Steady-state and controlled heating rate methanation of CO2 on Ni/MgO in a bench-scale fixed bed tubular reactor. (January 2018)

• Record Type: Journal Article
• Authors: Baldauf-Sommerbauer, Georg; Lux, Susanne; Aniser, Wolfgang; Bitschnau, Brigitte; Letofsky-Papst, Ilse; Siebenhofer, Matthäus
• Is Part Of: Journal of CO₂ utilization. Volume 23(2018)
• Page Start: 1
• Page End: 9
• Publication Date: 2018-01
• Subjects: AAS atomic absorption spectroscopy -- (EF)TEM (energy filtering) transmission electron microscopy -- FID flame ionization detector -- GC gas chromatography -- HT[Nr] numbered (Nr: 1–3) thermocouple position at reactor wall as specified in Fig. 1 -- ICSD inorganic crystal structure database at FIZ Karlsruhe -- ICP-OES inductively coupled plasma-optical emission spectroscopy -- ID inner diameter (mm) -- IR infrared -- Ni[Nr]-MgO nickel/magnesium oxide catalyst with nickel loading specified in wt.% as [Nr: 11, 17] -- OD outer diameter (mm) -- O(F, Ttar) operation point: one specific combination of feed flow rate and target temperature -- PtG power-to-gas -- RT reactor tube -- sccm standard cubic centimeter per minute (cm3STPmin−1) -- STP standard temperature and pressure 0 °C, 0.1 MPa -- SNG synthetic natural gas -- TC thermocouple casing -- TCD thermal conductivity detector -- T[Nr] numbered (Nr: 1-6) thermocouple position inside the reactor as specified in Fig. 1 -- TOC total organic carbon -- XRD X-ray diffraction; Carbon dioxide -- Hydrogen storage -- Magnesium oxide catalyst -- Methanation -- Nickel catalyst -- Power-to-gas; Carbon dioxide -- Periodicals; Carbon dioxide -- Environmental aspects -- Periodicals; Carbon dioxide mitigation -- Periodicals; Carbon dioxide; Carbon dioxide -- Environmental aspects; Carbon dioxide mitigation; Periodicals; 628.53205
• DOI: 10.1016/j.jcou.2017.10.022
• Languages: English
• ISSNs: 2212-9820

Abstract

Highlights: Preparation of stable Ni/MgO solid solution with cubic lattice. Reactor control for exothermic reaction. Time saving scanning procedure for catalyst performance. Steady-state and long-term methanation performance. Abstract: Chemical hydrogen storage via conversion with carbon dioxide into methane is a promising technology in an energy system that relies on renewable energy resources. Robust heterogeneous catalysts are needed for this reaction to proceed at relevant levels. Ni/MgO is a promising catalyst in terms of activity and stability. Although several microscale catalyst studies exist, there is a lack of knowledge on catalyst performance and reactor control at larger scale for carbon dioxide methanation at ambient pressure and a technically relevant stoichiometric H2 :CO2 (4:1) feed. Two catalysts with a loading of 11 and 17 wt.% nickel were prepared by wet impregnation, producing a Ni/MgO solid solution with a cubic lattice. Controlled increase ('scanning experiment') of the catalyst temperature to 500 °C for the highly exothermic CO2 methanation was compared to steady-state experiments. Scanning and steady-state experiments yield comparable results in terms of carbon dioxide conversion and methane selectivity, whereas scanning experiments lead to considerable time saving. At a moderate temperature of 325 °C and a feed flow consisting of H2 :CO2 :N2 = 4:1:5 at a flow rate of 250 cm 3 STP min −1, CO2 conversion and CH4 selectivity near thermodynamic equilibrium are achievable. The long-term stability of Ni/MgO (17 wt.% Ni) at 330 °C was proven during reactor operation for several days.