a b s t r a c tSorption enhanced CO 2 methanation is a complex process in which the key challenge lies in the combined optimization of the catalyst activity and water adsorption properties of the zeolite support. In the present work, improved nickel-based catalysts with an enhanced water uptake capacity were designed and catalytically investigated. Two different zeolite frameworks were considered as supports for nanostructured Ni, and studied with defined operation parameters. 5Ni/13X shows significantly increased, nearly three-fold higher, operation time in the sorption enhanced CO 2 methanation mode compared to the reference 5Ni/5A, likely due to its higher water sorption capacity. Both catalysts yield comparable CO 2 conversion in conventional CO 2 methanation (without water uptake). Regeneration of the catalysts performance is possible via a drying step between methanation cycles under both reducing and oxidizing atmospheres; however, operation time of 5Ni/13X increases further after drying under air.

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A small heat of reaction limits the efficiency of the catalytic hydrogenation of CO2 to form methanol; an improved efficiency can be achieved by shifting the thermodynamic equilibrium toward the formation of methanol. The exothermic adsorption of the products in sorption catalysts is shown to increase the reaction yield. The sorption catalysts consist of catalytically active Cu particles incorporated into a zeolite, which is known to strongly absorb water. In addition to high reaction yield of methanol, the sorption catalyst reduces CO2 to CO and dimethyl ether. An enhancement factor of up to 400% for CO and 130% for methanol and dimethyl ether at a relatively low pressure of 15 bar is shown. Furthermore, the following relevant parameters for future technical realization are derived: a high catalytic activity and the reversible adsorption of the products at reaction conditions. A key experiment that combines a catalytic reaction and a pressure swing desorption is presented and demonstrates the feasibility of sorption‐enhanced catalysis for efficient energy use in large‐scale reactors.

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