Yizhuo Han

Hydroxyapatite (CaHAP) has emerged as an attractive support material for Ni-based dry reforming of methane (DRM) catalysts in recent years, owing to its excellent thermal stability and surface basicity. However, the role of its unique anion and cation exchange capabilities in modulating catalyst activity and stability remains poorly understood. In this work, Ni was loaded onto commercial CaHAP by precipitation-impregnation, with the impregnation duration before precipitation systematically varied to probe ion exchange effects on catalytic performance. The results show that simply altering the impregnation time does not significantly promote ion exchange between Ni2+ and Ca2+. However, with prolonged impregnation, the structural −OH and PO43– in CaHAP are progressively replaced by CO32–. This carbonation process strengthens the metal–support interaction (MSI) and improves Ni dispersion, leading to enhanced CH4 conversion. Meanwhile, the incorporation of CO32– is equivalent to directly implanting chemisorbed CO2 into the support structure, which markedly enhances its adsorption and activation capacity. Under the relatively harsh reaction conditions of T = 700 °C and WHSV = 48,000 mL·gcat–1·h–1, CH4/CO2 = 1:1 without inert gas dilution, the 5NC-6h catalyst with the longest impregnation time achieves the highest CH4 and CO2 conversions (70.3% and 80.6%, respectively), while exhibiting surface deposited carbon with the lowest degree of inertness. This work reveals that prolonged impregnation unexpectedly induces CaHAP carbonation, a straightforward route to synergistically enhance DRM performance.

This review outlines the selective oxidation of small molecules to high value-added oxygenates and highlights the design of multifunctional metal-based catalysts.

The research and development of the green synthesis route of chemicals has become the focus of research in academia and industry. At present, the highly efficient oxidation of ethanol to acetaldehyde over non-precious metal catalysts under mild conditions is most promising, but remains a big challenge. Herein, the Mo–Sn oxide catalyst was designed to successfully realize low-temperature oxidation of ethanol to acetaldehyde, achieving an acetaldehyde selectivity of 89.3%, and ethanol conversion of 58.9% at 190 °C without CO_x formation. From the deep correlation of characterization and activity results, the weakened MoO bond and the enhanced mobility of lattice oxygen play crucial roles in the oxidation of C_α–H in the CH₃CH₂O* at lower temperatures. An optimal Mo/Sn ratio possessing multiple active centers can obviously promote the adsorption and dissociation of ethanol into CH₃CH₂O*. Furthermore, the reduced amount of medium-strong acid inhibited the formation of ethyl acetate as a byproduct.

The properties of supports (such as oxygen vacancies, oxygen species properties, etc.) significantly impact the anti-carbon ability due to their promotional effect on the activation of CO₂ in dry reforming of methane (DRM). Herein, pyrochlore-type La₂Ce₂O₇ compounds prepared using co-precipitation (CP), glycine nitrate combustion (GNC) and sol–gel (S-G) methods, which have highly thermal stability and unique oxygen mobility, are applied as supports to prepare Ni-based catalysts for DRM. The effect of the calcining temperature (500, 600 and 700 °C) on La₂Ce₂O₇(CP) has also been investigated. Based on multi-technique characterizations, it is found that the synthesis method and calcination temperature can influence the particle size of the La₂Ce₂O₇ support. Changes in particle size strongly modulate the pore volume, specific surface area and numbers of surface oxygen vacancies of the La₂Ce₂O₇ support. As a result, the distribution of supported Ni components is affected due to the different metal–support interaction, thereby altering the activity of the catalysts for cracking CH₄. Moreover, the supports’ abilities to adsorb and activate CO₂ are also adjusted accordingly, accelerating the removal of the carbon deposited on the catalysts. Finally, La₂Ce₂O₇(CP 600) with an appropriate particle size exhibits the best catalytic activity and stability in DRM.

Introduction of trace TiO₂ improves the performance of Ti(SO₄)₂/SiO₂ for DME oxidation to DMM.

NASICON material modulated by concomitantly-generated TiP₂O₇ phase shows highly-efficient production of acrylic acid from formaldehyde and acetic acid.

Synthesizing high value-added oxygenated chemicals through the oxidation process is a new and important research direction for high-quality conversion of methanol/DME.

The selectivity of C2 hydrocarbons reached 98.1%, along with the methane conversion of 8.6% over Mo1Sn3 catalyst. The deep oxidation of methane to CO ₂ was significantly inhibited due to the moderately strong basic sites and reactive oxygen species.

The effects of the calcination atmospheres (H₂, N₂, and O₂) on the performance of Ni/ZrO₂ catalysts prepared by the conventional co‐precipitation method for dry reforming of methane (DRM) were investigated in this work. The catalyst calcined in O₂ atmosphere (NZO) showed the highest Ni dispersion (10.99%), followed by the one calcined in N₂ (NZN, 8.14%) and H₂ atmosphere (NZH, 5.97%). Additionally, NZO and NZN exhibited relatively stronger metal‐support interaction than NZH and the incorporated Ni species on NZO and NZN were capable of stabilizing the metastable tetragonal ZrO₂, which possessed more oxygen vacancies and higher oxygen mobility than monoclinic ZrO₂. The evaluation results revealed that the activity of the employed catalysts displayed the following sequence: NZO > NZN > NZH, which was mainly determined by their Ni dispersion. The amount of carbon deposited on NZO (2.2%) was less than that on NZN (5.0%), and the deactivation rate of NZO (0.47% per hour) was slower than that of NZN (0.53% per hour). Due to its low CH₄ conversion and the weak metal‐support interaction, NZH showed the least carbon deposition (1.1%) and the slowest deactivation rate (0.37% per hour) among the representative catalysts.