A dual-bed catalyst system is designed to remove NOx at room temperature, which consists of a microporous spherical activated carbon (SAC) layer and a urea-supported spherical mesoporous carbon (SMC) layer. The SAC layer, with plenty of narrow micropores acting as a nano-cage for NO adsorption, could improve the oxidation of NO into NO2, while the urea-supported SMC layer with large surface area could provide a sufficient channel for gas kinetic diffusion and a high gas/urea interfacial area for efficient NO2 reduction. A high stationary-state NOx conversion of 88% for 70 h is achieved through the dual-bed catalyst system with SAC and 100 wt% urea supported SMC as the catalyst. The selective catalytic reduction (SCR) activity could be improved by increasing the NO and O2 feed concentration, due to the enhanced oxidation of NO to NO2. A low reaction temperature is beneficial for the SCR reaction because of the increased NO adsorption. Moreover, the apparent activation energies are calculated to be −16.8 kJ mol−1 for NO oxidation and 1.18 kJ mol−1 for NO2–urea SCR, respectively. The result reveals that the adsorption of reactants on SAC is of key importance for NO oxidation, while the surface reaction of NO2 with urea could be the crucial step for the SCR reaction.

The catalytic graphitization mechanism of coal-based carbon materials with light rare earth elements was investigated using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, selected-area electron diffraction, and high-resolution transmission electron microscopy. The interface between light rare earth elements and carbon materials was carefully observed, and two routes of rare earth elements catalyzing the carbon materials were found: dissolution–precipitation and carbide formation–decomposition. These two simultaneous processes certainly accelerate the catalytic graphitization of carbon materials, and light rare earth elements exert significant influence on the microstructure and thermal conductivity of graphite. Moreover, by virtue of praseodymium (Pr), it was found that a highly crystallographic orientation of graphite was induced and formed, which was reasonably attributed to the similar arrangements of the planes perpendicular to (001) in both graphite and Pr crystals. The interface between Pr and carbon was found to be an important factor for the orientation of graphite structure.

Carbon nanofiber (CNF) sponges have been prepared though a facile chemical vapor deposition method using C2H4 as carbon source and Ni–Cu alloy as catalyst. The as-prepared CNF sponges are composed of three-dimensional (3D) networks with thick CNFs as the reinforcing rods and thin CNFs as the binding wires that hold CNFs entangled together. Such CNF sponges exhibit controllable bulk density (0.02–0.14 g cm−3) and high porosity (92%–98%) through changing catalyst amount. The CNF sponges display admirable mechanical flexibility with large compressive strain (>90%). The CNF sponges also exhibit super hydrophobicity (contact angle > 153°) and super oleophilicity. The absorption capacities of the CNF sponges for oils can achieve 22–75 times their own weight and can even be controlled by altering their density or porosity. Furthermore, the CNF sponges demonstrate outstanding recyclability by mechanically squeezing. The present work suggests the CNF sponges a widespread potential for applications in the topics regarding environment protection.

Hydrous RuO2 nanoparticles have been uniformly deposited onto nitrogen-enriched mesoporous carbons (NMCs) via a facile hydrothermal method. The nitrogen doping in the carbon framework not only provides reversible pseudocapacitance but also guides uniform deposition of RuO2 nanoparticles. As a result, an extremely high specific capacitance of 1733 F/g per RuO2, comparable to the theoretic capacitance of RuO2, is reached when 4.3 wt % of RuO2·1.25H2O is loaded onto the NMCs. Systematic studies show that either nitrogen-free or excess nitrogen doping result in RuO2 clusters formation and worsen the electrochemical performances. With intermediate nitrogen and RuO2 content (8.1 wt % N, 29.6 wt % of RuO2·1.25H2O), the composites deliver excellent power performance and high specific capacitance (402 F/g) with reversible capacitive response at 500 mV/s. The unique properties of nitrogen in textual, morphological, and electrochemical aspects may also provide further understanding about the effects of nitrogen doping and metal oxide deposition on supercapacitor performance.Keywords: high power performance; hydrothermal method; nitrogen-enriched mesoporous carbon; pseudocapacitor; ruthenium oxide;

Commercially activated carbons are known for their high specific surface areas and low pack densities, thus giving a poor volumetric capacitance for supercapacitors. Here, nonporous pyrolyzed graphite oxides with high pack densities and controllable graphitic structures were prepared through a facile oxidation-heat treatment. XRD, Raman, SEM, and TEM were used to characterize the textural properties and morphologies of these materials. Galvanostatic charge–discharge and cyclic voltammetry revealed that the voltage-driven electrochemical ion intercalation process is, in fact, highly dependent on the graphitic structure. Less graphitized materials with larger interlayer spacings are more easily electrochemically activated, while a more rigid graphitic structure proves to be more difficult. After adequate electrochemical activation, abundant ion-accessible sites were created for charge storage, and the cell-specific capacitance dramatically increased from 3.5 to 23 F/g. The intercalation behaviors of TEA+ and BF4− were separately studied. The results revealed that, due to its smaller anion size, BF4− displayed superior intercalation capability as well as higher specific capacitance on the positively polarized electrode after electrochemical activation. Therefore, through optimizing the graphitic structure and the EA conditions, a high volumetric capacitance can be achieved.

