Manganese‐enhanced porous phosphoric acid–based geopolymer templated by carbon for efficient NH₃‐SCR of NO_x

Abstract Geopolymer‐based ceramics as catalysts or catalyst supports have attracted tremendous interests in recent years owing to their low‐cost and zeolite‐like structure characteristics. However, most of the reported works focus on alkaline‐based geopolymers, whereas the catalytic performance of acid based geopolymer has not yet been evaluated. This study aims to investigate the application potential of phosphoric acid–based geopolymer (PAG) for selective catalytic reduction (SCR) of NO x with NH 3 . To this end, the SCR reactivity of PAG and metal oxide (MnO x )‐loaded PAG were evaluated. Moreover, an activated carbon‐based hard template route was proposed for further enhancing the SCR reactivity of the PAG‐based catalyst. The as‐prepared catalyst under the optimal condition exhibited a high NO conversion greater than 85% in a wide temperature range of 250–350°C, which is among the top literature‐reported values, demonstrating its promising application prospect. A systematical X‐ray diffraction, X‐ray photoelectron spectroscopy, field emission scanning electron microscopy, Brunauer–Emmet–Teller, NH 3 ‐temperature‐programed desorption, and H 2 ‐temperature‐programed reduction spectroscopic analyses were also conducted to better understand the structure evolution of PAG under elevated temperature and the SCR catalytic mechanism of the acid‐based geopolymer catalysts. This study would provide valuable information on the potential application prospect of PAG and its modified form for efficient NO x removal.