentially dissolved and exsolved cobalt opportunely dispersed on the surface of the perovskite. The unique LCO catalysts could enhance the electron transfer and facilitate the activation of oxygen molecules through the interface Co2+/Co3+redox cycles. Among all as-synthesized LCO catalysts, the LCO-20 sample (LaCoO3treated with 1 M HNO3for 20 min) revealed the optimum catalytic performance (T50and T90of 184 and 206 °C at a space velocity of 15 000 mL/(g h) with 1000 ppm toluene, respectively), stability, and durability (5 vol % water). The excellent activity of LCO-20 might be mainly ascribed to the accelerated activation and circulation of the oxygen species initiated by the surface defects and Co2+/Co3+redox cycles.

The selective oxidation of benzyl alcohol to benzaldehyde is currently difficult to achieve with high benzyl alcohol conversion and high benzaldehyde selectivity simultaneously under mild conditions. Herein, the Fe-based catalysts anchored on nitrogen-doped carbon (x-Fe/NC) were prepared by thermal decomposition of the iron-doped zeolitic imidazolate framework precursors (x-Fe-ZIF). Among the various catalysts with different iron contents (x-Fe/NC), the 2-Fe/NC catalyst showed the best balance of conversion and selectivity, achieving 96.0% conversion of benzyl alcohol and around 98.0% selectivity for benzaldehyde. A range of characterization methods combined with kinetic analysis demonstrated that the high catalytic activity was attributed to the formed Fe–Nxactive sites, which can accelerate the adsorption process of reactant molecules, facilitating the oxidation process while minimizing overoxidation to carboxylic acids. Moreover, the 2-Fe/NC catalyst showed excellent recyclability and substrate resistance, indicating its stability and potential for industrial application. This study offers fresh perspectives on the synthesis of effective transition metal-based catalysts and explores their potential applications in organic oxidation reactions.

Controlling the crystal structure and composition of spinel and regulating the redox cycle can effectively improve the catalytic activity of spinel. In this paper, highly dispersed CuMn2O4was synthesized by utilizing the high specific surface area of a porous SiO2carrier and its hydroxyl anchoring effect, and the Cu–Mn ion ratio was adjusted to optimize the Cu–Mn redox cycle. The hydroxyl group anchoring function effectively complexed the Cu–Mn metal ions, ensuring the generation of the CuMn2O4phase. This not only enhanced the dispersion of CuMn2O4but also reduced the appearance of monometallic oxides. The higher proportions of Cu+and Mn4+in the catalysts promoted the appearance of abundant oxygen vacancies and effectively polished oxygen adsorption and activation. High Mn egoccupancy also changed the oxidation activity of spinel by affecting the adsorption of intermediates. This work provides a general strategy for the synthesis of high-activity and stable catalysts.

Alkyltrimethoxysilanes with different chain lengths (trimethoxypropylsilane, trimethoxyoctylsilane, and dodecyltrimethoxysilane) were utilized as mesopore-generating agents to synthesize hierarchical ZSM-5 samples with different amounts of mesoporous volume. The samples were characterized by X-ray powder diffraction, nitrogen adsorption–desorption, scanning electron microscopy, transmission electron microscopy, and CO2-temperature-programmed desorption. With the growth of chain length, the alkyltrimethoxysilanes showed low reactivity and affinity for the surfaces of zeolite precursors due to the increase of hydrophobic character of the alkyl moiety, which resulted in the decrease of mesoporous volume. CO2adsorption behaviors of the samples including adsorption capacity, adsorption kinetics, adsorption selectivity, adsorption thermodynamics, and adsorbent stability were studied. The experimental results indicated that hierarchical ZSM-5 modified by trimethoxypropylsilane exhibited the highest mesopores volume (0.12 cm3·g–1), corresponding to the fastest capture rate (about 2.5 times of conventional ZSM-5) and the highest capture capacity (2.15 mmol·g–1at 25 °C and 100 kPa). Therefore, hierarchical ZSM-5 synthesized by the alkyltrimethoxysilanes with short chain length can generate extra mesopores and active adsorption sites, which provided a new strategy to regulate the structure of ZSM-5 for rapid CO2adsorption.

Solid adsorbents modified with N-containing functional groups have been extensively studied due to their excellent CO2adsorption performance. In this work, an adsorbent was obtained to capture CO2by impregnating polyethylenimine (PEI) into MCM-41 with a reserved template that had different alkyl chain lengths [myristyltrimethylammonium bromide (C14), cetyltrimethylammonium bromide (C16), and stearyltrimethylammonium bromide (C18)]. The thermogravimetric analysis, small-angle X-ray diffraction, N2adsorption–desorption, Fourier transform infrared (FTIR) spectroscopy analysis, and in situ FTIR spectra were employed to study the properties of adsorbents. The results showed that the template had been successfully introduced into the supports in the synthetic process, and the CO2adsorption performance was quite sensitive to the alkyl chain length of the template. Besides, the adsorbent with the template (C16) exhibited the highest CO2adsorption capacity (2.49 mmol/g) and amine utilization rate (0.28 mmol CO2/mmol N) under 25 °C and pure CO2. It is believed that the appropriate alkyl chain length of the template could act as an important role in the enhancement of PEI distribution and decrease the CO2transfer resistance, thereby improving the CO2adsorption capacity.