Siyang Tang

Insight into the synergism between MnO2 and acid sites over Mn–SiO2@TiO2 nano-cups for low-temperature selective catalytic reduction of NO with NH3

The rational synthesis of low-temperature catalysts with high catalytic activity and stability is highly desirable for the selective catalytic reduction of NO with NH3. Here we synthesized a Mn–SiO2/TiO2 nano-cup catalyst via the coating of the mesoporous TiO2 layers on SiO2 spheres and subsequent inlay of MnO2 nanoparticles in the narrow annulus. This catalyst exhibited superior catalytic SCR activities and stability for low-temperature selective catalytic reduction of NO with NH3, with NO conversion of ∼100%, N2 selectivity above 90% at a temperature ∼140 °C. The characterization results, such as BET, XRD, H2-TPR, O2/NH3-TPD and XPS, indicated that this nano-cup structure catalyst possesses high concentration and dispersion of Mn4+ active species, strong chemisorbed O− or O22− species and highly stable MnOX active components over the annular structures of the TiO2 shell and SiO2 sphere, and thus enhanced the low-temperature SCR performance.

Molybdenum Disulfide-Alumina/Nickel-Foam Catalyst with Enhanced Heat Transfer for Syngas Sulfur-Resistant Methanation

Sulfur‐resistant CO methanation by using MoS2‐based catalysts possesses potential to produce synthetic natural gas from the direct use of un‐desulfurized syngas with a low H2/CO ratio in industry. However, hotspots raised in the high exothermic reaction lead to catalyst deactivation and an uncontrollable reactor temperature, both of which hinder industrial applications. A metal‐structured MoS2‐Al2O3/Ni‐foam catalyst with stable MoS2 active species and high heat‐transfer efficiency was synthesized to resist deactivation and to remove the heat of the reaction through a hydrothermal synthesis process. This catalyst exhibited superior activity and stability in the sulfur‐resistant methanation of syngas and has potential applications in highly exothermic and endothermic reactions.

Microwave-assisted seed preparation for producing easily phase-transformed anatase to rutile

Titanium dioxide, as one of the most important optical materials, is usually manufactured by the hydrolysis of titanyl salts, in which the seeds are a key to affect product properties. In the sulfate process, hydrolysis normally leads to anatase which is then converted to rutile in a high-temperature calcination with the help of a crystal transforming agent. In this work, the initial seeds were prepared through microwave heating and then the seeds were introduced to the hydrolysis of dilute titanyl sulfate solution. The results showed that the hydrolysis product had a narrower particle size distribution compared with traditional processes, and it was much more easily converted to rutile product under low-temperature calcination in the absence of a crystal transforming agent. The microwave effects on the seed preparation conditions were evaluated, and the kinetic behavior of the seeds in hydrolysis was also studied.