Qingruo Xie

Bio: Qingruo Xie is an academic researcher from Guangxi University. The author has contributed to research in topics: Materials science & Carbon fibers. The author has an hindex of 2, co-authored 2 publications receiving 24 citations.

Mechanism of the CO2 storage and in situ hydrogenation to CH4. Temperature and adsorbent loading effects over Ru-CaO/Al2O3 and Ru-Na2CO3/Al2O3 catalysts

Abstract: The use of fossil fuels to satisfy the growing energy demand results in the emission of a huge amount of CO2 to the atmosphere. One alternative to overcome this environmental issue is the CO2 valorization through the storage and in situ hydrogenation to CH4. In this work, Ru-CaO/Al2O3 and Ru-Na2CO3/Al2O3 dual function materials are synthesized with different adsorbent loadings, namely 5, 10 and 15 wt.%. The prepared catalysts are characterized in terms of surface area by N2 adsorption and desorption, crystallinity by XRD, Ru dispersion by H2-chemisorption and TEM, basicity by CO2-TPD and reducibility and oxidation state of the noble metal by H2-TPR and XPS. Temperature programmed surface reaction experiments with H2 on samples with pre-adsorbed CO2 reveal that the decomposition of surface carbonates and the subsequent hydrogenation occurs at lower temperatures for catalysts containing Na2CO3 than CaO. A complete reaction scheme describing the CO2 adsorption and hydrogenation process has been proposed based on the temporal evolution of reactants and products. Oxides (CaO or Na2O) and hydrated oxides (Ca(OH)2 or NaOH) have been identified as CO2 storage sites, the former oxides being more reactive towards the CO2 adsorption. CH4, H2O and minor amounts of CO are detected during the hydrogenation step. The CO2 storage and hydrogenation to CH4 is promoted with increasing the adsorbent loading. Maximum CH4 production of 414 μmol g−1 is observed for Ru15%CaO/Al2O3 at 400 °C. High temperature is needed to efficiently decompose the highly stable carbonates formed onto CaO. On the other hand, the higher Ru dispersion along with a lower stability of carbonates in Ru10%Na2CO3/Al2O3 promotes CH4 formation (383 μmol g−1) at notably lower temperature, i.e. 310 °C. Thus, Ru10%Na2CO3/Al2O3 is regarded as a suitable catalyst for the CO2 storage and in situ hydrogenation to CH4.

Total oxidation of propane over Co3O4-based catalysts: Elucidating the influence of Zr dopant

Abstract: A series of Zr-doped Co3O4 catalysts (x% Zr-Co3O4), prepared by citrate sol-gel method with a low doping amount of zirconium, was applied in the catalytic oxidation of 1000 ppm propane at a weight hourly space velocity of 40,000 mL g−1 h−1. Different techniques were used to characterize the catalysts. The results showed that the physicochemical properties and catalytic performances of the x% Zr-Co3O4 catalysts were significantly influenced by the addition of zirconium. Only a small part of Zr could be doped into the Co3O4 lattice and the spare Zr would prefer to aggregate on the surface to form zirconium oxide. In the x% Zr-Co3O4 catalysts, Zr disordered Co3O4 spinel is formed by entering into the Co3O4 lattice and forming Co-O-Zr species, resulting in smaller Co3O4 crystallite size, larger specific surface area, better low-temperature reducibility, higher surface Co2+ concentration, and higher content of surface oxygen vacancies and active oxygen species. The best performance was achieved on 1% Zr-Co3O4 for propane oxidation, with 90% propane conversion at 241 °C. The most active catalyst showed excellent performance in toluene and propene oxidation as well. Propane reaction tests, carried out without oxygen in the gas stream, indicated the promoting effect of the low amount of Zr on the oxygen mobility of x% Zr-Co3O4 catalysts. Durability tests of propane oxidation showed that stable conversion could be achieved over 1% Zr-Co3O4, thus being a potential active catalyst for practical application.

Titanium Carbide (Ti3C2) MXene as a Promising Co-catalyst for Photocatalytic CO2 Conversion to Energy-Efficient Fuels: A Review

Abstract: Photocatalytic CO2 reduction to produce valuable chemicals and fuels using solar energy provides an appealing route to alleviate global energy and environmental problems. However, available semicon...

A Review on MXene Synthesis, Stability, and Photocatalytic Applications.

Abstract: Photocatalytic water splitting, CO2 reduction, and pollutant degradation have emerged as promising strategies to remedy the existing environmental and energy crises. However, grafting of expensive and less abundant noble-metal cocatalysts on photocatalyst materials is a mandatory practice to achieve enhanced photocatalytic performance owing to the ability of the cocatalysts to extract electrons efficiently from the photocatalyst and enable rapid/enhanced catalytic reaction. Hence, developing highly efficient, inexpensive, and noble-metal-free cocatalysts composed of earth-abundant elements is considered as a noteworthy step toward considering photocatalysis as a more economical strategy. Recently, MXenes (two-dimensional (2D) transition-metal carbides, nitrides, and carbonitrides) have shown huge potential as alternatives for noble-metal cocatalysts. MXenes have several excellent properties, including atomically thin 2D morphology, metallic electrical conductivity, hydrophilic surface, and high specific surface area. In addition, they exhibit Gibbs free energy of intermediate H atom adsorption as close to zero and less than that of a commercial Pt-based cocatalyst, a Fermi level position above the H2 generation potential, and an excellent ability to capture and activate CO2 molecules. Therefore, there is a growing interest in MXene-based photocatalyst materials for various photocatalytic events. In this review, we focus on the recent advances in the synthesis of MXenes with 2D and 0D morphologies, the stability of MXenes, and MXene-based photocatalysts for H2 evolution, CO2 reduction, and pollutant degradation. The existing challenges and the possible future directions to enhance the photocatalytic performance of MXene-based photocatalysts are also discussed.