Salt-assisted surface charge driven synthesis of large pores alumina as carbon tolerance support for propane dehydrogenation.

Porous alumina has been widely used as catalytic support for industrial processes. Under carbon emission constraints, developing a low-carbon porous aluminum oxide synthesis method is a long-standing challenge for low-carbon technology. Herein, we report a method involving the only use of elements of the aluminum-containing reactants (e.g. sodium aluminate and aluminum chloride), sodium chloride was introduced as the coagulation electrolyte to adjust the precipitation process. Noticeably, the adjustment of the dosages of NaCl would allow us to tailor the textural properties and surface acidity with a volcanic-type change of the assembled alumina coiled plates. As a result, porous alumina with a specific surface area of 412 m2/g, large pore volume of 1.96 cm3/g, and concentrated pore size distribution at 30 nm was obtained. The function of salt on boehmite colloidal nanoparticles was proven by colloid model calculation, dynamic light scattering, and scanning/transmission electron microscopy. Afterward, the synthesized alumina was loaded with PtSn to prepare catalysts for the propane dehydrogenation reaction. The obtained catalysts were active but showed different deactivation behavior that was related to the coke resistance capability of the support. We figure out the correlation between pore structure and the activity of the PtSn catalysts associated with the maximum conversion of 53 % and minimum deactivation constant occurring at the pore diameter around 30 nm of the porous alumina. This work offers new insight into the synthesis of porous alumina.

Auto-accelerated dehydrogenation of alkane assisted by in-situ formed olefins over boron nitride under aerobic conditions.

Oxidative dehydrogenation (ODH) of alkane over boron nitride (BN) catalyst exhibits high olefin selectivity as well as a small ecological carbon footprint. Here we report an unusual phenomenon that the in-situ formed olefins under reactions are in turn actively accelerating parent alkane conversion over BN by interacting with hydroperoxyl and alkoxyl radicals and generating reactive species which promote oxidation of alkane and olefin formation, through feeding a mixture of alkane and olefin and DFT calculations. The isotope tracer studies reveal the cleavage of C-C bond in propylene when co-existing with propane, directly evidencing the deep-oxidation of olefins occur in the ODH reaction over BN. Furthermore, enhancing the activation of ethane by the in-situ formed olefins from propane is successfully realized at lower temperature by co-feeding alkane mixture strategy. This work unveils the realistic ODH reaction pathway over BN and provides an insight into efficiently producing olefins.

Dual-Wavelength Photoacoustic Computed Tomography with Piezoelectric Ring-Array Transducer for Imaging of Indocyanine Green Liposomes Aggregation in Tumors.

Recently, indocyanine green (ICG), as an FDA-approved dye, has been widely used for phototherapy. It is essential to obtain information on the migration and aggregation of ICG in deep tissues. However, existing fluorescence imaging platforms are not able to obtain the structural information of the tissues. Here, we prepared ICG liposomes (ICG-Lips) and built a dual-wavelength photoacoustic computed tomography (PACT) system with piezoelectric ring-array transducer to image the aggregation of ICG-Lips in tumors to guide phototherapy. Visible 780 nm light excited the photoacoustic (PA) effects of the ICG-Lips and near-infrared 1064 nm light provided the imaging of the surrounding tissues. The aggregation of ICG-Lips within the tumor and the surrounding tissues was visualized by PACT in real time. This work indicates that PACT with piezoelectric ring-array transducer has great potential in the real-time monitoring of in vivo drug distribution.

Plasma Tuning Local Environment of Hexagonal Boron Nitride for Oxidative Dehydrogenation of Propane.

Hexagonal boron nitride (h-BN) has lately received great attention in the oxidative dehydrogenation (ODH) reaction of propane to propylene for its extraordinary olefin selectivity in contrast to metal oxides. However, high crystallinity of commercial h-BN and elusive cognition of active sites hindered the enhancement of utilization efficiency. Herein, four kinds of plasmas (N2 , O2 , H2 , Ar) were accordingly employed to regulate the local chemical environment of h-BN. N2 -treated BN exhibited a remarkable activity, i.e., 26.0 % propane conversion with 89.4 % selectivity toward olefins at 520 °C. Spectroscopy demonstrated that "three-boron center" N-defects in the catalyst played a pivotal role in facilitating the conversion of propane. While the sintering effect of the "BOx " species in O2 -treated BN, led to the suppressed catalytic performance (12.4 % conversion at 520 °C).