RESUMEN
Zinc molybdate (ZMO) is a safe and effective grafting material for anticorrosion. Herein, we reported the synthesis of ZMO/h-BN with the labyrinth of capillary pores owing to the in situ growth of ZMO on flake hexagonal boron nitride (h-BN) using the hydrothermal method. The special morphological structure provided a tortuous path for aggressive species to the steel substrate, which extended and blocked the transmission of aggressive species, enhancing the physical corrosion barrier performance. In addition, the capillary pores of ZMO contributed to the competitive adsorption of Cl- in an electrolyte and reduced the diffusion of aggressive species, thus further delaying the corrosion process. Moreover, the capture of oxygen by forming a B-O bond with h-BN and the formation of a molybdate passive film are beneficial for the inhibition of cathodic and anodic reactions. As verified by electrochemical impedance spectroscopy (EIS), the anticorrosion performance of ZMO/h-BN coating increased by 49.58% and 130.72% compared with ZMO and epoxy resin (EP) coatings after immersing in a NaCl aqueous solution (3.50 wt%) for 72 h. This coating matrix provides an avenue for molybdate-based corrosion remediation.
RESUMEN
The methanol promoted naphtha catalytic pyrolysis system to obtain light olefins (ethylene and propylene) was studied over Zn-modified high-silicon HZSM-5 (Zn/HZSM-5) catalysts. Compared with the individual naphtha catalytic pyrolysis to light olefins, the addition of methanol remarkably improved the naphtha conversion and the yield of the light olefins. All Zn/HZSM-5 samples were characterized by using a variety of techniques including inductively coupled plasma-optical emission spectrometry (ICP-OES), X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption, NH3-temperature programmed desorption (NH3-TPD), X-ray photoelectron spectroscopy (XPS), pyridine adsorption infrared spectroscopy (Py-IR), and Fourier transform infrared spectroscopy (FT-IR). The performances of the catalysts for methanol promoted naphtha catalytic pyrolysis were evaluated in a fixed-bed reactor. In the methanol promoted naphtha catalytic pyrolysis reaction, the yield of the light olefins was strongly dependent on the reaction conditions and the degree of Zn ion-exchange. Due to the heterogeneous distribution of the protons of high silicon ZSM-5, two types of Lewis acid sites were formed by the interaction of Zn with hydroxyl groups (OH) adsorbed on HZSM-5. The 0.3-Zn/HZSM-5 (0.3 mol L-1 Zn ion-exchange HZSM-5) sample holds a comparatively high light olefin yield of 51.7 wt% possibly because of the moderate density and distribution of the acid sites on the catalyst.