Nowadays, we face a series of global challenges, including the growing depletion of fossil energy, environmental pollution, and global warming. The replacement of coal, petroleum, and natural gas by secondary energy resources is vital for sustainable development. Hydrogen (H2) energy is considered the ultimate energy in the 21st century because of its diverse sources, cleanliness, low carbon emission, flexibility, and high efficiency. H2 fuel cell vehicles are commonly the end-point application of H2 energy. Owing to their zero carbon emission, they are gradually replacing traditional vehicles powered by fossil fuel. As the H2 fuel cell vehicle industry rapidly develops, H2 fuel supply, especially H2 quality, attracts increasing attention. Compared with H2 for industrial use, the H2 purity requirements for fuel cells are not high. Still, the impurity content is strictly controlled since even a low amount of some impurities may irreversibly damage fuel cells’ performance and running life. This paper reviews different versions of current standards concerning H2 for fuel cell vehicles in China and abroad. Furthermore, we analyze the causes and developing trends for the changes in these standards in detail. On the other hand, according to characteristics of H2 for fuel cell vehicles, standard H2 purification technologies, such as pressure swing adsorption (PSA), membrane separation and metal hydride separation, were analyzed, and the latest research progress was reviewed.

Solvent-free synthetic method was employed for the construction of mesoporous α-MnO2 nanosheets. Benefited from solid interface reaction, the obtained MnO2 nanosheets with large oxygen vacancy exhibit high surface area of up to 339 m 2 /g and mesopore size of 4 nm. The MnO2 nanosheets as a catalyst were applied in NH3-assited selective catalytic reduction (NH3-SCR) of DeNOx at relatively low temperature range. The conversion efficiency could reach 100% under gas hourly space velocity (GHSV) of 700,000 h -1 at 100 o C. To gain insight into the mechanism about NH3-SCR of nitric oxide on the MnO2 nanosheets, temperature-programmed desorption of NH3, density function theory study and in situ diffuse reflectance infrared Fourier transform spectra were carried out, revealing the cooperative effect of catalytic sites on the reduction of nitric oxide.This work provides a strategy for facile preparation of porous catalysts in low-temperature DeNOx.

The adsorption of CO2 on superactivated carbon was measured for the near-critical region, and a comparative study between the excess and the absolute adsorption was presented. The quantity of absolute adsorption was determined based on the principle that it is equal to the excess one if the product of the gas-phase density and the volume of the adsorbed phase can be neglected. However, all isotherms in the ranges of 273−360 K and 0−18 MPa can be satisfactorily modeled by properly accounting for such product. The number of molecular layers in the adsorbed phase was estimated based on the density and volume of the adsorbed phase as evaluated. It was shown that multilayer adsorption is possible for near-critical temperatures but seems impossible if the temperature is fairly far away from the critical. Finally, it was shown that the difference between the absolute and the excess isotherms of CO2 at 273 K could yield about 20% difference in adsorbent characterization.

The equilibrium and dynamic adsorption data of H(2) and D(2) on different micro- and mesoporous adsorbents with orderly structure including 3A, 4A, 5A, Y, and 10X zeolites; carbon CMK-3; silica SBA-15; and so forth were collected. Critical effect of the nanodimension of adsorbents on the adsorption behavior of hydrogen and its isotopes is shown. The highest adsorption capacity was observed at pore size 0.7 nm, but equal or even larger isotope difference in the equilibrium adsorption was observed at larger pore sizes, whereas the largest isotope difference in the dynamic adsorption was observed at 0.5 nm. The adsorption rate of D(2) is larger than that of H(2) in microporous adsorbents, but the sequence could be switched over in mesoporous materials. Linear relationship was observed between the adsorption capacity for hydrogen and the specific surface area of adsorbents although the adsorbents are made of different material, which provides a convincing proof of the monolayer mechanism of hydrogen adsorption. The linear plot for microporous adsorbents has a larger slope than that for mesoporous adsorbents, which is attributed to the stronger adsorption potential in micropores.

We developed a simple and facile one-pot hydrothermal methods for synthesis of GO-dots without the need to use strong concentrated acid and the entire synthetic process only took 90 min.