Browsing by Author "Osatiashtiani, Amin"

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    Experimental and DFT study of (sorption-enhanced) steam methane reforming over bimetallic Ni-Cu catalysts
    (Elsevier, 2025-02-01) Wang, Siqi; Shen, Ziqi; Osatiashtiani, Amin; Nabavi, Seyed Ali; Clough, Peter T.
    The catalytic performance of a monometallic Ni/Al2O3 and three bimetallic Ni-Cu catalysts (with Cu loading of 2.5, 5, and 7.5 mol%, respectively) for the (sorption-enhanced) steam methane reforming reaction was evaluated. Physico-chemical characterization of the materials confirmed the formation of Ni-Cu alloy and the even distribution of active metals within the porous high-surface area support. All three bimetallic catalysts showed enhanced methane conversion compared to the conventional Ni/Al2O3 catalyst at higher temperatures (800 °C), which was attributed to the promotion of the water–gas shift reaction by the addition of Cu. The experimental observations were supported by the Density Functional Theory calculations of carbon and oxygen adsorption on the mono and bimetallic surfaces. Ni3Cu1 and Ni1Cu1 were calculated to have a similar level of catalytic activity as Ni, based on results from a microkinetic model of the steam methane reforming reaction. Ni1Cu3 showed slightly lower activity, potentially due to its low carbon adsorption ability which impedes the rate-determining methane decomposition process. The SMR reaction was further improved by adding calcium oxide as the CO2 sorbent, which increased both methane conversion and hydrogen yield. Ni3Cu1/Al2O3 and Ni1Cu1/Al2O3 were identified as promising SMR catalysts with a high methane conversion of approximately 90 % at 800 °C and 97 % at 700 °C, without and with the sorbent, respectively.
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    Formulation, adsorption performance, and mechanical integrity of triamine grafted binder-based mesoporous silica pellets for CO2 capture
    (Elsevier, 2021-07-16) Wadi, Basil; Mahomed, Anisa; Bai, Yang; Osatiashtiani, Amin; Manovic, Vasilije; Nabavi, Seyed Ali
    This work explored formulation of mesoporous silicas pellets using a range of bentonite and colloidal silica (LUDOX), aiming to optimise the binder composition that minimises any deteriorating effects on adsorption performance, while provides an adequate mechanical integrity. Thermogravimetric analysis, scanning electron microscopy, and dynamic mechanical analysis were used to structurally characterise the pellets. Furtherer, CO2 adsorption isotherms of synthesised pellets, pre and post triamine grafting, were measured. Bentonite was found to be an effective single binder that forms mechanically strong pellets and retains up to 85% of CO2 capacity of the base adsorbent. At the presence of LUDOX, hardness of the pellets was lower, caused the largest decrease in CO2 capacity. Formulation with 25% bentonite was found to provide pellets with post triamine functionalisation CO2 capacity equivalent to powder SBA-15, at an amine efficiency of 0.41 mol CO2/mol, while minimising pore blockage and maintaining a compressive strength of 1.5 MPa.
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    Ni-based bimetallic catalysts for hydrogen production via (sorption-enhanced) steam methane reforming
    (Elsevier, 2024-04-15) Wang, Siqi; Shen, Ziqi; Osatiashtiani, Amin; Nabavi, Seyed Ali; Clough, Peter T.
    The catalytic performance of a monometallic Ni/Al2O3 and three bimetallic catalysts (Ni3M1/Al2O3, with M = Cu, Fe, and Ge) for the (sorption-enhanced) steam methane reforming reaction was evaluated. Ni3Cu1/Al2O3 was found to be the optimal catalyst in terms of methane conversion, hydrogen yield, and purity. Ge also has a promoting effect on the monometallic Ni catalyst, whereas the addition of Fe negatively influenced its performance. Physico-chemical characterization of the materials indicated the formation of alloys upon activation of the materials with hydrogen. The addition of Cu increased the surface area and metal dispersion, and improved the overall morphology of the catalyst. The experimental observations were also supported by a numerical study combining Density Functional Theory-based calculations and Microkinetic modelling of the SMR process. Ni3Cu1 and Ni3Ge1 were calculated to have a similar level of catalytic activity as Ni, whereas Ni3Fe1 was unsuitable for the reaction. The SMR reaction was further improved by adding calcium oxide as the CO2 sorbent, which increased methane conversion, CO selectivity, hydrogen yield, and hydrogen purity. The highest methane conversion of 97 % was achieved by Ni/Al2O3 and Ni3Cu1/Al2O3 at 700 °C.