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A novel idea is proposed to improve the SO2 tolerance of low-temperature selective catalytic reduction (SCR) catalysts by using a RHO zeolite membrane to separate NO from SO2 to reduce the contact between SO2 and the SCR catalysts. RHO zeolite membranes were prepared on a macroporous stainless steel tube. The results from XRD and SEM measurements indicated that the crystals on the surface were pure RHO zeolites and a uniform and continuous layer of RHO zeolite membrane covered the surface of the support. Permeation measurements using different feed gases indicated that the prepared RHO zeolite membrane could effectively separate NO from SO2. A maximum NO/SO2 selectivity of 36.14 was obtained when using NO/SO2/N2 mixtures. The SO2 permeation decreased a lot in the present of water. Surface diffusion and activated diffusion were believed to be the main transport mechanisms of the RHO zeolite membrane.

As a highly toxic element of coal, arsenic (As) is mainly converted into As2O3 vapor during coal combustion. Mineral oxides are effective and abundant sorbents to control As2O3 emissions. In this paper, the characteristics of As2O3 adsorption by mineral oxides were studied in a two-stage reactor, and the density of states, adsorption sites, and adsorption energies for the adsorption reaction were investigated using molecular simulation. The results demonstrate that CaO is an excellent As2O3 sorbent. The As2O3 adsorption effect of CaO, MgO, and Al2O3 was found to become better with increasing temperature within the range of 300–900 °C. The order of As2O3 adsorption at 300–700 °C follows CaO > Fe2O3 > Na2O > MgO > Al2O3 > SiO2, and SiO2 hardly adsorbs any As2O3. At 900 °C, the melting of Na2O and Fe2O3 greatly reduces their As2O3 adsorption capacity. The O atoms in Na2O/CaO/MgO/Al2O3/SiO2 and the Fe atoms in Fe2O3 are the adsorption active sites for As2O3. The order of the calculated adsorption energy follows Fe2O3 > Na2O > CaO > Al2O3 > MgO > SiO2, and the As2O3 adsorption involves chemical adsorption. The adsorption products are Ca3(AsO4)2, FeAsO4, AlAsO4, etc., for which As exists in the form of As3+ and As5+, with As3+ transformed into As5+ with increasing adsorption temperature.