Browsing by Author "Ran, Jingyu"

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    Compatibility of NiO/CuO in Ca‐Cu chemical looping for high‐purity H2 production with CO2 capture
    (Wiley, 2018-02-04) Tan, Lili; Qin, Changlei; Zhang, Zhonghui; Ran, Jingyu; Manovic, Vasilije
    Ca‐Cu chemical looping is a novel and promising approach in converting methane into pure H2 following the principle of sorption‐enhanced reforming. Its operational efficiency is largely determined by an appropriate coexistence of Cu‐based oxygen carriers and Ni‐based catalysts. In this work, NiO/CuO composites were synthesized and their catalytic activity for H2 production was measured using a fixed‐bed reactor system equipped with an online gas analyzer. It is reported for the first time that the presence of CuO could hinder the activity of Ni‐based catalysts in H2 production, and experimental results show that the negative effect of CuO is strengthened with increasing CuO content and calcination temperature during sample preparation. With the help of a series of specific test and characterization techniques (SEM‐EDS, BET, XRD, TPR and XPS), interaction rules between NiO and CuO was further investigated and understood, and based on that an action mechanism model was proposed. Furthermore, an arrangement of mixed particles that avoiding the intimate contact of CuO/NiO was suggested and tested, and a superior performance was demonstrated while observing no restrictions of CuO on Ni‐based catalysts in sorption‐enhanced steam‐methane reforming under the conditions of Ca‐Cu chemical looping.
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    Kinetic study and modeling on the regeneration of Li4SiO4-based sorbents for high-temperature CO2 capture
    (Elsevier, 2021-08-06) Chen, Shuzhen; Qin, Changlei; Yuan, Weiyang; Hanak, Dawid P.; Ran, Jingyu
    Li4SiO4 is acknowledged as a promising sorbent candidate in high-temperature CO2 adsorption. However, reaction kinetics for the regeneration process of Li4SiO4, especially its dependence on CO2 pressure is lack of understanding. This work designed and carried out a series of isothermal tests on the regeneration of pure Li4SiO4 and K-Li4SiO4 under CO2 partial pressure of 0–0.5 atm and temperature of 625–725 °C. For the first time, the expression of (Peq − PCO2)n is introduced into the regeneration rate equation so as to reveal its dependence on CO2 pressure. The reaction order (n) is found to grade according to the value of (Peq − PCO2), and the apparent activation energy is calculated as 284.42 kJ•mol−1 and 146.31 kJ•mol−1 for the regeneration of Li4SiO4 and K-Li4SiO4, respectively. Furthermore, this work proposes that power law model with m = 4/3 is the most probable mechanism function for the regeneration of Li4SiO4-based sorbents.
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    Simulation of the calcination of a core-in-shell CuO/CaCO 3 particle for Ca–Cu chemical looping
    (Elsevier, 2016-05-12) Qin, Changlei; Manovic, Vasilije; Ran, Jingyu; Feng, Bo
    The internal heat balance through heat generation due to CuO reduction and its consumption by CaCO3 decomposition makes calcination a critical step in a novel Ca–Cu chemical looping process (CaL–CLC). Thus, the calcination behaviour of composite Ca/Cu particles needs to be well understood, especially taking into account that mismatching of heat generation and consumption in the particles can lead to local superheating, agglomeration and loss of activity due to enhanced sintering. In this work, a composite particle model was developed to study the calcination behaviour within a spherical core-in-shell type of particle containing grains of CuO and CaCO3. Simulation results showed that ambient temperature, shell porosity, particle size, and CaCO3 grain size significantly affected the CuO and CaCO3 reaction processes, while the impact of initial particle temperature and CuO grain size can be ignored in the range of parameters considered in the study. By comparison of different types of particles, it was concluded that the core-in-shell pattern was more advantageous if such particles are being applied in CaL–CLC cycles due to better matching in reaction kinetics resulting in more stable and uniform particle temperature distribution during the calcination stage.