Hydrogen Rich Syngas Production over Ni Catalysts on Mg‐Stabilized Zirconia through Partial Oxidation of Methane: The Role of Magnesium as Stabilizer for Support & Active Sites

The role of 8–14 mol% MgO along with 92–86 mol% ZrO₂ as support for Ni-catalyst is investigated toward partial oxidation of methane (POM). Upon raising the proportion of MgO from 8 to 14 mol%, the physico-chemical properties are modified and catalyst activities toward POM are increased at 600° accordingly. Upon increasing temperature from 600 to 700 °C further, the H₂ yield is increased, whereas the CO₂ yield and H₂/CO ratio are decreased proportionally.

Catalytic conversion of methane in the presence of O₂ into hydrogen-rich syngas is known as partial oxidation of methane (POM). Achieving good H₂ yield with H₂/CO ≈ 3 by using a low amount of Ni-based active sites at a low reaction temperature (600 °C) through POM remains challenging. Herein, magnesia-stabilized zirconia (MSZ) is prepared by the coprecipitation method by varying the amount of Mg from 8 to 14 mol%. Ni supported over MSZ catalysts are investigated for POM reaction and characterized by diffraction techniques, spectroscopic techniques, surface area-porosity, temperature-programed reduction-oxidation, and thermogravimetry. The incorporation of magnesium stabilizes both the support and the active sites. Under the oxidizing environment, the strong interaction of NiO surmounts over moderate interaction. Upon incorporation of 14 mol% Mg into ZrO₂ (14MSZ), the catalyst attains stable support and the largest surface area, where most of the active sites are formed by “NiO under strong interaction”. The catalyst surface is also enriched by Ni, Mg, and lattice oxygen. 5 wt% Ni dispersed over 14MSZ acquires the highest H₂ yield (37%) and H₂/CO ≈ 3 at 600 °C and 85% H₂ yield with ≈ 2 H₂/CO at 750 °C. Over 5Ni/14MSZ catalyst, the high reaction temperature restricts the indirect pathway of POM by limiting the CO₂ yield and ensures high hydrogen yield through the direct pathways of POM.

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