The catalytic reduction of NO with NH₃ (NH₃-SCR) on phosphorus-doped carbon aerogels (P-CAs) was studied in the temperature range of 100–200 °C. The P-CAs were prepared by a one-pot sol–gel method by using phosphoric acid as a phosphorus source followed by carbonization at 600–900 °C. A correlation between catalytic activity and surface P content is observed. The P-CA-800_vac sample obtained via carbonization at 800 °C and vacuum treatment at 380 °C shows the highest NO conversion of 45.6–76.8% at 100–200 °C under a gas hourly space velocity of 500 h⁻¹ for the inlet gas mixture of 500 ppm NO, 500 ppm NH₃ and 5.0 vol% O₂. The coexistence of NH₃ and O₂ is essential for the high conversion of NO on the P-CA carbon catalysts, which can decrease the spillover of NO₂ and N₂O. The main Brønsted acid sites derived from P-doping and contributed by the C–OH group at edges of carbon sheets are beneficial for NH₃ adsorption. In addition, the C₃–PO configuration seems to have the most active sites for favorable adsorption and dissociation of O₂ and facilitates the formation of NO₂. Therefore, the simultaneous presence of acidic groups for NH₃ adsorption and the C₃–PO active sites for NO₂ generation due to the activation of O₂ molecules is likely responsible for the significant increase in the NH₃-SCR activity over the P–CAs. The transformation of C₃–PO to C–O–P functional groups after the reaction is found, which could be assigned to the oxidation of C₃–PO by the dissociated O*, resulting in an apparent decrease of catalytic activity for P-CAs. The C–O–P based functional groups are also active in the NH₃-SCR reaction.

Four activated carbons (ACs) activated by different activation methods from different precursors were heat-treated at 600℃ to decrease surface oxygen functional groups and to separate the effect of pore texture from surface chemistry on their sulfur adsorption performance. The ACs and the heat-treated ones were used as adsorbents for thiophene (T), dibenzothiophene (DBT), and 4,6-dimethyl dibenzothiophene (4,6-DMDBT) for model fuels with or without a competing benzene. The correlations of surface functional groups and pore textures to their adsorption capacities for T, DBT and 4,6-DMDBT were investigated. Results indicated that the heat treatment not only decreased surface oxygen content, but also caused a pore texture modification. The adsorption isotherms can be well fitted by the Langmuir–Freundlich single solute isotherm. The sulfur adsorption capacity of ACs after the treatment for T, DBT, and 4,6-DMDBT has a good linear relationship with the pore volume of pores within 0.536–1.090, 0.536–1.179, and 0.679–1.268 nm, respectively. The decreased percentage of surface oxygen of ACs by the heat treatment is correlated linearly with the decreased percentage of the sulfur adsorption capacity for all the thiophenic compounds. Micropore filling via the π–π interaction is the dominant adsorption mechanism of thiophenic compounds for both the untreated and heat-treated ACs. Surface oxides contribute to the thiophenic adsorption by a cooperative interaction of the π–π interaction and the acid–base interaction between the basic sulfur atom and the acidic carbon atoms linked with oxygen in graphene edges. A flat adsorption is the most possible geometry in the adsorption of thiophenic compounds.

Novel Mn–Ce–Ti–O composite aerogels with large mesopore size were prepared via a one-pot sol–gel method by using propylene oxide as a network gel inducer and ethyl acetoacetate as a complexing agent. The effect of calcination temperature (400, 500, 600, and 700 °C) on the NH₃–selective catalytic reduction (SCR) performance of the obtained Mn–Ce–Ti–O composite aerogels was investigated. The results show that the Mn–Ce–Ti–O catalyst calcined at 600 °C exhibits the highest NH₃–SCR activity and lowest apparent activation energy due to its most abundant Lewis acid sites and best reducibility. The NO conversion of the MCTO-600 catalyst maintains 100% at 200 °C in the presence of 100 ppm SO₂, showing the superior resistance to SO₂ poisoning as compared with the MnO_x–CeO₂–TiO₂ catalysts reported the literature. This should be mainly attributed to its large mesopore sizes with an average pore size of 32 nm and abundant Lewis acid sites. The former fact facilitates the decomposition of NH₄HSO₄, and the latter fact reduces vapor pressure of NH₃. The NH₃–SCR process on the MCTO-600 catalyst follows both the Eley–Rideal (E–R) mechanism and the Langmuir–Hinshelwood (L–H) mechanism.

Boron doped carbon aerogel could increase the number of active sites effectively and enhance NO reduction to N ₂ via NH ₃ -SCR.