Conquering ammonium bisulfate poison over low-temperature NH3-SCR catalysts: A critical review

The urgent need for the treatment of flue gas from non-electric industries has stimulated great interest in developing NH3-SCR (selective catalytic reduction of NO with NH3) catalysts that can work stably at low temperatures (< 300 °C). However, the performance of low-temperature NH3-SCR catalysts is expected to be largely hindered by surface accumulation of ammonium bisulfate (ABS), which inclines to induce significant deactivation of NH3-SCR catalysts due to active sites blocking. As such, how to solve the problem of ABS poisoning becomes a timely research topic. Herein, we focus on the recent progress on controlling ABS deposition/decomposition during the NH3-SCR process for sustainable denitration. The review starts with a brief introduction on physicochemical properties of ABS, then the common methods used for qualitative and quantitative analysis of ABS on catalyst surface are introduced. Afterwards, recent developed strategies on restraining ABS formation and accelerating ABS decomposition are reviewed. Lastly, some suggestions for the future study of ABS poisoning are prospected. We hope that this review can provide helpful guidance for designing NH3-SCR catalysts with great tolerance to ABS poisoning.