Mesoporous carbon (MC) prepared using colloidal silica templates was used as a support to synthesize TiO2/MC composites using a sol-gel method. The TiO2 content and the crystalline structure of TiO2/MC photocatalysts can be tuned by the precursor composition and calcination temperature, respectively. MC and TiO2/MC composites were characterized by nitrogen adsorption, XRD, TG, SEM, TEM and electron energy dispersive spectroscopy. Results showed that the anatase TiO2 nanoparticles were highly dispersed on the surface of the carbon framework. As-prepared composites exhibited high photocatalytic activities for methyl orange (MO) degradation under UV irradiation, and a synergistic effect of adsorption and photocatalytic degradation was observed. The MO removal rate reached 89% after UV irradiation for 75 min. The kinetics of MO degradation can be well fitted with a first-order reaction model and the largest rate constant observed was 0.015 min−1.

The kinetics and mechanism of selective catalytic reduction (SCR) of NO with urea supported on pitch-based spherical activated carbons (PSACs) were studied at low temperatures. NO oxidation to NO2 catalyzed by the 0.5−0.8 nm micropores in PSACs was found to be the rate-limiting step in urea−SCR reaction, which was confirmed by both the apparent activation energy calculations and the kinetics results of urea−SCR reaction and NO oxidation on PSAC. These two reactions gave very similar negative apparent activation energies (−16.5 kJ/mol for urea−SCR reaction and −15.2 kJ/mol for NO oxidation), indicating that the adsorption of reactants on PSAC is of key importance in these two reactions. Moreover, these two reactions were both approximately first-order with respect to NO and one-half order with respect to O2. It was found that NO3 from the disproportionation of the produced NO2 was quickly reduced by supported urea into N2. After the complete consumption of supported urea, NO2 started to release, and the carbon surface was gradually oxidized by adsorbed NOx species. NO3 was found to be stably adsorbed on the oxidized carbon surface. On the basis of the results obtained, a reaction mechanism of low-temperature urea-SCR reaction on PSAC was proposed and discussed.

Urea as a reducing agent supported on pitch-based spherical activated carbon (PSAC) was studied for NO reduction at low temperatures (30−90 °C). The results showed that PSAC with 8 wt % urea loading exhibited high activity in the selective catalytic reduction (SCR) of NO at 30 °C. The SCR activity decreased markedly when urea loading was increased above 8 wt % due to pore plugging, which restricted the adsorption of gas phase reactants on PSAC, although the NOx removal period was extended. A low reaction temperature was favorable for NO reduction on account of the increased NO adsorption on PSAC. It was found that the SCR activity was improved by increasing NO or O2 concentration in the feed gas, owing to the enhanced NO oxidation by O2 to NO2, which was then reduced by urea to form N2. Increasing space velocity not only decreased the SCR activity but also shortened the NOx removal period. More than 85% NOx conversion for 55 h could be achieved over PSAC with 8 wt % urea loading at 30 °C under the conditions of 500 ppmv NO, 21 vol % O2, and a space velocity of 2000 h−1. Furthermore, PSAC showed a superior hydrodynamic property, and the pressure drop ratio of PSAC to a commercial granule activated carbon with the equivalent particle size was about 35% with the apparent air flow velocity in a range of 0.12∼0.51 m/s.

Mesoporous carbon (MC) with high surface area and large pore volume was synthesized using mesophase pitch as a carbon precursor and nanosized MgO as an additive. The maximum surface area, largest pore volume and highest mesoporous ratio of as-prepared MC were up to 1400 m2/g, 2.8 cm3/g and 89%, respectively. The mesoporous structures (3–40 nm) of MC were directly observed under SEM and TEM. The adsorption capacity and adsorption rate of MC to vitamin B12 (VB), chicken egg white albumin (CEWA) and bovine serum albumin (BSA) were proportional to the mesopore volume and average pore size. MC (PM4-OC) exhibited the maximum adsorption capacity to the typical biomolecules, 486, 140 and 176 mg/g for VB, CEWA and BSA, respectively. In contrast, Maxsorbs (commercial activated carbons) with a surprising surface area gave a very low adsorption to such biomolecules. The research indicates that MC may be potential in the selective adsorption and separation of biomolecules, based on a molecule sieve effect.